PLC-based Automatic Welding Method, System and Storage Medium for Elbows

Abstract

The present application relates to the field of welding technology, and discloses an automatic elbow welding method, system and storage medium based on PLC. The method divides the elbow into a first and a second bent pipe along the axial direction, determines a first section plane and a first positioning section plane, and takes the point farthest from the first positioning section plane among the intersection points of the first and second section planes on the inner wall of the first bent pipe as the welding origin. The welding torch arcs at the origin and moves along a trajectory parallel to the positioning section plane, changes lanes on the side of the origin far from the second bent pipe, and at the same time clarifies the arc starting and arc stopping rules when the welding torch switches between the inner wall and the end face of the bent pipe. Compared with the traditional segmented welding method that is prone to produce defects at the joints, the present application effectively reduces welding defects, significantly improves the welding quality of the inner wall surfacing of the elbow, enhances welding safety, is convenient for automatic control, improves production efficiency, and optimizes the welding process by accurately positioning the welding origin, standardizing the movement trajectory of the welding torch and the arc starting and stopping operations.

Description

Technical Field

[0001] The present application relates to the field of welding technology, and in particular, to an automatic elbow welding method, system and storage medium based on PLC. Background Art

[0002] A 90-degree elbow is a pipe fitting, usually used to change the flow direction of the fluid in the pipe, so that the fluid makes a 90-degree turn in the pipe.

[0003] In some industries such as chemical engineering, petroleum, and natural gas, the media transported in the pipeline often have corrosiveness. By surfacing corrosion-resistant alloy materials such as stainless steel and nickel-based alloys on the inner wall of the elbow, a dense protective layer can be formed to isolate the contact between the medium and the base metal of the elbow, thereby improving the corrosion resistance of the elbow and extending its service life. For example, in the oil pipeline of an offshore oil production platform, due to the presence of seawater, the pipeline corrosion risk is high, and surfacing corrosion-resistant alloys on the inner wall of the elbow can effectively resist the erosion of corrosive components in seawater and oil.

[0004] The existing traditional welding method for elbow surfacing is usually sectional welding, that is, the 90-degree elbow is divided into 3 sections, each section is 30 degrees, and after surfacing the anticorrosive layer for each section, they are reassembled and welded. This method is prone to welding defects at the joints, affecting the overall welding quality and safety. Summary of the Invention

[0005] In order to improve the welding quality of the inner wall surfacing of the elbow, the present application provides an automatic elbow welding method, system and storage medium based on PLC.

[0006] In the first aspect, the present application provides an automatic elbow welding method based on PLC, adopting the following technical solutions:

[0007] An automatic elbow welding method based on PLC includes the following steps:

[0008] Divide the elbow axially into a first elbow pipe and a second elbow pipe connected in series, and the connection surface between the first elbow pipe and the second elbow pipe is a first section plane;

[0009] Adjust the posture of the elbow so that the cross-section of the middle part of the first elbow pipe is in a horizontal state, and this cross-section is a first positioning cross-section;

[0010] Take the plane where the axis of the elbow is located as the second section plane, take the intersection point of the first section plane and the second section plane on the inner wall of the first elbow pipe, and take the intersection point farthest from the first positioning cross-section as the first welding origin;

[0011] Arc starting is performed at the first welding origin, and the welding torch moves relatively along a trajectory parallel to the first positioning section to perform surfacing on the inner wall of the first elbow pipe; the welding torch is driven to change lanes on the side of the first welding origin away from the second elbow pipe;

[0012] Among them, when the welding torch enters the end face of the first elbow pipe from the inner wall of the first elbow pipe, the arc is stopped, and when the welding torch enters the inner wall of the first elbow pipe from the end face of the first elbow pipe, the arc is started.

[0013] By adopting the above technical solutions, the elbow is axially divided into a series-connected first elbow pipe and second elbow pipe. By determining reasonable welding origins, positioning sections, etc., surfacing is performed on the inner wall of the first elbow pipe, and the timing of arc starting and stopping of the welding torch and the lane-changing position are clarified, reducing defects caused by assembly connection during the welding process and avoiding quality problems prone to occur at the joints of traditional segmented welding. Thereby, the overall welding quality is effectively improved. By adjusting the posture of the elbow to a specific state and determining fixed welding origins, positioning sections, etc., the welding process has clear operation guidelines, which is conducive to the realization of automated welding. Compared with the complex process of traditional segmented welding and then assembly, the operation process of this method is more standardized, orderly, more operable, and also convenient for automated control through PLC. The realization of automated welding reduces cumbersome steps such as manual segmented welding and assembly. At the same time, due to the improvement of welding quality, additional work such as subsequent repair due to welding defects is reduced, thereby improving the overall efficiency of the welding work to a certain extent and shortening the production cycle.

[0014] Optionally, the step of the welding torch moving relatively along a trajectory parallel to the first positioning section includes:

[0015] Driving the first elbow pipe to rotate in a rotation plane parallel to the first positioning section.

[0016] By adopting the above technical solutions, the first elbow pipe rotates in a rotation plane parallel to the first positioning section, enabling the welding torch to perform surfacing on the inner wall of the first elbow pipe relatively evenly. Since the elbow pipe rotates as a whole around the axis, the relative movement speed between the welding torch and each point on the inner wall of the elbow pipe is relatively stable, and there will be no situation where the local surfacing speed is too fast or too slow, thereby ensuring that the thickness of the surfacing layer is uniform and being conducive to improving the quality and protection performance of the surfacing layer.

[0017] Optionally, the step of the welding torch moving relatively along a trajectory parallel to the first positioning section includes:

[0018] Driving the welding torch to rotate, and the rotation plane of the welding torch is parallel to the first positioning section.

[0019] By adopting the above technical solution, the way of the welding torch rotating can more flexibly adapt to the first elbows of different sizes and shapes. Compared with a fixed welding torch, the rotating welding torch can adjust the welding angle and position according to the specific situation of the elbow, and can better complete the surfacing task for some elbows with special specifications or special requirements.

[0020] Optionally, taking the height direction perpendicular to the first positioning section as the Y-axis and marking the height of the first welding origin on the Y-axis as 0, the method further includes the following steps:

[0021] Obtain the specification parameters of the elbow and calculate the end face height;

[0022] Obtain the height data of the welding torch on the Y-axis, judge whether the welding torch needs to close the hole according to the height data, and if it needs to close the hole, calculate the starting arc angle and stopping arc angle for closing the hole;

[0023] Wherein, when the welding torch passes through the stopping arc angle, it changes lanes along the height direction of the Y-axis.

[0024] By adopting the above technical solution, through the automatic control of the hole closing operation during the welding process, the errors of manual judgment and operation are reduced, and the accuracy and consistency of the hole closing operation are ensured. In the case where the hole needs to be closed, accurately controlling the starting arc angle and stopping arc angle for closing the hole helps to ensure the quality of the hole closing, avoid welding defects, and improve the overall performance of the elbow.

[0025] Optionally, the step of the welding torch changing lanes further includes the following sub-steps:

[0026] Calculate the welding arc length of one circle of the welding torch according to the height data of the welding torch on the Y-axis and the specification parameters of the elbow;

[0027] Regulate the lane-changing speed of the welding torch in a positive correlation according to the welding arc length; the larger the welding arc length, the faster the lane-changing speed of the welding torch; the smaller the welding arc length, the slower the lane-changing speed of the welding torch.

[0028] By adopting the above technical solution, when the welding arc length is large, accelerating the lane-changing speed can reduce the welding time and improve the production efficiency; while when the arc length is small, reducing the lane-changing speed can give the welding torch more sufficient time to complete the lane-changing action, ensure the coherence and stability of the welding, and avoid welding defects caused by too fast or too slow lane-changing speed, thereby improving the welding quality.

[0029] Optionally, in the step of the welding torch moving relatively along a trajectory parallel to the first positioning section, the following sub-steps are further included:

[0030] Obtain the height data of the welding torch in real time;

[0031] Calculate the distance value between the welding torch and the first positioning section according to the height data of the welding torch;

[0032] Adjust the welding speed of the welding torch in real time according to the real-time value of the distance value; the smaller the distance value, the faster the welding torch speed; the larger the distance value, the slower the welding torch speed.

[0033] By adopting the above technical solution, when the distance between the welding torch and the first positioning section is close, the welding arc length is approximately a complete circle, and accelerating the welding speed can make full use of the high efficiency of the welding path and shorten the welding duration per unit time; when the distance is far, the welding arc length is fan-shaped, and appropriately reducing the speed can ensure the welding accuracy and quality of the fan-shaped area and avoid uneven distribution of the welding material or welding defects caused by too fast speed. This way of dynamically adjusting the speed according to the shape of the welding arc length not only ensures the welding efficiency but also maintains the stability of the welding quality.

[0034] Optionally, the method further includes the following steps:

[0035] Obtain the historical product quality parameters of N within a set time period before processing;

[0036] Calculate the average value of the N quality parameters;

[0037] Calculate the ratio of the average value to the preset standard quality value as the quality value;

[0038] Adjust the welding speed of the welding torch positively correlated with the quality value. The larger the quality value, the faster the welding speed of the welding torch; the smaller the quality value, the slower the welding speed of the welding torch.

[0039] By adopting the above technical solution, calculating the quality value according to the historical product quality parameters and adjusting the welding speed of the welding torch positively correlated with the quality value can make the welding speed adaptively adjusted according to the previous production situation. If the historical product quality is good, that is, the quality value is large, it means that the current welding process parameters are more appropriate, and the welding speed can be appropriately increased to improve production efficiency; on the contrary, if the historical product quality is not ideal and the quality value is small, the welding speed is reduced so that there is more time to ensure the welding quality, make the welding process more stable, and reduce the generation of defects.

[0040] Optionally, the method further includes the following steps:

[0041] Obtain the height data of the welding torch on the Y-axis, judge whether the first elbow is welded completed according to the height data, and if it is welded completed, turn the elbow;

[0042] Adjust the posture of the elbow so that the cross-section of the middle part of the second elbow is in a horizontal state, and this cross-section is the second positioning section;

[0043] Take the intersection points of the first cutting plane and the second cutting plane on the inner wall of the second elbow, and take the intersection point farthest from the second positioning section as the second welding origin;

[0044] Start arc welding at the second welding origin, and the welding torch moves relatively along a trajectory parallel to the second positioning section to perform surfacing welding on the inner wall of the second elbow; drive the welding torch to change lanes on the side of the second welding origin away from the first elbow;

[0045] Among them, when the welding torch enters the end face of the second elbow from the inner wall of the second elbow, stop arc welding, and when the welding torch enters the inner wall of the second elbow from the end face of the second elbow, start arc welding.

[0046] By adopting the above technical solutions, the second elbow is automatically surfaced welded by the same method, so as to realize the standardization and unity of the welding processes of different parts of the whole elbow, avoid uneven welding quality caused by process differences, and ensure the corrosion resistance and structural strength of the whole elbow.

[0047] In a second aspect, the present application provides an automatic elbow welding system based on a PLC, adopting the following technical solutions:

[0048] An automatic elbow welding system based on a PLC includes a processor, and the processor executes the steps of the automatic elbow welding method based on a PLC as described in any one of the above.

[0049] In a third aspect, the present application provides a storage medium, adopting the following technical solutions:

[0050] A storage medium stores a program, and when the program is executed by a processor, it implements the steps of the automatic elbow welding method based on a PLC as described in any one of the above.

[0051] In summary, the present application includes at least one of the following beneficial technical effects:

[0052] By reasonably dividing the elbow, determining the welding origin and positioning section, etc., welding defects are reduced, and the overall welding quality is improved. At the same time, by various means such as real-time adjusting parameters such as welding speed according to the height of the welding torch, welding arc length, historical quality data, etc., the uniformity and compactness of the surfacing layer are ensured, and the welding quality is further improved. Automated welding reduces cumbersome steps such as manual segmental welding and assembly. By dynamically adjusting the welding speed, the welding time is shortened on the premise of ensuring quality, the additional work for repairing welding defects is reduced, and the overall production efficiency is improved, and the production cycle is shortened. The welding method is applicable to elbows of different specifications and types. Whether it is the first elbow or the second elbow, high-quality automatic surfacing welding can be achieved through the same welding process and rules, enhancing the versatility of the welding process and the adaptability to diversified products. Brief Description of the Drawings

[0053] Figure 1 It is a step diagram of the automatic welding method for elbows based on PLC.

[0054] Figure 2 It is a schematic diagram for showing the welding origin, the first positioning section and the first cutting plane.

[0055] Figure 3 It is a schematic diagram of the surfacing sequence of the elbow.

[0056] Figure 4 It is the welding effect diagram of the inner wall of the elbow.

[0057] Figure 5 It is the welding process flow diagram in the prior art.

[0058] Figure 6 It is the welding effect diagram of the inner wall of the elbow in the prior art. Detailed Embodiments

[0059] The following details the embodiments of the present application, and the examples of the embodiments are shown in the drawings.

[0060] In the description of this specification, the description referring to the terms "certain embodiments", "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the said embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0061] The embodiments of the present application disclose an automatic welding method for elbows based on PLC, referring to Figure 1 , Figure 2 and Figure 3 , including the following steps:

[0062] The elbow is axially symmetrically divided into a series-connected first elbow pipe and a second elbow pipe. Taking a 90° elbow as an example, both the first elbow pipe and the second elbow pipe are 45° elbows. The connection surface between the first elbow pipe and the second elbow pipe is the first cutting plane, that is, the first cutting plane is one of the end faces of the first elbow pipe and the second elbow pipe.

[0063] Adjust the attitude of the elbow so that the cross-section of the middle part of the first elbow pipe is in a horizontal state, and this cross-section is the first positioning section. For the convenience of calculation, the first positioning section is a cross-section symmetric along the axial direction of the first elbow pipe and is in a horizontal state.

[0064] Take the plane where the axis is located inside the elbow as the second cutting plane, and find the intersection points of the first cutting plane and the second cutting plane on the inner wall of the first elbow. The intersection point farthest from the first positioning section is the first welding origin, that is, the lowest position when the first elbow is placed is the first welding origin.

[0065] Arc starting is carried out at the first welding origin, and the welding torch moves relatively along a trajectory parallel to the first positioning section, and surfacing welding is carried out on the inner wall of the first elbow; the welding torch is driven to change lanes on the side of the first welding origin away from the second elbow. Among them, when the welding torch enters the end face of the first elbow from the inner wall of the first elbow, the arc is stopped, and when the welding torch enters the inner wall of the first elbow from the end face of the first elbow, the arc is started. The welding torch starts arc welding from the starting position under the lower fan-shaped surface ( Figure 3 the lower red area in the figure). After welding a full circle, that is, after the turntable rotates 360 degrees in a circle, the welding torch changes lanes from bottom to top along the sliding shoe, and completes Figure 3 the welding of the green area in the figure until it reaches the stopping position on the upper fan-shaped surface ( Figure 3 the upper red area in the figure) of the elbow. The entire equipment is equipped with AVC automatic arc voltage tracking, which can automatically adjust the distance between the tungsten needle and the workpiece according to the surface height.

[0066] Compared with the traditional segmented welding process, through the innovative elbow splitting method, accurate determination of the welding origin and positioning section, and combined with the standardized welding torch operation process, this method significantly reduces the generation of welding defects and greatly improves the welding quality of the surfacing welding on the inner wall of the elbow. Through the standardized operation process and combined with the PLC control system, it not only reduces the difficulty and intensity of manual operation, but also realizes the automatic operation of the welding process. The introduction of the automatic welding mode greatly reduces the cumbersome processes of manual segmented welding and assembly. At the same time, the rework and repair work reduced due to the improvement of welding quality further shortens the production cycle, significantly improves the production efficiency, and provides strong support for the enterprise to reduce production costs and improve economic benefits.

[0067] There are the following two implementation methods for the relative movement of the welding torch along a trajectory parallel to the first positioning section:

[0068] The first one:

[0069] The first elbow is installed at the center of the turntable, and the turntable is driven to rotate in a rotation plane parallel to the first positioning section. The welding torch is located inside the first elbow, and the elbow rotates uniformly around the axis as a whole, which enables the relative movement speed between the welding torch and each point on the inner wall of the elbow to remain stable. The welding torch does not rotate. According to the AVC automatic arc voltage tracking, it can automatically adjust the distance between the tungsten needle and the workpiece according to the surface height. By driving the first elbow to rotate, the thickness of the surfacing layer is ensured to be uniform, so that every part of the entire surfacing layer has good quality and protection performance, can more effectively isolate the contact between the medium and the base metal of the elbow, and improve the corrosion resistance and service life of the elbow.

[0070] The second type:

[0071] The first elbow is fixedly installed, and the welding torch is driven to rotate. The rotation plane of the welding torch is parallel to the first positioning section. Compared with a fixed welding torch that can only weld at a fixed position and angle, the rotating welding torch can freely adjust the welding angle and position according to the specific situation of the elbow. For elbows with special bending radii, the rotating welding torch can adjust the welding angle in real time according to the curve shape of the elbow, so that the welding material can evenly cover the inner wall of the elbow, ensuring the surfacing quality. Therefore, the method of driving the welding torch to rotate can better adapt to first elbows of different sizes and shapes, providing an effective solution for welding various special specifications of elbows.

[0072] Taking the height direction perpendicular to the first positioning section as the Y-axis, marking the height of the first welding origin on the Y-axis as 0, the method further includes the following steps:

[0073] Obtain the specification parameters of the elbow and calculate the end face height; the specification parameters include parameters such as pipe diameter size, wall thickness, and bending radius.

[0074] Obtain the height data of the welding torch on the Y-axis, and judge whether the welding torch needs to close the hole according to the height data. If it is necessary to close the hole, calculate the starting arc angle and stopping arc angle for closing the hole.

[0075] Among them, when the welding torch passes through the stopping arc angle, it changes lanes along the height direction of the Y-axis.

[0076] During the surfacing process on the inner wall of the elbow, "closing the hole" refers to the operation of performing closed welding on a specific area of the inner wall of the elbow (usually near the end face or at a part with a special structure), such as the part in the green horizontal line area in the figure. When the welding torch performs surfacing on the inner wall of the elbow, as the welding process progresses, at the end stage near the end face of the elbow or in some annular welding areas, it is necessary to perform specific welding operations to well connect the starting and ending parts of the weld seam, forming a continuous, closed and gapless welding layer to avoid defects such as gaps and pores.

[0077] The calculation of the starting arc angle and stopping arc angle for closing the hole needs to comprehensively consider various factors such as the geometric shape, size specifications, welding process parameters of the elbow and the current position of the welding torch. Its core goal is to determine the appropriate angular positions for the welding torch to start and end the closed-hole welding to ensure the continuity of the weld seam and the welding quality.

[0078] For a circular weld, its circumference L = 2πR, which is the total length that the welding torch needs to weld. Assuming that the welding torch starts welding from a certain point on the weld and considering the weld circumference as a circumferential angle of 360°, the starting arc angle θ1 can be calculated based on the welding speed and the arc burning time. First, calculate the distance d = v×t that the welding torch moves during the arc burning time. Then, the proportion of the starting arc angle θ1 in the circumferential angle is equal to the proportion of the distance d that the welding torch moves to the weld circumference L, that is, θ1=(L / d)×360°=(v×t / 2πR)×360°. The stopping arc angle θ2 is the angular position of the welding torch when it completes the welding of the entire weld. Since it is closed-hole welding, the angular difference between the stopping arc angle θ2 and the starting arc angle θ1 should be equal to the circumferential angle 360°, so θ2 = θ1 + 360°.

[0079] In the case of needing to close the hole, accurately controlling the starting arc angle and the stopping arc angle for closing the hole plays a crucial role in ensuring the quality of closing the hole. If the starting arc angle for closing the hole is set improperly, it may lead to welding defects such as pores and lack of fusion at the starting point of the weld; and if the stopping arc angle is inaccurate, it may cause problems such as cracks and pits at the end of the weld. By accurately calculating and controlling the starting arc angle and the stopping arc angle for closing the hole, the weld can maintain a good quality state at both the starting and ending positions, avoiding various welding defects.

[0080] The steps of the welding torch changing lanes also include the following sub-steps:

[0081] According to the height data of the welding torch on the Y-axis and the specification parameters of the elbow, the specification parameters include the pipe diameter, wall thickness, bending angle, etc. of the elbow, calculate the welding arc length for the welding torch to go around one circle.

[0082] Regulate the lane-changing speed of the welding torch in a positive correlation according to the welding arc length; the larger the welding arc length, the faster the lane-changing speed of the welding torch; the smaller the welding arc length, the slower the lane-changing speed of the welding torch. The specific lane-changing speed is obtained based on a large amount of empirical data. When in use, the corresponding speed can be directly matched.

[0083] When the welding arc length is large, it means it is in the Figure 3 area of the green line. Accelerating the lane-changing speed can reduce the welding time and improve production efficiency. Continuing with the above example of an elbow with a pipe diameter of 500 mm, when the welding torch is in a position close to the end and the welding arc length is 1500 mm, if the operation is carried out at the conventional lane-changing speed, it will cause the entire welding process to take too long. At this time, by accelerating the lane-changing speed, for example, increasing the original lane-changing speed of moving 100 mm per minute to 150 mm per minute, the lane-changing time can be effectively shortened, thereby reducing the entire welding cycle and improving production efficiency.

[0084] And when the arc length is small, it means it is in the Figure 3In the area of the red line, reducing the lane-changing speed allows the welding torch to have more sufficient time to complete the lane-changing action, ensuring the continuity and stability of welding, avoiding welding defects caused by too fast or too slow lane-changing speed, and thus improving the welding quality. Suppose when the welding torch moves to a position close to the middle of the elbow, after calculation, the welding arc length becomes 800 mm. At this time, if a relatively high lane-changing speed is still maintained, the welding torch may not be able to accurately reach the new welding position, resulting in problems such as discontinuous welds and uneven thickness. By reducing the lane-changing speed, for example, reducing the lane-changing speed to 80 mm per minute, the welding torch has enough time to move smoothly to the new welding position, thus ensuring the continuity and stability of welding and improving the welding quality.

[0085] In the step of the relative movement of the welding torch along a trajectory parallel to the first positioning section, the following sub-steps are further included:

[0086] Obtain the height data of the welding torch in real time;

[0087] Calculate the distance value between the welding torch and the first positioning section according to the height data of the welding torch; assume that the height of the first positioning section is h0 and the real-time height of the welding torch is h, then the distance value d between the welding torch and the first positioning section can be calculated by the formula d = ∣h - h0∣. For example, when the height of the first positioning section h0 = 500 mm and the height of the welding torch h = 520 mm at a certain moment, then the distance value d = ∣520 - 500∣ = 20 mm.

[0088] Adjust the welding speed of the welding torch in real time according to the real-time value of the distance value; the smaller the distance value, the faster the welding torch speed; the larger the distance value, the slower the welding torch speed. The relationship between the welding speed v and the distance value d: v = v max -k×d, where v max is the maximum welding speed of the welding torch, and k is a proportionality coefficient determined according to the actual welding process.

[0089] When the distance between the welding torch and the first positioning section is close, the welding arc length is approximately a complete circle. At this time, increasing the welding speed can make full use of the high efficiency of the welding path and shorten the welding duration per unit time. For example, assume v max = 200 mm / min, k = 5. When the distance value d = 5 mm, according to the formula, the welding speed v = 200 - 5×5 = 175 mm / min. At this speed, the welding torch can quickly complete the welding path of an approximately complete circle, improving the welding efficiency.

[0090] When the distance is far, the welding arc length is fan-shaped. Appropriately reducing the speed can ensure the welding accuracy and quality in the fan-shaped area, and avoid uneven distribution of welding materials or welding defects caused by too high a speed. Continuing with the above parameters as an example, when the distance value d = 20 mm, the welding speed v = 200 - 5×20 = 100 mm / min. The lower welding speed allows the welding torch to have more sufficient time to weld in the fan-shaped area, ensuring that the welding materials can be evenly distributed, avoiding welding defects that may occur due to too high a speed, and thus improving the welding quality.

[0091] The method further includes the following steps:

[0092] Obtain the historical product quality parameters of N within a set time period before processing; the quality parameters cover multiple aspects, such as the width, height, flatness, porosity, hardness, etc. of the weld seam. These parameters can comprehensively reflect the welding quality of the product. The selection of the set time period can be adjusted according to the actual production situation, such as selecting the product data within the past week, month, or a production batch. For example, select the quality parameters such as the weld seam width and porosity of 50 elbows produced in the past month as reference data. During the calculation process, after normalizing multiple quality parameters, a weighted calculation is performed to obtain a comprehensive value as the quality parameter.

[0093] Calculate the average value of the N quality parameters; calculate the ratio of the average value to the preset standard quality value as the quality value. The larger the quality value, the better the quality of the historical products, and the current welding process parameters may be more appropriate. The welding speed can be appropriately increased to improve production efficiency; on the contrary, the smaller the quality value, the less satisfactory the quality of the historical products, and the welding speed needs to be reduced so as to have more time to ensure the welding quality, make the welding process more stable, and reduce the generation of defects.

[0094] Among them, the relationship between the welding speed v and the quality value Q is: v = v0 + k×(Q - 1), where v0 is the initial welding speed and k is an adjustment coefficient determined according to the actual production situation. Assume that the initial welding speed v0 = 150 mm / min and the adjustment coefficient k = 50.

[0095] When the quality value Q = 1.2, it indicates that the quality of the historical products is good. According to the formula, the welding speed v = 150 + 50×(1.2 - 1) = 160 mm / min, which is 10 mm / min higher than the initial speed, thus improving the production efficiency.

[0096] When the quality value Q = 0.8, it indicates that the quality of the historical products is not very satisfactory. At this time, the welding speed v = 150 + 50×(0.8 - 1) = 140 mm / min, which is 10 mm / min lower than the initial speed, providing more time to ensure the welding quality.

[0097] The second elbow is automatically surfacing welded using the same method. The specific method further includes the following steps:

[0098] Obtain the height data of the welding torch on the Y-axis, and determine whether the first elbow is welded completed according to the height data. If the welding is completed, turn the elbow.

[0099] Adjust the attitude of the elbow so that the cross-section of the middle part of the second elbow is in a horizontal state, and this cross-section is the second positioning cross-section.

[0100] Take the intersection points of the first cutting plane and the second cutting plane on the inner wall of the second elbow, and take the intersection point farthest from the second positioning cross-section as the second welding origin.

[0101] Start the arc at the second welding origin, and the welding torch moves relatively along a trajectory parallel to the second positioning cross-section, and surfacing weld the inner wall of the second elbow; drive the welding torch to change lanes on the side of the second welding origin away from the first elbow.

[0102] Among them, when the welding torch enters the end face of the second elbow from the inner wall of the second elbow, stop the arc, and when the welding torch enters the inner wall of the second elbow from the end face of the second elbow, start the arc.

[0103] After welding the second elbow in the same way, the welding processes for different parts of the entire elbow are realized. Refer to Figure 4 the schematic diagram of the completed welding in. Through this method, standardization and unity are achieved, avoiding uneven welding quality caused by process differences, and ensuring the overall corrosion resistance and structural strength of the elbow.

[0104] Refer to Figure 5 , which is the process flow chart of welding in the prior art:

[0105] Preparations before welding:

[0106] 1. Clean the workpiece: Before welding, it is necessary to remove contaminants such as grease, coatings, machining lubricants, and oxide films on the surface of the welded part to ensure clean welding.

[0107] 2. Select appropriate parameters: According to the material and thickness of the elbow, select appropriate welding current, voltage, and argon gas flow rate. Generally, the argon gas purity for stainless steel should be ≥99.7%.

[0108] Welding steps:

[0109] 1. The first stage: Starting from the starting end of the elbow, ignite the arc using an appropriate arc starting method (such as high-frequency arc starting). Control the torch inclination angle between 70° and 85° to ensure the best protection effect. During welding, keep the torch stable and avoid moving too fast to ensure that the molten pool has an appropriate shape and size.

[0110] 2. Second stage: After the first-stage welding is completed, move to the middle part of the elbow for welding. Pay attention to adjusting the torch inclination angle and welding speed to ensure the welding quality. At this time, attention should be paid to the effective isolation of the shielding gas to prevent air from entering the weld.

[0111] 3. Third stage: After completing the second-stage welding, continue to move to the end of the elbow for welding. Keep the same welding parameters and techniques as the previous two stages to ensure the consistent welding quality of the entire elbow.

[0112] Precautions for welding:

[0113] 1. Controlling the molten pool: The shape and size of the molten pool have an important impact on the welding quality. Improper temperature can lead to various welding defects such as hot cracks and undercutting. Therefore, it is necessary to strictly control the welding temperature and the flow rate of the shielding gas.

[0114] 2. Precautions for arc movement: The best shielding effect is achieved when the torch inclination angle is controlled between 70° and 85°. As the moving speed of the torch increases, the shielding gas flow will deviate backward, and a balance needs to be struck between the shielding effect and the welding efficiency.

[0115] Refer to Figure 6 , which is a schematic diagram of the welding effect obtained by using the elbow welding process in the prior art. The main welding step is segmented welding, that is, the 90-degree elbow is divided into 3 segments, each segment is 30 degrees, and after surfacing the anti-corrosion layer on each segment, they are reassembled and welded. This method is prone to welding defects at the joints, affecting the overall welding quality and safety.

[0116] The embodiment of the present application also discloses an automatic elbow welding system based on PLC, including a processor, and the processor executes the steps of the automatic elbow welding method based on PLC as described in any one of the above.

[0117] The embodiment of the present application also discloses a storage medium, in which a program is stored, and when the program is executed by the processor, the steps of the automatic elbow welding method based on PLC as described in any one of the above are implemented.

[0118] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. An automatic elbow welding method based on PLC, characterized in that, The method includes the following steps: Axially divide the elbow into a first elbow pipe and a second elbow pipe connected in series. The connection surface between the first elbow pipe and the second elbow pipe is a first cutting surface; Adjust the posture of the elbow so that the cross-section of the middle part of the first elbow pipe is in a horizontal state, and this cross-section is a first positioning cross-section; Take the plane where the axis is located inside the elbow as a second cutting surface, and find the intersection points of the first cutting surface and the second cutting surface on the inner wall of the first elbow pipe. The intersection point farthest from the first positioning cross-section is the first welding origin; Start arc welding at the first welding origin. The welding torch moves relatively along a trajectory parallel to the first positioning cross-section, and surfacing welding is carried out on the inner wall of the first elbow pipe; Drive the welding torch to change lanes on the side of the first welding origin away from the second elbow pipe; Among them, when the welding torch enters the end face of the first elbow pipe from the inner wall of the first elbow pipe, stop arc welding, and when the welding torch enters the inner wall of the first elbow pipe from the end face of the first elbow pipe, start arc welding.

2. The elbow automatic welding method based on PLC according to claim 1, wherein The step of the welding torch moving relatively along a trajectory parallel to the first positioning cross-section includes: Drive the first elbow pipe to rotate in a rotation plane parallel to the first positioning cross-section.

3. The elbow automatic welding method based on PLC according to claim 1, characterized in that, The step of the welding torch moving relatively along a trajectory parallel to the first positioning cross-section includes: Drive the welding torch to rotate, and the rotation plane of the welding torch is parallel to the first positioning cross-section.

4. The automatic elbow welding method based on PLC according to claim 1, characterized in that, Take the height direction perpendicular to the first positioning cross-section as the Y-axis, and mark the height of the first welding origin on the Y-axis as 0. The method further includes the following steps: Obtain the specification parameters of the elbow and calculate the end face height; Obtain the height data of the welding torch on the Y-axis, and judge whether the welding torch needs to close the hole according to the height data. If it needs to close the hole, calculate the closing arc starting angle and the stopping arc angle; Among them, when the welding torch passes through the stopping arc angle, change lanes in the height direction along the Y-axis.

5. The automatic elbow welding method based on PLC according to claim 4, characterized in that, The step of the welding torch changing lanes further includes the following sub-steps: According to the height data of the welding torch on the Y-axis and the specification parameters of the elbow, calculate the welding arc length for one circle of the welding torch; Regulate the lane-changing speed of the welding torch in a positive correlation according to the welding arc length; the larger the welding arc length, the faster the lane-changing speed of the welding torch; the smaller the welding arc length, the slower the lane-changing speed of the welding torch.

6. The automatic elbow welding method based on PLC according to claim 4, characterized in that, In the step of the welding torch moving relatively along a trajectory parallel to the first positioning cross-section, the following sub-steps are further included: Obtain the height data of the welding torch in real time; Calculate the distance value between the welding torch and the first positioning cross-section according to the height data of the welding torch; Adjust the welding speed of the welding torch in real time according to the distance value; the smaller the distance value, the faster the welding torch speed; the larger the distance value, the slower the welding torch speed.

7. The automatic elbow welding method based on PLC according to claim 1, characterized in that, The method further includes the following steps: Obtain the historical product quality parameters of N within a set time period before processing; Calculate the average value of the N quality parameters; Calculate the ratio of the average value to the preset standard quality value as the quality value; Regulate the welding speed of the welding torch in a positive correlation according to the quality value. The larger the quality value, the faster the welding speed of the welding torch; the smaller the quality value, the slower the welding speed of the welding torch.

8. The automatic elbow welding method based on PLC according to claim 1, characterized in that The method further includes the following steps: Obtain the height data of the welding torch on the Y-axis, and determine whether the first elbow is welded completed according to the height data. If the welding is completed, turn the elbow; Adjust the posture of the elbow so that the cross-section of the middle part of the second elbow is in a horizontal state, and this cross-section is the second positioning cross-section; Take the intersection point of the first cutting plane and the second cutting plane on the inner wall of the second elbow, and take the intersection point farthest from the second positioning cross-section as the second welding origin; Start arc at the second welding origin, the welding torch moves relatively along a trajectory parallel to the second positioning cross-section, and carry out surfacing welding on the inner wall of the second elbow; drive the welding torch to change lanes on the side of the second welding origin away from the first elbow; Among them, stop arc when the welding torch enters the end face of the second elbow from the inner wall of the second elbow, and start arc when the welding torch enters the inner wall of the second elbow from the end face of the second elbow.

9. An automatic elbow welding system based on PLC, characterized in that, It includes a processor, and the processor executes the steps of the PLC-based automatic welding method for elbows according to any one of claims 1-8.

10. A storage medium, characterized in that, A program is stored in the medium, and when the program is executed by the processor, the steps of the PLC-based automatic welding method for elbows according to any one of claims 1-8 are realized.

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