CN118875590A - Multi-layer multi-pass welding planning method, computer equipment and readable storage medium - Google Patents

Abstract

The present invention relates to the field of welding automation technology. The present invention provides a multi-layer multi-pass welding planning method, a computer device and a readable storage medium. The multi-layer multi-pass welding planning method comprises the following steps: S1, a visual recognition system obtains the thickness and characteristic size of a cast steel thick plate, and transmits these data to a process database and a control system; S2, the process database determines the base weld height h ₀ , the filling and cap weld heights _ha and the weld fill area A ₀ based on the thickness and characteristic size of the cast steel thick plate, and transmits these data to the control system; S3, the control system determines the number of welding layers, the number of weld passes and the multi-layer multi-pass welding sequence by combining the equal height and equal area assumptions, the base weld height h ₀ , the filling and cap weld heights _ha and the weld fill area A _0. The multi-layer multi-pass welding planning method of the present invention is applicable to welding of all groove shapes and can achieve continuous improvement of the multi-layer multi-pass welding planning method.

Description

Multi-layer multi-pass welding planning method, computer equipment and readable storage medium

Technical Field

The present invention relates to the technical field of welding automation, and in particular to a multi-layer and multi-pass welding planning method, a computer device and a readable storage medium.

Background Art

The stern shaft frame and rudder arm of large ships use thick steel castings as rigid nodes, and involve welding with the main hull and between cast steels. The thickness of the welded joints between cast steels can reach 50~300mm. Once cracks occur in welding and casting thick plates, it is difficult to stop the cracks. The quality and performance of the welds are important guarantees for equipment safety. Thick plate joints require multi-layer and multi-pass welding filling. This type of weld is labor-intensive and repetitive, and it is difficult to ensure sufficient stability of welding quality, and the production efficiency is low.

Replacing manual welding with multi-pass welding is a general trend for multi-pass welding of thick plate structures of hull structures in the future. However, this technology has not been well applied in the multi-pass welds of ship structures. Specifically, most of the multi-pass equipment in shipyards is in the "teaching-reproduction" automatic welding mode, which cannot automatically correct the welding trajectory or adjust the process parameters according to the on-site conditions, and lacks the ability to perceive and feedback the external environment. Since the position and morphology of the weld will change during the actual welding process, as the welding layer increases, the cumulative error exceeds the work requirements. It is very likely that the welding trajectory will deviate or the welding parameters will not match during the welding process, resulting in welding failure; in addition, each welding needs to be planned through the teaching pendant teaching trajectory, resulting in the teaching time being several times the welding time, and the efficiency is even lower than that of manual welding. Although some multi-pass automatic welding uses the offline programming method without teaching to achieve multi-pass welding of thick plates, it uses the double-sided root cleaning welding method, which is not easy to ensure the performance level of the thick plate weld root.

The patent with publication number CN112276390A in the prior art discloses a multi-layer and multi-pass welding trajectory planning method for thick plates with large grooves. The method first obtains the groove size information of the workpiece to be welded, and determines the welding parameters of the base weld, the filling weld and the cover weld during welding according to the groove angle and the characteristics of the plate; determines the layer height, weld cross-sectional area and weld width of the corresponding base weld layer, the filling weld layer and the cover weld layer according to the welding parameters of the base weld, the filling weld and the cover weld; determines the number of welding layers of the base weld layer, the filling weld layer and the cover weld layer and the number of welding passes for each layer; except for the base weld layer, a symmetrical welding method is adopted when welding each layer of the filling weld layer and the cover weld layer, and at the same time, the last pass of each layer is determined in combination with the number of welding passes, and the weaving welding parameters of the last pass of each layer are determined to perform weaving welding. Although this patent clearly solves the current problems of low welding efficiency and unstable welding quality caused by manual teaching before robot welding; however, this method is only applicable to the welding of V-shaped or Y-shaped grooves, and cannot achieve continuous improvement of multi-layer and multi-pass welding planning methods; in addition, it is not double-sided welding, which is inconsistent with the actual engineering situation, and the welding filling order is from both sides to the middle, which may not be applicable to all multi-layer and multi-pass welding situations.

In view of this, the present invention is proposed.

Summary of the invention

The purpose of the present invention is to propose a multi-layer multi-pass welding planning method, computer equipment and readable storage medium to solve the problem that the prior art is only applicable to V-shaped or Y-shaped groove welding and cannot achieve continuous improvement of the multi-layer multi-pass welding planning method.

To achieve the above object, the technical solution of the present invention is achieved as follows:

A multi-layer multi-pass welding planning method, the multi-layer multi-pass welding planning method is applicable to a cast steel thick plate butt joint robot, the cast steel thick plate butt joint robot comprises a process database, a visual recognition system, a welding system and a control system, the multi-layer multi-pass welding planning method comprises the following steps:

S1. The visual recognition system obtains the thickness and characteristic dimensions of the cast steel plate and transmits these data to the process database and control system;

S2. The process database determines the base weld height h ₀ , the filler and cap weld heights _ha and the weld fill area A ₀ based on the thickness and characteristic dimensions of the cast steel thick plate, and transmits these data to the control system;

S3. The control system determines the number of welding layers, the number of weld passes and the multi-layer and multi-pass welding sequence based on the assumptions of equal height and equal area, the base weld height h ₀ , the filling and cap weld heights _ha and the weld filling area A ₀ .

Furthermore, in step S1, the characteristic dimensions include welding position, groove shape, groove angle, and actual total height _Hfirst of the first welding surface.

Further, step S3 includes the following steps:

S31, weld surface welding plan before root cleaning;

S32, root cleaning;

S33, rear welding surface welding planning;

S34, weld the surface first after root cleaning.

Further, step S31 includes the following steps:

S311, the control system draws the contour lines on both sides of the welding surface and obtains the groove width L _{corresponding} to different heights;

S312, the control system calculates the estimated total number of layers _{nfirst of} the first welding surface filling and covering based on the equal height assumption, the base weld height h ₀ , the filling and covering weld heights h _a , and the actual total height H _{first of} the first welding surface, and the formula is: _nfirst =(H _first -h ₀ )/ _ha ;

S313, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _{nfirst based} on the estimated total number of layers nfirst of the first weld surface filling and cover surface, and then the control system determines the first weld surface filling and cover surface lifting amount _hfirst based on the estimated weld height _hfirst ′ of the first weld surface and the heights of the filling and cover surface welds h _a ;

S314, the control system calculates the height of each weld bead of the first weld surface before root cleaning, and determines the number of welding layers n ₁ of the first weld surface before root cleaning;

S315, the control system calculates the weld filling area A _first of each layer of the weld surface before root cleaning based on the weld height of each layer of the weld surface before root cleaning, the groove width L _first corresponding to different heights, and the groove shape;

S316, the control system determines the number of weld passes _mxian1 of each layer of the first weld surface before root cleaning based on the equal area assumption, _mxian1 = _Axian1 / _A0 ;

S317, the control system determines whether tag=1, if yes, it goes to step S318; if no, it goes directly to step S319;

S318, add a layer of cover, the number of layers is one more than the number of layers of the original cover, and go to step S319;

S319. The control system determines the multi-layer and multi-pass welding sequence of the welding surface before root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side, and welding is carried out to the _n1th layer.

Further, step S33 includes the following steps:

S331, the control system draws the contour lines on both sides of the rear welding surface and obtains the groove width L corresponding _to different heights;

S332, the control system calculates the estimated total number of layers n of the back weld filling and cover based on the equal height assumption, the base weld height h ₀ , the filling and cover weld heights h _a , and the actual total height H _back of the _back weld, and the formula is: n _back = (H _back - _{h 0} ) / h _a ;

S333, the control system calculates the estimated weld height of the _rear weld surface hafter=( _Hafter - _h0 )/ _{nafter based on} the estimated total number of layers nafter of the rear weld surface filling and capping, and then the control system determines the rear weld surface filling and capping lifting amount hafter based on the estimated weld height _hafter , the filling and capping weld heights h _a ;

S334, the control system calculates the height of each weld bead on the rear welding surface;

S335, the control system calculates the weld filling area _A of each layer of the rear weld surface _based on the height of each weld bead of the rear weld surface, the groove width L corresponding to different heights, and the groove shape;

S336, the control system determines the number of weld passes m _after each layer of the rear welding surface based on the equal area assumption, m _after = A _after / A ₀ ;

S337, the control system determines whether tag=1, if yes, it goes to step S338; if no, it goes directly to step S339;

S338, add a layer of cover, the number of layers is one more than the number of layers of the original cover, and go to step S339;

S339. The control system determines the multi-layer and multi-pass welding sequence of the rear welding surface. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side.

Further, step S34 includes the following steps:

S341, the control system determines the number of welding layers of the first welding surface after root cleaning n ₂ =n _first -n ₁ ;

S342, the control system calculates the fill area A of each layer of the weld on the first weld surface after root cleaning ₂ ;

S343, the control system determines the number of weld passes _mxian2 of each layer of the first welding surface after root cleaning based on the equal area assumption, _{where mxian2} = _Axian2 / _A0 ;

S344. The control system determines the multi-layer and multi-pass welding sequence of the first welding surface after root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side.

Further, step S313 includes the following steps:

S3131, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst ;

S3132, the control system determines whether _0.9ha < _hfirst '< _1.1ha , if yes, proceeds to step S3133, if no, proceeds to step S3134;

S3133, first weld surface filling, cover surface lifting amount _hfirst = _hfirst ′, tag=0;

S3134, the control system determines whether h _first ′＜0.9 h _a , if so, it proceeds to step S3135, if not, it proceeds to step S3136;

S3135, first weld surface filling, cover surface lifting amount h _first = h _a , tag = 0;

S3136, fill the weld surface first, and lift the cover surface by the amount h _first = _ha , tag = 1.

Further, step S333 includes the following steps:

S3331, the control system calculates the estimated weld height of the rear weld surface _hhou ′=( _Hhou -h ₀ )/ _nhou ;

S3332, the control system determines whether _0.9ha < _hafter '< _1.1ha , if so, proceeds to step S3333, if not, proceeds to step S3334;

S3333, rear welding surface filling, cover lifting amount _hafter = _hafter ′, tag=0;

S3334, the control system determines whether _hhou ′＜0.9h _a , if so, proceeds to step S3335, if not, proceeds to step S3336;

S3335, after welding surface filling, cover lifting amount h _after = h _a , tag = 0;

S3336, _after welding surface filling, cover surface lifting amount h = _ha , tag = 1.

In a second aspect of the present invention, a computer device is provided, which includes a processor and a memory, wherein the memory stores a computer program, and when the computer program is read and executed by the processor, the steps of any one of the multi-layer and multi-pass welding planning methods are implemented.

According to a third aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is read and executed by a processor, the steps of any one of the multi-layer and multi-pass welding planning methods are implemented.

Compared with the prior art, the multi-layer multi-pass welding planning method, computer device and readable storage medium described in the present invention have the following beneficial effects:

The multi-layer and multi-pass welding planning method, computer equipment and readable storage medium described in the present invention, through the close integration of the visual recognition system and the process database, can, firstly, complete the multi-layer and multi-pass welding process planning of the robot for butt joints of cast steel thick plates, and has a wide range of applications, and is suitable for all groove shapes; secondly, complete the online automatic accumulation of welding process data, and realize the continuous improvement of the multi-layer and multi-pass welding planning method, so that the multi-layer and multi-pass welding planning method has more flexibility and reliability, and can better meet the needs of the digital transformation of ship welding construction; thirdly, it can ensure welding quality and mechanical properties and save manpower and welding costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a process flow of a multi-layer multi-pass welding planning method according to an embodiment of the present invention;

FIG2 is one of the schematic diagrams of the groove structure of a multi-layer multi-pass welding planning method according to an embodiment of the present invention;

FIG3 is a second flow chart of a multi-layer multi-pass welding planning method according to an embodiment of the present invention;

FIG4 is a second schematic diagram of a groove structure of a multi-layer multi-pass welding planning method according to an embodiment of the present invention;

FIG5 is a third schematic diagram of a groove structure of a multi-layer multi-pass welding planning method according to an embodiment of the present invention;

FIG6 is a fourth schematic diagram of a groove structure of a multi-layer multi-pass welding planning method according to an embodiment of the present invention;

FIG. 7 is a physical picture of welding a butt joint of a cast steel thick plate using a multi-layer and multi-pass welding planning method described in an embodiment of the present invention.

DETAILED DESCRIPTION

It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

Aiming at the future demand for automated welding of ship structures, the present invention takes the X-shaped groove and U-shaped groove of ZG230-450H thick plate flat butt joint and vertical butt joint as the object, and develops a multi-layer multi-pass trajectory planning method for welding robots: firstly, based on the historical records of manual welding process, the characteristic dimension measurement data and offset of the welding joint are determined; then, combined with the equal height and equal area assumptions, the number of welding layers and passes corresponding to the process parameters are determined; finally, the multi-layer multi-pass welding sequence is determined. On this basis, it is integrated with computer equipment and storage media.

The purpose of the present invention is to address the problems faced by multi-layer and multi-pass automatic welding of thick plate structures of marine steel castings, and to develop a multi-layer and multi-pass automatic welding planning method suitable for thick plate large grooves of steel castings, as well as its calculation and storage medium. It has the characteristics of wide application range, simple application, guaranteed welding quality and mechanical properties, and saving manpower and welding costs. And connected with the process database, it can realize the continuous improvement of the automatic welding planning scheme, which can better meet the needs of digital transformation of ship welding construction.

The main method flow of this application is shown in Figure 1.

Specifically, first, based on the welding data accumulated from actual products or welding process tests, the weld heights of multi-layer and multi-pass welding base, filling and capping welds under typical process parameters are estimated, and the number of multi-layer and multi-pass welding layers of the first weld surface is determined based on the weld heights. Subsequently, the planned heights of the filling and capping welds of the first weld surface are determined through the equal height assumption, and the cumulative errors in subsequent welding processes are estimated. The total area of each layer of weld is given based on the height of each layer of weld on the first weld surface, and the number of welds on each layer of weld is determined based on the equal area assumption.

In particular, for the rear welding surface, it is necessary to fill the side groove of the welding surface with 1/4~3/4 before cleaning the weld root. The weld root is cleaned using a CNC boring machine with a root cleaning amount of 5~15mm. After cleaning, it is necessary to re-scan and plan the weld beads for both sides of the groove according to the above steps.

The welding sequence is determined based on finite element analysis and processability tests. The process data and weld feature size data of the multi-layer and multi-pass welding process of the joint are simultaneously updated to the welding process database. Thus, a robot multi-layer and multi-pass welding planning method for cast steel thick plate butt joints based on process data is established.

As shown in Figures 1 to 7, the present invention proposes a multi-layer and multi-pass welding planning method, which is suitable for a cast steel thick plate butt joint robot. The cast steel thick plate butt joint robot includes a process database, a visual recognition system, a welding system and a control system. The process database, the visual recognition system and the welding system are all connected to the control system, and the visual recognition system is connected to the process database.

The multi-layer multi-pass welding planning method comprises the following steps:

S1. The visual recognition system obtains the thickness and characteristic dimensions of the cast steel plate and transmits these data to the process database and control system;

The visual recognition system improves the accuracy and real-time performance of data acquisition and reduces the errors and time costs of manual measurement.

Wherein, the thickness of the cast steel thick plate is 50~300mm;

S2. The process database determines the base weld height h ₀ , the filler and cap weld heights _ha and the weld fill area A ₀ based on the thickness and characteristic dimensions of the cast steel thick plate, and transmits these data to the control system;

The process database can obtain welding parameters such as different base weld heights h ₀ , filling and cap weld heights _ha and weld fill area A ₀ according to different cast steel plate thicknesses and characteristic dimensions, and provide the most optimized parameter configuration for each welding.

S3. The control system determines the number of welding layers, the number of weld passes and the multi-layer and multi-pass welding sequence based on the assumptions of equal height and equal area, the base weld height h ₀ , the filling and cap weld heights _ha and the weld filling area A ₀ .

When planning the welding path, the control system adopts the equal height and equal area assumptions, that is, it assumes that the filling height of each layer of weld is basically the same and the total filling area meets the weld requirements. This assumption simplifies the calculation process and ensures the uniformity of welding quality. A reasonable welding sequence can reduce welding deformation and residual stress and improve the mechanical properties and appearance quality of the welded joint.

Specifically, in step S1, the characteristic dimensions include welding position, groove shape, groove angle, and actual total height _Hfirst of the first welding surface.

Specifically, step S3 includes the following steps:

S31, weld surface welding plan before root cleaning;

S32, root cleaning;

S33, rear welding surface welding planning;

S34, weld the surface first after root cleaning.

In step S3, steps S31 to S34 are interrelated and inseparable. The multi-layer and multi-pass welding planning method described in the present invention is double-sided welding, which is consistent with the actual engineering situation. The method of alternating welding the first welding surface and the rear welding surface can suppress deformation during welding, because alternating welding can balance welding stress and reduce bending or distortion caused by single-sided welding; root cleaning can improve welding quality, and by removing impurities, oxides and unfused parts at the root of the weld, the firmness and sealing of subsequent welding can be ensured.

Specifically, step S31 includes the following steps:

S311. The control system draws the contour lines on both sides of the welding surface and obtains the groove width L _{corresponding} to different heights; this is to accurately understand the shape and size of the welding surface for subsequent calculations.

S312, the control system calculates the estimated total number of layers _{nfirst of} the first welding surface filling and covering based on the equal height assumption, the base weld height h ₀ , the filling and covering weld heights h _a , and the actual total height H _{first of} the first welding surface, and the formula is: _nfirst =(H _first -h ₀ )/ _ha ;

S313, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _{nfirst based} on the estimated total number of layers nfirst of the first weld surface filling and cover surface, and then the control system determines the first weld surface filling and cover surface lifting amount _hfirst based on the estimated weld height _hfirst ′ of the first weld surface and the heights of the filling and cover surface welds h _a ;

S314, the control system calculates the height of each weld bead of the weld surface before root cleaning as 1/4H _first to 3/4H _first , and determines the number of welding layers n ₁ of the weld surface before root cleaning;

S315, the control system calculates the weld filling area A _first of each layer of the weld surface before root cleaning based on the weld height of each layer of the weld surface before root cleaning, the groove width L _first corresponding to different heights, and the groove shape;

S316, the control system determines the number of weld passes _mxian1 of each layer of the first weld surface before root cleaning based on the equal area assumption, _mxian1 = _Axian1 / _A0 ;

S317, the control system determines whether tag=1, if yes, it goes to step S318; if no, it goes directly to step S319;

S318, add a layer of cover, the number of layers is one more than the number of layers of the original cover, and go to step S319;

S319. The control system determines the multi-layer and multi-pass welding sequence of the welding surface before root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side, and welding is carried out to the _n1th layer.

In step S319, different welding methods and welding sequences can be adopted according to different welding positions to ensure welding quality and welding efficiency.

Steps S311 to S319 are interrelated and inseparable. The entire process ensures the accuracy and efficiency of the welding process of welding the surface before root cleaning through precise calculation and planning.

In step S32, the root clearing amount is 4 to 15 mm.

Specifically, step S33 includes the following steps:

S331, the control system draws the contour lines on both sides of the rear welding surface and obtains the groove width L corresponding _to different heights;

S332, the control system calculates the estimated total number of layers n of the back weld filling and cover based on the equal height assumption, the base weld height h ₀ , the filling and cover weld heights h _a , and the actual total height H _back of the _back weld, and the formula is: n _back = (H _back - _{h 0} ) / h _a ;

S333, the control system calculates the estimated weld height of the _rear weld surface hafter=( _Hafter - _h0 )/ _{nafter based on} the estimated total number of layers nafter of the rear weld surface filling and capping, and then the control system determines the rear weld surface filling and capping lifting amount hafter based on the estimated weld height _hafter , the filling and capping weld heights h _a ;

S334, the control system calculates the height of each weld bead on the rear welding surface;

S335, the control system calculates the weld filling area _A of each layer of the rear weld surface based on the height of each weld bead of the rear weld surface, the groove width _L corresponding to different heights, and the groove shape;

S336, the control system determines the number of weld passes m _after each layer of the rear welding surface based on the equal area assumption, m _after = A _after / A ₀ ;

S337, the control system determines whether tag=1, if yes, it goes to step S338; if no, it goes directly to step S339;

S338, add a layer of cover, the number of layers is one more than the number of layers of the original cover, and go to step S339;

S339. The control system determines the multi-layer and multi-pass welding sequence of the rear welding surface. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side.

In step S339, different welding methods and welding sequences can be adopted according to different welding positions to ensure welding quality and welding efficiency.

Steps S331 to S339 are interrelated and inseparable, and the entire process ensures the accuracy and efficiency of the rear welding process through precise calculation and planning.

Specifically, step S34 includes the following steps:

S341, the control system determines the number of welding layers of the first welding surface after root cleaning n ₂ =n _first -n ₁ ;

S342, the control system calculates the fill area A of each layer of the weld on the first weld surface after root cleaning ₂ ;

S343, the control system determines the number of weld passes _mxian2 of each layer of the first welding surface after root cleaning based on the equal area assumption, _{where mxian2} = _Axian2 / _A0 ;

S344. The control system determines the multi-layer and multi-pass welding sequence of the first welding surface after root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side.

In step S344, different welding methods and welding sequences can be adopted according to different welding positions to ensure welding quality and welding efficiency.

Steps S341 to S344 are interrelated and inseparable. The entire process ensures the accuracy and efficiency of the welding process of welding the surface first after root cleaning through precise calculation and planning.

Specifically, step S313 includes the following steps:

S3131, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst ;

S3132, the control system determines whether _0.9ha < _hfirst '< _1.1ha , if yes, proceeds to step S3133, if no, proceeds to step S3134;

S3133, first weld surface filling, cover surface lifting amount _hfirst = _hfirst ′, tag=0;

S3134, the control system determines whether h _first ′＜0.9 h _a , if so, it proceeds to step S3135, if not, it proceeds to step S3136;

S3135, first weld surface filling, cover surface lifting amount h _first = h _a , tag = 0;

S3136, fill the weld surface first, and lift the cover surface by the amount h _first = _ha , tag = 1.

Steps S3131 to S3136 are interrelated and inseparable. Through precise calculation and condition judgment, the weld height of the first weld surface is ensured to be neither too high nor too low, and to be kept within a reasonable range, thereby ensuring the welding quality and structural stability. The tag setting may be used for subsequent detection, analysis or adjustment to enable more precise control and management of the welding process.

Alternatively, step S313 includes the following steps:

S3131, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst ;

S3132, the control system determines whether _{nfirst*| hfirst′} - _ha |/ _hfirst ′＜40%, if so, proceeds to step S3133, if not, proceeds to step S3134;

S3133, first weld surface filling, cover surface lifting amount _hfirst = _hfirst ′, tag=0;

S3134, the control system determines whether _hxian '< _ha , if so, it proceeds to step S3135, if not, it proceeds to step S3136;

S3135, fill the weld surface first, and the lifting amount of the cover surface h _first = h _a , tag = 0, or fill the weld surface first, and the lifting amount of the cover surface h _first = h _first ′, tag = 1;

S3136, fill the weld surface first, and lift the cover surface by the amount h _first = _ha , tag = 1.

Specifically, step S333 includes the following steps:

S3331, the control system calculates the estimated weld height of the rear weld surface _hhou ′=( _Hhou -h ₀ )/ _nhou ;

S3332, the control system determines whether _0.9ha < _hafter '< _1.1ha , if so, proceeds to step S3333, if not, proceeds to step S3334;

S3333, rear welding surface filling, cover lifting amount _hafter = _hafter ′, tag=0;

S3334, the control system determines whether _hhou ′＜0.9h _a , if so, it proceeds to step S3335, if not, it proceeds to step S3336;

S3335, after welding surface filling, cover lifting amount h _after = h _a , tag = 0;

S3336, _after welding surface filling, cover surface lifting amount h = _ha , tag = 1.

Alternatively, step S333 includes the following steps:

S3331, the control system calculates the estimated weld height of the rear weld surface _hhou ′=( _Hhou -h ₀ )/ _nhou ;

S3332, the control system determines whether n_后*| h_后′-h _a |/h_后′＜40%, if so, proceeds to step S3333, if not, proceeds to step S3334;

S3333, rear welding surface filling, cover lifting amount _hafter = _hafter ′, tag=0;

S3334, the control system determines whether _hhou ′＜ _ha , if so, it proceeds to step S3335, if not, it proceeds to step S3336;

S3335, after welding surface filling, cover surface lifting amount h _after = h _a , tag = 0, or after welding surface filling, cover surface lifting amount h _after = h _after ′, tag = 1;

S3336, _after welding surface filling, cover surface lifting amount h = _ha , tag = 1.

Steps S3331 to S3336 are interrelated and inseparable. Through precise calculation and condition judgment, the weld height of the rear weld surface is ensured to be neither too high nor too low, and to be kept within a reasonable range, thereby ensuring the welding quality and structural stability. The tag setting may be used for subsequent detection, analysis or adjustment to enable more precise control and management of the welding process.

Example 1

This embodiment proposes a multi-layer and multi-pass welding planning method. In this embodiment, the multi-layer and multi-pass welding planning method is applicable to a cast steel thick plate butt joint robot. The cast steel thick plate butt joint robot includes a process database, a visual recognition system, a welding system and a control system. The process database, the visual recognition system and the welding system are all connected to the control system, and the visual recognition system is connected to the process database.

The multi-layer multi-pass welding planning method comprises the following steps:

S1. The visual recognition system obtains the thickness and characteristic dimensions of the cast steel plate and transmits these data to the process database and control system;

In step S1 , the characteristic dimensions include welding position, groove shape, groove angle and actual total height H of the groove.

In this embodiment, as shown in FIG. 2 , the thickness T of the cast steel thick plate is 50 mm, the welding position is vertical butt joint, the groove shape is an X-shaped groove, the groove angles θ1=75°, θ2=30°, and the actual total height _Hfirst of the first weld surface is 30 mm.

Among them, the height of the rear weld surface is 29mm, the blunt edge is 1mm, the height of the rear weld surface is 20mm; the groove is symmetrical about the Y axis. The actual total height H of the first weld surface _is 30mm.

S2. The process database determines the base weld height h ₀ , the filler and cap weld heights _ha and the weld fill area A ₀ based on the thickness and characteristic dimensions of the cast steel thick plate, and transmits these data to the control system;

Specifically, in this embodiment, in step S2, the obtained butt joint bottom weld height _h0 is 6 mm; the butt joint filling and cover weld heights _ha are 4.3 mm; and the obtained butt joint determined weld filling area _A0 is 38.68 mm ² .

It should be noted that the above values are merely averages based on historical data.

S3, the control system determines the number of welding layers, the number of weld passes and the multi-layer and multi-pass welding sequence by combining the equal height and equal area assumptions, the base weld height h ₀ , the fill and cover weld heights h _a and the weld fill area A ₀ ;

Step S3 includes the following steps:

S31, weld surface welding plan before root cleaning;

S32, root cleaning;

S33, rear welding surface welding planning;

S34, weld the surface first after root cleaning.

In this implementation, specifically, step S31 includes the following steps:

S311, the control system draws the contour lines on both sides of the welding surface and obtains the groove width L _{corresponding} to different heights;

S312. The control system calculates the estimated total number of filling and covering layers _nfirst for the first weld surface based on the equal height assumption, the base weld height _h0 , the filling and capping weld heights _ha , and the actual total height Hfirst of the _first weld surface. The formula is: _nfirst = ( _Hfirst - _h0 )/ _ha = (30-6)/4.3 = 5.58, rounded to the nearest integer _nfirst = 6; to fill the first weld surface, a total of 6 layers of filling + capping are required (excluding the base weld. In the equal area assumption, the characteristic dimensions of the filling and capping welds are the same).

S313, the control system calculates the estimated weld height of the first weld surface _hfirst =( _Hfirst - _h0 )/ _nfirst =(30-6)/6=4mm based on the estimated total number of layers of the _first weld surface filling and cover surface _nfirst , and determines the first weld surface filling and cover surface lifting amount (i.e., weld height) _{hfirst based} on the estimated weld height hfirst' of the first weld surface and the height of the filling and cover surface welds ha;

Step S313 includes the following steps:

S3131, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst =(30-6)/6=4mm;

S3132, 0.9h _a =0.9*4.3=3.87＜h _first ′=4 mm＜1.1h _a =1.1*4.3=4.73 mm, go to step S3133;

S3133, fill the weld surface first, lift the cover surface _by hfirst= _hfirst ′=4mm, tag=0.

S314. The control system calculates the height of each weld bead of the first weld surface before root cleaning, and determines the number of welding layers _n1 of the first weld surface before root cleaning. Then, from the first weld surface base-filling-capping, the height of each layer of weld is: 6mm, 10mm, 14mm, 18mm, 22mm, 26mm, 30mm. The height of the weld bead of the first weld surface _before root cleaning is selected as 3/5Hfirst=3/5*30=18mm, that is, fill 3 layers and then root cleaning, and the number of welding layers _n1 =3 of the first weld surface before root cleaning; in this way, it can be ensured that the first weld surface after root cleaning is the same height as the rear weld surface, and the first weld surface is connected.

S315, the control system calculates the fill area _A1 of each layer of the weld on the weld surface before root cleaning based on the height of each layer of the weld on the weld surface _before root cleaning, the groove width L1 corresponding to different heights and the groove shape. The areas of each layer of the first three fill welds are: ^68.53mm2 , ^87.00mm2 , ^105.48mm2 ;

S316. The control system determines the number of weld passes _mxian1 of each layer of the first weld surface before root cleaning based on the equal area assumption, _mxian1 = _Axian1 / _A0 , _mxian1 = 1.7718, 2.2494, 2.7271, rounded to the nearest integer, then the number of weld passes mxian1 of each layer of the first weld surface before root cleaning ₌ 2, 2, 3;

S317, tag=0, directly go to step S319;

S319. The control system determines the multi-layer and multi-pass welding sequence of the welding surface before root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle, and welding is carried out to the third layer.

During the welding process, the welding laser vision equipment and database can also be combined to obtain the size changes in the groove in real time and update the database, so as to dynamically adjust the multi-layer and multi-pass planning scheme to make it more flexible and reliable.

To ensure the weld root performance and metallurgical quality, step S32 is performed to clean the root. Step S32 is specifically: boring machine or carbon arc gouging is used to clean the root, and the processing depth is to the thickness T/2=50/2=25mm, and the root cleaning amount is 13mm.

Preferably, in this embodiment, a boring machine is used for root cleaning to ensure the accuracy of shape and size. The shape after root cleaning is shown in FIG. 4 , and θ1 is 75°.

Step S33 includes the following steps:

S331, the control system draws the contour lines on both sides of the rear welding surface and obtains the groove width L corresponding _to different heights;

S332, the control system calculates the estimated total number of layers n _after the back weld surface filling and covering based on the equal height assumption, the base weld height h ₀ , the filling and covering weld heights h _a , and the actual total height H _after of the back weld surface, and the formula is: n _after = (H _after - h ₀ ) / h _a = (25-6) / 4.3 = 4.42, rounded to an integer n _after = 4;

_Among them, H = 25mm.

S333, the control system calculates the estimated weld height of the _rear weld surface hafter=( _Hafter -h ₀ )/ _nafter =(25-6)/4=4.75 mm based on the estimated total number of layers _{nafter of} the rear weld surface filling and covering, and determines the rear weld surface filling and covering lifting amount hafter based on the estimated weld height hafter, the filling and covering weld heights h _{a of} the rear weld surface;

Step S333 includes the following steps:

S3331, the control system calculates the estimated weld height of the _rear weld surface hafter′=( _Hafter -h ₀ )/ _nafter =(25-6)/4=4.75mm;

S3332, h _after ′ = 4.75 mm > 1.1 ha = 1.1 * 4.3 = 4.73 mm, go to step S3334;

S3334, h _after ′ = 4.75 mm > 1.1 _{h a} = 1.1 * 4.3 = 4.73 mm, go to step S3336;

S3336, post-weld surface filling, cover surface lifting amount _hpost = h _a = 4.3 mm, tag = 1.

S334, the control system calculates the height of each weld bead of the rear weld surface, and the height h of each weld bead of the filling weld bead is 6.00mm, 10.30mm, 14.60mm, 18.90mm, and 23.20mm;

S335, the control system calculates the weld filling area A _of each layer of the rear weld surface based on the weld height of each layer of the rear weld surface, the groove width L corresponding to _different heights and the groove shape, and the weld area of each layer is 35.0450mm ² , 53.5350mm ² , 72.0250mm ² , and 90.5150mm ² ;

S336. The control system determines the number of weld passes m _{after for} each layer of the rear weld surface based on the equal area assumption, m _after = A _after / A ₀ , m _after = 0.9060, 1.3840, 1.8621, 2.3401, rounded to the nearest integer, then the number of weld passes m _after for each layer of the rear weld surface = 1, 1, 2, 2;

S337, tag=1, then go to step S338;

S338, add a cover layer, the number of the original cover layer is 1 more, that is, 2+1=3, and go to step S339;

S339. Determine the welding sequence planning for the multi-layer and multi-pass welding sequence of the rear welding surface. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle.

In summary, the back welding surface welding filling welding is 4 layers, each layer needs to be filled 1, 1, 2, 2 passes; the cover surface welding is 1 layer, and the cover surface welding 1 layer is 3 passes. The filling cover surface is 5 layers and 9 passes in total.

Based on the above analysis, based on the total groove height, the base weld height, and the filling and cover weld heights, and based on the equal height assumption, the total number of filling and cover layers can be estimated, and the height of each weld layer can be calculated and adjusted according to the estimated number of layers.

Step S34 includes the following steps:

S341, the control system determines the number of welding layers of the first welding surface after root cleaning n ₂ =n _first -n ₁ =6-3=3 layers;

S342, the control system calculates the area _A of each layer of the first weld surface after root cleaning, and the area of each layer of the first weld surface after root cleaning is 123.9586mm ² , 142.4338mm ² , and 160.9090mm ² respectively;

S343, the control system determines the number of weld passes _mxian2 of each layer of the first weld surface after root cleaning based on the equal area assumption, _mxian2 = _Axian2 / _A0 , _mxian2 =3.2047, 3.6824, 4.1600, rounded to the nearest integer, then the number of weld passes _mxian2 of each layer of the first weld surface after root cleaning =3, 4, 4;

S344. The control system determines the multi-layer and multi-pass welding sequence of the surface after root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle.

During the welding process, the welding laser vision equipment and database can be combined to obtain the dimensional changes in the groove in real time and update the database, so as to dynamically adjust the multi-layer and multi-pass planning scheme to make it more flexible and reliable.

The welding system performs welding according to the multi-layer and multi-pass welding planning method.

Example 2

In this embodiment, different from the embodiment 1,

In step S1, the thickness of the cast steel is 300 mm; the welding position is flat butt welding; as shown in FIG5 and FIG6, the groove shape is a U-shaped groove.

Among them, the height of the first welding surface and the rear welding surface is 149mm, the blunt edge is 2mm, and the actual total height H of the _first welding surface is 150mm; the groove is symmetrical about the X-axis and the Y-axis, and the groove angle θ=20°.

In step S2, it is determined that the base weld height _h0 is 4 mm; the filler and cap weld heights _ha are 3.3 mm; and the weld fill area _A0 is 26.91 ^mm2 .

In step S31, step S31 includes the following steps:

S311, the control system draws the contour lines on both sides of the welding surface and obtains the groove width L _{corresponding} to different heights;

S312, the control system calculates the estimated total number of layers _{nfirst of} the first welding surface filling and covering based on the equal height assumption, the base weld height h ₀ , the filling and covering weld heights h _a , and the actual total height H _first of the first welding surface, and the formula is: _nfirst =(H _first -h ₀ )/ _ha =(150-4)/3.3=44.24 layers, rounded to an integer _nfirst =44 layers;

S313, based on the estimated total number of layers _nfirst of the first weld surface filling and cover surface, calculate the estimated seam height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst =(150-4)/44=3.31 mm, and based on the estimated weld seam height _hfirst ′ of the first weld surface, the height of the filling and cover surface welds h _a, determine the lifting amount of the first weld surface filling and cover surface _hfirst ;

Step S313 includes the following steps:

S3131, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst =(150-4)/44=3.31mm;

S3132, 0.9h _a =0.9*3.3=2.97＜h _first ′=3.31mm＜1.1h _a =1.1*3.3=3.63mm, go to step S3333;

S3133, fill the weld surface first, lift the cover surface _by hfirst= _hfirst ′=3.31mm, tag=0.

S314, the control system calculates the height of each weld bead of the first weld surface before root cleaning, and determines the number of welding layers n ₁ of the first weld surface before root cleaning, then the height of each layer of weld seam from the first weld surface base-filling-capping is: 4.00mm, 7.31mm, 10.62mm, 13.93mm, 17.24mm, 20.55mm, 23.86mm, 27.17mm, 30.48mm, 33.79mm, 37.10mm, 40.41mm, 43.72mm, 47.03mm, 50.34mm, 63.58mm, 66.89mm, 70.20mm, 73.51mm, 76.82mm, 80.13mm, 83.44mm, 86.75mm, 90.06mm, 93.37mm, 96.68mm, 99.99mm, 103.30mm, 106.61mm, 109.92mm, 113.23mm, 116.54mm, 119.85mm, 123.16mm, 126.47mm, 129.78mm, 133.09mm, 136.40mm, 139.71mm, 143.02mm, 146.33mm, 149.64mm, select the weld height of the first weld surface before root cleaning as 1/3H _first = 1/3 * 150 = 50mm, fill 14 layers of weld height is 50.34mm, that is, fill 14 layers and then root cleaning, the number of weld layers before root cleaning n ₁ = 14;

S315, the control system calculates the weld filling area A _first of each layer of the weld surface before root cleaning based on the weld height of each layer of the weld surface before root cleaning, the groove width L _first corresponding to different heights, and the groove shape;

S316. The control system determines the number of weld passes _mxian1 of each layer of the first weld surface before root cleaning based on the equal area assumption, _mxian1 = _Axian1 / _A0 , mxian1 = 1.6413, 1.8300, 1.9736, 2.1172, 2.2608, 2.4044, 2.5479, 2.6915, 2.8351, 2.9787, 3.1223, 3.2658, 3.4094, 3.5530, 3.6966, rounded to the nearest integer, then the number of weld passes _mxian1 of each layer of the first weld surface before root cleaning = 2, 2 _{, 2} , 2, 2, 3, 3, 3, 3, 3, 4, 4;

S317, tag=0, directly go to step S319;

S319. The control system determines the multi-layer and multi-pass welding sequence of the welding surface before root cleaning. If the welding position is flat butt, flat welding is adopted, and the welding sequence is from one side to the other side, and welding is carried out to the 14th layer.

In step S32, since the rear weld surface of the original groove is consistent with the height of the rear weld surface, the processing depth does not need to be too deep. It is necessary to remove the base weld of the rear weld surface with a depth of about 4mm and a root clearing amount of 4mm; and remove the parent material near the weld root with a width of about 6mm, which is consistent with the radius of the bottom fillet of the U-shaped groove.

Step S33 includes the following steps:

S331, the control system draws the contour lines on both sides of the rear welding surface and obtains the groove width L corresponding _to different heights;

S332, the control system calculates the estimated total number of layers n _after the back weld surface filling and covering based on the equal height assumption, the base weld height h ₀ , the filling and covering weld heights h _a , and the actual total height H _after of the back weld surface, and the formula is: n _after = (H _after - h ₀ ) / h _a = (150-4) / 3.3 = 44.24, rounded to an integer n _after = 44;

H _back = H _first = 150mm.

S333, based on the estimated total number of layers n _of the back weld surface filling and capping, calculate the estimated weld height of the _back weld surface hafter′=( _Hafter -h ₀ )/ _nafter =(150-4)/44=3.31 mm, and determine the _back weld surface filling and capping lifting amount hafter based on the estimated weld height hafter′, the filling and capping weld heights h _{a of} the back weld surface;

Step S333 includes the following steps:

S3331, the control system calculates the estimated weld height of the _rear weld surface hafter′=( _Hafter -h ₀ )/ _nafter =(150-4)/44=3.31mm;

S3332, 0.9h _a =0.9*3.3=2.97＜ _hhou ′=3.31mm＜1.1h _a =1.1*3.3=3.63mm; which means _nhou =44 is reasonable.

S3333, filling and covering lifting amount _hafter = _hafter ′ = 3.31mm, tag = 0.

S334, the control system calculates the height of each layer of weld on the rear welding surface, and the height of each layer of weld from the rear welding surface base-filling-capping is: 4.00mm, 7.31mm, 10.62mm, 13.93mm, 17.24mm, 20.55mm, 23.86mm, 27.17mm, 30.48mm, 33.79mm, 37.10mm, 40.41mm, 43.72mm, 47.03mm, 50.34mm, 63.58mm, 66.89mm, 70.20mm, 73.51mm, 76. 82mm, 80.13mm, 83.4400, 86.75mm, 90.06mm, 93.37mm, 96.68mm, 99.99mm, 103.30mm, 106.61mm, 109.92mm, 113.23mm, 116.54mm, 119.85mm, 123.16mm, 126.47mm, 129 .78mm, 133.09mm, 136.40mm, 139.71mm, 143.02mm, 146.33mm, 149.6400mm;

S335, the control system calculates the weld filling area _A of each layer of the rear weld surface _based on the height of each weld bead of the rear weld surface, the groove width L corresponding to different heights, and the groove shape;

S336, the control system determines the number of weld passes m _after each layer of the rear welding surface based on the equal area assumption, m _after = A _after / A ₀ , _mafter =1.6413, 1.8300, 1.9736, 2.1172, 2.2608, 2.4044, 2.5479, 2.6915, 2.8351, 2.9787, 3.1223, 3.2658, 3.4094, 3.5530, 3.6966, rounded _to the nearest integer, then the number of weld passes per layer of the rear weld surface mafter=2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8 passes;

S337, tag=0, directly go to step S339;

S339. The control system determines the multi-layer and multi-pass welding sequence of the rear welding surface. If the welding position is flat butt, flat welding is adopted, and the welding sequence is from one side to the other side.

In step S33, after root cleaning, since the base weld of the rear weld surface is removed, one base weld is required before welding the rear weld surface. In addition, the size of the rear weld surface itself is symmetrical with the first weld surface. The calculation process of the remaining filling and covering is the same as that of step S31. There are 44 layers of filling and covering, and each layer requires welding 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8 respectively.

Step S34 includes the following steps:

S341, the control system determines the number of welding layers of the first welding surface after root cleaning n ₂ =n _first -n ₁ =44-14=30 layers;

S342, the control system calculates the area of each layer of the first welding surface after root cleaning A _{first 2} ;

S343, the control system determines the number of weld passes _mxian2 of each layer of the first welding surface after root cleaning based on the equal area assumption, _{where mxian2} = _Axian2 / _A0 ;

In step S343, since the grooves of the first weld surface and the rear weld surface are symmetrical, the filling scheme for the remaining 30 layers of welds on the first weld surface after root cleaning is the same as the filling scheme for the last 30 layers of welds on the rear weld surface in step S33, that is, after root cleaning, the remaining 30 layers of the first weld surface are filled with 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8 respectively.

S344. After root cleaning, determine the multi-layer and multi-pass welding sequence of the welded surface. If the welding position is flat butt, use flat welding, and weld from one side to the other.

The welding system performs welding according to the multi-layer and multi-pass welding planning method, as shown in FIG7 , which is a physical picture of 300 mm cast steel flat butt multi-layer and multi-pass welding.

Example 3

This embodiment proposes a computer device, which includes a processor and a memory. The memory stores a computer program. When the computer program is read and executed by the processor, the steps of the multi-layer and multi-pass welding planning method as described in any one of Embodiment 1 and/or Embodiment 2 are implemented.

The computer device includes not only the processor and the memory but also other related components. Since the specific structures and specific assembly relationships of the related components are prior art, they will not be described in detail here.

The advantages of the computer device described above and the multi-layer multi-pass welding planning method described above over the prior art are the same and will not be described in detail here.

Example 4

This embodiment proposes a computer-readable storage medium, which stores a computer program. When the computer program is read and executed by a processor, the steps of the multi-layer and multi-pass welding planning method as described in any one of Embodiment 1 and/or Embodiment 2 are implemented.

The computer-readable storage medium includes not only the computer program but also other related components. Since the specific structures and specific assembly relationships of the related components are prior art, they are not described in detail here.

The advantages of the computer-readable storage medium and the above-mentioned multi-layer multi-pass welding planning method over the prior art are the same, which will not be repeated here.

Performance Testing

According to GB/T 2651-2023 "Destructive testing of welds on metallic materials - Transverse tensile test", the room temperature tensile properties of the cast steel thick plate butt joint welded using the multi-layer and multi-pass welding planning method described in Examples 1 and 2 were tested, and the results are shown in Table 1.

Table 1 Test results of tensile strength of butt joints of cast steel thick plates in Example 1~2

It can be seen from Table 1 that the tensile strength of the cast steel thick plate butt joints welded using the multi-layer and multi-pass welding planning method described in Examples 1 to 2 is greater than 470 MPa, and the fracture position is located on the substrate, not at the weld, indicating that the welding quality and mechanical properties of the cast steel thick plate butt joints welded using the multi-layer and multi-pass welding planning method described in Examples 1 to 2 of the present invention are excellent.

Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims (10)

1. A multi-layer multi-pass welding planning method, characterized in that the multi-layer multi-pass welding planning method is applicable to a cast steel thick plate butt joint robot, the cast steel thick plate butt joint robot comprises a process database, a visual recognition system, a welding system and a control system, and the multi-layer multi-pass welding planning method comprises the following steps: S1. The visual recognition system obtains the thickness and characteristic dimensions of the cast steel plate and transmits these data to the process database and control system; S2. The process database determines the base weld height h ₀ , the filler and cap weld heights _ha and the weld fill area A ₀ based on the thickness and characteristic dimensions of the cast steel thick plate, and transmits these data to the control system; S3. The control system determines the number of welding layers, the number of weld passes and the multi-layer and multi-pass welding sequence based on the assumptions of equal height and equal area, the base weld height h ₀ , the filling and cap weld heights _ha and the weld filling area A ₀ . 2. A multi-layer and multi-pass welding planning method according to claim 1, characterized in that, in step S1, the characteristic dimensions include welding position, groove shape, groove angle, and actual total height H _of the first welding surface. 3. The multi-layer multi-pass welding planning method according to claim 1, characterized in that step S3 comprises the following steps: S31, weld surface welding plan before root cleaning; S32, root cleaning; S33, rear welding surface welding planning; S34, weld the surface first after root cleaning. 4. The multi-layer multi-pass welding planning method according to claim 3, characterized in that step S31 comprises the following steps: S311, the control system draws the contour lines on both sides of the welding surface and obtains the groove width L _{corresponding} to different heights; S312, the control system calculates the estimated total number of layers _{nfirst of} the first welding surface filling and covering based on the equal height assumption, the base weld height h ₀ , the filling and covering weld heights h _a , and the actual total height H _{first of} the first welding surface, and the formula is: _nfirst =(H _first -h ₀ )/ _ha ; S313, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _{nfirst based} on the estimated total number of layers nfirst of the first weld surface filling and cover surface, and then the control system determines the first weld surface filling and cover surface lifting amount _hfirst based on the estimated weld height _hfirst ′ of the first weld surface and the heights of the filling and cover surface welds h _a ; S314, the control system calculates the height of each weld bead of the first weld surface before root cleaning, and determines the number of welding layers n ₁ of the first weld surface before root cleaning; S315, the control system calculates the weld filling area A _first of each layer of the weld surface before root cleaning based on the weld height of each layer of the weld surface before root cleaning, the groove width L _first corresponding to different heights, and the groove shape; S316, the control system determines the number of weld passes _mxian1 of each layer of the first weld surface before root cleaning based on the equal area assumption, _mxian1 = _Axian1 / _A0 ; S317, the control system determines whether tag=1, if yes, it goes to step S318; if no, it goes directly to step S319; S318, add a layer of cover, the number of layers is one more than the number of layers of the original cover, and go to step S319; S319. The control system determines the multi-layer and multi-pass welding sequence of the welding surface before root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side, and welding is carried out to the _n1th layer. 5. The multi-layer multi-pass welding planning method according to claim 3, characterized in that step S33 comprises the following steps: S331, the control system draws the contour lines on both sides of the rear welding surface and obtains the groove width L corresponding _to different heights; S332, the control system calculates the estimated total number of layers n of the back weld filling and cover based on the equal height assumption, the base weld height h ₀ , the filling and cover weld heights h _a , and the actual total height H _back of the _back weld, and the formula is: n _back = (H _back - _{h 0} ) / h _a ; S333, the control system calculates the estimated weld height of the _rear weld surface hafter=( _Hafter - _h0 )/ _{nafter based on} the estimated total number of layers nafter of the rear weld surface filling and capping, and then the control system determines the rear weld surface filling and capping lifting amount hafter based on the estimated weld height _hafter , the filling and capping weld heights h _a ; S334, the control system calculates the height of each weld bead on the rear welding surface; S335, the control system calculates the weld filling area _A of each layer of the rear weld surface _based on the height of each weld bead of the rear weld surface, the groove width L corresponding to different heights, and the groove shape; S336, the control system determines the number of weld passes m _after each layer of the rear welding surface based on the equal area assumption, m _after = A _after / A ₀ ; S337, the control system determines whether tag=1, if yes, it goes to step S338; if no, it goes directly to step S339; S338, add a layer of cover, the number of layers is one more than the number of layers of the original cover, and go to step S339; S339. The control system determines the multi-layer and multi-pass welding sequence of the rear welding surface. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side. 6. A multi-layer multi-pass welding planning method according to claim 3, characterized in that step S34 comprises the following steps: S341, the control system determines the number of welding layers of the first welding surface after root cleaning n ₂ =n _first -n ₁ ; S342, the control system calculates the fill area A of each layer of the weld on the first weld surface after root cleaning ₂ ; S343, the control system determines the number of weld passes _mxian2 of each layer of the first welding surface after root cleaning based on the equal area assumption, _{where mxian2} = _Axian2 / _A0 ; S344. The control system determines the multi-layer and multi-pass welding sequence of the first welding surface after root cleaning. If the welding position is vertical butt welding, vertical welding is adopted, and the welding sequence is from both sides to the middle; if the welding position is flat butt welding, flat welding is adopted, and the welding sequence is from one side to the other side. 7. The multi-layer multi-pass welding planning method according to claim 6, characterized in that step S313 comprises the following steps: S3131, the control system calculates the estimated weld height of the first weld surface _hfirst ′=( _Hfirst -h ₀ )/ _nfirst ; S3132, the control system determines whether _0.9ha < _hfirst '< _1.1ha , if yes, proceeds to step S3133, if no, proceeds to step S3134; S3133, first weld surface filling, cover surface lifting amount _hfirst = _hfirst ′, tag=0; S3134, the control system determines whether h _first ′＜0.9 h _a , if so, it proceeds to step S3135, if not, it proceeds to step S3136; S3135, first weld surface filling, cover surface lifting amount h _first = h _a , tag = 0; S3136, fill the weld surface first, and lift the cover surface by the amount h _first = _ha , tag = 1. 8. The multi-layer multi-pass welding planning method according to claim 1, characterized in that step S333 comprises the following steps: S3331, the control system calculates the estimated weld height of the rear weld surface _hhou ′=( _Hhou -h ₀ )/ _nhou ; S3332, the control system determines whether _0.9ha < _hafter '< _1.1ha , if so, proceeds to step S3333, if not, proceeds to step S3334; S3333, rear welding surface filling, cover lifting amount _hafter = _hafter ′, tag=0; S3334, the control system determines whether _hhou ′＜0.9h _a , if so, it proceeds to step S3335, if not, it proceeds to step S3336; S3335, after welding surface filling, cover lifting amount h _after = h _a , tag = 0; S3336, _after welding surface filling, cover surface lifting amount h = _ha , tag = 1. 9. A computer device, characterized in that the computer device includes a processor and a memory, the memory stores a computer program, and when the computer program is read and executed by the processor, the steps of the multi-layer and multi-pass welding planning method as described in any one of claims 1 to 8 are implemented. 10. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, and when the computer program is read and executed by a processor, the steps of the multi-layer multi-pass welding planning method as described in any one of claims 1 to 8 are implemented.