Forming process method of cutting through-line before bending tube of vehicle body pipe

Abstract

This invention discloses a forming process for vehicle body tubular components where the intersecting lines are cut first, followed by bending. The process includes calculating the bending and unfolding of the steel pipe without allowance, and determining the cutting length of the steel pipe for each component. Based on the calculated cutting length, the total cutting length, cutting lines, and arc direction marking lines of the part's 3D model are processed to form a 3D model for laser pipe cutting. The 3D model is then imported into the laser pipe cutting machine for cutting, clamping, and bending. This invention utilizes the precision of laser pipe cutting equipment for cutting the steel pipe intersecting lines without allowance, ensuring accuracy through the 3D model unfolding length calculation and the laser pipe cutting machine's own cutting precision. This invention employs a process technology of processing the intersecting lines first, followed by bending, using CNC pipe bending equipment to bend the pipe first and then process the intersecting lines. This reduces the clamping and positioning from two times to one, achieving the effect of reducing random errors by reducing the number of clamping operations, thus compensating for the shortcomings of the previous process technology of bending the steel pipe first and then processing the intersecting lines.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile manufacturing, in particular to a forming process method for cutting a pipe joint first and then bending a pipe. BACKGROUND

[0002] At present, the processing of the intersecting line (arc opening) at the end of the steel pipe and the forming of the bent pipe mainly have the following ways: the first way is to polish the intersecting line by the traditional angle grinder, which has the disadvantages of long polishing time for single piece, low efficiency, inability to mass production, poor polishing arc precision of the steel pipe, and difficulty to guarantee the size precision; the second way is to process the intersecting line by using a milling machine, which needs to cut and blank the steel pipe first, then process the intersecting line (arc opening) at the end of the bent pipe, and needs to use a fixture for positioning and clamping when processing after bending, which is easy to cause errors in angle positioning, and has low positioning and processing efficiency, resulting in high processing cost; the third way is to use an arc punching device at the end of the steel pipe to punch and cut the intersecting line, which has high processing efficiency, but the punched surface is rough and has a certain degree of deformation, and when punching and cutting different pipe diameters or different sizes of the intersecting line, the tool needs to be switched, and the punch tool has high consumption and high frequency of grinding and polishing.

[0003] Recently, with the wide application of three-dimensional drawing software in the mechanical processing process, the three-dimensional modeling and reprocessing technology is also used in the production of the pipe member with the intersecting line, and the method provided in the published patent application "Construction method of large-section intersecting pipe steel member" (application number: CN201710779384.5) adopts Creo software to perform three-dimensional full modeling on the pipe steel member, then expands the three-dimensional full model, imports the 1:1 plan into the Sinocam software to compile a cutting program, obtains a steel plate cutting program file, accurately blanks the steel plate by using a full-automatic cutting machine according to the cutting program file, places the steel plate on a plate rolling machine to roll and form, and performs jointing and longitudinal seam welding and roundness processing on the rolled and formed pipe steel member. The technology improves the production precision, but it cannot complete the accurate processing of the intersecting line and the preparation of the bent pipe by using the pipe, because it blanks the steel plate, then rolls and welds the steel plate into a pipe, and then processes the roundness.

[0004] In summary, there is still a lack of systematic and efficient production and processing scheme for the processing of the intersecting line (arc opening) at the end of the steel pipe and the bent pipe. SUMMARY

[0005] In order to overcome the above problems in the prior art, the present application provides a forming process method for cutting a pipe joint first and then bending a pipe, which can effectively shorten the production cycle, guarantee the production progress, reduce the production cost, and improve the pipe processing quality while reducing the clamping times and random errors. The present application adopts the following technical scheme:

[0006] The forming process method of the vehicle body pipe with the intersecting line cut first and then bent, comprising the following steps:

[0007] Step 1, using three-dimensional model drawing software to model the forming bent pipe with intersecting line, calculating and determining the cutting length of the steel pipe;

[0008] Step 2, straighten the curved steel pipe in the three-dimensional model generated in step 1, process the total cutting length of the part three-dimensional model according to the cutting length of the steel pipe calculated in step 1, and make an arc opening direction marking line to form a three-dimensional model for laser pipe cutting machine cutting;

[0009] Step 3, import the three-dimensional model obtained in step 2 into the laser pipe cutting machine for cutting, and cut the arc opening direction marking line on the surface of the steel pipe, and additionally make a direction reference marking line at the fixed position of the bending machine clamp;

[0010] Step 4, according to the position of the arc opening direction marking line on the steel pipe obtained in step 3, compare the direction reference marking line on the bending machine clamp to ensure that the pipe is clamped for bending at the correct intersecting line angle;

[0011] Step 5, bending machine bending forming;

[0012] Step 6, after checking the dimensions, it is ready for welding.

[0013] Preferably, in step 1, three-dimensional model drawing software is used to model the forming bent pipe with intersecting line, and the cutting length of the blank is calculated, which is calculated by the following formula:

[0014] L=L1+L2+L3+S1+S2-ΔS1-ΔS2;

[0015] Wherein, L is the cutting length of the blank, L2 is the center line length of the intermediate straight pipe section, L1 and L3 are the center line lengths of the straight pipe sections at both ends respectively, S1 and S2 are the center line lengths of the curved pipe sections at both ends respectively, and ΔS1 and ΔS2 are the stretching change amounts of the steel pipe at both ends when bending.

[0016] Further, the stretching change amount of the steel pipe is statistically analyzed, and ΔS1 and ΔS2 are obtained by the following way: the actual data of the length of the same batch of steel pipes after bending is measured, and then the actual cutting length is subtracted to obtain the stretching change amount summary table of the same batch of steel pipes under the same operation; when calculating the cutting length, the stretching change amount ΔS1 or ΔS2 is determined according to the steel pipe specification and the bending angle by referring to the stretching change amount summary table.

[0017] Further, the three-dimensional model drawing software can be selected from Creo, UG, SolidWorks, 3ds max, SketchUp, Zbrush or Maya.

[0018] Preferably, in step 2, the curved steel pipe is processed to a straight state by a "flattening / straightening" function or a physical "moving-rotating" function which rotates one end of the steel pipe to 180°. The total cutting length of the processed three-dimensional model is determined as follows: the cutting length L calculated in step 1 is compared with the length of the straightened steel pipe. If there is a difference, the length of the straightened steel pipe is adjusted according to the cutting length L calculated in step 1.

[0019] Preferably, in step 2, an arc direction marking line is drawn on the axis plane of the steel pipe after the "straight line drawing" command is executed, forming a three-dimensional model for laser pipe cutting.

[0020] Further, the arc direction marking line is drawn along the axis direction at the end of the intersecting line, with a length of 5-10 mm, to match the direction reference marking line on the bending machine clamp mold.

[0021] Preferably, in step 2, the model cutting line interference part is processed by drawing on the axis plane of the straightened steel pipe model as the reference plane, using the "draw straight line / curve command" to draw the cutting path line, and executing the "stretching cutting" command to cut off the excess part along the drawing cutting line in the pipe diameter direction.

[0022] Preferably, in step 3, the arc direction marking line in the three-dimensional model obtained in step 2 is marked. After the cutting in step 3 is completed, a straight pipe with an arc direction marking line is obtained by cutting. In addition, a direction reference marking line is made at a fixed position of the bending machine clamp mold, which can be vertical or horizontal. The arc direction marking line and the direction reference marking line are compared to determine the bending direction when the steel pipe enters the bending machine. Specifically, the arc direction marking line is marked by laser pipe cutting machine by recognizing the arc direction marking line on the surface of the steel pipe or directly cutting a straight line notch.

[0023] Preferably, in step 5, the method for determining the springback and springback angle of the steel pipe bending is included. In step 5, the bending angle is set to the sum of the theoretical bending angle and the springback angle. The springback angle is determined according to the actual measurement results of the springback angle of the same batch of steel pipes after bending.

[0024] The process flow of the super-light high-mobility off-road vehicle frame steel pipe is relatively simple by cutting the intersecting line first and then bending pipe forming, but there are many factors affecting the size accuracy of the intersecting line cutting and the size accuracy of the steel pipe bending forming. No matter which way is used to cut the intersecting line, using different ways and using different equipment to cut the intersecting line also has advantages and disadvantages. Due to the elastic-plastic bending of the pipe bending process, the bending angle will be smaller and the pipe axis will be longer after the bending springback, that is, the springback and extension problems, so it is difficult to determine the bending angle and the pipe length according to the drawing. In order to solve the above problems, the technical scheme is researched in the following three points: first, the steel pipe no allowance cutting and bending development calculation; second, the steel pipe bending direction is consistent with the intersecting line angle direction; third, the determination of the steel pipe bending springback angle. Among them, the no allowance cutting process is the basis of the steel pipe manufacturing intersecting line cutting and bending pipe forming process, and the springback and length extension of the steel pipe after bending need to be tested and a large amount of experience data is accumulated, and the experience data is used as the basis for compensation.

[0025] Compared with the prior art, the beneficial effects of the present application are:

[0026] 1. The present application provides a forming process for preparing a bent pipe for a round pipe, which adopts the method of cutting the intersecting line first and then bending the pipe, determines the steel pipe cutting length by using a three-dimensional model, realizes no allowance cutting of the steel pipe intersecting line, ensures the cutting accuracy through three-dimensional model development length processing and laser pipe cutting machine, and uses software model for data calculation, thereby improving the work efficiency.

[0027] 2. Compared with the traditional intersecting line (arc opening) cutting and pipe bending process, the present application provides the process technology of cutting the intersecting line (arc opening) first and then bending the pipe, which reduces the clamping and positioning from twice to once, can reduce the random error accumulation effect by reducing the clamping times, improves the steel pipe forming size accuracy, and makes up for the deficiency of the intersecting line (arc opening) cutting and pipe bending process.

[0028] 3. The steel pipe intersecting line cutting and pipe bending forming process provided by the present application has the following advantages: it can shorten the process flow, reduce the process, improve the production efficiency of the steel pipe forming, reduce the labor intensity, shorten the production cycle, and can be produced in batches. BRIEF DESCRIPTION OF DRAWINGS

[0029] The drawings accompanying the specification of the present application form a part of the present application and serve to provide further understanding of the present application, and the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute improper limitations on the present application.

[0030] Figure 1 It is a schematic diagram of the steel pipe no allowance intersecting line cutting in step 1 of the present application;

[0031] Figure 2 is an enlarged view of the end of

[0032] Figure 3 is an enlarged view of the end of Figure 2

[0033] Figure 4 is a diagram of a reference mark line for the arcuate intersecting line direction provided by the bending machine jig mold in step 2 of the present application, wherein 2 is a steel pipe, 3 is a bending machine jig mold, and 4 is a reference mark line for the direction.

[0034] Figure 5 is another diagram of a reference mark line for the arcuate intersecting line direction provided by the bending machine jig mold in step 2 of the present application, wherein 2 is a steel pipe, 3 is a bending machine jig mold, and 4 is a reference mark line for the direction.

[0035] Figure 6 is an effect diagram before the model cutting line is processed in step 2 of the present application, 5 is an inner end line, and 6 is an outer end line.

[0036] Figure 7 is an effect diagram after the model cutting line is processed in step 2 of the present application. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0038] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0039] A certain ultra-lightweight high-mobility off-road vehicle frame is formed by steel pipe splicing, the production raw material is high-strength steel pipe, the steel pipe is bent to a corresponding angle, and then a plurality of steel pipes are butt-jointed and spliced into an integral frame structure. The bending angle and the intersecting line (arc) cutting precision of each steel pipe will affect the final welding quality, so the bending precision of each steel pipe and the intersecting line (arc) cutting precision are crucial.

[0040] ​As introduced in the background, the existing production technology lacks systematic and high-efficiency production and processing scheme for the intersecting line (arc opening) of the end of the steel pipe and the bending pipe processing. In order to solve the above technical problems, the present application proposes a process method of cutting the intersecting line first and then bending the pipe for the steel pipe of the super-light high-mobility off-road vehicle frame, which can effectively shorten the production cycle, ensure the production progress, reduce the production cost, and improve the pipe processing quality while reducing the clamping times and reducing random errors.

[0041] The test material of the pipe of the vehicle body used by a super-light high-mobility off-road vehicle is 30CrMo, Φ38x2 and Φ32x2 two specifications of steel pipe, and the forming process method of cutting the intersecting line first and then bending the pipe is used for test research. The processing flow is divided into four stages of process treatment stage, intersecting line cutting stage, bending pipe forming stage, and inspection and shaping stage, and six steps.

[0042] Model process treatment stage: first, using three-dimensional model drawing software to model the forming bend pipe with intersecting line, determine the cutting length of the steel pipe. Second, the bent steel pipe is processed to a straight state, and the total cutting length, cutting line and arc opening direction marking line of the part three-dimensional model are marked according to the cutting length of the steel pipe calculated in the first step, and then the three-dimensional model for laser pipe cutting machine cutting is formed.

[0043] Intersecting line cutting stage: third, the three-dimensional model obtained in step two is imported into the laser pipe cutting machine for cutting, and at the same time, the "arc opening direction marking line" is cut on the surface of the steel pipe, and another "direction reference marking line" is made at the fixed position of the bending machine clamp mold.

[0044] Bending pipe forming stage: fourth, according to the position of the "arc opening direction marking line" on the steel pipe of the laser pipe cutting machine, compare the direction reference marking line on the bending machine clamp mold to ensure that the pipe is clamped for bending at the intersecting line angle in the three-dimensional drawing or two-dimensional drawing. Fifth, confirm the correct clamping direction, and the bending pipe is formed by the bending machine.

[0045] Inspection and shaping stage: the sixth step is to check the dimensions and then use the backup welding.

[0046] Specifically, the operation process is as follows:

[0047] Step 1, steel pipe intersecting line blanking and cutting

[0048] Use Creo or UG three-dimensional model drawing software to model the forming bend pipe with intersecting line, and calculate the accurate blanking cutting length according to the three-dimensional model;

[0049] The length of each pipe section is determined by the distance between the intersection of the pipe section and the extension line of the adjacent pipe section. The cutting length is the total length of the pipe after bending and forming. In theory, it is the sum of the length of each straight pipe section and the length of the bending arc. However, due to the plastic deformation of the material during bending, the length of the bending arc is slightly stretched. Therefore, the sum of the lengths of each pipe section is not equal to the total length of the actual material used (i.e., the cutting length). The actual cutting length is slightly shorter than the theoretical length.

[0050] Specifically, as shown in Figure 1 , Figure 1 A and B are the bending angles of the steel pipe, and the cutting length is calculated using the following formula:

[0051] L = L1 + L2 + L3 + S1 + S2 - ΔS1 - ΔS2

[0052] Where L is the cutting length for cutting, L2 is the center line length of the intermediate straight pipe section, L1 and L3 are the center line lengths of the two end straight pipe sections, S1 and S2 are the center line lengths of the two end bending pipe sections, and ΔS1 and ΔS2 are the stretching changes of the steel pipe during bending.

[0053] The elongation during the bending process of the steel pipe is related to the material of the steel pipe, the bending angle, the performance of the bending machine, the size of the bending die radius, and the operation conditions. It is necessary to statistically analyze the elongation of the steel pipe during bending. ΔS1 and ΔS2 are obtained by the following method: measuring the actual data of the length of the same batch of steel pipes after bending, then subtracting the actual cutting length, and obtaining the stretching change amount table of the same operation of this batch of steel pipes. When calculating the cutting length, refer to the stretching change amount table to determine the stretching change amount ΔS1 or ΔS2 value according to the steel pipe specification and bending angle. When the bending angle does not appear in the table, take the value according to the linear law, for example, draw a straight line of a one-variable equation using the four data of the nearest two side angles and the latter corresponding bending change amount, and calculate the corresponding bending change amount value according to the bending angle.

[0054] For example, in one test, the bending stretching change rates of different specifications of steel pipes were measured as shown in Table 1:

[0055] Table 1 Bending stretching change amount of Φ38×2, Φ32×2 steel pipes of 30CrMo (unit: mm)

[0056]

[0057]

[0058] Note: The bending radius R of the steel pipe is 2.5D.

[0059] Step 2, the three-dimensional model generated in step 1 is straightened, the total cutting length of the part three-dimensional model is processed according to the cutting length of the steel pipe calculated in step 1, and the cutting line and the arc opening direction marking line are processed, and then a three-dimensional model for laser pipe cutting machine cutting is formed. The specific processing method is as follows:

[0060] 1. The bent steel pipe is processed to a straightened state by the "flattening / straightening" function or the entity "moving-rotating" function, that is, one end of the steel pipe is rotated by a corresponding angle to 180°, and then the length value of the straightened bent pipe is checked according to the cutting length L value calculated in step 1. If there is an error, the length value of the straightened bent pipe is adjusted according to the cutting length L value, so as to ensure the size accuracy of the bent pipe.

[0061] 2. Cutting line processing method: draw a graph on the axis surface of the straightened steel pipe model as a reference surface, draw a cutting path line by using the "draw straight line / curve command", and execute the "stretch cutting" command to cut off the excess part along the drawn cutting path line in the pipe diameter direction.

[0062] 3. Arc opening direction marking line: execute the "straight line drawing" command to draw a 5-10mm line segment along the axis direction at the end position of the intersection line of the steel pipe axis surface, as shown in Figure 2 and Figure 3 to form a three-dimensional model for laser pipe cutting machine cutting. At the end position of the intersection line of the steel pipe, the "direction reference marking line" on the bending machine clamp mold can be well matched and adapted, and the direction can be compared and adjusted when the bending machine starts to clamp.

[0063] The above functions are provided in three-dimensional model software such as SolidWorks, 3ds max, SketchUp, Zbrush, Maya, etc. The above three-dimensional software can be used in the implementation of the present application, and a person skilled in the art can select according to the use habit.

[0064] Step 3, the three-dimensional model obtained in step 2 is imported into the laser pipe cutting machine for cutting, and a cutting pipe with an intersection line at both ends is directly obtained, which is ready for bending.

[0065] The present application also provides a method for determining the relative position of the bending direction of the steel pipe and the angle direction of the intersection line (the accuracy of the intersection line direction).

[0066] After the cutting surface is formed by cutting the intersecting line of the steel pipe, the angle direction of the intersecting line is ensured to be correct to ensure that the position angle of the intersecting line after the bending forming meets the requirements. In order to ensure the bending forming efficiency and the angle direction accuracy, the cutting marking method is used for comparison and direction positioning. A 5-10mm straight line segment, i.e. the arc opening direction marking line, is drawn on the cutting model in step 2, and the marking is made according to the "arc opening direction marking line" in the model while cutting the steel pipe in step 3. Specifically, the automatic laser pipe cutting machine recognizes the "arc opening direction marking line" of the model for cutting. The cutting method of the arc opening direction marking line can be to make a line on the surface of the steel pipe or directly cut a straight line notch. The selection can be made according to the equipment and production needs. The direct cutting method of the straight line notch of 5-10mm can be used. The straight line notch is just covered by the weld when welding, and has no influence on the structural strength and appearance. After the cutting in step 3 is completed, the straight pipe with the "arc opening direction marking line" is obtained by cutting the blank. At this time, another marking line (see Figure 4 ) is made at the fixed position of the bending machine die, which is the "direction reference marking line" and is used to compare the arc opening "direction marking line" of the steel pipe with the bending machine die "direction reference marking line" to determine the bending direction when the steel pipe enters the bending machine. As a first choice, the vertical position edge line of the bending machine die can be selected as the direction reference marking line as shown in Figure 4 . As a second choice, a horizontal center line can be made on the die as shown in Figure 5 .

[0067] The problem that the bending direction of the steel pipe is consistent with the angle direction of the intersecting line has been solved by the three-dimensional model marking processing. The reliability and accuracy have been verified through tests and inspections.

[0068] In actual production, because the cutting surface formed by the intersecting line of the circular tube is a curved surface, the torch needs to be tilted at a certain angle and orientation, the torch needs to be displaced in the radial and axial directions of the steel tube, the steel tube needs to be displaced at an angle, and the torch needs to be displaced in the axial and radial directions, so as to cut out the intersecting line that meets the requirements. When the pipe wall thickness is small and the welding groove requirement is not high, a 3-axis 2-linkage laser pipe cutting machine can be used, the torch cannot be deflected, and the torch is always perpendicular to the surface of the steel tube during the cutting process. Due to the existence of the pipe wall thickness, it is no longer an intersecting line but an intersecting surface (curved surface), which will add an extra piece due to the wall thickness, thereby causing interference and failing to realize the intersection. The thicker the wall thickness, the more serious the interference. Taking the steel tubes Φ38x2 and Φ32x2 as examples, firstly, the intersecting line curved surface cannot be cut out, and secondly, due to the small wall thickness, the cutting of the curved surface is also affected by the small thickness, which affects the welding strength. At this time, the cutting line needs to be adaptively processed, and the interference part is processed by processing the model cutting line without affecting the precision requirements of the product splicing and welding. The specific processing method is as follows: draw a graph on the basis of the straightened steel tube model axis surface, draw the cutting path line by using the "draw straight line / curve command", and cut off the extra part along the drawn cutting line in the pipe diameter direction by executing the "stretch cutting" command.

[0069] The cutting path is determined in the following manner: as shown in Figure 6 , the points on the outer wall of the inner end of the intersecting line are projected inward (i.e. in the axial direction) to form an inner end line 5, and the points on the inner wall of the outer end of the intersecting line are projected outward (i.e. away from the axial direction) to form an outer end line 6. The inner end line 5 and the outer end line 6 coincide at a certain point in the middle of the intersecting line, forming a closed loop vertical surface, which is the cutting path line. The cutting path line is in the pipe diameter direction. The comparison effects before and after processing are shown in Figure 6 and Figure 7 .

[0070] As can be seen from the comparison, Figure 7 the intersecting line curved surface after processing in the above-mentioned avoids the problem that the intersecting line curved surface formed by cutting is too thin due to the small wall thickness of the pipe, thereby affecting the welding strength of the subsequent steel tube end. At the same time, through the processing of the three-dimensional model, the equipment capacity requirement for cutting the intersecting line of such thin-walled pipe is reduced, the use requirement is met, the difficulty of cutting is reduced, the cutting efficiency is improved, and the production cost is reduced.

[0071] Step 4: According to the position of the "arc opening direction mark line" of the laser pipe cutting machine on the steel tube, compare the direction reference mark line on the bending machine die, and ensure that the circular tube is bent and clamped at the correct intersecting line angle.

[0072] Step 5, confirm the clamping direction is correct, and bend the pipe into shape by the pipe bender; in the pipe bending process, the bending angle is set as the sum of the theoretical bending angle and the springback angle, and the springback angle is determined according to the actual measurement results of the springback angles of the steel pipes of the same batch after bending.

[0073] The application also provides a method for studying the springback of steel pipe bending and determining the springback angle (bending angle accuracy).

[0074] There are many factors affecting the springback angle. The springback angles of the steel pipes of the same model, same batch, same bending equipment, same material, same specification and same bending pipe are not the same. The performance of the pipe bender itself has a certain influence on the springback angle. In addition, the lead of the mandrel, the tightness of the chuck, the operation of the operator, etc. have a certain influence on the springback. When the pipe is bent, plastic deformation occurs at the same time, accompanied by elastic deformation. When the pipe bender chuck is loosened or the pipe is taken out of the bending die, the elastic deformation part recovers when the pipe is no longer subjected to external force, which makes the bending angle smaller. In order to make the bending angle after bending meet the theoretical bending angle, the springback angle needs to be added during bending to obtain the design required bending angle.

[0075] At present, the raw material of the same model and different batches has a slight difference, which has little influence on the bending springback and can be ignored. The pipe bender equipment also has a certain influence which can be ignored. The test data can be used as a reference for the forming of steel pipes of the same model and material. In addition, the test data can provide reference values within a certain range. If a special situation with high precision requirement is encountered, a fixed pipe bending equipment needs to be used, and the springback angle measurement test needs to be conducted before each batch of raw material steel pipe is put into production, so as to improve the precision of the bending angle.

[0076] Considering the precision of the pipe bending after the intersecting line cutting of the steel pipe, the springback angle of the commonly used pipe material needs to be measured to find the change rule. The actual measurement of the springback angle of 30CrMo, Φ38x2 and Φ32x2 steel pipes is carried out, and the statistical results are shown in Table 2.

[0077] Table 2 Actual measurement data of 30CrMo steel pipe bending springback angle

[0078]

[0079] Note: The bending radius of the steel pipe is R=2.5D; the degree in the first row is the bending angle, and the corresponding column value is the measured springback angle.

[0080] Step 6, check the dimensions and use the backup welding.

[0081] Through research on a new off-road vehicle frame pipe cutting intersecting line first and then bending pipe process, the application provides a calculation method and forming process technology of cutting intersecting line first and then bending pipe of steel pipe. According to repeated tests of the summarized process method, the size of the vehicle body pipe meets the process requirements, and the production and processing efficiency is greatly improved.

[0082] Taking a new off-road vehicle as an example, the vehicle body pipe is processed according to the traditional process of steel pipe blanking-bending pipe-cutting intersecting line arc opening / machining arc opening, which is a three-step two-time clamping process; according to the method provided by the application, the steel pipe is laser cutting intersecting line blanking-marking bending pipe forming in the opposite direction, which is a two-step one-time clamping process. The process flow is shortened, the efficiency is improved, the clamping times are reduced, the cumulative machining error of repeated positioning is reduced, and the blanking and bending forming efficiency of a single frame steel pipe (the number of single vehicle body steel pipe is 100) can be improved by more than 5 times. It can be gradually applied in the steel pipe processing and forming industry, and provides a certain reference for the production process of new off-road vehicle frame steel pipe processing and forming products and related steel pipe forming and splicing structure.

[0083] The above only describes the preferred embodiments of the application and is not used to limit the application. For those skilled in the art, the application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A forming process method of a vehicle body pipe member, in which a cutting of a first intersecting line and a bending of a pipe are performed, characterized in that, The method comprises the following steps: Step 1: using three-dimensional model drawing software to make three-dimensional modeling of the formed elbow pipe with intersecting lines, and calculating the cutting length of the steel pipe; Step 2: straightening the curved steel pipe in the three-dimensional model generated in step 1, processing the total cutting length of the three-dimensional model of the part according to the cutting length of the steel pipe calculated in step 1, and marking a line in the direction of the arc opening to form a three-dimensional model for laser pipe cutting; Step 3: importing the three-dimensional model obtained in step 2 into the laser pipe cutting machine for cutting, and cutting a mark line in the direction of the arc opening on the surface of the steel pipe, and additionally marking a direction reference line at the fixed position of the clamp mold of the elbow pipe machine; Step 4: comparing the position of the mark line in the direction of the arc opening on the steel pipe with the direction reference line on the clamp mold of the elbow pipe machine to ensure that the pipe is clamped for bending at the correct intersecting line angle; Step 5: bending the pipe into shape by the elbow pipe machine; Step 6: checking the dimensions and reserving for welding; In step 1, the three-dimensional modeling of the formed elbow pipe with intersecting lines is made by using three-dimensional model drawing software, and the cutting length of the blank is calculated, wherein the cutting length of the blank is calculated by the following formula: L = L1 + L2 + L3 + S1 + S2 - ΔS1 - ΔS2; Wherein, L is the cutting length of the blank, L2 is the center line length of the middle straight pipe section, L1 and L3 are the center line lengths of the straight pipe sections at both ends respectively, S1 and S2 are the center line lengths of the curved pipe sections at both ends respectively, and ΔS1 and ΔS2 are the stretching change amounts of the steel pipe at both ends when bending.

2. The method according to claim 1, wherein the method is characterized by, ΔS1 and ΔS2 are obtained by the following method: the actual data of the length of the same batch of steel pipes after bending is measured, and then the actual cutting length is subtracted to obtain the stretching change amount summary table of the same batch of steel pipes under the same operation; when calculating the cutting length, the stretching change amount ΔS1 or ΔS2 is determined according to the steel pipe specification and the bending angle by referring to the stretching change amount summary table.

3. The forming process method for vehicle body tubular components by first cutting the intersecting lines and then bending the tubing according to claim 1, characterized in that, The three-dimensional model drawing software is selected from Creo, UG, SolidWorks, 3ds max, SketchUp, Zbrush or Maya.

4. The method of claim 1, wherein the method further comprises: In step 2, the curved steel pipe is processed to a straightened state by rotating one end of the steel pipe to 180° through the "flatten / straighten" function or the entity "move-rotate" function; the total cutting length of the three-dimensional model of the part is processed by the following method: comparing the cutting length L value calculated in step 1 with the straightened steel pipe, and if there is a difference, the length value of the straightened elbow pipe is adjusted according to the cutting length L value calculated in step 1.

5. The forming process method for vehicle body tubular components by first cutting the intersecting lines and then bending the tubing according to claim 1, characterized in that, In step 2, the arc opening direction mark line is drawn on the steel pipe axis surface after executing the "straight line drawing" command to form a three-dimensional model for laser pipe cutting.

6. The method of forming a tube of a vehicle body by cutting and then bending a first cut intersecting line of a tube member according to claim 1, characterized in that, The arc opening direction mark line is drawn at the intersecting line end position along the axis direction, and the length is 5-10 mm.

7. The method of forming a tube of a vehicle body by cutting and then bending a first cut intersecting line of a tube member according to claim 1, characterized in that, In step 2, the model cutting line interference part is processed, and the processing method is: taking the straightened steel pipe model axis surface as the reference surface, drawing a cutting path line by using the "draw straight line / curve command", and executing the "stretching cutting" command to cut off the excess part along the drawing cutting line in the pipe diameter direction.

8. The method of claim 1, wherein the method further comprises: cutting the tube member to form a first cut intersecting line; and bending the tube member to form a second cut intersecting line. The cutting mode of the arc-shaped direction marking line in step 3 is selected from the group consisting of marking lines on the surface of the steel pipe or directly cutting into straight line notches; and the direction reference marking line is a vertical or horizontal direction.

9. The method of claim 1, wherein the method further comprises: cutting the tube member to form a first cut intersecting line; and bending the tube member to form a second cut intersecting line. In step 5, the bending angle is set as the sum of the theoretical bending angle and the springback angle, and the springback angle is determined according to the actual measurement results of the springback angles of the steel pipes in the same batch.

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