Spinning forming method for drum pressing blank
Through the drum press and the staged spin forming method, the thinning and material waste of large curved bus parts during multi-pass spin are solved, and efficient forming and material utilization are improved.
Patent Information
- Application Number
- CN202410003857.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-03
- Publication Date
- 2025-07-04
AI Technical Summary
When large curved bus parts are spinned multiple times, the blank is severely thinned and does not attach to the mold, resulting in waste of materials.
The flat blank is pressed into a drum blank by using a drum press. By determining the trajectory boundary points P0, P1, P2, P3, P4, and P5, spin forming is carried out in stages, including shear spinning and ordinary spinning, and the spinning spacing and pass spacing are controlled to avoid excessive thinning of the blank and edge instability.
Effectively reduce blank edge instability and cracking, improve manufacturing efficiency, reduce material waste, and ensure product quality.
Smart Images
Figure CN120243720A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of metal plastic forming, and particularly relates to a method for spinning forming a bulging blank. Background Art
[0002] Metal spinning is a process of clamping a metal sheet blank or cylindrical blank on a spinning machine tool and rotating it, while pressing tightly on its surface with a spinning wheel or rolling bar to apply pressure point by point, causing local plastic deformation, and finally forming various hollow rotating parts. Spinning is a near-net forming process that combines the process characteristics of forging, stretching, extrusion, bending, ring rolling, cross rolling, and rolling. It can efficiently form thin-walled rotating parts integrally, and has the advantages of good deformation conditions, high product performance, high dimensional accuracy, high material utilization rate, and a wide range of products. Since the spinning wheel and the metal are in point contact during spinning, the deformation occurs point by point and there is no cutting, which is not only beneficial to metal deformation, improves the product performance, but also can improve the material utilization rate, especially suitable for forming metals with poor plasticity.
[0003] For a curved generatrix part, the semi-cone angle changes continuously from the small end to the large end, and generally has a large change range. It is difficult to form the required curved generatrix part by simple spinning or single-pass power spinning. Multi-pass spinning is a process of gradually deforming the blank into the target rotating part by spinning the blank with a spinning wheel multiple times. In contrast, multi-pass conventional spinning has stable forming, high repeatability, and can improve the forming limit and forming accuracy. This feature also enables the spinning forming of difficult-to-deform materials and workpieces with complex shapes.
[0004] Based on the above advantages of multi-pass spinning, multi-pass spinning is currently commonly used to form precision curved generatrix parts. However, when multi-pass spinning a large (5m-class) curved generatrix part, the blank often shows serious thinning and non-conforming to the die. To solve the above problems, the blank is often thickened, resulting in a great waste of materials.
[0005] Therefore, there is an urgent need for a method for spinning forming a bulging blank to solve the problems of serious thinning and non-conforming to the die of the blank during multi-pass spinning of large curved generatrix parts in the prior art, and the waste of materials caused by thickening the blank. Summary of the Invention
[0006] In view of the above analysis, the embodiment of the present invention aims to provide a method for spinning forming a bulging blank to solve the problems of serious thinning and non-conforming to the die of the blank during multi-pass spinning of large curved generatrix parts 1 in the prior art, and the waste of materials caused by thickening the blank.
[0007] The object of the present invention is mainly achieved by the following technical solutions:
[0008] A method for spinning forming a bulging blank includes the following steps:
[0009] A. Pressing a bulging blank;
[0010] B. Determine the trajectory demarcation points;
[0011] C. Load the drum blank;
[0012] D. First-stage spinning forming;
[0013] E. Second-stage spinning forming;
[0014] F. Demold and complete the spinning forming.
[0015] Furthermore, step A, pressing the drum blank includes: calculating the blanking size.
[0016] Furthermore, the trajectory demarcation points include P0, P1, P2, P3, P4, and P5, which are divided by shear spinning and conventional spinning or the blank instability point.
[0017] Furthermore, P0 is the workpiece center.
[0018] Furthermore, P1 is the starting point of spinning.
[0019] Furthermore, P2 is the demarcation point between shear spinning and conventional spinning.
[0020] Furthermore, P3 is the blank instability point.
[0021] Furthermore, P4 is the end point of the blank shape transition.
[0022] Furthermore, P5 is the end point of spinning.
[0023] Furthermore, step D, the first-stage spinning forming includes: P1 - P2 is the first-stage spinning forming, adopting one-pass shear spinning, and the shear spinning pass spacing is 635.5 mm.
[0024] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:
[0025] (1) The forming method of the present invention uses a drum press to press a flat blank into a drum blank. After forming the drum blank, the blank can be closer to the outer profile of the core mold. During the forming process, the deformation degree is small, avoiding excessive wall thickness reduction, and is more conducive to reducing product rejection caused by blank edge instability;
[0026] (2) In the forming method of the present invention, P3 is the instability point of the blank. After exceeding the instability point, instability phenomena such as cracking and eccentricity occur during the spinning process due to excessive deformation of the blank. This occurs when the length of the bus bar in the undeformed area of the bulged blank accounts for 55%-60% of the bus bar length; during the process of the blank conforming to the die in the P3-P4 interval, the cross-section of the blank is in the transition stage from an arc shape to a straight shape, and the deformation of the blank is large. Reducing the pass spacing can reduce the deformation of the flange part and prevent the occurrence of edge cracking. Not using continuous floating tool passes can prevent the blank from thinning, and at the same time greatly improve the manufacturing efficiency of the workpiece.
[0027] In the present invention, the above technical solutions can be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the following content. Moreover, some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the text and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The drawings are only for the purpose of showing specific embodiments and are not considered as limiting the present invention. Throughout the drawings, the same reference signs denote the same components.
[0029] Figure 1 is a schematic flow chart of the spinning forming method;
[0030] Figure 2 is a schematic axial sectional structure diagram of the curved bus bar part of the present invention;
[0031] Figure 3 is an overall schematic diagram of the spinning trajectory.
[0032] Reference signs: 1 - curved bus bar part; 2 - core mold. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0033] The following will specifically describe the preferred embodiments of the present invention with reference to the drawings. Among them, the drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, and are not used to limit the scope of the present invention.
[0034] As Figure 2 shown, the curved bus bar part 1 to be formed in the present invention has a diameter of 5002 mm and a height of 1800 mm. The inner surface of the curved bus bar part 1 is composed of two arcs and a straight edge; the arc radii are 2800 mm and 520 mm respectively, and the length of the straight edge is 50 mm.
[0035] A specific embodiment of the present invention, as Figure 1 shown, discloses a spinning forming method for a bulged blank (hereinafter referred to as the forming method), including the following steps:
[0036] Step 1: Press the bulged blank;
[0037] Calculate the blanking size:
[0038] Preferably, the flat blank is designed according to the principle that the surface area of the flat blank will increase by 3%-5% after spinning. Then, the radius R of the bulged blank is calculated according to the empirical formula R = D*0.833 / 1.2, and the height of the bulged blank is obtained based on the principle of equal area. Here, D is the diameter of the flat blank.
[0039] Preferably, a bulging machine is used to press the flat blank into a bulged blank. After forming the bulged blank, the blank can be closer to the outer surface of the core mold 2, with a small deformation degree during the forming process, avoiding excessive thinning of the wall thickness, and being more conducive to reducing the product scrap caused by the instability of the blank edge.
[0040] Step 2: Determine the trajectory demarcation points
[0041] Preferably, as Figure 3 shown, the trajectory demarcation points P0, P1, P2, P3, P4, P5 are divided by the shear spinning and ordinary spinning, and the blank instability points.
[0042] P0 is the center of the workpiece;
[0043] P1 is the starting point of spinning;
[0044] P2 is the demarcation point between shear spinning and ordinary spinning; the point P2 is determined according to the shear spinning gap;
[0045] P3 is the blank instability point. After exceeding the instability point, instability phenomena such as cracking and eccentricity will occur during the spinning process due to excessive deformation of the blank, which appears when the length of the busbar of the undeformed area of the bulged blank accounts for 55%-60% of the busbar length; by identifying the two points P3 and P4, it is possible to prevent instability phenomena such as edge cracking and wrinkling caused by large blank deformation; it is possible to avoid using floating tool passes to thin the blank; and it is possible to timely adjust the pass spacing to improve production efficiency.
[0046] P4 is the end point of the blank shape transition;
[0047] P5 is the end point of spinning.
[0048] H is the spinning gap, which is the gap between the spinning wheel and the core mold 2, and h is the blank thickness.
[0049] Step 3: Load the bulged blank
[0050] Load the formed bulged blank on the core mold 2, and use the tailstock to press the bulged blank and the core mold 2 tightly.
[0051] Step 4: Spinning forming in the first stage
[0052] No spinning is performed in the tailstock area from P0 to P1;
[0053] P1 - P2 is the first - stage spin - forming, using single - pass shear spinning. The spacing between shear - spinning passes is 635.5 mm, which can make the gap between the blank and the die smaller. At the same time, it can reduce the number of spinning passes, facilitate the replacement of a larger tailstock, and improve the spin - forming efficiency.
[0054] Preferably, the spinning spacing is 635.5 mm. Because when the spacing exceeds this value, the gap between the formed area and the die increases sharply, and at the same time, the blank thinning is serious.
[0055] Preferably, H = h * sinα. The included angle α between the mandrel 2 and the blank is in a changing state, so H also changes accordingly, and the trajectory also changes accordingly.
[0056] Step 5: Second - stage spin - forming
[0057] P2 - P3 is the second - stage spin - forming, using conventional spinning, and the spinning spacing is 150 - 180 mm.
[0058] Preferably, H = h.
[0059] Step 6: Third - stage spin - forming
[0060] P3 - P4 is the third - stage spin - forming, using conventional spinning, and the spinning spacing is 75 - 90 mm.
[0061] Preferably, in the Abaqus finite - element simulation and the workpiece production practice, it is found that during the process of the blank conforming to the die in the P3 - P4 interval, the cross - section of the blank is in the transition stage from an arc - shape to a straight - shape, and the deformation of the blank is large. Narrowing the pass spacing can reduce the deformation of the flange part and prevent the occurrence of edge cracking. Not using continuous floating - tool passes can prevent the blank from thinning, and at the same time, it greatly improves the workpiece manufacturing efficiency.
[0062] Preferably, H = h.
[0063] Step 7: Fourth - stage spin - forming
[0064] P4 - P5 is the fourth - stage spin - forming, using conventional spinning, and the spinning spacing is 150 - 180 mm.
[0065] Preferably, when the blank edge does not wrinkle, the conforming gap is small, and the forming efficiency is the highest, the maximum average spinning pass spacing in conventional spinning can be 180 mm.
[0066] Conventional spinning can increase the surface area of the flat blank by 3% - 5%. When forming, the area between the starting point and the ending point of the spinning part increases by 8 - 12%. When forming a bulged blank, the area between the starting point and the ending point of the spinning part increases by about 4.4% - 7.2%. The blank thinning mainly occurs in the P4 - P5 interval.
[0067] Preferably, in the fourth-stage spin forming, for the Nth pass, H ranges from H = h - h * 4.4% * (N - 1) to H = h - h * 7.2% * (N - 1).
[0068] Preferably, to determine H for the last pass: Use an ultrasonic thickness gauge to measure the wall thickness value on the billet generatrix every 100 - 150 mm, measure the H value on one generatrix every 60°, finally take the average thickness, and add the radius of the mandrel 2 to the average thickness. Then, a spinning trajectory can be obtained by fitting with a CAD spline curve. Compared with using a uniform spinning gap to obtain the spinning trajectory by fitting, the billet mold-fitting gap can be made smaller, and the spinning gap at the billet edge will not increase during the spinning process, resulting in the billet being unable to be formed or requiring re-spinning for repair.
[0069] Step 8: Spin forming in the demolding stage
[0070] Preferably, the trajectory in the demolding section adopts the tangent at the end point of the last pass. The force of the spinning wheel on the billet is along the tangent direction, reducing the force in the normal direction, thereby reducing the influence on the mold-fitting section and decreasing the demolding gap.
[0071] Step 9: Demold and complete the spin forming
[0072] Remove the tailstock, take the curved generatrix part 1 off the mandrel 2, and complete the spin forming.
[0073] Compared with the prior art, the forming method in this embodiment uses a bulging machine to press a flat billet into a bulged billet. After forming the bulged billet, the billet can be closer to the outer contour surface of the mandrel 2. During the forming process, the deformation degree is small, avoiding excessive wall thickness reduction, and being more conducive to reducing product scrapping caused by instability at the billet edge; P3 is the instability point of the billet. After exceeding the instability point, instability phenomena such as cracking and eccentricity occur during the spinning process due to excessive billet deformation, which appears when the length of the generatrix in the undeformed area of the bulged billet accounts for 55% - 60% of the generatrix length; during the interval from P3 to P4, the cross-section of the billet is in the transition stage from an arc shape to a straight shape during the mold-fitting process of the billet, and the billet deformation is large. Narrowing the pass spacing can reduce the deformation amount of the flange part and prevent the occurrence of edge cracking. Not using continuous floating tool passes can prevent billet thinning, and at the same time greatly improve the workpiece manufacturing efficiency.
[0074] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. A method for spin forming a drum blank, characterized in that, It includes the following steps: A. Press the blank of the pressure drum; B. Determine the trajectory demarcation points; C. Load the blank of the pressure drum; D. Spin forming in the first stage; E. Spin forming in the second stage; F. Demold and complete the spin forming.
2. The spinning forming method of the press drum blank according to claim 1, characterized in that The step A, pressing the blank of the pressure drum, includes: calculating the blanking size.
3. The spinning forming method of the drum blank according to claim 1, characterized in that, The step B, the trajectory demarcation points, includes P0, P1, P2, P3, P4 and P5, which are demarcated by shear spinning and conventional spinning or the instability point of the blank.
4. The method for spin forming a drum blank according to claim 3, characterized in that, The P0 is the center of the workpiece.
5. The method for spin forming a drum blank according to claim 3, characterized in that, The P1 is the starting point of spinning.
6. The method for spin forming a drum blank according to claim 3, wherein, The P2 is the demarcation point between shear spinning and conventional spinning.
7. The method for spin forming a drum blank according to claim 3, wherein The P3 is the instability point of the blank.
8. The method for spin forming a drum blank according to claim 3, characterized in that, The P4 is the ending point of the blank shape transition.
9. The method for spin forming a drum blank according to claim 3, characterized in that, The P5 is the ending point of spinning.
10. The method for spin forming a drum blank according to claim 3, wherein The step D, spin forming in the first stage, includes: P1 - P2 is spin forming in the first stage, adopting one-pass shear spinning, and the shear spinning pass pitch is 635.5 mm.