Bending machine and thick plate bending forming method

Abstract

The invention discloses a bending machine and a thick plate bending forming method, and belongs to the technical field of building structure construction. The bending machine comprises a bending machine rack, a PLC control cabinet, a bending lower die arranged on the bending machine rack, a jack arranged on the bending machine rack and a bending upper die. An oil cylinder is arranged on the bending machine rack, an oil pump installed on the bending machine rack is connected out of the oil cylinder, the oil pump is connected to the jack and connected with the PLC control cabinet, and pressing process quantity parameters are input into the PLC control cabinet. The invention further discloses a plate bending forming method adopting the bending machine. The forming precision of the curved surface outer plate can be improved, the dependence on the experience of an operator is reduced, and the more accurate forming effect is achieved; the forming efficiency is improved, the forming technological process is optimized, and the forming period is shortened; the unloading springback problem of thick plate bending is solved, and the actual engineering requirement of curved surface outer plate forming is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of building structure construction, and particularly relates to a bending machine and a method for bending and forming thick plates. Background Art

[0002] Buildings with variable outer surface curves can create a personalized artistic space with their powerful artistic expressiveness, enhancing the visual impact and appeal of the building. Different from traditional steel structure buildings, such buildings involve various structural systems with different shapes and sizes, such as hyperboloids and circular arcs. The curved outer plate not only realizes the appearance of the building but also is the main load-bearing component, with a thickness usually between 15 mm and 50 mm and high precision requirements.

[0003] The curved outer plate and its forming have the characteristics of complex shape, large plate thickness, high precision requirements, unsuitability for die forming, large forming workload, and high difficulty. For a plate to be formed, the currently commonly used forming process is as follows: First, select the larger curvature direction in the target shape to be formed, and after cold press bending to form a single-curvature deformation, then use a handheld oxyacetylene torch to perform local heating correction on certain lines or points on the front or back of the plate to form the required curvature shape. The entire forming process is basically based on the operator's instructions, and the action positions, routes, and process parameters of the cold and hot loads on the plate mostly rely on the long-term experience accumulation of the operator. In addition, before forming, to determine the accuracy of the shape gradual change of the plate to be formed, multiple two-dimensional section templates are usually made, and for shapes with high precision requirements, three-dimensional sample boxes are also made. These detection tools based on the target shape are manually inserted and used during the forming process, and the accuracy is judged by visual comparison with the hand, and then a new loading scheme is formulated based on experience. This is repeated until the forming process of the curved plate ends under the condition that the visual error meets the accuracy requirements. However, this forming process highly depends on the operator's experience, resulting in unsatisfactory forming accuracy and low forming efficiency.

[0004] In terms of bending equipment, existing small bending machines can usually handle thin plates with a thickness of about 1 - 5 mm, medium-sized bending machines can handle plates with a thickness of 1 - 10 mm, and large bending machines can handle steel plates with a thickness of about 10 - 30 mm, unable to meet the bending requirements of more plate thicknesses. In addition, when bending thick plates (such as more than 30 mm), due to the large force applied by local cold loading forming, there is a problem of unloading springback.

[0005] Therefore, providing a bending machine for thick plates and a thick plate bending method to improve the forming accuracy of the curved outer plate, enhance the forming efficiency, overcome the problem of unloading springback, and meet the actual engineering requirements of the curved outer plate forming has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a bending machine and a thick plate bending forming method to at least solve some of the above technical problems.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention discloses a bending machine, comprising a bending machine frame, a PLC control cabinet, a bending lower die arranged on the bending machine frame, a jack arranged on the bending machine frame, and a bending upper die;

[0009] An oil cylinder is provided on the frame of the bending machine, and an oil pump installed on the frame of the bending machine is connected to the oil cylinder. The oil pump is connected to the jack, and the oil pump is connected to the PLC control cabinet. The downward pressure process quantity parameters are input into the PLC control cabinet.

[0010] In some embodiments of the present invention, the bending upper die includes an upper die plate disposed on a telescopic rod of a jack, and a bending knife disposed on the upper die plate and located directly above the bending lower die for cooperating with the bending lower die to press and form the material sheet.

[0011] In some embodiments of the present invention, the bending lower die includes a lower die plate installed on a frame of a bending machine, and a pair of baffles distributed in parallel on the lower die plate.

[0012] In some embodiments of the present invention, a group of bending support plate groups are provided between the inner side of the baffle and the lower template, the two groups of bending support plate groups are spaced apart, and the bending support plate groups include at least three tightly fitting bending support plates; a plurality of reinforcing plates are spaced apart between the outer side of the baffle and the lower template.

[0013] In some implementation schemes of the present invention, the baffle plate is perpendicular to the lower template, the bending knife is perpendicular to the lower template, and the bending knife is located in the middle between the two sets of bending support plate groups.

[0014] The second aspect of the present invention discloses a thick plate bending forming method, which is performed by the bending machine described in the above item; the method comprises the following steps:

[0015] Step 1: Cut and form the sheet;

[0016] Step 2: Draw the forming bending line and the inspection reference line after forming on the sheet;

[0017] Step 3: Determine the pressing process quantity of each bending line by simulation calculation according to the bending line spacing;

[0018] Step 4: Input the pressing process parameters into the bending machine to press the sheet.

[0019] In some embodiments of the present invention, in the first step, when blanking and cutting the formed plate, the dimensions of the formed curved plate are determined according to the processing drawing. The coordinate values of several curves representing the three-dimensional shape of the workpiece are input into the 3D software to determine the four edges of the component, and then the wall thickness is input to generate the solid model of the component, so as to obtain any spatial coordinates on each curved plate. The wall plate is automatically unfolded in the 3D software and the unfolded dimension data of the curved plate is calculated. The unfolded dimension data of the curved plate is input into the flame CNC cutting machine, and the flame CNC cutting machine cuts and forms the raw material into a plate according to the input dimension data;

[0020] Preferably, when calculating the unfolded dimension data of the curved plate, a 10 cm reserved plate value is added to the curved edges on both the left and right sides of the actual unfolded dimension data of the curved plate;

[0021] Preferably, after the plate is cut and formed, the boundary line representing the actual size of the curved plate is marked, and the part outside the boundary line is the reserved plate value area.

[0022] In some embodiments of the present invention, in the second step, when processing the bending line, the bending line is equally divided parallel to the end face linear shape according to the end face linear angle of the curved plate;

[0023] Preferably, when processing the bending line, the distance B between adjacent bending lines conforms to the calculation formula B = 1.2t, where t is the wall thickness of the wall plate.

[0024] In some embodiments of the present invention, in the third step, when calculating and determining the downward pressing process amount, the dynamic explicit incremental algorithm is used to perform cyclic iterative calculations on the sheet metal forming process to accurately obtain the dynamic evolution of the stress-strain field and the displacement field gradient change characteristics of the material during the full cycle of plastic deformation; an inverse analytical model is established based on the preset strain path, the target configuration is predicted through parametric coupling calculations, the geometric parameters of the upper and lower die surfaces are synchronously output, and the reliability of the forming process parameters is evaluated and iteratively optimized in combination with the multi-physical field coupling verification mechanism. The above downward pressing process amount calculation methods of the present invention are all common general knowledge in the technical field. Therefore, the specific calculation process, calculation formula, and detailed calculation principle of the above calculation methods are not described herein.

[0025] In some embodiments of the present invention, in the fourth step, during pressing, the point with the maximum reference strain on the plate is selected as the starting point of the processing path, and then the bending line on the plate is aligned with the bending machine knife edge. During bending and pressing, it is carried out step by step from one end to the other end, and a small downward pressing amount and multiple loading forming methods are adopted to eliminate the influence of the loading sequence on the shape, and an angle template is used for process measurement and control to avoid excessive pressing. The above pressing method is repeated until the curved plate is formed.

[0026] In some embodiments of the present invention, when forming a large-sized curved plate, segmented pressing forming is adopted. During pressing, the forming surface of the material plate is divided into two parts: a forming area and a transition area. First, the forming area is pressed and formed, and then the material plate is moved to press and form the transition area.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention has a simple structure, is scientifically and reasonably designed, and is easy to use. The bending machine of the present invention is more flexible in use and has a lower equipment cost compared with large bending equipment. The bending machine of the present invention is especially suitable for bending steel plates with a smaller area and does not require other auxiliary hoisting or turning-over equipment during use.

[0029] The folding knife of the bending machine of the present invention can be replaced according to the bending requirements to meet various bending needs.

[0030] The method of the present invention can improve the forming accuracy of the curved outer plate, reduce the dependence on the operator's experience, and achieve a more accurate forming effect; improve the forming efficiency, optimize the forming process flow, and shorten the forming cycle; overcome the unloading springback problem of thick plate bending, and meet the actual engineering requirements of the curved outer plate forming.

[0031] The present invention plans the processing path according to the target shape of the plate to be formed, outputs the process parameters obtained from the simulation calculation to the control part of the forming machine, and drives the loading device of the bending machine to perform one or multiple times of loading on the plate to be formed through data, and finally forms the target shape that meets the accuracy requirements.

[0032] In the present invention, the forming of various curved plates can be realized through the planning of the processing path and the configuration of the process parameters. The present invention uses the full-process numerical simulation technology to accurately simulate the deformation and springback during the forming process of the curved plate, guide the optimization of the forming process, the verification of the scheme, and the on-site trial die. It can quickly predict the deformation corresponding to the plate under the loading scheme, and at the same time synchronously correct the downward pressing amount of the curved plate based on the bending compensation, reducing the influence of the springback of the curved plate bending on the forming accuracy.

[0033] The forming method of the present invention has relatively high efficiency for plates with large thickness and curvature. The bending tool used in the forming method of the present invention can be designed according to different usage requirements and the tool can be replaced during the forming process to achieve complex forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the bending machine of the present invention;

[0035] Figure 2 It is an exploded view of the bending machine of the present invention;

[0036] Figure 3 It is a schematic structural diagram of the lower bending die of the present invention;

[0037] Figure 4 This is a schematic structural diagram of the bending upper die of the present invention;

[0038] Figure 5 This is a schematic flow chart of the forming method of the present invention;

[0039] Figure 6 It is a model diagram of a curved surface line

[0040] Figure 7 It is a schematic diagram of the machining path layout

[0041] Figure 8 It is a deformation diagram of the finite element calculation plate;

[0042] Figure 9 It is a flow chart for calculating the downward pressure;

[0043] Figure 10 It is a schematic diagram of the generation of the machining path;

[0044] Figure 11 It is a schematic diagram of the downward pressure of the curved plate

[0045] Figure 12 It is a schematic diagram of the panel pressing;

[0046] Figure 13 It is a schematic diagram of the angle template inspection.

[0047] The names corresponding to the reference numerals in the drawings are as follows: 1 - bending machine frame, 2 - bending lower die, 3 - jack, 4 - bending upper die, 5 - lower template, 6 - baffle, 7 - bending support plate group, 8 - reinforcement plate, 9 - oil cylinder, 10 - oil pump, 11 - PLC control cabinet, 12 - upper template, 13 - bending knife. Detailed implementation manners

[0048] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0049] Embodiment 1

[0050] As shown in the Figure 1-4 accompanying drawings, a bending machine of the present invention includes a bending machine frame 1, a PLC control cabinet 11, a bending lower die 2 provided on the bending machine frame 1, a jack 3 provided on the bending machine frame 1, and a bending upper die 4;

[0051] The bending machine frame 1 is provided with an oil cylinder 9. The oil cylinder 9 leads out an oil pump 10 installed on the bending machine frame 1. The oil pump 10 is connected to the jack 3. The oil pump 10 is connected to the PLC control cabinet 11, and the downward pressing process quantity parameter is input into the PLC control cabinet 11.

[0052] The structure of the present invention is simple, scientifically reasonable in design and convenient to use. Compared with large bending equipment, the bending machine of the present invention is more flexible in use and has a lower equipment cost. The bending machine of the present invention is particularly suitable for bending steel plates with a smaller area and does not require other auxiliary hoisting or turning-over equipment during use.

[0053] Embodiment 2

[0054] As shown in the attached Figure 1-4 figure, a bending machine of the present invention includes a bending machine frame 1, a PLC control cabinet 11, a bending lower die 2 provided on the bending machine frame 1, a jack 3 provided on the bending machine frame 1, and a bending upper die 4;

[0055] The bending machine frame 1 is provided with an oil cylinder 9. The oil cylinder 9 leads out an oil pump 10 installed on the bending machine frame 1. The oil pump 10 is connected to the jack 3. The oil pump 10 is connected to the PLC control cabinet 11, and the downward pressing process quantity parameter is input into the PLC control cabinet 11.

[0056] The bending upper die 4 includes an upper template 12 provided on the telescopic rod of the jack 3 and a bending knife 13 provided on the upper template 12 and located directly above the bending lower die 2 for cooperating with the bending lower die 2 to press and form the material plate.

[0057] On the basis of Embodiment 1, Embodiment 2 gives a more preferable technical solution. Specifically, it is defined that the bending upper die 4 includes an upper template 12 provided on the telescopic rod of the jack 3 and a bending knife 13 provided on the upper template 12 and located directly above the bending lower die 2 for cooperating with the bending lower die 2 to press and form the material plate. The bending knife of the present invention can be replaced according to the bending requirements to meet various bending requirements.

[0058] Embodiment 3

[0059] As shown in the attached Figure 1-4 figure, a bending machine of the present invention includes a bending machine frame 1, a PLC control cabinet 11, a bending lower die 2 provided on the bending machine frame 1, a jack 3 provided on the bending machine frame 1, and a bending upper die 4;

[0060] The bending machine frame 1 is provided with an oil cylinder 9. The oil cylinder 9 leads out an oil pump 10 installed on the bending machine frame 1. The oil pump 10 is connected to the jack 3. The oil pump 10 is connected to the PLC control cabinet 11, and the downward pressing process quantity parameter is input into the PLC control cabinet 11.

[0061] The upper bending die 4 comprises an upper die plate 12 arranged on the telescopic rod of the jack 3 , and a bending knife 13 arranged on the upper die plate 12 and located just above the lower bending die 2 for cooperating with the lower bending die 2 to press and form the material plate.

[0062] The bending lower die 2 comprises a lower die plate 5 mounted on a bending machine frame 1 , and a pair of baffles 6 distributed in parallel on the lower die plate 5 .

[0063] A group of bending support plate groups 7 is provided between the inner side of the baffle 6 and the lower template 5, and the two groups of bending support plate groups 7 are distributed at intervals. The bending support plate groups 7 include at least three tightly fitting bending support plates; a plurality of reinforcing plates 8 are distributed at intervals between the outer side of the baffle 6 and the lower template 5.

[0064] The baffle plate 6 and the lower template 5 are perpendicular to each other, the bending knife 13 and the lower template 5 are perpendicular to each other, and the bending knife 13 is located in the middle between the two groups of bending support plate groups 7.

[0065] This embodiment 3 provides a more preferred technical solution based on embodiment 2. Specifically, it defines the specific structure and connection system of the lower bending mold; at the same time, it defines the position system of the lower mold plate, the baffle plate and the bending knife.

[0066] Example 4

[0067] This embodiment discloses a thick plate bending forming method, and its process flow is as follows: Figure 5 As shown, the specific steps include:

[0068] Step 1: Cut and form the sheet;

[0069] When cutting and forming the material plate, determine the size of the formed curved plate according to the processing drawing, input the coordinate values ​​of several curves on the workpiece that represent its three-dimensional shape in the three-dimensional software, determine the four edges of the component, and then input the wall thickness to generate the component solid model, so as to obtain any spatial coordinates on each curved plate; the surface line model diagram is as shown in the attached figure. Figure 6 shown.

[0070] The wall panels are automatically unfolded and the unfolded dimension data of the curved panels are calculated in the three-dimensional software. The unfolded dimension data of the curved panels are input into the flame CNC cutting machine, and the flame CNC cutting machine cuts the raw materials into formed panels according to the input dimension data.

[0071] When calculating the unfolded size data of the curved plate, add a 10cm board surface reserve value to the curved edges on both sides of the actual unfolded size data of the curved plate. By setting the reserve value, it is possible to prevent the occurrence of pressing defects at the board boundaries on both sides of the panel due to pressing during the pressing process, such as: tearing of thick plates, edge breaking, and board side warping. After the pressing is completed, the reserved part of the material is cut off along the designed edge line, and the cut is polished flat.

[0072] After the material plate is cut and formed, mark the boundary line indicating the actual size of the curved plate, and the area outside the boundary line is the reserved value area of the plate surface.

[0073] Step Two: Draw the processing forming bending lines and the inspection reference lines after forming on the material plate;

[0074] When processing the bending lines, set the bending lines equally divided according to the linear angle of the end face of the curved plate and parallel to the end face line shape. When processing the bending lines, the distance B between adjacent bending lines conforms to the calculation formula B = 1.2t, where t is the wall thickness of the wall plate.

[0075] In this embodiment, t is taken as 70 mm;

[0076] b = 1.2t = 1.2×70 = 84 mm;

[0077] Finally, take the distance between the rolling tracks as 80 mm.

[0078] As shown in the appendix Figure 7 Mark the boundary line of the panel in the steel plate. The area outside the boundary line is the reserved area to avoid quality defects caused by the accuracy problem of the rolling process.

[0079] Step Three: Simulate and calculate according to the bending line distance to determine the downward pressing process amount of each bending line;

[0080] When calculating and determining the downward pressing process amount, use the dynamic explicit incremental algorithm to perform cyclic iterative calculations on the sheet metal forming process, accurately obtain the dynamic evolution of the stress-strain field and the displacement field gradient change characteristics of the material during the full cycle of plastic deformation; establish an inverse analytical model based on the preset strain path, predict the target configuration through parametric coupling calculations, synchronously output the geometric parameters of the upper and lower die surfaces, and combine the multi-physical field coupling verification mechanism to evaluate the reliability of the forming process parameters and perform iterative optimization.

[0081] In this embodiment, the deformation diagram of the finite element calculation plate is as shown in the appendix Figure 8 shown; the flowchart of the downward pressing amount calculation is as shown in the appendix Figure 9 shown, the schematic diagram of the path generation is as shown in the appendix Figure 10 shown, and the schematic diagram of the downward pressing amount of the curved plate is as shown in the appendix Figure 11 shown.

[0082] Step Four: Input the downward pressing process amount parameters into the bending machine to press the material plate.

[0083] During pressing, select the place with the maximum reference strain on the material plate as the starting point of the processing path, then align the bending lines on the material plate with the cutting edge of the bending machine, and gradually press from one end to the other end during bending pressing. Adopt the forming method of small downward pressing amount and multiple loading to eliminate the influence of the loading sequence on the shape, and use an angle template to measure and control the process to avoid excessive pressing. Repeat the above pressing method until the curved plate is formed.

[0084] In this embodiment, the fillet of the bending knife is controlled to be 0.3 mm, and the width of the lower die groove is 6t, that is, 420 mm.

[0085] When forming a large-sized curved plate, segmented pressing forming is adopted. During pressing, the forming surface of the material plate is divided into two parts: a forming area and a transition area. First, the above-mentioned pressing method is used to press and form the forming area, and then the material plate is moved, and the above-mentioned pressing method is used to press and form the transition area.

[0086] The schematic diagram of panel pressing is as shown in the appendix Figure 12 shown, and the schematic diagram of angle template inspection is as shown in the appendix Figure 13 shown.

[0087] Finally, it should be noted that the above embodiments are only relatively preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting it, and certainly not limiting the patent scope of the present invention. Any meaningless changes or polish made on the main design idea and spirit of the present invention, as long as the technical problems solved are still the same as those of the present invention, should be included in the protection scope of the present invention; in addition, directly or indirectly applying the technical solutions of the present invention to other related technical fields shall also be included in the patent protection scope of the present invention by the same token.

Claims

1. A bending machine, characterized in that, It includes a bending machine frame (1), a PLC control cabinet (11), a lower bending die (2) provided on the bending machine frame (1), a jack (3) provided on the bending machine frame (1), and an upper bending die (4); An oil cylinder (9) is provided on the bending machine frame (1). An oil pump (10) installed on the bending machine frame (1) is connected to the oil cylinder (9). The oil pump (10) is connected to the jack (3) and is also connected to the PLC control cabinet (11). The downward pressing process quantity parameter is input into the PLC control cabinet (11).

2. A bending machine according to claim 1, characterized in that, The upper bending die (4) includes an upper template (12) provided on the telescopic rod of the jack (3), and a bending knife (13) provided on the upper template (12) and located directly above the lower bending die (2) for cooperating with the lower bending die (2) to press and form the material plate.

3. A bending machine according to claim 1 or 2, characterized in that, The lower bending die (2) includes a lower template (5) installed on the bending machine frame (1), and a pair of baffles (6) parallelly distributed on the lower template (5).

4. A bending machine according to claim 3, characterized in that, A group of bending support plate groups (7) are provided between the inner side of the baffle (6) and the lower template (5). The two groups of bending support plate groups (7) are spaced apart. The bending support plate group (7) includes at least three closely fitting bending support plates. A plurality of reinforcing plates (8) are spaced apart between the outer side of the baffle (6) and the lower template (5).

5. A bending machine according to claim 3, characterized in that, The baffle (6) is perpendicular to the lower template (5), and the bending knife (13) is perpendicular to the lower template (5). The bending knife (13) is located at the middle position between the two groups of bending support plate groups (7).

6. A method for bending and forming thick plates, characterized in that, It is carried out by using the bending machine described in any one of claims 1-5; the method includes the following steps: Step 1, cutting and forming the material plate; Step 2, drawing the processing forming bending line and the detection reference line after forming on the material plate; Step 3, simulating and calculating according to the bending line spacing to determine the downward pressing process quantity of each bending line; Step 4, inputting the downward pressing process quantity parameter into the bending machine to press the material plate.

7. A thick plate bending and forming method according to claim 6, characterized in that, In the said Step 1, when cutting and forming the material plate, determine the size of the formed curved plate according to the processing drawing. Input the coordinate values of several curves representing the three-dimensional shape of the workpiece in the three-dimensional software, determine the four edges of the component, then input the wall thickness, generate the solid model of the component, so as to obtain any spatial coordinates on each curved plate. Automatically unfold the wall plate in the three-dimensional software and calculate the unfolded size data of the curved plate. Input the unfolded size data of the curved plate into the flame numerical control cutting machine, and the flame numerical control cutting machine cuts and forms the material plate according to the input size data; Preferably, when calculating the unfolded size data of the curved plate, add a 10-cm plate surface reserved value to the curved edges on both the left and right sides of the actual unfolded size data of the curved plate; Preferably, mark the boundary line representing the actual size of the curved plate after the material plate is cut and formed. The part outside the boundary line is the plate surface reserved value area.

8. A method for bending and forming thick plates according to claim 6 or 7, characterized in that, In the said Step 2, when processing the bending line, set the bending lines equally divided parallel to the end face linear shape according to the end face linear shape angle of the curved plate; Preferably, when processing the bending line, the distance B between adjacent bending lines conforms to the calculation formula B = 1.2t, where t is the wall thickness of the wall plate.

9. A thick plate bending and forming method according to claim 6 or 7, characterized in that, In the fourth step, during pressing, select the location with the maximum reference strain on the material plate as the starting point of the processing path. Then align the bending line on the material plate with the cutting edge of the bending machine. During the bending and pressing process, proceed step by step from one end to the other end. Adopt the forming method with small downward displacement and multiple loadings to eliminate the influence of the loading sequence on the shape. Use an angle template for process measurement and control to avoid excessive pressing. Repeat the above pressing method until the curved plate is formed.

10. A method for bending and forming thick plates according to claim 9, characterized in that, When forming a large-sized curved plate, use segmented pressing to form. During pressing, divide the forming surface of the material plate into two parts: a forming area and a transition area. First, press and form the forming area, and then move the material plate to press and form the transition area.

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