Method of hydroforming a part using a bladder

Abstract

The application provides a part rubber bag hydraulic forming method, and belongs to the technical field of rubber bag hydraulic forming. The method comprises the following steps: firstly, designing a preliminary process model suitable for rubber bag forming of an irregular complex hyperboloid part with large deformation; secondly, designing a final process model suitable for rubber bag forming of the part with resilience; thirdly, determining an unfolded raw material according to the final process model with resilience; then, performing rubber bag hydraulic forming to form a process model structure workpiece; if the raw material of the part is an aluminum alloy, performing quenching heat treatment on the process model structure workpiece, and then using a cutting die to correct the shape; finally, fixing the process model structure workpiece on the cutting die, removing the process allowance, and cutting the part. Through the method, the part shape accuracy and the part surface quality can be improved, the part consistency can be improved, and the waste product rate can be reduced.

Description

Technical Field

[0001] This application belongs to the field of rubber bladder hydroforming technology, and particularly relates to a method for rubber bladder hydroforming of a part. Background Technology

[0002] Irregular and complex hyperboloid parts with large deformation amounts exhibit both compression and tension deformations simultaneously, with some areas approaching or even exceeding the deformation limit.

[0003] Sheet metal parts with complex shapes and rapidly changing curves are generally formed by drop forming, followed by shaping or trimming to meet the requirements of the drawings. However, drop forming is a semi-mechanical, semi-manual forming process, which is prone to wrinkles, cracks, and misalignment. The accuracy of the part shape and the surface quality of the part are poor, the consistency of the parts is poor, and the scrap rate is high. Summary of the Invention

[0004] To address the problems of poor part shape accuracy and surface quality, poor part consistency, and high scrap rate caused by drop forming methods in related technologies, this invention provides a rubber bladder hydroforming method for irregular and complex hyperboloid parts with large deformation. The technical solution is as follows:

[0005] A method for hydroforming a rubber bladder for a part, the method comprising:

[0006] Step 1: Using process compensation methods, design a preliminary process model for rubber bladder forming of irregular and complex hyperboloid parts with large deformation.

[0007] Step 2: Using springback compensation, design the final process model suitable for the springback of the rubber bladder forming part;

[0008] Step 3: Determine the unfolded raw material according to the final process model with springback;

[0009] Step 4: Rubber bladder hydroforming to form the process model structure workpiece;

[0010] Step 5: If the raw material of the part is aluminum alloy, the workpiece of the process model structure is quenched and heat-treated, and then shaped using a cutting die.

[0011] Step 6: Fix the workpiece of the process model structure onto the cutting die, remove the process allowance, and cut the shaped part.

[0012] Optionally, in step 1, a process compensation method is used to design a preliminary process model suitable for the rubber bladder forming of irregular and complex hyperboloid parts with large deformation by analyzing the stress and strain of the parts.

[0013] Optionally, in step 1, the process compensation process includes:

[0014] When there is significant compressive deformation at the end of a part, the outer extension is increased to allow for bulging.

[0015] When there is significant tensile deformation at the end of a part, the allowance is increased as the inner shape extends outward.

[0016] The extra allowance at the end of the part connects with the rest of the part to form a conformal, irregular, three-dimensional hollow structure.

[0017] The height is increased along the opening direction of the three-dimensional hollow structure to form a sidewall of a predetermined depth.

[0018] Optionally, step 2 includes:

[0019] Design rubber bladder forming molds suitable for irregular and complex hyperboloid parts with large deformation;

[0020] Finite element simulation of rubber bladder formation and rebound compensation was performed.

[0021] Springback compensation is applied to the surface of the rubber bladder forming mold.

[0022] Based on the mold surface with springback compensation, create the final process model with springback.

[0023] Optionally, the rubber bladder forming mold includes a mold body, a pressure cap, and a cutting mold, with the mold body and pressure cap connected.

[0024] The mold body is designed according to the external shape of the final process model with springback, and is a concave mold structure;

[0025] The cutting die is designed according to the inner surface of the preliminary process model. It is a punch structure and requires the marking of cutting lines.

[0026] The cap is designed according to the mold body, and is a ring structure with an opening in the middle. The size of the opening in the middle of the cap is designed according to the forming contour size of the concave surface of the mold body; the lower surface of the cap is designed according to the upper surface of the mold body.

[0027] Optionally, in step 3, the shape and size of the unfolded fabric are determined by the final process model with springback.

[0028] Optionally, step 4 includes:

[0029] The raw material is processed and unfolded using CNC milling equipment, the edge burrs are removed, and the end face is sanded.

[0030] The unrolled material is placed on the mold body, and the pressure cap is pressed down on the unrolled material. The mold body and the pressure cap are connected by pins.

[0031] Using a rubber bladder hydraulic forming machine, the rubber bladder acts as a soft punch, causing the unfolded blank to adhere to the mold body and form a workpiece with a process model structure.

[0032] Optionally, in step 6, the process model structure workpiece is fixed on the cutting die, and the increased process allowance is removed according to the cutting line of the cutting die to complete the processing and manufacturing of the part.

[0033] The present invention provides a rubber bladder hydroforming method for irregular and complex hyperboloid parts. This method forms irregular and complex hyperboloid parts with large deformation, improves the accuracy of part shape and surface quality, enhances part consistency, and reduces scrap rate. It has the advantages of high forming quality, low processing cost, short production cycle and simple mold structure, and is suitable for mass production. Attached Figure Description

[0034] Figure 1 A schematic diagram of an irregular and complex hyperboloid part with large deformation is provided for an embodiment of this application;

[0035] Figure 2 This is a schematic flowchart of a method for hydroforming a rubber bladder for a part, provided in an embodiment of this application.

[0036] Figure 3 A schematic diagram of a process model for forming a rubber bladder for irregular and complex hyperboloid parts with large deformation, provided in an embodiment of this application;

[0037] Figure 4 A structural diagram of a rubber bladder forming mold provided in an embodiment of this application;

[0038] Figure 5 A schematic diagram of a phantom provided in an embodiment of this application;

[0039] Figure 6 A schematic diagram of a cutting mold provided in an embodiment of this application;

[0040] Figure 7 A schematic diagram of a capping device provided in an embodiment of this application;

[0041] Figure 8 This application provides a schematic diagram of the unfolded shape and dimensions of a piece of wool fabric as an embodiment.

[0042] Figure 9 A schematic diagram of the fit between a mold body and a pressure cap provided in an embodiment of this application;

[0043] Figure 10 A schematic diagram of a process model workpiece after hydroforming of a rubber bladder, provided in an embodiment of this application;

[0044] Figure 11 A schematic diagram of a workpiece structure modeled by a cutting die forming process is provided in an embodiment of this application;

[0045] Figure 12This is a schematic diagram of the upper right fairing component provided in an embodiment of this application;

[0046] Figure 13 A schematic diagram of a manufacturing process model for an upper right fairing component provided in this application embodiment;

[0047] Figure 14 A schematic diagram of the rubber bladder forming mold for the upper right fairing component provided in this application embodiment;

[0048] Figure 15 This is a schematic diagram of another phantom provided in an embodiment of this application;

[0049] Figure 16 This is a schematic diagram of another cutting mold provided in an embodiment of this application;

[0050] Figure 17 Another schematic diagram of the capping provided in this application embodiment;

[0051] Figure 18 This is a schematic diagram of the unfolded blank of the upper right fairing part provided in an embodiment of this application;

[0052] Figure 19 This is a schematic diagram of another mold and gland assembly provided in an embodiment of this application;

[0053] Figure 20 A schematic diagram of another process model workpiece after hydroforming of a bladder, provided in an embodiment of this application;

[0054] Figure 21 This is a schematic diagram of a workpiece structure for another cutting mold straightening process provided in an embodiment of this application. Detailed Implementation

[0055] The present application will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0056] Rubber bladder hydroforming is a type of rubber forming technology, which can currently be applied to the forming of simple sheet metal parts such as aircraft frames and ribs. However, this rubber forming technology is currently difficult to apply to the forming of sheet metal parts with complex shapes and rapidly changing curvatures.

[0057] For example, Figure 1 This invention provides a method for hydroforming an irregular, complex hyperboloid part with large deformation, as shown in the schematic diagram. Figure 2 As shown, it includes the following steps:

[0058] Step 1: Using process compensation methods, design a preliminary process model for rubber bladder forming of irregular and complex hyperboloid parts with large deformation.

[0059] By employing a process compensation approach and analyzing the stress and strain of the part, a preliminary process model suitable for the forming of rubber bladders for irregular and complex hyperboloid parts with large deformations is designed. The process compensation process is as follows:

[0060] 1) When there is significant compressive deformation at the end of the part, the bulging allowance is increased on the outer edge;

[0061] 2) When there is significant tensile deformation at the end of the part, the allowance is increased as the inner shape extends outward;

[0062] 3) The added allowance at the end of the part connects with the rest of the part to form a conformal, irregular, three-dimensional hollow structure;

[0063] 4) Increase the overall height along the opening direction of the three-dimensional hollow structure to form a sidewall of a preset depth.

[0064] Step 2: Using springback compensation, design the final process model suitable for the springback of the rubber bladder forming of the part.

[0065] Step 21: Design a rubber bladder forming mold suitable for irregular and complex hyperboloid parts with large deformation.

[0066] Step 22: Perform finite element simulation of rubber bladder forming and rebound compensation.

[0067] Step 23: Perform springback compensation on the surface of the rubber bladder forming mold.

[0068] Step 24: Based on the mold surface with springback compensation, create the final process model with springback compensation. For example... Figure 3 As shown, Figure 3 10 indicates that the shape extends outward from the inner end, 20 indicates the part, 30 indicates that the end has an increased bulging allowance, and 40 indicates that the overall height has increased.

[0069] Design a rubber bladder forming mold suitable for irregular and complex hyperboloid parts with large deformation, comprising a mold body 3, a pressure cap 2, and a cutting mold 1. Figure 4 As shown, mold body 3 and pressure cap 2 are connected by pins. The mold body is designed according to the external shape of the final process model with springback, and is a cavity mold structure. It is the main forming component, such as... Figure 5 As shown. The cutting die is designed according to the inner surface of the preliminary process model. It is a punch structure and requires the marking of cutting lines, such as... Figure 6 As shown. The gland is designed according to the mold body, and is a ring structure with an opening in the middle. The size of the opening in the middle of the gland is designed according to the forming contour size of the concave surface of the mold body. The lower surface of the gland 2 is designed according to the upper surface of the mold body, as shown. Figure 7 As shown. The pressure cap is used to compress and unfold the raw material, increasing the pressure during forming. The mold body and the pressure cap are connected by pins and are used in the rubber bladder hydroforming stage. The cutting mold is used in the shaping and cutting stage of the process model workpiece after rubber bladder hydroforming.

[0070] Step 3: Determine the unfolded material according to the final process model with springback.

[0071] The parts are made from unfolded blank. The shape and size of the unfolded blank are determined according to the final process model with springback, such as... Figure 8 As shown.

[0072] Step 4: Rubber bladder hydroforming to form the process model structure workpiece.

[0073] The unrolled blank is processed using a CNC milling machine, removing edge burrs and sanding the end faces. The unrolled blank is placed on the mold body. The pressure cap 2 presses the unrolled blank 100 against it. The mold body 3 and the pressure cap 2 are connected by pins 4, as shown. Figure 9 As shown. Using a rubber bladder hydroforming machine, the rubber bladder acts as a soft punch, causing the unfolded blank to adhere to the mold body, forming a workpiece with a process model structure, such as... Figure 10 As shown.

[0074] Step 5: If the raw material of the part is aluminum alloy, after quenching and heat treatment of the workpiece 111 in the process model structure, use cutting die 1 to correct the shape to eliminate heat treatment deformation, such as... Figure 11 As shown.

[0075] Step 6: Fix the workpiece of the process model structure onto the cutting die, remove the process allowance, and cut the shaped part.

[0076] The process model structure workpiece is fixed on the cutting die, and the additional process allowance is removed according to the cutting line of the cutting die to complete the processing and manufacturing of the part.

[0077] The rubber bladder hydroforming process in this invention has fewer steps and higher efficiency. The rubber forming mold has a simple structure and is easy to design, enabling the mass production of irregular and complex hyperboloid parts with large deformation.

[0078] Example 1: The inner skin parts of the YC-type civil helicopter (Yun-12E light multi-purpose aircraft) are made of 2A12 aluminum alloy with a thickness of 0.8mm. Figure 1 As shown.

[0079] Design a process model suitable for rubber bladder forming of irregular and complex hyperboloid parts with large deformation:

[0080] By employing a process compensation approach and analyzing the stress-strain of the inner skin component, a preliminary process model suitable for the forming of the rubber bladder of the inner skin component is designed. The process compensation is as follows:

[0081] 1) Increase the bulging allowance by 450mm on the end with greater compression deformation.

[0082] 2) Extend the other end with greater stretching deformation outward along the inner shape to form a 400mm process allowance.

[0083] 3) The extra allowance at the end of the part is connected with the rest of the part to form a shape-following, irregular, three-dimensional hollow structure.

[0084] 4) Increase the overall height by 40mm along the opening direction of the three-dimensional hollow structure.

[0085] Using a springback compensation method, a final process model suitable for the springback-induced molding of rubber bladders for inner skin parts was designed, such as... Figure 3 As shown:

[0086] 1) First, design the rubber bladder forming mold for the inner skin part.

[0087] 2) Perform finite element simulation of rubber bladder forming and rebound compensation.

[0088] 3) Perform springback compensation on the surface of the rubber bladder forming mold.

[0089] 4) Based on the mold surface with springback compensation, create the final process model with springback.

[0090] Design a rubber bladder forming mold suitable for irregular and complex hyperboloid parts with large deformation:

[0091] The rubber bladder forming mold for inner skin parts includes a mold body, a pressure cap, and a cutting mold, and its design structure is as follows: Figure 4 As shown, the design process is as follows:

[0092] 1) The mold body is designed according to the external shape of the final process model with springback, and is a concave mold structure, which is the main forming component, such as... Figure 5 As shown.

[0093] 2) The cutting die is designed according to the inner surface of the preliminary process model. It is a punch structure and requires the marking of cutting lines, such as... Figure 6 As shown.

[0094] 3) The gland is designed according to the mold body, and is a ring structure with an opening in the middle. The size of the opening in the middle of the gland is designed according to the forming contour size of the concave surface of the mold body. The lower surface of the gland is designed according to the upper surface of the mold body, such as... Figure 7 As shown.

[0095] Determine the fabric size:

[0096] The inner skin parts are made from unfolded blank. The shape and size of the unfolded blank are determined according to the final process model with springback, such as... Figure 8 As shown.

[0097] Rubber bladder hydroforming:

[0098] The following are the steps for forming the inner skin part of a rubber bladder using a rubber bladder hydroforming machine:

[0099] 1) Use CNC milling equipment to process and unfold the raw material, remove edge burrs, and sand the end face.

[0100] 2) Unfold the blank material and place it on the mold body. Press the mold cap firmly onto the unfolded blank material. The mold body and the mold cap are connected with pins, such as... Figure 9 As shown.

[0101] 3) Using a rubber bladder hydroforming machine, the rubber bladder acts as a soft punch, causing the unfolded blank to adhere to the mold body, forming a workpiece with a process model structure, such as... Figure 10 As shown.

[0102] Correction:

[0103] The inner skin parts are made of aluminum alloy. The workpiece of the process model structure undergoes quenching heat treatment, and is shaped using a cutting die during the quenching aging period. Figure 11 As shown.

[0104] Cutting and shaping:

[0105] The process model structure workpiece is fixed on the cutting die, and the additional process allowance is removed according to the cutting line of the cutting die to complete the processing and manufacturing of the part.

[0106] Example 2: The upper right fairing component of the YC-type civil helicopter is made of 2A12 aluminum alloy with a thickness of 0.8mm. Figure 12 As shown.

[0107] Design a process model suitable for rubber bladder forming of irregular and complex hyperboloid parts with large deformation:

[0108] By employing a process compensation approach and analyzing the stress-strain of the upper right fairing component, a preliminary process model suitable for the rubber bladder forming of the upper right fairing component was designed. The process compensation process is as follows:

[0109] 1) Increase the bulging allowance by 100mm on the end with greater compression deformation.

[0110] 2) Extend the other end with greater stretching deformation outward along the inner shape to form a 100mm process allowance.

[0111] 3) The extra allowance at the end of the part is connected with the rest of the part to form a shape-following, irregular, three-dimensional hollow structure.

[0112] 4) Increase the overall height by 50mm along the opening direction of the three-dimensional hollow structure.

[0113] Using a springback compensation method, a final process model was designed for the springback forming of the rubber bladder of the upper right fairing component, such as... Figure 13 As shown, Figure 13In the diagram, 10 indicates outward extension following the inner shape of the end, 20 represents the part, 30 indicates additional bulging allowance at the end, and 40 indicates an overall increase in height.

[0114] 1) First, design the rubber bladder forming mold for the upper right fairing part.

[0115] 2) Perform finite element simulation of rubber bladder forming and rebound compensation.

[0116] 3) Perform springback compensation on the surface of the rubber bladder forming mold.

[0117] 4) Based on the mold surface with springback compensation, create the final process model with springback.

[0118] Design a rubber bladder forming mold suitable for irregular and complex hyperboloid parts with large deformation:

[0119] The rubber bladder forming mold for the upper right fairing component includes mold body 3, pressure cap 2, and cutting mold 1, and its design structure is as follows: Figure 14 As shown.

[0120] 1) The mold body is designed according to the external shape of the final process model with springback, and is a concave mold structure, which is the main forming component, such as... Figure 15 As shown.

[0121] 2) The cutting die is designed according to the inner surface of the preliminary process model. It is a punch structure and requires the marking of cutting lines, such as... Figure 16 As shown.

[0122] 3) The gland is designed according to the mold body, and is a ring structure with an opening in the middle. The size of the opening in the middle of the gland is designed according to the forming contour size of the concave surface of the mold body. The lower surface of the gland is designed according to the upper surface of the mold body, such as... Figure 17 As shown.

[0123] Determine the fabric size:

[0124] The upper right fairing component uses unfolded blank material. The shape and size of the unfolded blank material are determined according to the final process model with springback, such as... Figure 18 As shown.

[0125] Rubber bladder hydroforming:

[0126] The following are the steps for forming the upper right fairing part using a rubber bladder hydroforming machine:

[0127] 1) Use CNC milling equipment to process and unfold the raw material, remove edge burrs, and sand the end face.

[0128] 2) Unfold the blank 100 and pre-form it according to the mold body 3, then place it on the mold body 3. Press the unfolded blank 100 firmly with the pressure cap 2. The mold body 3 and the pressure cap 2 are connected by pins 4, as shown below. Figure 19As shown, the mold body and the pressure cap are used for the hydroforming of the rubber bladder.

[0129] 3) Using a rubber bladder hydroforming machine, the rubber bladder acts as a soft punch, causing the unfolded blank to adhere to the mold body, forming a workpiece with a process model structure, such as... Figure 20 As shown.

[0130] Correction:

[0131] The upper right fairing component is made of aluminum alloy. The workpiece 111 of the process model structure undergoes quenching heat treatment, and is shaped using cutting die 1 during the quenching aging period. Figure 21 As shown.

[0132] Cutting and shaping:

[0133] The process model structure workpiece is fixed on the cutting die, and the additional process allowance is removed according to the cutting line of the cutting die to complete the processing and manufacturing of the part.

[0134] The advantages of this invention are at least as follows:

[0135] 1) Innovatively design a process model for forming rubber bladders of irregular and complex hyperboloid parts with large deformation, as the basis for mold design and calculation of unfolded raw materials.

[0136] 2) An innovative rubber bladder forming mold suitable for irregular and complex hyperboloid parts with large deformation is designed, comprising a mold body, a pressure cap, and a cutting mold. The mold has a simple structure, is easy to design, and can be used in combination at different stages of rubber bladder hydroforming.

[0137] 3) In the process of designing the process model, process compensation and springback compensation techniques are adopted. By increasing the bulging allowance, extension allowance, forming height, and other methods, wrinkles and cracks in the workpiece are eliminated, so that the part qualification rate reaches 100%.

[0138] 4) The rubber bladder hydraulic forming machine is used for one-time forming, resulting in high production efficiency.

[0139] 5) The parts have high surface quality and shape accuracy, resulting in high forming quality.

[0140] 6) The process is stable, highly operable, and has low dependence on the operator's technical level.

[0141] 7) It broadened the application scope of rubber bladder hydroforming.

[0142] The above description merely illustrates the embodiments of this application, and while the description is relatively specific and detailed, it should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Furthermore, any parts of this invention not described in detail are conventional techniques.

Claims

1. A method for hydroforming a rubber bladder for a part, characterized in that, The raw material for the part is aluminum alloy, and the method includes: Step 1: Using a process compensation method, design a preliminary process model for the rubber bladder forming of irregular and complex hyperboloid parts with large deformation. Specifically, the process compensation method is adopted. Through stress-strain analysis of the part, a preliminary process model for the rubber bladder forming of irregular and complex hyperboloid parts with large deformation is designed. The process compensation process includes: when there is large compressive deformation at the end of the part, the expansion allowance is increased on the outer side; when there is large tensile deformation at the end of the part, the allowance is increased on the outer side along the inner shape; the increased allowance at the end of the part is connected with the rest of the part to form a conformal irregular three-dimensional hollow structure; the overall height is increased along the opening direction of the three-dimensional hollow structure to form a sidewall of a preset depth. Step 2: Using springback compensation, design the final process model suitable for the springback forming of the rubber bladder part. This includes: designing a rubber bladder forming mold suitable for irregular and complex hyperboloid parts with large deformation; performing finite element simulation of springback compensation for rubber bladder forming; performing springback compensation on the surface of the rubber bladder forming mold; creating the final process model with springback based on the springback-compensated mold surface; the rubber bladder forming mold includes a mold body, a pressure cap, and a cutting mold. The mold body and pressure cap are connected. The mold body is designed according to the outer surface of the final process model with springback, and is a concave mold structure; the cutting mold is designed according to the inner surface of the preliminary process model, and is a convex mold structure, requiring the marking of cutting lines; the pressure cap is designed according to the mold body, and is a ring structure with a central opening. The size of the central opening of the pressure cap is designed according to the forming contour size of the concave surface of the mold body; the lower surface of the pressure cap is designed according to the upper surface of the mold body. Step 3: Determine the unfolded blank according to the final process model with springback; the shape and size of the unfolded blank are determined by the final process model with springback. Step 4: Rubber bladder hydroforming to form the process model structure workpiece; Step 5: After quenching and heat treatment, the workpiece of the process model structure is shaped using a cutting die; Step 6: Fix the workpiece of the process model structure onto the cutting die, remove the process allowance, and cut the shaped part.

2. The method according to claim 1, characterized in that, Step 4 includes: The raw material is processed and unfolded using CNC milling equipment, the edge burrs are removed, and the end face is sanded. The unrolled material is placed on the mold body, and the pressure cap is pressed down on the unrolled material. The mold body and the pressure cap are connected by pins. Using a rubber bladder hydraulic forming machine, the rubber bladder acts as a soft punch, causing the unfolded blank to adhere to the mold body and form a workpiece with a process model structure.

3. The method according to claim 1, characterized in that, In step 6, the process model structure workpiece is fixed on the cutting die, and the increased process allowance is removed according to the cutting line of the cutting die to complete the processing and manufacturing of the part.

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