A processing technology and production line for special-shaped large-sized fine blanking parts

Abstract

The present invention relates to a processing technology and production line for special-shaped large-sized fine blanking parts. The technology includes dividing the processing of special-shaped large-sized fine blanking parts into steps of blanking the outer shape, punching splines, and punching nine holes; processing a sample to obtain the change amount of the outer shape profile. If the change amount C of the outer shape profile exceeds the tolerance range required by the product, it is necessary to modify the fine blanking die, either by applying constraints to the outer shape of the product through the die or by performing reverse compensation on the outer shape dimensions of the product through the die; processing the sample with the modified die until the final change amount C of the outer shape profile is within the tolerance range required by the product. Different from the prior art, the present invention reduces the pressure tonnage of the fine blanking press, can reduce the change of the outer shape dimensions of the product, and reserves the part of the outer shape dimensions of the product that will be deformed through the die. Even after processing, if the outer shape dimensions of the product expand outward, they are still within a reasonable range.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic transmissions, and particularly relates to a processing technology and production line for special-shaped large-sized fine blanking parts. Background Art

[0002] In the prior art, a thick plate fine blanking part is required in an automatic transmission. This part is a key part on the transmission, with a large thickness, large external dimensions, complex shape, and high dimensional accuracy requirements. It belongs to a high-precision thick plate fine blanking part, so the fine blanking processing is very difficult.

[0003] This fine blanking part is a large flat fine blanking part. For most flat fine blanking parts, compound dies or multi-station progressive dies are often used. However, due to the large external dimensions of this product (400 mm in the length direction and 301 mm in the width direction), large sheet thickness (8 mm), and the presence of a spline structure, it can be calculated that for a compound die or a multi-station progressive die, a fine blanking press with a capacity of more than 2000T is required. There is a lack of fine blanking presses with a capacity above this tonnage in the country, so it is not feasible to use a compound die or a multi-station progressive die.

[0004] In the following documents, more information related to the above technical solutions can be found:

[0005] In the Chinese patent with the patent publication number CN108080897A, a forming method for a low-strength thick plate fine blanking part with a counterbore and a slender blind hole is disclosed. S1. Step-by-step fine blanking: including three working steps, punching a positioning hole, punching an extrusion pre-hole; positioning with the positioning hole, extruding the counterbore, punching the thread bottom hole; positioning with the positioning hole, punching the counterbore, punching a large hole, and blanking the outer shape; S2. Grinding the thickness: using a grinding machine to grind the thick plate fine blanking part to the dimensions required by the drawing; S3. Drilling the slender blind hole: using a drilling fixture to fix the thick plate fine blanking part, and drilling the slender blind hole through a drilling machine; S4. Deburring: using a deburring fixture to fix the thick plate fine blanking part after drilling, and deburring through a vibratory finishing device. This invention uses step-by-step fine blanking forming, and a low-strength thick plate fine blanking part with multiple processes such as blanking and counterbore extrusion can be stamped and completed on a single die.

[0006] In the Chinese patent with the patent publication number CN113591167A, a stamping deformation compensation method for a press is disclosed, including the following steps. Step 1, using software to model the die surface model; Step 2, selecting four corners of the die surface as reference points A, the midpoint of the wide side of the die surface as target point B, the midpoint of the long side of the die surface as target point C, and the center point of the die surface as target point D; Step 3, measuring the length of each side; Step 4, calculating the deformation differences of target points B, C, and D according to the measured lengths. By reversely compensating the die deformation differences in the concave die, which are quickly determined according to the size of the die, the working efficiency is effectively improved.

[0007] In the process of implementing the present invention, the inventors found the following problems in the prior art:

[0008] When fine blanking large-sized thick-plate fine blanking parts with a set of dies, a fine blanking press with too high pressure is required, and the cost is too high; when fine blanking large-sized thick-plate fine blanking parts in multiple steps, the errors after multiple fine blankings accumulate, which easily exceeds the tolerance range required by the product, and it is difficult to obtain a suitable processing technology. Summary of the Invention

[0009] Therefore, it is necessary to provide a processing technology and production line for special-shaped large-sized fine blanking parts to solve the problems that when fine blanking large-sized thick-plate fine blanking parts with a set of dies, a fine blanking press with too high pressure is required, and the cost is too high; when fine blanking large-sized thick-plate fine blanking parts in multiple steps, the errors after multiple fine blankings accumulate, which easily exceeds the tolerance range required by the product, and it is difficult to obtain a suitable processing technology.

[0010] To achieve the above object, in the first aspect, the inventors provide a processing technology for special-shaped large-sized fine blanking parts, including:

[0011] The processing technology of the special-shaped large-sized fine blanking parts is divided into step-by-step processing of outer shape blanking, punching splines, and punching nine holes, and fine blanking dies for each step are designed according to the outer shape of the special-shaped large-sized fine blanking parts;

[0012] Process the specimen to obtain the change amount of the outer shape profile

[0013] Fine blank the outer shape of the specimen, measure the change amount of the outer shape profile of the specimen, and obtain the change amount A of the outer shape profile of the specimen after fine blanking the outer shape of the specimen; fine blank the spline holes of the specimen, test the change amount of the outer shape profile of the specimen, and obtain the change amount B of the outer shape profile of the specimen after fine blanking the spline holes; fine blank 9 round holes of the specimen, test the change amount of the outer shape profile of the specimen, and obtain the change amount C of the outer shape profile of the specimen after fine blanking 9 round holes of the specimen;

[0014] Compare the change amount C of the outer shape profile with the tolerance range required by the product, and judge whether the change amount C of the outer shape profile exceeds the tolerance range required by the product. If the change amount C of the outer shape profile exceeds the tolerance range required by the product, it is necessary to modify the fine blanking die, apply constraints to the product outer shape through the die or perform reverse compensation on the product outer shape size through the die;

[0015] Process the specimen with the modified die, repeat the above processing steps to obtain the change amount of the outer shape profile until the final change amount C of the outer shape profile is within the tolerance range required by the product.

[0016] Different from the prior art, the above technical solution divides the processing technology of the special-shaped large-sized fine blanking parts into three steps: blanking the outer shape, punching the spline, and punching nine holes, and designs the fine blanking dies for each step according to the outer shape of the special-shaped large-sized fine blanking parts; the inventor found that the main factors for the special-shaped large-sized fine blanking parts to require a large blanking force lie in the outer shape, spline, and nine holes. If only blanking or punching the spline or punching nine holes, the required equipment tonnage is nearly 1000T. Such a tonnage of equipment is acceptable and conforms to the actual production situation.

[0017] Since the fine blanking process is carried out in three steps, the dimensional accuracy of the sample outer shape is affected not only by the first-step blanking fine blanking itself but also by the subsequent fine blanking of the spline hole and nine round holes. It is necessary to ensure that the final outer shape size after fine blanking nine holes meets the drawing requirements. In order to solve the problem that the contour variation C of the outer shape should meet the drawing requirements, the product outer shape is constrained by the die or the product outer shape size is compensated reversely by the die; by applying constraints to the product outer shape, the change of the product outer shape size can be reduced. In addition, by compensating the product outer shape size reversely; that is, before processing, the part where the product outer shape size will deform is reserved by the die. Even after processing, when the product outer shape size expands outward, it is within a reasonable range.

[0018] As an embodiment of the present invention, the specific method for compensating the product outer shape size reversely is as follows:

[0019] Compensate reversely the size of the fine blanking die for blanking the outer shape. Let the coordinate of a certain measurement point be (xP, yP), the theoretical coordinate of the corresponding point on the part be (x0, y0), and the original die design be (xm, ym). Let Δx = x0 – xP, Δy = y0 - yP, then the corrected die coordinate point is (xm + Δx, ym + Δy).

[0020] In this way, by compensating reversely through the product outer shape size, by presetting a measurement point, the size change of the outer shape of each point of the die can be measured first, and then the die is corrected, and the size change of the outer shape is reserved in advance. After processing, when the product outer shape size expands outward, it is within a reasonable range.

[0021] As an embodiment of the present invention, the outer shape of the special-shaped large-sized fine blanking parts is a closed contour composed of straight lines and arcs. The compensation methods for various line elements are as follows:

[0022] Straight line segment

[0023] If the measurement points on a straight line segment are two points, the straight line segment determined by the corrected coordinates of these two points is used as the die design size; if the measurement points are multiple points, the spline curve segment fitted by the corrected multiple-point coordinates is used as the die design size;

[0024] Arc segment

[0025] If there are three measurement points on an arc segment, a new arc determined by the corrected coordinates of these three points is used as the die design dimension, with the center position remaining unchanged; if there are multiple measurement points, a new arc determined by the coordinates of the three points with the largest deformation is selected as the die design dimension, with the center position remaining unchanged;

[0026] Intersection treatment of straight line segments and arc segments

[0027] If the fitted straight line and the arc are not tangent, an arc with a size of R100 is used for transition.

[0028] In this way, for the different shapes of the outer contours of special-shaped large-sized fine-blanking parts, different measurement points and correction methods are designed for straight line segments, arc segments, and the intersections of straight line segments and arc segments, which can be more suitable for special-shaped large-sized fine-blanking parts.

[0029] As an implementation manner of the present invention, when fine-blanking a spline hole, a constraint is applied to the outer contour of the special-shaped large-sized fine-blanking part through a die.

[0030] In this way, when fine-blanking a spline hole, the size of the outward expansion of the outer contour of the special-shaped large-sized fine-blanking part is the largest. Therefore, when fine-blanking a spline hole, applying a constraint to the outer contour of the special-shaped large-sized fine-blanking part through a die can effectively reduce the influence of fine-blanking the spline hole on the outer contour of the special-shaped large-sized fine-blanking part, and finally meet the tolerance range required by the product.

[0031] As an implementation manner of the present invention, the Deform-3D software is used to simulate and analyze the fine-blanking forming process of the sample spline hole. Three teeth of the die and the sample blank are selected for numerical simulation. Three-dimensional modeling is completed in the SOLIDWORKS software and imported into the Deform-3D preprocessing to establish a finite element model for simulation.

[0032] In this way, in order to ensure the dimensional accuracy of fine-blanking the spline hole while applying a constraint to the outer contour of the special-shaped large-sized fine-blanking part, it is necessary to simulate and analyze the fine-blanking forming process of the spline hole, which can effectively reduce the calculation amount, improve the calculation efficiency, and provide an effective basis for actual production.

[0033] As an implementation manner of the present invention, a V-shaped tooth ring is arranged on the stripper block, and the numerical simulation of the forming process is carried out in two steps:

[0034] (1) The punch and the tooth ring plate move downward together to press the sample blank against the stripper block and the die, and the V-shaped tooth ring on the stripper block is pressed into the sample blank;

[0035] (2) Under the action of the blank holding force and the counter pressure, the punch moves downward to complete the fine-blanking of the spline hole of the sample blank.

[0036] In this way, because the spline hole fine blanking of the special-shaped large-size fine blanking part is a punching process, and the special-shaped large-size fine blanking part is an ultra-large fine blanking part, a V-shaped gear ring needs to be set to reduce the lateral flow of the material and improve the fine blanking quality. In order to avoid the V-shaped gear ring from causing indentations on the surface of the part after forming, the V-shaped gear ring is set on the stripping block, and the gear ring plate is not set with a V-shaped gear ring.

[0037] As an implementation mode of the present invention, the point tracking analysis module provided by the software is used to take 7 points on the tooth top and tooth root to evaluate the dimensional accuracy of the spline fine blanking simulation;

[0038] The horizontal displacement of each point from the start of fine blanking to the completion of fine blanking is statistically recorded. The average displacement reflects the horizontal flow degree of the material during the fine blanking process of the spline hole, and the dimensional accuracy of the spline hole fine blanking is obtained.

[0039] In this way, the forming dimensional accuracy of the spline hole of the special-shaped large-size fine-blanking part is mainly reflected in the addendum circle, root circle and span. It is difficult to directly measure the accurate values ​​of the addendum circle, root circle and span after forming in the numerical simulation post-processing, and the accuracy of the dimensional data of the spline hole directly measured is not ideal due to the limitation of the numerical simulation accuracy. The horizontal displacement of each point from the start of fine-blanking to the completion of fine-blanking is statistically recorded, and the size of the average displacement reflects the horizontal flow degree of the material in the fine-blanking process of the spline hole, that is, the dimensional accuracy of the spline hole fine-blanking.

[0040] As an implementation mode of the present invention, a comprehensive experimental design method is used to carry out numerical simulation tests, and the blank holding force, punch corner radius and punch-die gap are adjusted by combining the comprehensive experimental design with point tracking data analysis and processing.

[0041] In this way, the factors that have the greatest impact on the dimensional accuracy of fine blanking are the blank holder force, fillet radius and punch-die gap. Since the main factors are relatively few, the comprehensive experimental design method is used for numerical simulation experiments. Combining comprehensive experimental design with point tracking data analysis and processing, the spline hole fine blanking forming process parameters are optimized to achieve the purpose of improving the dimensional accuracy of spline hole fine blanking and meet design and production requirements.

[0042] As an embodiment of the present invention, based on simulation analysis, the process parameters are converted into a complete structure, the gap between the punch and die, the punch corner radius and the clamping force are selected, the spline holes are fine-punched on the sample, and the product after the spline holes are fine-punched is inspected. If it is within the tolerance range required by the product drawing, the processing technology of special-shaped large-sized fine-punched parts is obtained.

[0043] In this way, the corresponding test scheme is obtained by combining different test factors and test levels, and the influence of each factor on the dimensional accuracy of spline hole fine blanking is as follows: A punch-die gap > B fillet radius > C blanking force. Finally, the process parameters are converted into a complete structure, and the punch-die gap of 0.04mm, the punch corner radius of 0.4mm and the blanking force of 724KN are selected for fine blanking of the spline hole of the part. After mass production testing, the size of the spline hole of the part meets the technical requirements and the tolerance band is smaller than before the process parameters are optimized. The life of the punch meets expectations, and the frequency of die repair is close to the predicted life.

[0044] To achieve the above objectives, in a second aspect, the inventor provides a production line for special-shaped large-sized precision blanking parts, which is used to execute any of the special-shaped large-sized precision blanking parts processing processes provided by the inventors above.

[0045] Different from the prior art, the main factors that require a large blanking force for the technical solution of the present application for large-sized special-shaped precision punching parts are the shape, splines and nine holes. If only blanking or punching splines or nine holes is required, the required equipment tonnage is nearly 1000T. Equipment of this tonnage is acceptable and in line with actual production conditions. In order to solve the problem that the change in the contour degree C must meet the requirements of the drawings, constraints are imposed on the product shape through the mold or the product shape dimensions are reversely compensated through the mold; by imposing constraints on the product shape, the change in the product shape dimensions can be reduced, and in addition, by reversely compensating the product shape dimensions; that is, before processing, the mold is used to reserve the part of the product shape dimensions that will be deformed. Even after processing, the product shape dimensions expand outward, which is within a reasonable range.

[0046] The above-mentioned records related to the invention content are only an overview of the technical solution of the present application. In order to enable ordinary technicians in the field to more clearly understand the technical solution of the present application, and then implement it according to the text of the specification and the contents recorded in the drawings, and to make the above-mentioned purpose and other purposes, features and advantages of the present application easier to understand, the following is an explanation in combination with the specific implementation mode and drawings of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings are only used to illustrate the principles, implementation methods, applications, characteristics and effects of the specific embodiments of the present application and other related contents, and shall not be considered as limitations of the present application.

[0048] In the drawings of the specification:

[0049] Figure 1 A process roadmap of a processing technology for a special-shaped large-size fine blanking part according to an embodiment of the present application;

[0050] Figure 2 This is a diagram showing the change in the profile of a sample after fine blanking in accordance with an embodiment of the present application;

[0051] Figure 3 The contour change diagram after fine blanking the spline hole of the specimen for an embodiment of this application;

[0052] Figure 4 The contour change diagram after fine blanking 9 round holes of the specimen for an embodiment of this application;

[0053] Figure 5 The contour change diagram for reverse compensation of the product's external dimensions for an embodiment of this application;

[0054] Figure 6 The numerical simulation fine blanking forming process diagram for an embodiment of this application;

[0055] Figure 7 The position diagram of taking points on the tooth top and tooth root for an embodiment of this application. Detailed implementation manners

[0056] To illustrate in detail the possible application scenarios, technical principles, feasible specific solutions, achievable purposes and effects, etc. of this application, the following will be described in detail with reference to the listed specific embodiments and in conjunction with the attached drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of this application, so they are only examples and cannot be used to limit the protection scope of this application.

[0057] Referring to "embodiment" herein means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The term "embodiment" that appears in various positions in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in this application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form the corresponding feasible technical solutions.

[0058] Unless otherwise defined, the meanings of the technical terms used herein are the same as those generally understood by those skilled in the technical field to which this application belongs; the use of the relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0059] In the description of this application, the phrase "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist. For example, A and / or B means: there is A, there is B, and there is both A and B at the same time. In addition, the character " / " herein generally represents an "or" logical relationship between the associated objects before and after.

[0060] In this application, terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantitative, primary-secondary, or sequential relationship between these entities or operations.

[0061] Without further limitation, in this application, the expressions such as "comprising", "including", "having", or other similar expressions used in a statement are intended to cover non-exclusive inclusion. These expressions do not exclude the possibility that there may be additional elements in the process, method, or product that includes the said elements. Thus, in a process, method, or product that includes a series of elements, it may include not only those defined elements, but also other elements not explicitly listed, or elements inherent to such a process, method, or product.

[0062] Similar to the understanding in the "Examination Guidelines", in this application, expressions such as "greater than", "less than", "exceeding", etc. are understood not to include the number itself; expressions such as "above", "below", "within", etc. are understood to include the number itself. In addition, in the description of the embodiments of this application, the meaning of "a plurality of" is two or more (including two). Similar expressions related to "many", such as "multiple groups", "multiple times", etc., are understood in the same way, unless otherwise specifically defined.

[0063] In the description of the embodiments of this application, the spatially related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "perpendicular", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the specific embodiment or the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the specific embodiments of this application or for the reader's understanding, rather than indicating or implying that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of this application.

[0064] Unless otherwise clearly specified or limited, in the description of the embodiments of this application, the terms such as "installed", "connected", "joined", "fixed", "set", etc. should be understood in a broad sense. For example, the said "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements or the interaction relationship between two elements. For those skilled in the art to which this application pertains, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0065] In the prior art, when processing large flat fine blanking parts, the pressure required by the fine blanking press is too high. When using a set of dies to fine blank large-size thick plate fine blanking parts, a fine blanking press with too high pressure is required, resulting in too high cost. When fine blanking large-size thick plate fine blanking parts in multiple steps, the errors after multiple fine blankings accumulate, easily exceeding the tolerance range required by the product, and it is difficult to obtain a suitable processing technology.

[0066] The applicant's research found that large flat fine blanking parts can be processed step by step into blanking the outer shape, punching splines and punching nine holes, so as to reduce the pressure tonnage of the fine blanking press. By applying constraints to the outer shape of the product through the die or by performing reverse compensation on the outer shape dimensions of the product through the die, the change in the outer shape dimensions of the product can be reduced. By leaving a part of the outer shape dimensions of the product that will be deformed in the die, even after processing, if the outer shape dimensions of the product expand outward, it is still within a reasonable range.

[0067] The processing technology and production line of special-shaped large-size fine blanking parts involved in this embodiment can be applicable to the processing of various large flat parts.

[0068] According to some embodiments of the present application, please refer to Figures 1 to 7 , this embodiment relates to a processing technology of special-shaped large-size fine blanking parts, including:

[0069] The processing technology of special-shaped large-size fine blanking parts is divided into step-by-step processing of blanking the outer shape, punching splines and punching nine holes, and fine blanking dies for each step are designed according to the outer shape of the special-shaped large-size fine blanking parts;

[0070] Processing the specimen to obtain the change amount of the outer shape profile

[0071] Fine blank the outer shape of the specimen, measure the change amount of the outer shape profile of the specimen, and obtain the change amount A of the outer shape profile of the specimen after fine blanking the outer shape of the specimen; fine blank the spline holes of the specimen, test the change amount of the outer shape profile of the specimen, and obtain the change amount B of the outer shape profile of the specimen after fine blanking the spline holes of the specimen; fine blank 9 round holes of the specimen, test the change amount of the outer shape profile of the specimen, and obtain the change amount C of the outer shape profile of the specimen after fine blanking 9 round holes of the specimen;

[0072] Compare the change amount C of the outer shape profile with the tolerance range required by the product, and judge whether the change amount C of the outer shape profile exceeds the tolerance range required by the product. If the change amount C of the outer shape profile exceeds the tolerance range required by the product, the fine blanking die needs to be modified, and constraints are applied to the outer shape of the product through the die or reverse compensation is performed on the outer shape dimensions of the product through the die;

[0073] Process the specimen with the modified die, repeat the above processing steps to obtain the change amount of the outer shape profile until the final change amount C of the outer shape profile is within the tolerance range required by the product.

[0074] In this embodiment, the special-shaped large-sized fine blanking part has a large thickness, large external dimensions, complex shape, and high dimensional accuracy requirements. It belongs to a high-precision thick-plate fine blanking part, so the fine blanking process is very difficult.

[0075] According to the structural characteristics of the product, the inventor found that the main factors for the large blanking force required for this product are the external shape, spline, and nine holes. Therefore, if only blanking or punching splines or nine holes is carried out for this product, the required equipment tonnage is nearly 1000T. Considering the equipment situation of our company, it was finally decided to process the external shape blanking, punching splines, and punching nine holes step by step, and develop a set of fine blanking dies for high-precision thick-plate parts, including one fine blanking die for blanking, one fine blanking die for punching spline holes, and one fine blanking die for punching nine holes.

[0076] As Figure 1 shown, the specific processing route is as follows:

[0077] (1) Using the strong blank-holding fine blanking process, first process the external shape and two positioning holes;

[0078] (2) Positioning with two positioning holes, and fine blank the spline holes;

[0079] (3) Positioning with the spline holes, and fine blank the other 9 round holes on the product.

[0080] In this embodiment, by dividing the processing process of the special-shaped large-sized fine blanking part into step-by-step processing of external shape blanking, punching splines, and punching nine holes, and designing the fine blanking dies for each step according to the external shape of the special-shaped large-sized fine blanking part; the inventor found that the main factors for the large blanking force required for the special-shaped large-sized fine blanking part are the external shape, spline, and nine holes. If only blanking or punching splines or nine holes is carried out, the required equipment tonnage is nearly 1000T. Such a tonnage of equipment is acceptable and in line with the actual production situation.

[0081] In the actual blanking process, the workpiece is strongly pressed into the die by the punch. In addition to shear separation, the sheet metal will also be subjected to compressive stress due to the extrusion of the inner wall of the die in the direction perpendicular to the shear surface. When the formed part is ejected from the die by the counter-pressure block, the constraint of the inner wall of the die disappears, and the compressive stress is released, and the part will undergo a small amount of elastic deformation, that is, springback. Since the elastic modulus of general steel is relatively large, the springback amount of fine blanking formed parts is generally small. However, for parts with high requirements for external dimensions, the influence of the springback phenomenon on the dimensions of fine blanking parts cannot be ignored. Especially for large-sized fine blanking parts, the springback phenomenon will be more obvious, and the existence of the springback phenomenon will greatly affect the dimensions of the fine blanking formed products.

[0082] Since the fine blanking process is carried out in three steps, the dimensional accuracy of the sample external shape is affected not only by the first-step blanking fine blanking itself, but also by the subsequent fine blanking of spline holes and 9 round holes. It is necessary to ensure that the final external shape dimensions after fine blanking 9 holes meet the drawing requirements.

[0083] In this embodiment, the required profile tolerance of the specimen is 0.6 mm, that is, after fine blanking forming, the dimensions of each point on its outer shape should be within ±0.3 mm of the theoretically correct dimension. After each step of fine blanking, the profile tolerance of the outer shape is measured with a scanner.

[0084] After the first step of fine blanking and blanking, the measurement results of the profile tolerance of the outer shape are as Figure 2 shown. It can be seen that the maximum profile tolerance is only 0.22 * 2 = 0.44 mm, the value is positive, and it expands outwards, but it is within the specimen tolerance of 0.60.

[0085] Next, in the second step of fine blanking the spline hole, the measurement results of the profile tolerance of the outer shape are as Figure 3 shown. It can be seen that the maximum profile tolerance has reached 1.16 * 2 = 2.32 mm, the value is positive, and it continues to expand outwards, and it has exceeded the specimen tolerance of 0.60.

[0086] Then continue with the third step of fine blanking 9 round holes. The measurement results of the profile tolerance of the outer shape are as Figure 4 shown. It can be seen that the maximum profile tolerance has further expanded to 1.2 * 2 = 2.4 mm, and the value is still positive, indicating that it continues to expand outwards.

[0087] Although the outer shape fine blanking die is designed according to the theoretically correct dimensions of the outer shape of the drawing at the latest, after blanking, punching the spline hole and punching 9 holes, the outer shape of the specimen has changed. The maximum error between the finally obtained outer shape dimensions of the specimen and the design value reaches 2.4 mm, which has exceeded the tolerance range required by the product drawing.

[0088] Therefore, in order to solve that the change amount C of the profile tolerance of the outer shape should meet the requirements of the drawing, a constraint is applied to the outer shape of the product through the die or a reverse compensation is made to the outer shape dimensions of the product through the die; by applying a constraint to the outer shape of the product, the change of the outer shape dimensions of the product can be reduced. In addition, by making a reverse compensation to the outer shape dimensions of the product; that is, before processing, the part where the outer shape dimensions of the product will be deformed is reserved through the die. Even after processing, even if the outer shape dimensions of the product expand outwards, it is still within a reasonable range.

[0089] According to some embodiments of the present application, optionally, the specific method for making a reverse compensation to the outer shape dimensions of the product is as follows:

[0090] Make a reverse compensation to the dimensions of the fine blanking die for outer shape blanking. Let the coordinate of a certain measurement point be (xP, yP), the theoretical coordinate of the corresponding point on the part be (x0, y0), and the original die design be (xm, ym). Let Δx = x0 - xP, Δy = y0 - yP, then the corrected die coordinate point is (xm + Δx, ym + Δy).

[0091] The outer shape of the special-shaped large-size fine blanking part is a closed contour composed of straight lines and arcs.

[0092] In this way, through reverse compensation based on the product's external dimensions, a measurement point is preset. First, the dimensional changes in the external dimensions of each point of the mold can be measured, and then the mold can be corrected by leaving a margin for the dimensional changes in the external dimensions in advance. After processing, the external dimensions of the product expand outward within a reasonable range.

[0093] According to some embodiments of the present application, optionally, the external shape of the special-shaped large-sized fine blanking part is a closed contour composed of straight lines and arcs. The compensation methods for various line elements are as follows:

[0094] Straight line segment

[0095] If there are two measurement points on a straight line segment, the straight line segment determined by the corrected coordinates of these two points is used as the mold design dimension; if there are multiple measurement points, the spline curve segment fitted by the corrected coordinates of the multiple points is used as the mold design dimension.

[0096] Arc segment

[0097] If there are three measurement points on an arc segment, the new arc determined by the corrected coordinates of these three points is used as the mold design dimension, with the center position remaining unchanged; if there are multiple measurement points, the new arc determined by the coordinates of the three points with the largest deformation amount is used as the mold design dimension, with the center position remaining unchanged.

[0098] Intersection processing of straight line segment and arc segment

[0099] If the fitted straight line and arc are not tangent, an arc with a size of R100 is used for transition.

[0100] Using the corrected blanking die for fine blanking experiments, the inspection data of the external contour accuracy is as Figure 5 shown. The maximum contour accuracy dimension is only 0.26 mm, meeting the requirements of the product drawing.

[0101] In this way, for different shapes of the external shape of the special-shaped large-sized fine blanking part, namely straight line segments, arc segments, and the intersections of straight line segments and arc segments, different measurement points and correction methods are designed, which can be more suitable for special-shaped large-sized fine blanking parts.

[0102] According to some embodiments of the present application, optionally, when fine blanking spline holes, the mold exerts constraints on the external shape of the special-shaped large-sized fine blanking part.

[0103] In this way, when fine blanking spline holes, the size of the outward expansion of the external shape of the special-shaped large-sized fine blanking part is the largest. Therefore, when fine blanking spline holes, by exerting constraints on the external shape of the special-shaped large-sized fine blanking part through the mold, the influence of fine blanking spline holes on the external shape of the special-shaped large-sized fine blanking part can be effectively reduced, ultimately meeting the tolerance range required by the product.

[0104] According to some embodiments of the present application, optionally, the Deform-3D software is used to simulate the fine blanking forming process of the sample spline hole. Three teeth of the die and the sample blank are selected for numerical simulation. Three-dimensional modeling is completed in the SOLIDWORKS software and imported into the Deform-3D preprocessing to establish a finite element model for simulation.

[0105] Specifically, for the fine blanking of the sample spline hole, the Deform-3D software is used to simulate the fine blanking forming process of the sample spline hole. To reduce the amount of calculation and improve the calculation efficiency, three teeth of the die and the blank are selected for numerical simulation. Three-dimensional modeling is completed in the SOLIDWORKS software and imported into the Deform-3D preprocessing to establish a finite element model. The blank is set as a plastic body, the material is set as AISI-1045, the rest is set as a rigid body, the number of meshes is set to 50,000, and the meshes in the shear zone are further locally refined with a refinement ratio of 0.01. The forming temperature is normal temperature of 20 °C, the friction coefficient is 0.12, the contact relationship between each part is established, and the Normalized C&L fracture criterion is selected for simulation.

[0106] Thus, in order to ensure the dimensional accuracy of the fine blanking of the spline hole and to apply constraints to the outer shape of the special-shaped large-sized fine blanked part, it is necessary to simulate the fine blanking forming process of the spline hole, which can effectively reduce the amount of calculation, improve the calculation efficiency, and provide an effective basis for actual production.

[0107] The fine blanking of the spline hole of this part belongs to the punching process, and this part is an extra-large fine blanked part. Therefore, a V-shaped tooth ring needs to be set to reduce the lateral flow of the material and improve the fine blanking quality. To avoid the V-shaped tooth ring leaving indentations on the surface of the part after forming, the V-shaped tooth ring is set on the stripper block, and the tooth ring plate is not provided with a V-shaped tooth ring. The forming process is numerically simulated as Figure 6 shown.

[0108] According to some embodiments of the present application, optionally, a V-shaped tooth ring is set on the stripper block, and the numerical simulation of the forming process is carried out in two steps:

[0109] (1) The punch and the tooth ring plate move downward together to press the sample blank against the stripper block and the die, and the V-shaped tooth ring on the stripper block presses into the sample blank;

[0110] (2) Under the action of the blank holding force and the counter pressure, the punch moves downward to complete the fine blanking of the spline hole of the sample blank.

[0111] Thus, since the fine blanking of the spline hole of this special-shaped large-sized fine blanked part belongs to the punching process, and this special-shaped large-sized fine blanked part is an extra-large fine blanked part, a V-shaped tooth ring needs to be set to reduce the lateral flow of the material and improve the fine blanking quality. To avoid the V-shaped tooth ring leaving indentations on the surface of the part after forming, the V-shaped tooth ring is set on the stripper block, and the tooth ring plate is not provided with a V-shaped tooth ring.

[0112] In addition to the forming surface quality requirements, the precision blanking forming quality requirements for the spline hole also include dimensional accuracy requirements. The forming dimensional accuracy of the spline hole of this part is mainly reflected in the addendum circle, root circle and span diameter. In the post-processing of numerical simulation, it is difficult to directly measure the accurate values of the addendum circle, root circle and span diameter after forming, and limited by the numerical simulation accuracy, the accuracy of directly measuring the dimensional data of the spline hole is not ideal either.

[0113] According to some embodiments of the present application, optionally, a point tracking analysis module built into the software is used to select a total of 7 points on the addendum and root, and evaluate the simulation dimensional accuracy of the spline precision blanking forming;

[0114] Statistically record the horizontal displacements of each point throughout the entire process from the start to the completion of the precision blanking, and the magnitude of its average displacement reflects the degree of material flow in the horizontal direction during the precision blanking process of the spline hole, thereby obtaining the precision blanking dimensional accuracy of the spline hole. As Figure 7 shown.

[0115] In this way, the forming dimensional accuracy of the spline hole of this special-shaped large-sized precision blanking part is mainly reflected in the addendum circle, root circle and span diameter. In the post-processing of numerical simulation, it is difficult to directly measure the accurate values of the addendum circle, root circle and span diameter after forming, and limited by the numerical simulation accuracy, the accuracy of directly measuring the dimensional data of the spline hole is not ideal either. Statistically record the horizontal displacements of each point throughout the entire process from the start to the completion of the precision blanking, and the magnitude of its average displacement reflects the degree of material flow in the horizontal direction during the precision blanking process of the spline hole, that is, the precision blanking dimensional accuracy of the spline hole.

[0116] According to some embodiments of the present application, optionally, a full factorial design method is used to conduct numerical simulation experiments, and by combining the full factorial design with the point tracking data analysis and processing, the blank holder force, punch fillet radius and punch-die clearance are adjusted.

[0117] In this way, the factors that have a greater impact on the precision blanking forming dimensional accuracy are the blank holder force, fillet radius and punch-die clearance respectively. Since the main factors are relatively few, the full factorial design method is used to conduct numerical simulation experiments. By combining the full factorial design with the point tracking data analysis and processing, the precision blanking forming process parameters of the spline hole are optimized to achieve the purpose of improving the precision blanking dimensional accuracy of the spline hole and meeting the design and production requirements.

[0118] The full factorial design can obtain a large amount of information and can accurately reflect the magnitude of the main effects of the experimental factors. Using the full factorial design is superior to the orthogonal design under suitable conditions, and the process parameters that have a significant impact on the precision blanking dimensional accuracy of the spline hole can be found through range analysis.

[0119] According to some embodiments of the present application, optionally, based on simulation analysis, process parameters are converted into a complete structure, the clearance between the punch and die, the radius of the punch fillet, and the blank holding force are selected, and the spline hole is precision blanked for the specimen. The product after precision blanking of the spline hole is inspected. If it is within the tolerance range required by the product drawing, the processing technology for precision blanking of special-shaped large-sized parts is obtained.

[0120] In this embodiment, the selection of the clearance between the punch and die is related to the sheet thickness, the punch size, and the material properties, etc. If the clearance between the punch and die is not selected reasonably, the stress on the material at the edge of the cutting edge during the precision blanking process will be more complex. In addition to tensile and compressive stresses, there is also the existence of bending stress. Under the combined action of these stresses, the dimensions of the precision blanking formed product will change. Therefore, the clearance between the punch and die should be reasonably selected to improve the precision of the spline hole precision blanking size.

[0121] In this embodiment, the precision blanking of the spline hole belongs to the punching process, so the fillet is set on the punch. The existence of the radius of the punch fillet improves the distribution of the hydrostatic pressure in the deformation zone during the precision blanking process, making the deformation zone in a state of triaxial compressive stress during the precision blanking process and improving the plasticity of the sheet material. The selection of the radius of the punch fillet is related to the sheet thickness and material strength, etc.

[0122] In this embodiment, the blank holding force is one of the key factors affecting the quality of the precision blanking formed product. The existence of the blank holding force makes the blank holder press the sheet material tightly on the die of the precision blanking die, reducing the tearing and transverse flow of the sheet material in the shearing area. The selection of the blank holding force is very important. The magnitude of the blank holding force can be estimated according to the following empirical formula:

[0123] P 2 =f 2 L 0 hσ b

[0124] In the formula, f2 is a coefficient, which is taken as 1.9 by looking up the table; L0 is the length of the outer contour of the workpiece (mm); h is the height of the V-shaped tooth; σ_b is the tensile strength of the material (N / mm2). Table 1 is the comprehensive test factor level table.

[0125] Table 1 Comprehensive test factor levels

[0126]

[0127] Corresponding test schemes are obtained through different combinations of test factors and test levels. The process parameter settings and results of each test scheme, that is, the average displacement of the points, are shown in Table 2.

[0128] Table 2 Comprehensive test results

[0129]

[0130]

[0131] Table 3 shows the analysis table of dimensional accuracy results, where Ki (i = 1, 2, 3) represents the sum of the average displacements of each factor at the i-th level; ki (i = 1, 2, 3) represents the average value of the average displacements of each factor at the i-th level; the range R is the difference between the maximum and minimum values among the average values of the average displacements under each factor, and the magnitude of the range value indicates the significant degree of the influence of each factor on the dimensional accuracy. The larger the R value, the greater the influence degree. Therefore, from the R values in Table 3, it can be seen that the order of the influence degrees of each factor on the fine blanking dimensional accuracy of the spline hole is: A punch-die clearance > B fillet radius > C blank holding force. According to the comprehensive test results in Table 3, the best combination after optimizing the process parameters is test number 11, that is, the punch-die clearance is 0.04 mm, the fillet radius is 0.4 mm, and the blank holding force is 35 KN.

[0132] Table 3 Analysis Table of Dimensional Accuracy Results

[0133]

[0134] Based on the simulation analysis, the process parameters are converted into a complete structure. The punch-die clearance of 0.04 mm, the punch fillet radius of 0.4 mm, and the blank holding force of 724 KN are selected for the fine blanking of the spline hole of the part. The actual fine blanking forming result of the product is good, and there are no obvious defects such as tearing and warping in the tooth part. After mass production testing, the dimensions of the spline hole of the part meet the technical requirements and the tolerance band is smaller than that before optimizing the process parameters. The punch life meets the expectations, and the die repair frequency is close to the predicted life.

[0135] In this way, through different combinations of test factors and test levels, the corresponding test schemes are obtained, and the order of the influence degrees of each factor on the fine blanking dimensional accuracy of the spline hole is: A punch-die clearance > B fillet radius > C blank holding force. Finally, the process parameters are converted into a complete structure. The punch-die clearance of 0.04 mm, the punch fillet radius of 0.4 mm, and the blank holding force of 724 KN are selected for the fine blanking of the spline hole of the part. After mass production testing, the dimensions of the spline hole of the part meet the technical requirements and the tolerance band is smaller than that before optimizing the process parameters. The punch life meets the expectations, and the die repair frequency is close to the predicted life.

[0136] In this embodiment, there is also provided a production line for special-shaped large-sized fine blanked parts, which is used to execute the processing process of special-shaped large-sized fine blanked parts provided by any one of the above-mentioned inventors.

[0137] Among them, the production line for special-shaped large-sized fine blanked parts includes three sets of test dies and corresponding fine blanking equipment, specifically a fine blanking die for spline holes, an external shape blanking fine blanking die, and a fine blanking die for 9 holes.

[0138] Different from the prior art, the main factors for the need of large blanking force for the special-shaped large-sized fine blanking parts in the technical solution of this application lie in the outer shape, spline and nine holes. If only blanking, or punching splines or punching nine holes, the required equipment tonnage is nearly 1000T. Such a tonnage of equipment is acceptable and conforms to the actual production situation. In order to solve that the variation C of the outer contour degree should meet the requirements of the drawing, constraints are imposed on the product outer shape through the mold or reverse compensation is carried out on the product outer shape size through the mold; by imposing constraints on the product outer shape, the change of the product outer shape size can be reduced. In addition, by carrying out reverse compensation on the product outer shape size; that is, before processing, the part where the product outer shape size will be deformed is reserved through the mold. Even after processing, even if the product outer shape size expands outward, it is within a reasonable range.

[0139] Through the theoretical and experimental research on the variation law of the fine blanking spline hole size of the asymmetric outer shape, the compensation method for the outer shape size of the typical product and the edge dimensions of the spline punch and die is obtained, and then an involute spline hole with a 9th-level accuracy is manufactured; a new structure die for accurately controlling the position degree of multiple holes in fine blanking of large-thickness and large-size parts; an outer shape and inner hole fine blanking die insert structure for large-size fine blanking parts that is convenient for batch production, maintenance and repair.

[0140] It should be noted that although the above-mentioned embodiments have been described in this article, the patent protection scope of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, the changes and modifications made to the embodiments described in this article, or the equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, directly or indirectly applying the above technical solutions to other related technical fields are all included in the patent protection scope of the present invention.

Claims

1. A processing technology for special-shaped large-sized fine blanking parts, characterized in that, it includes: Dividing the processing technology of special-shaped large-sized fine blanking parts into three steps: blanking the outer shape, punching splines, and punching nine holes, and designing fine blanking dies for each step according to the outer shape of the special-shaped large-sized fine blanking parts; Processing the specimen to obtain the change amount of the outer profile Fine blank the outer shape of the specimen, measure the change amount of the outer profile of the specimen, and obtain the change amount A of the outer profile of the specimen after fine blanking; fine blank the spline holes of the specimen, test the change amount of the outer profile of the specimen, and obtain the change amount B of the outer profile of the specimen after fine blanking the spline holes; fine blank 9 round holes of the specimen, test the change amount of the outer profile of the specimen, and obtain the change amount C of the outer profile of the specimen after fine blanking 9 round holes of the specimen; Compare the change amount C of the outer profile with the tolerance range required by the product, and judge whether the change amount C of the outer profile exceeds the tolerance range required by the product. If the change amount C of the outer profile exceeds the tolerance range required by the product, it is necessary to modify the fine blanking die, apply constraints to the outer shape of the product through the die or perform reverse compensation on the outer dimension of the product through the die; Process the specimen with the modified die, repeat the above processing steps to obtain the change amount of the outer profile until the final change amount C of the outer profile is within the tolerance range required by the product.

2. The processing technology for special-shaped large-sized fine blanking parts according to claim 1, characterized in that, The specific method for reverse compensation of the outer dimension of the product is as follows: Perform reverse compensation on the size of the fine blanking die for blanking the outer shape. Let the coordinate of a certain measurement point be (xP, yP), the theoretical coordinate of the corresponding point on the part be (x0, y0), and the original die design coordinate be (xm, ym). Let ∆x = x0 – xP, ∆y = y0 - yP, and the corrected die coordinate point is (xm + ∆x, ym + ∆y).

3. The processing technology for special-shaped large-sized fine blanking parts according to claim 2, characterized in that, The outer shape of the special-shaped large-sized fine blanking part is a closed contour composed of straight lines and arcs. The compensation methods for various line elements are as follows: Straight line segment If there are two measurement points on a straight line segment, use the straight line segment determined by the corrected coordinates of these two points as the die design dimension; if there are multiple measurement points, use the spline curve segment fitted by the corrected coordinates of multiple points as the die design dimension; Arc segment If there are three measurement points on an arc segment, use the new arc determined by the corrected coordinates of these three points as the die design dimension, and the center position remains unchanged; if there are multiple measurement points, select the new arc determined by the three coordinates with the largest deformation amount as the die design dimension, and the center position remains unchanged.

4. The processing technology for special-shaped large-sized fine blanking parts according to claim 1, characterized in that, When fine blanking the spline holes, apply constraints to the outer shape of the special-shaped large-sized fine blanking parts through the die.

5. The processing technology for special-shaped large-sized fine blanking parts according to claim 4, characterized in that, Deform-3D software was used to simulate the fine blanking forming process of the spline hole of the specimen. The three teeth of the mold and the specimen sheet were selected for numerical simulation. The three-dimensional modeling was completed in SOLIDWORKS software and imported into Deform-3D pre-processing. The finite element model was established for simulation.

6. The processing technology for processing special-shaped large-size fine blanking parts according to claim 5, It is characterized in that A V-shaped gear ring is set on the stripping block, and the numerical simulation forming process is carried out in two steps: (1) The punch and the gear ring plate move downward together, pressing the sample sheet toward the stripper block and the die, and the V-shaped gear ring on the stripper block presses into the sample sheet; (2) Under the action of the blank holding force and the counter pressure, the punch moves downward to complete the fine punching of the spline hole of the sample sheet.

7. The processing technology for processing special-shaped large-size fine blanking parts according to claim 6, It is characterized in that The software’s built-in point tracking analysis module is used to select 7 points on the tooth top and tooth root to evaluate the dimensional accuracy of the spline fine blanking simulation. The horizontal displacement of each point from the start of fine blanking to the completion of fine blanking is statistically recorded. The average displacement reflects the horizontal flow degree of the material during the fine blanking process of the spline hole, and the dimensional accuracy of the spline hole fine blanking is obtained.

8. The processing technology for processing special-shaped large-size fine blanking parts according to claim 7, It is characterized in that The comprehensive experimental design method is used to carry out numerical simulation tests. The blank holding force, punch corner radius and punch-die gap are adjusted by combining comprehensive experimental design with point tracking data analysis and processing.

9. The processing technology for processing special-shaped large-size fine blanking parts according to claim 8, It is characterized in that Based on simulation analysis, the process parameters are converted into a complete structure, the gap between the punch and die, the radius of the punch corner and the blank holding force are selected, and the spline holes are fine-punched on the sample. The product after spline hole fine-punching is inspected. If it is within the tolerance range required by the product drawing, the processing technology of special-shaped large-size fine-punching parts is obtained.

10. A production line for special-shaped and large-sized precision blanking parts. It is characterized in that Used to perform the processing technology of special-shaped large-sized fine blanking parts as described in any one of claims 1 to 9.

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