阅读说明：本技术 一种前围板蒙皮压型模具的设计方法 (Design method of front wall plate skin profiling mold ) 是由 张洋 付莹 周双起 关立明 马艺宁 于越 于冀明 陈耀峰 吴迪 王秋雪 于 2021-08-17 设计创作，主要内容包括：本发明提供一种前围板蒙皮压型模具的设计方法,包括如下步骤：获得由多条曲线相互连接构成的蒙皮曲面；根据凸模圆角半径的计算所得到的蒙皮曲面的4条边界曲率半径,三维软件中画出该曲面,在曲面上取横纵相交且投影平面相互垂直的多条曲线；将三维曲面模型导入二维软件,绘制并加工出各曲线对应的多块插板、组对图及下料卡片,在组对图中对各插板进行标号；加工出各插板；将各插板下方相互拼插,上方经各曲线拼接成所要成型的曲面,构成插板结构；在插板结构骨架中注入水泥,获得简易压型模具；待水泥干透,将上下模具把到压力机上,调整压型位置,把下好的两块盖板分别放到上下模具的压型面上压型,成型后分别与上下模具焊接,并喷涂防锈漆。(The invention provides a design method of a front wall plate skin profiling mold, which comprises the following steps: obtaining a skin curved surface formed by connecting a plurality of curves; drawing the curved surface in three-dimensional software according to the curvature radius of the boundary of 4 edges of the skin curved surface obtained by calculating the fillet radius of the male die, and taking a plurality of curves which are intersected in the horizontal direction and the longitudinal direction and have mutually vertical projection planes on the curved surface; importing the three-dimensional curved surface model into two-dimensional software, drawing and processing a plurality of plugboards, assembly diagrams and blanking cards corresponding to all curves, and labeling each plugboard in the assembly diagrams; processing each plugboard; splicing and inserting the lower parts of the inserting plates, and splicing the upper parts of the inserting plates into a curved surface to be formed through curves to form an inserting plate structure; cement is injected into the inserting plate structure framework to obtain a simple profiling mold; and after the cement is completely dried, the upper die and the lower die are placed on a press machine, the pressing position is adjusted, the two lower cover plates are respectively placed on the pressing surfaces of the upper die and the lower die for pressing, the upper die and the lower die are respectively welded after molding, and the antirust paint is sprayed.)

1. A design method of a front wall plate skin profiling mold is characterized by comprising the following steps:

simplifying the front wall plate special-shaped skin into a plurality of criss-cross curves, and connecting the curves to form a curved surface of the skin;

drawing the curved surface in three-dimensional software according to the 4-edge boundary curvature radius of the skin curved surface obtained by calculating the fillet radius of the male die, and taking a plurality of curves which are intersected horizontally and longitudinally and have mutually vertical projection planes on the curved surface;

step three, importing the three-dimensional curved surface model drawn in the step two into two-dimensional software, and drawing a plurality of plugboards corresponding to each curve in the two-dimensional software according to the positions among the curves;

step four, processing each plugboard by a numerical control plasma cutting machine after the single two-dimensional graph derived in the step three is subjected to a graph-derived numerical cutting program; simultaneously drawing a group diagram and a blanking card, and labeling each inserting plate in the group diagram so as to facilitate the group identifier to identify the material;

splicing the lower parts of the inserting plates together, and splicing the upper parts of the inserting plates into a curved surface to be formed through curves to form an inserting plate structure;

step six, cement is injected into the framework of the insert plate structure, the upper curved surface is required to be smooth and flat according to the outline of each insert plate, and the insert plate structure is filled into the smooth curved surface to obtain a simple profiling mold;

and seventhly, after the cement is dried completely, putting the upper die and the lower die on a matched press machine, adjusting the pressing position, respectively putting the two lower cover plates on the pressing surfaces of the upper die and the lower die for pressing, respectively welding the upper die and the lower die after molding, and spraying antirust paint.

2. The design method of the dash panel skin profiling mold according to claim 1, wherein in the second step, the calculation of the convex mold fillet radius satisfies the following formula:

in the formula, r_{Convex part}The radius of the convex die fillet is mm; r is₀Is the fillet radius of the workpiece, mm; t is the thickness of the workpiece material, mm; k is a simplified coefficient and is determined according to the material of the workpiece, and the value of K is 0.0055.

3. The method for designing the front wall panel skin profiling mold according to claim 2, wherein the profiling curvature of the mold is a convex mold fillet radius r calculated by a formula based on that the rebound phenomenon of the bending of the plate material during the profiling process of the material is not negligible_{Convex part}Rather than the final forming radius r of the workpiece₀While the fillet radius r of the male die_{Convex part}The rebound angle is correlated with the rebound angle, when the relative bending radius is larger, namely r/t is more than or equal to 10, the rebound angle not only reaches a considerable value, but also the radius of the convex die fillet is greatly changed, and the rebound is determined by the mechanical property of the pressed workpiece material; the rebound angle satisfies the following formula:

wherein Δ α is a rebound angle, °; alpha is alpha₀Is the bend angle, deg., of the workpiece.

4. The method for designing the front wall panel skin profiling mold according to claim 3, characterized in that the relative numerical values of the four side lines of the front wall panel skin are substituted into a calculation formula of a convex mold fillet radius to obtain the joint surfaces of the convex mold and the concave mold in three dimensions; the die joint surface is a curved surface formed by a material neutral layer when an upper die and a lower die of the die completely close and extrude the material under the action of a press machine;

substituting the relevant numerical values of the four side lines of the front wall panel skin into a rebound angle calculation formula to obtain the rebound curvature of the boundary curve of the 4 side lines of the front wall panel curved surface;

because each side line has more than one curvature radius, the compression quality is prevented from being influenced by stress concentration phenomena such as wrinkling and tearing of materials in the compression process due to excessive and unsmooth curves, and each curvature of the side lines is scaled according to a certain proportion according to actual conditions; according to the special-shaped curved surface appearance of the front wall panel skin of the power centralized electric multiple unit, the rebound radius of each curvature contact part is calculated according to a half of each theoretical curvature.

5. The design method of the dash panel skin profiling mold according to claim 1, wherein the specific steps of the third step are as follows:

the drawn three-dimensional graph is placed in three-dimensional software to derive three views, namely a main view, a top view and a left view, into two-dimensional software, a plurality of plugboards corresponding to all curves are correspondingly found out in the two-dimensional software according to the position distance among all the curves, and the plugboards are arranged from top to bottom and from left to right in the two-dimensional software; the method comprises the following steps of firstly, drawing a three-dimensional graph, flattening the drawn three-dimensional graph in three-dimensional software, and introducing the three-dimensional graph into two-dimensional software which is an upper cover plate and a lower cover plate of a mold, namely a direct contact surface with materials during profiling, and is used for completing cement grouting to play a role in sealing an inner cavity of the mold; then drawing a connecting plate for connecting to the press machine in two-dimensional software according to the outline of the front view; to facilitate the determination of the up-down direction for the paired pairs, the upper/left part of the insert plate is chamfered, i.e. chamfered.

6. The method for designing the dash panel skin profiling mold according to claim 5, wherein in the fourth step, a field operator assembly-welds the mold according to the number and position dimensions in the assembly drawing and the corner cutting position: and according to the corresponding label positions, after the plurality of plugboards are inserted by the sockets, the rest plugboards surround the periphery and are welded fully.

7. The design method of the front wall panel skin profiling mold according to claim 1, characterized in that in the seventh step, a matched press is selected according to the calculation of the bending force, the front wall panel is molded by using a mold with an average radius of R400, and when an R400 arc is profiled on the press, the upper mold and the lower mold are tightly pressed against the workpiece, which belongs to the correction bending; the simplified calculation formula for correcting the bending force is as follows:

P_V＝pF；

wherein p is a correction force per unit area, N/mm²The value is 10N/mm depending on the thickness and material²(ii) a F is the vertical projection area of the correction surface, mm²Namely the projection area of the contact part of the die and the workpiece during profiling;

because the shape of the front face skin of the cab is special, the projection of the contact area with the die during profiling is not a simple rectangle, for simplification, the maximum rectangle is taken for calculation, the length and the width are respectively a and b, and the correction bending force P is obtained after the calculation formula is substituted into the correction bending force simplification calculation formula_V10 × a × b; the actual efficiency of the press machine is calculated according to 80% of rated tonnage, and the press machine can be pressed by combining the size of a workpiece and the condition of workshop equipment.

Technical Field

The invention relates to the technical field of vehicles, in particular to a design method of a front wall plate skin profiling mold.

Background

The power centralized electric multiple unit provides the latest traction power with high technical content for the railways in China, and lays a foundation for the research and development of subsequent high-speed passenger locomotives. In recent years, with the continuous updating and upgrading of domestic locomotive products, the attention degree of the industry to the appearance quality of the whole locomotive, particularly the end part of the underframe, is higher and higher, and the appearance with streamline and smooth smoothness is more easily accepted by the market.

A front wall plate of a power centralized electric motor train unit is an important part of the total assembly of an underframe, a front wall plate skin is an important appearance part at the end part of the underframe, and the surface quality of the front wall plate skin directly influences the appearance quality of the surface flatness, arc transition and the like of a finished train body. As an important part of the appearance of the locomotive, the profiling quality of the skin is particularly important. The front wall plate of the power centralized electric motor train unit is formed by processing and profiling after laser blanking of weather-resistant steel plates with the thickness of 2 mm. The skin belongs to the dysmorphism curved surface spare, and the radius of curvature of skin upper and lower side is different and along the irregular change of boundary. Because the front wall panel skin of the power centralized electric multiple unit is a special-shaped curved surface (namely 4 edges on one curved surface contain more than 2 curvature radiuses), the skin is formed and needs to be processed on a processing center, and the cost is very high. Meanwhile, the design size of the front wall plate of the power centralized electric motor train unit is different from the design size of the front wall plates of locomotives of other models of a company, so that the existing profiling mold cannot meet the production requirement.

Disclosure of Invention

The skin forming according to the above proposal requires processing in a processing center, which is very expensive; meanwhile, the design size of the front wall plate of the power centralized electric motor train unit is different from the design size of the front wall plates of locomotives of other models of a company, and the existing profiling mold cannot meet the technical problem of production requirements, so that the design method of the front wall plate skin profiling mold is provided. According to the method, a mould simplifying technology is mainly utilized, complex parting curved surfaces are efficiently and sparingly manufactured, and the profiling mould for the front wall panel skin of the power centralized electric motor train unit is designed through profiling parameter calculation, so that an operator can easily master the profiling mould, the proficiency period is shortened, and the profiling cost and time for the front wall panel skin of the power centralized electric motor train unit are saved.

The technical means adopted by the invention are as follows:

a design method of a front wall plate skin profiling mold comprises the following steps:

simplifying the front wall plate special-shaped skin into a plurality of criss-cross curves, and connecting the curves to form a curved surface of the skin;

drawing the curved surface in three-dimensional software according to the 4-edge boundary curvature radius of the skin curved surface obtained by calculating the fillet radius of the male die, and taking a plurality of curves which are intersected horizontally and longitudinally and have mutually vertical projection planes on the curved surface;

step three, importing the three-dimensional curved surface model drawn in the step two into two-dimensional software, and drawing a plurality of plugboards corresponding to each curve in the two-dimensional software according to the positions among the curves;

step four, processing each plugboard by a numerical control plasma cutting machine after the single two-dimensional graph derived in the step three is subjected to a graph-derived numerical cutting program; simultaneously drawing a group diagram and a blanking card, and labeling each inserting plate in the group diagram so as to facilitate the group identifier to identify the material;

splicing the lower parts of the inserting plates together, and splicing the upper parts of the inserting plates into a curved surface to be formed through curves to form an inserting plate structure;

step six, cement is injected into the framework of the insert plate structure, the upper curved surface is required to be smooth and flat according to the outline of each insert plate, and the insert plate structure is filled into the smooth curved surface to obtain a simple profiling mold;

and seventhly, after the cement is dried completely, putting the upper die and the lower die on a matched press machine, adjusting the pressing position, respectively putting the two cover plates which are previously put on the pressing surfaces of the upper die and the lower die for pressing, respectively welding the formed cover plates with the upper die and the lower die, and spraying antirust paint.

Further, in the second step, the calculation of the fillet radius of the male die satisfies the following formula:

in the formula, r_{Convex part}The radius of the convex die fillet is mm; r is₀Is the fillet radius of the workpiece, mm; t is the thickness of the workpiece material, mm; k is a simplified coefficient and is determined according to the material of the workpiece, and the value of K is 0.0055.

Further, based on the fact that the rebound phenomenon of bending of the plate material in the profiling process of the material cannot be ignored, the profiling curvature of the die is the convex die fillet radius r calculated through a formula_{Convex part}Rather than the final forming radius r of the workpiece₀While the fillet radius r of the male die_{Convex part}The rebound angle is correlated with the bending angle, when the relative bending radius is larger, namely r/t is more than or equal to 10, the rebound angle not only reaches a considerable value, but also the fillet radius of the male die has larger change, and the rebound is mainly determined by the mechanical property of the pressed workpiece material; the rebound angle satisfies the following formula:

wherein Δ α is a rebound angle, °; alpha is alpha₀Is the bend angle, deg., of the workpiece.

Furthermore, substituting the relevant numerical values of the four side lines of the front wall panel skin into a calculation formula of the fillet radius of the male die can obtain the joint surfaces of the male die and the female die in three dimensions; the die joint surface is a curved surface formed by a material neutral layer when an upper die and a lower die of the die completely close and extrude the material under the action of a press machine;

substituting the relevant numerical values of the four side lines of the front wall panel skin into a rebound angle calculation formula to obtain the rebound curvature of the boundary curve of the 4 side lines of the front wall panel curved surface;

because each side line has more than one curvature radius, the compression quality is prevented from being influenced by stress concentration phenomena such as wrinkling and tearing of materials in the compression process due to excessive and unsmooth curves, and each curvature of the side lines is scaled according to a certain proportion according to actual conditions; according to the special-shaped curved surface appearance of the front wall panel skin of the power centralized electric multiple unit, the rebound radius of each curvature contact part is calculated according to a half of each theoretical curvature.

Further, the third step comprises the following specific steps:

the drawn three-dimensional graph is placed in three-dimensional software to derive three views, namely a main view, a top view and a left view, into two-dimensional software, a plurality of plugboards corresponding to all curves are correspondingly found out in the two-dimensional software according to the position distance among all the curves, and the plugboards are arranged from top to bottom and from left to right in the two-dimensional software; the method comprises the following steps of firstly, drawing a three-dimensional graph, flattening the drawn three-dimensional graph in three-dimensional software, and introducing the three-dimensional graph into two-dimensional software which is an upper cover plate and a lower cover plate of a mold, namely a direct contact surface with materials during profiling, and is used for completing cement grouting to play a role in sealing an inner cavity of the mold; then drawing a connecting plate for connecting to the press machine in two-dimensional software according to the outline of the front view; to facilitate the determination of the up-down direction for the paired pairs, the upper/left part of the insert plate is chamfered, i.e. chamfered.

Further, in the fourth step, the field operator assembles and welds the die according to the number and the position size in the pairing drawing and the position of the corner cutting edge: and according to the corresponding label positions, after the plurality of plugboards are inserted by the sockets, the rest plugboards surround the periphery and are welded fully.

Further, in the seventh step, a matched press machine is selected according to the calculation of the bending force, the front wall plate is molded by a mold with the average radius of R400, and the upper mold and the lower mold are tightly pressed against the workpiece when the R400 arc is pressed on the press machine, which belongs to the bending correction; the simplified calculation formula for correcting the bending force is as follows:

P_V＝pF；

wherein p is a correction force per unit area, N/mm²The value is 10N/mm depending on the thickness and material²(ii) a F is the vertical projection area of the correction surface, mm²Namely the projection area of the contact part of the die and the workpiece during profiling;

because the shape of the front face skin of the cab is special, the projection of the contact area with the die during profiling is not a simple rectangle, for simplification, the maximum rectangle is taken for calculation, the length and the width are respectively a and b, and the correction bending force P is obtained after the calculation formula is substituted into the correction bending force simplification calculation formula_V10 × a × b; the actual efficiency of the press machine is calculated according to 80% of rated tonnage, and the press machine can be pressed by combining the size of a workpiece and the condition of workshop equipment.

Compared with the prior art, the invention has the following advantages:

1. according to the design method of the front wall panel skin profiling mold, the foundation is simplified through the mold, the complex parting curved surface is efficiently and sparingly manufactured, and the front wall panel skin profiling mold of the power centralized electric motor train unit is designed through profiling parameter calculation.

2. The design method of the front wall panel skin profiling mold provided by the invention has the advantages that an operator can easily operate the mold, the proficiency period is shortened, the manufacturing cost and time of the front wall panel skin profiling of the power centralized electric motor train unit are saved, and the profiling quality of the front wall panel skin is further ensured.

In conclusion, the technical scheme of the invention can solve the problems that the skin forming in the prior art needs to be processed on a processing center, and the cost is very high; meanwhile, the design size of the front wall plate of the power centralized electric motor train unit is different from the design size of the front wall plates of locomotives of other models of a company, so that the existing profiling mold cannot meet the production requirement.

Based on the reasons, the invention can be widely popularized in the fields of power centralized electric multiple units and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a simplified diagram of the skin structure of the present invention.

FIG. 2 is a schematic diagram showing the operation of the press according to the present invention in various parts, wherein (a) is a front view and (b) is a side view.

FIG. 3 is a schematic diagram of the boards arranged from top to bottom and from left to right in two-dimensional software according to the present invention.

FIG. 4 is a set-up diagram of the present invention.

FIG. 5 is a schematic diagram of the insertion manner of the lower mold insert plate according to the present invention.

FIG. 6 is a schematic view of the working and clamping surfaces of the mold of the present invention.

Fig. 7 is a schematic view of a simple profiling mold for injecting cement according to the present invention.

Fig. 8 is a schematic view of a skin profiling mold of a dash panel of the power centralized electric multiple unit.

In the figure: 1. a curve I; 2. curve II; 3. curve III; 4. a curve IV; 5. curve V; 6. curve VI; 7. curve VII; 8. curve VIII; 9. a first plug board; 10. a second plug board; 11. inserting a plate III; 12. inserting a plate IV; 13. inserting a plate V; 14. inserting a plate six; 15. a seventh plug board; 16. an eighth plug board; 17. a ninth plug board; 18. ten inserting plates; 19. a trapezoidal groove I; 20. an upper platform of the press machine; 21. a lower platform of the press machine; 22. a trapezoidal groove II; 23. the side of the press machine is tightly propped; 24. cutting corner edges; 25. an initial position of an upper platform of the press machine; 26. the position of an upper platform of the press machine during die assembly; 27. the position of an upper die of the die when the die is closed; 28. when the die is closed, the workpiece is clamped; 29. the position of the lower die of the die when the die is closed; 30. and (5) a neutral layer line of the workpiece.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

As shown in the figure, in order to reduce the manufacturing cost of the front dash panel skin and save the manufacturing time of the front dash panel skin, the invention provides a design method of a front dash panel skin profiling mold, which comprises the following steps:

simplifying the front wall plate special-shaped skin into a plurality of criss-cross curves, and connecting the curves to form a curved surface of the skin;

drawing the curved surface in three-dimensional software according to the 4-edge boundary curvature radius of the skin curved surface obtained by calculating the fillet radius of the male die, and taking a plurality of curves which are intersected horizontally and longitudinally and have mutually vertical projection planes on the curved surface;

step three, importing the three-dimensional curved surface model drawn in the step two into two-dimensional software, and drawing a plurality of plugboards corresponding to each curve in the two-dimensional software according to the positions among the curves;

step four, processing each plugboard by a numerical control plasma cutting machine after the single two-dimensional graph derived in the step three is subjected to a graph-derived numerical cutting program; simultaneously drawing a group diagram and a blanking card, and labeling each inserting plate in the group diagram so as to facilitate the group identifier to identify the material;

splicing the lower parts of the inserting plates together, and splicing the upper parts of the inserting plates into a curved surface to be formed through curves to form an inserting plate structure;

step six, cement is injected into the framework of the insert plate structure, the upper curved surface is required to be smooth and flat according to the outline of each insert plate, and the insert plate structure is filled into the smooth curved surface to obtain a simple profiling mold;

and seventhly, after the cement is dried completely, putting the upper die and the lower die on a matched press machine, adjusting the pressing position, respectively putting the two cover plates which are previously put on the pressing surfaces of the upper die and the lower die for pressing, respectively welding the formed cover plates with the upper die and the lower die, and spraying antirust paint.

In a preferred embodiment, in the second step, the calculation of the fillet radius of the punch satisfies the following formula:

in the formula, r_{Convex part}The radius of the convex die fillet is mm; r is₀Is the fillet radius of the workpiece, mm; t is the thickness of the workpiece material, mm; k is a simplified coefficient and is determined according to the material of the workpiece, and the value of K is 0.0055.

As a preferred embodiment, the profiling curvature of the die is the convex die fillet radius r calculated by a formula based on the fact that the rebound phenomenon of the bending of the plate material in the profiling process of the material is not negligible_{Convex part}Rather than the final forming radius r of the workpiece₀While the fillet radius r of the male die_{Convex part}The rebound angle is correlated with the bending angle, when the relative bending radius is larger, namely r/t is more than or equal to 10, the rebound angle not only reaches a considerable value, but also the fillet radius of the male die has larger change, and the rebound is mainly determined by the mechanical property of the pressed workpiece material; the rebound angle satisfies the following formula:

wherein Δ α is a rebound angle, °; alpha is alpha₀Is the bend angle, deg., of the workpiece.

As a preferred embodiment, the relative numerical values of the four side lines of the front wall panel skin are substituted into a calculation formula of the fillet radius of the male die, so that the joint surfaces of the male die and the female die can be obtained in three dimensions; the die joint surface is a curved surface formed by a material neutral layer when an upper die and a lower die of the die completely close and extrude the material under the action of a press machine;

substituting the relevant numerical values of the four side lines of the front wall panel skin into a rebound angle calculation formula to obtain the rebound curvature of the boundary curve of the 4 side lines of the front wall panel curved surface;

because each side line has more than one curvature radius, the compression quality is prevented from being influenced by stress concentration phenomena such as wrinkling and tearing of materials in the compression process due to excessive and unsmooth curves, and each curvature of the side lines is scaled according to a certain proportion according to actual conditions; according to the special-shaped curved surface appearance of the front wall panel skin of the power centralized electric multiple unit, the rebound radius of each curvature contact part is calculated according to a half of each theoretical curvature.

As a preferred embodiment, the specific steps of the third step are as follows:

the drawn three-dimensional graph is placed in three-dimensional software to derive three views, namely a main view, a top view and a left view, into two-dimensional software, a plurality of plugboards corresponding to all curves are correspondingly found out in the two-dimensional software according to the position distance among all the curves, and the plugboards are arranged from top to bottom and from left to right in the two-dimensional software; the method comprises the following steps of firstly, drawing a three-dimensional graph, flattening the drawn three-dimensional graph in three-dimensional software, and introducing the three-dimensional graph into two-dimensional software which is an upper cover plate and a lower cover plate of a mold, namely a direct contact surface with materials during profiling, and is used for completing cement grouting to play a role in sealing an inner cavity of the mold; then drawing a connecting plate for connecting to the press machine in two-dimensional software according to the outline of the front view; to facilitate the determination of the up-down direction for the paired pairs, the upper/left part of the insert plate is chamfered, i.e. chamfered.

In a preferred embodiment, in the fourth step, the field operator assembles and welds the mold according to the number and the position size in the group diagram and the position of the corner cutting edge: and according to the corresponding label positions, after the plurality of plugboards are inserted by the sockets, the rest plugboards surround the periphery and are welded fully.

In the seventh step, a matched press is selected according to the calculation of the bending force, the front wall plate is formed by a die with the average radius of R400, and the upper die and the lower die are tightly pressed against the workpiece when the R400 arc is pressed on the press, which belongs to the bending correction; the simplified calculation formula for correcting the bending force is as follows:

P_V＝pF；

wherein p is a correction force per unit area, N/mm²The value is 10N/mm depending on the thickness and material²(ii) a F is correctionArea of plane vertical projection, mm²Namely the projection area of the contact part of the die and the workpiece during profiling;

because the shape of the front face skin of the cab is special, the projection of the contact area with the die during profiling is not a simple rectangle, for simplification, the maximum rectangle is taken for calculation, the length and the width are respectively a and b, and the correction bending force P is obtained after the calculation formula is substituted into the correction bending force simplification calculation formula_V10 × a × b; the actual efficiency of the press machine is calculated according to 80% of rated tonnage, and the press machine can be pressed by combining the size of a workpiece and the condition of workshop equipment.

Example 1

As shown in fig. 1 to 8, a method for designing a dash panel skin profiling mold comprises the following steps: through mould simplification and die mould parameter calculation, design the preceding bounding wall skin die mould of the centralized electric EMUs of power, make the operator use the die mould to carry out preceding bounding wall skin die mould, save certain time for production, more guaranteed preceding bounding wall skin die mould quality. The method comprises the following specific steps:

1. the design principle is as follows:

the curved surface is formed by connecting a plurality of curves. Based on the principle, the special-shaped skin is approximately simplified into a plurality of criss-cross curves, and then the curves are connected with each other to form the curved surface of the skin.

As shown in fig. 1, the curved surface of the skin can be approximated by a curve i 1, a curve ii 2, a curve iii 3, a curve iv 4, a curve v 5, a curve vi 6, a curve vii 7, and a curve viii 8. Specifically, according to the curvature radius of 4 edges of the curved surface of the front wall plate obtained by calculating the fillet radius of the convex die, the curved surface is drawn in three-dimensional software, and 8 curves which are intersected horizontally and longitudinally and have mutually perpendicular projection planes are taken from the curved surface. And (3) importing the drawn three-dimensional graph into two-dimensional software, drawing a plurality of inserting plates (an inserting plate I9, an inserting plate II 10, an inserting plate III 11, an inserting plate IV 12, an inserting plate V13, an inserting plate VI 14, an inserting plate VII 15, an inserting plate VIII 16, an inserting plate V17 and an inserting plate VIII 18) which respectively correspond to curves I1 to VIII 8 in the graph 1 in the two-dimensional software according to the positions among the curves, and drawing a pairing graph and a blanking card. A set of simple profiling dies is constructed by 8 inserting plates which can be spliced together at the lower part and curved surfaces to be formed at the upper part through curves.

2. Profiling parameter calculation

2.1 calculation of the fillet radius of the Male die

The bending resilience of the plate material in the profiling process of the material is usually not negligible, so the profiling curvature of the die is usually the convex die fillet radius r calculated by a formula_{Convex part}Rather than the final forming radius r of the workpiece₀While the fillet radius r of the male die_{Convex part}In general, this is again correlated with the rebound angle, which, when the relative bending radius is large (r/t ≧ 10), not only reaches a considerable value, but also there is a large variation in the fillet radius. The spring back is determined mainly by the mechanical properties of the material of the workpiece being profiled. Thus, the punch fillet radius and the rebound angle can be calculated as follows:

the fillet radius of the male die is as follows:

the values of the rebound angle are:

in the formula, r_{Convex part}Is the convex die fillet radius (mm); r is₀Is the fillet radius (mm) of the workpiece; t is the workpiece material thickness (mm); k is a simplified coefficient, and the value of the simplified coefficient is 0.0055 by looking up a table according to the material of the workpiece; Δ α is rebound angle, °; alpha is alpha₀Is the bend angle (°) of the workpiece.

Because in this embodiment, dash the characteristics that the bounding wall covering has multiple great positive and negative camber on same covering, can calculate multiple different resilience angle on same covering like this, these resilience angles are great moreover, and each curve transition on the unable covering is smooth curve and this great resilience angle is less to the radius influence of rebounding of covering, so will not consider the resilience angle in the design of this embodiment mould.

Relevant numerical values of four side lines (such as a curve I1, a curve IV 4, a curve V5 and a curve VIII 8 in the graph 1) of the front wall panel skin required in a convex die fillet radius calculation formula are substituted into the convex die fillet radius calculation formula, and the joint surfaces of a convex die and a concave die can be obtained in three dimensions, wherein as shown in the graph 6, the joint surfaces are curved surfaces formed by material neutral layers when an upper die and a lower die of the die completely close and extrude the material under the action of a press machine, namely, planes formed by all workpiece neutral layer lines 30 in the graph 6 are the joint surfaces. In fig. 6, the press upper platen initial position 25 is moved downward in the feed direction to the press upper platen clamping position 26, and the clamped workpiece 28 is positioned between the upper and lower dies, which are the upper die clamping position 27 and the lower die clamping position 29 in fig. 6, respectively.

And substituting the relevant numerical values required by the four side lines of the front wall panel skin in the rebound angle calculation formula into the rebound angle calculation formula to obtain the rebound curvature of the boundary curve of the 4 sides of the front wall panel curved surface.

Because each sideline all has more than one kind of curvature radius, in order to avoid because the excessive unsmooth stress concentration phenomenon such as the material wrinkling appears in the die mould in-process of curve, tears, has influenced the die mould quality, so according to actual conditions, zoom according to certain proportion with each camber of sideline. According to the special-shaped curved surface appearance of the front wall panel skin of the power centralized electric multiple unit, the rebound radius of each curvature contact part is calculated according to a half of each theoretical curvature.

2.2 calculation of bending force

The magnitude of the bending force is not only related to the blank size, the mechanical properties of the material, the stamping performance, the distance between the supporting points of the female die, the bending radius, the die clearance and other factors, but also has a great relationship with the bending mode. Therefore, it is theoretically complicated to calculate the bending force, and the calculation accuracy is not high, and it is usually calculated by an empirical formula or a simplified theoretical formula in production.

The front wall plate of the power centralized electric motor train unit is molded by a mold with the average radius of R400, and the upper mold and the lower mold are tightly compacted with a workpiece when an R400 arc is pressed on a press machine, so that the bending correction is realized.

The simplified calculation formula for correcting the bending force is as follows: p_V＝pF；

Wherein p is a correction force per unit area (N/mm)²) The approximate value of 10N/mm is obtained by table look-up according to the thickness and the material²(ii) a F is the vertical projection area (mm) of the correction surface²) I.e. the projected area of the contact part of the die and the workpiece during profiling.

Because the shape of the front face skin of the cab is special, the projection of the contact area with the die during profiling is not a simple rectangle, for simplification, the maximum rectangle is taken for calculation, namely the length and the width are 843mm and 766mm respectively, and the corrected bending force P is obtained by substituting the values into a formula_V＝10×843×766≈6.45×106N。

According to the calculated numerical value, the actual efficiency of the press machine is calculated according to 80% of the rated tonnage, and the press machine with the tonnage of more than 60T can be adopted. According to the size of the workpiece and the condition of workshop equipment, a 100T press is selected for pressing in the embodiment.

The operation of the various parts of the 100T press is schematically illustrated in fig. 2 (a) and (b), and the respective connecting and fastening portions of the die are designed according to these dimensions. The working parts of the press comprise an upper press platform 20, a lower press platform 21, a side jacking 23, a first trapezoidal groove 19 and a second trapezoidal groove 22, wherein the first trapezoidal groove 19 and the second trapezoidal groove 22 are used for connecting the dies.

3. Design of the mould

3.1 design of mold insert plate

Drawing the curved surface in three-dimensional software according to the curvature radius of the 4 edges of the curved surface of the front wall plate calculated in the step 2.1, and taking 8 curves which are intersected horizontally and longitudinally and have mutually perpendicular projection planes on the curved surface.

The drawn three-dimensional graph is placed in three-dimensional software to derive three views, namely a front view, a top view and a left view, into two-dimensional software (as shown in figure 3), then a plurality of insert plates corresponding to curves I1 to VIII 8 in figure 1 are correspondingly found in the two-dimensional software according to the position distance between lines, and are arranged from top to bottom and from left to right in the two-dimensional software, as shown by part numbers 9, 10, 11, 12, 15, 16, 17 and 18 in figure 3 (namely, an insert plate I9, an insert plate II 10, an insert plate III 11, an insert plate IV 12, an insert plate VII 15, an insert plate I16, an insert plate IX 17 and an insert plate VI 18); in addition, a drawn three-dimensional image is flattened in the three-dimensional software and is guided into the two-dimensional software, namely, the two-dimensional software is shown as part number 13 (namely, five insert plates 13) in the following figure 3, and the three-dimensional software is a direct contact surface between an upper cover plate and a lower cover plate of the mold and materials during profiling, and simultaneously, cement grouting is completed to play a role in closing the inner cavity of the mold in the future; then, the connection plate for connection to the press, indicated by the part number 14 (insert plate six 14) in fig. 3, is drawn in two-dimensional software according to the outline of the front view. As shown in the circles marked in fig. 3 below, the upper/left portions of the insert plate are chamfered (hereinafter referred to as chamfered edges 24) to facilitate the determination of the up-down direction during assembly.

Finally, after the derived single two-dimensional graph is subjected to a graph digital cutting program, a corresponding material (inserting plate) can be processed by using a numerical control plasma cutting machine. Meanwhile, drawing a pairing diagram according to fig. 3, as shown in fig. 4 below, a field operator can assemble and weld the dies according to the number and position sizes in the diagram and the position of the corner cutting edge (i.e. the chamfer mentioned in the above paragraph): according to the corresponding reference positions in the upper graph 3 and the lower graph 4, after the second plug board 10, the third plug board 11, the eighth plug board 16 and the ninth plug board 17 are plugged by using the plug sockets (the plugging mode is shown in the graph 5), the first part plug board 9, the fourth plug board 12, the seventh plug board 15 and the tenth plug board 18 surround the periphery, and are welded fully around the periphery to be spliced into a plug board structure. According to this design, the mold can be manufactured in the same manner. It should be noted that, because the inserts are similarly shaped, the inserts must be numbered in the assembly drawing to allow the assembler to identify the material.

However, the insert plate structure cannot be used as a profiling mold to form a plate, and in order to fill the insert plate structure into a smooth curved surface, cement is firstly injected into the insert plate structure framework, and the upper curved surface is required to be smooth and flat according to the outline of each insert plate. A simple compression mold for injecting cement was obtained as shown in fig. 7.

And after the cement is completely dried, putting the upper die and the lower die on a press machine, adjusting the pressing position, respectively putting the upper cover plate and the lower cover plate (part number 5 in the upper figure 3) which are previously arranged on the pressing surfaces of the upper die and the lower die for pressing, respectively welding the upper die and the lower die after molding, and spraying antirust paint. Thereby obtaining the skin profiling mold of the front wall plate of the power centralized electric multiple unit, as shown in fig. 8.

The design of the skin profiling mold of the front wall plate of the power centralized electric motor train unit ensures that a machining center is not needed for skin profiling manufacture. The skin is manufactured by using the pressing die, so that an operator can easily use the skin, the proficiency period is shortened, and the skin pressing cost and time are saved.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.