Sheet drawing process, sheet drawing apparatus and drawing die

Abstract

The present application relates to a kind of sheet drawing process, sheet drawing equipment and drawing die, wherein sheet (2) is drawn by the drawing equipment with movable die (1) and static die (4), in the drawing process, when the position of recoil hole is set at a distance before movable die (1) reaches the end of drawing stroke, through the punching convex die (7) on static die (4) and the punching concave die (6) on movable die, the punching set point (11) around the compressed drawing rib (8) of sheet (2) is synchronously punched as movable die (1) moves, so that positioning hole is formed by stamping when or before movable die reaches the end of drawing stroke.The present application creatively analyzes and utilizes the characteristics of material inflow in the last forming stage of drawing, and ingeniously designs a unique punching process, which synchronously forms positioning hole in the subsequent process during the sheet drawing process, and has the advantages of high positioning accuracy, wide adaptability and easy installation.

Description

Technical Field

[0001] The present invention relates to a sheet metal processing technology, specifically, a sheet metal drawing technology. In addition, the present invention also relates to a sheet metal drawing device for supporting the drawing technology, and a drawing die dedicated to the sheet metal drawing device. Background Art

[0002] For the forming of sheet metal (such as sheet metal parts like metal thin plates), in various industries, especially in the heavy machinery industry, the vehicle industry and other industries, generally the sheet metal is placed on a drawing device (such as a press) equipped with a drawing die for drawing, and then processes such as trimming, flanging, and shaping are carried out to form. Usually, drawing is a separate process, and the part needs to enter the subsequent process for continuous processing after the drawing process, and for the part after drawing, generally profile positioning, edge positioning, or both are used for positioning in the subsequent process.

[0003] For the above-mentioned positioning methods in the subsequent process, for parts with relatively complex shapes, although there are many process reference features such as profiles available on the parts, the positioning accuracy can basically be met, but the positioning method is relatively complex, and the positioning accuracy will inevitably be affected by drawing deformation to a certain extent. In addition, especially for parts with relatively simple shapes, since there are very few relatively reliable process reference features that can be utilized on these parts,勉强采用型面定位、边定位等,往往定位精度很难满足产品高精度需求. For example, for some components, in order to reduce the die cost of their trimming process, a three-dimensional laser device and a simple special fixture are used for cutting instead of trimming, but because the simple fixture lacks a reliable positioning structure, it is difficult to meet the high-precision assembly requirements of the product.

[0004] It should be noted that there seems to be an incomplete or incorrect expression in the original Chinese text at the end of line 11. I have translated it as best as possible based on the context, but it might need further clarification in the original text.To simplify the positioning methods of various subsequent processes after drawing and improve positioning accuracy, those skilled in the art have considered hole positioning methods and have made numerous technical attempts and improvements over a long period of time. However, since the drawing process itself is a relatively special process that is prone to causing part deformation, and the parts it targets are basically thin-plate parts, it is extremely difficult to process positioning holes in the drawing process. Often, the resulting positioning holes cannot meet the accuracy requirements as positioning references. Furthermore, since punching generally involves the punching motion of a punching punch in conjunction with a stationary punching die to create a hole, in drawing equipment, the upper die is usually a moving die. The drawing process itself requires the moving die to perform the drawing motion, and the sheet metal generally follows the moving die. Adding a punching die to the drawing equipment often requires designing a secondary punching motion drive structure and a corresponding special sheet metal plane suitable for punching. This greatly increases the structural complexity of the drawing die or drawing equipment. In particular, due to the complexity of sheet metal deformation in the drawing process itself, these existing technologies lack technical specificity. The positioning holes processed by these technologies have also proven in actual use in subsequent processes that the positioning accuracy of such positioning holes is often difficult to meet the requirements.

[0005] For example, Chinese invention patent CN101869943B (application number: CN201010215362.4) discloses a punching device and sheet metal positioning method for a drawing die. This belongs to the technology of installing a punching device on a drawing die to create positioning holes for subsequent processes. It mainly involves installing a punching punch assembly on the upper die surface and a punching die assembly on the lower die surface. See this prior art for details. Figure 1 The prior art punching device for drawing dies includes a support 1, a punching die 2, a bushing 3, a punching punch 5, and a pressure sleeve 6 (i.e., a pressure ring). The punching die 2 is installed at the lower part of the support 1, and the punching punch 5 is installed at the upper part of the support 1. The punching die 2 and the punching punch 5 located above it are shaped to fit together for punching. The bushing 3 is sleeved inside the punching die 2, and the pressure sleeve 6 is sleeved outside the punching punch 5. The bushing 3 and the pressure sleeve 6 located above it are shaped to fit together for pressing and storing the material.

[0006] The main purpose of this existing technology, which employs a complex structure, is to punch positioning holes in the scrap portion of the workpiece during the drawing process. Figure 1 The drawing and punching mechanism shown needs to be installed on a flat surface of at least Φ40mm in the scrap area of ​​the upper and lower die cavities. When the drawing is nearing completion, the punching punch and die first punch out the positioning holes required for subsequent processes. Then, the pressure sleeve and bushing press the positioning holes and the surrounding area together and press out a certain shape to store the material. This can alleviate the deformation of the positioning holes to a certain extent and control the deformation generated in the subsequent process to be uniform deformation. The scrap is smoothly ejected by the relative position difference between the ejector pin and the punching punch.

[0007] This typical existing technology has the following serious drawbacks: First, this forward punching process requires mounting on a flat surface with a scrap area of ​​at least Φ40mm. However, the selection of the positioning hole location in the scrap area has high requirements on the shape of the scrap and the amount of material flowing in during the part forming process. Moreover, the scrap area generally refers to the scrap area in the profile, not the scrap on the blank holder. This results in the selection of the positioning hole location being severely constrained by the part design. Second, this existing technology is basically unapplicable to relatively deep-drawn parts due to the limitations of the punching structure. Third, in this existing technology, the punching punch on the Φ40mm flat surface protrudes from the upper mold cavity of the drawing die, which is not conducive to material... The normal inflow of material easily leads to frequent wear and scratches on the sheet metal caused by the punching punch, resulting in defects such as dents or dents on the product surface; fourth, this existing technology makes the drawing die or drawing equipment structurally extremely complex, requiring not only the addition of punching punches and dies, but also special design of the shape of the scrap area of ​​the drawing die. In addition, the shapes of the bushing 3 and the pressure sleeve 6 also need to be designed accordingly; fifth, although this existing technology uses the pressure sleeve and bushing to press the positioning hole and the surrounding area and press out a certain shape to store the material, thereby alleviating the deformation of the positioning hole, it is not only complex in process, but also very unsatisfactory in actual operation. The positioning hole often has relatively large deformation, resulting in a high scrap rate.

[0008] The current state of the aforementioned existing technology is limited by the universality of material deformation during the drawing process, which makes the subsequent machining of positioning holes after drawing a relatively difficult technical problem to solve, and it has always been difficult to find a suitable and precise technical solution.

[0009] In view of this, it is necessary to design a sheet metal drawing process and its supporting equipment that can overcome the above-mentioned technical problems and effectively solve or alleviate the above-mentioned technical difficulties. Summary of the Invention

[0010] The fundamental technical problem to be solved by this invention is to provide a sheet metal drawing process that can simultaneously complete the processing of subsequent positioning holes during the drawing process. The process is scientific, the supporting equipment is simple, and there is basically no deformation, effectively ensuring the positioning accuracy requirements.

[0011] Furthermore, the technical problem to be solved by the present invention is to provide a sheet metal drawing device that can simultaneously complete the processing of subsequent positioning holes during the sheet metal drawing process. It has a simple structure and the positioning holes are basically free from deformation, effectively ensuring the positioning accuracy requirements.

[0012] In addition, the technical problem to be solved by the present invention is a drawing die that can be applied to the sheet metal drawing equipment of the present invention, so that the sheet metal drawing equipment can simultaneously complete the processing of subsequent positioning holes during the sheet metal drawing process, the positioning holes are basically free from deformation, and the positioning accuracy requirements are effectively guaranteed.

[0013] To solve the aforementioned fundamental technical problems, the present invention provides a sheet metal drawing process, comprising the following steps: First, a sheet metal drawing device equipped with a moving die and a stationary die is used to draw the sheet metal. During the drawing process, the draw bead clamping structure of the sheet metal drawing device clamps the draw beads of the sheet metal. Second, when the moving die reaches a pre-set punching position at a distance before the end of the drawing stroke, the punching punch on the stationary die and the punching die on the moving die simultaneously punch the pre-set punching point around the clamped draw beads of the sheet metal as the moving die moves, thereby forming the positioning hole when or before the moving die reaches the end of the drawing stroke.

[0014] Specifically, the set distance is 1-5 times the thickness of the sheet material.

[0015] Particularly preferably, the punching point is located outside the corner of the pressed drawbeam of the sheet metal.

[0016] Preferably, the moving die is an upper die and the stationary die is a lower die; and / or the drawbead clamping structure includes a blank holder of the sheet metal drawing equipment and the moving die, the blank holder and the moving die having corresponding flanges and grooves. During the drawing process, the moving die and the blank holder press against each other to clamp and limit the drawbead through the flanges and grooves, and to clamp the area around the drawbead.

[0017] More preferably, the draw beads are formed by clamping the sheet metal with the flange and groove on the blank holder before or at the start of drawing.

[0018] Specifically, the pressure ring has a through hole for the punch to pass through.

[0019] Corresponding to the above-mentioned drawing process, the present invention provides a sheet metal drawing apparatus, including a stationary die, a moving die, and a drawing bead clamping structure for clamping and limiting the drawing beads of the sheet metal. The stationary die is provided with a punching punch, and the moving die is provided with a punching die. The positions and dimensions of the punching punch and the punching die are configured to cooperate with each other so that during the drawing process, when the moving die reaches a back-punching hole position at a predetermined distance before the end of the drawing stroke, back-punching is performed synchronously on the punching point around the clamped drawing bead of the sheet metal as the moving die moves, thereby punching and forming the positioning hole when or before the moving die reaches the end of the drawing stroke.

[0020] Specifically, the set distance is 1-5 times the thickness of the sheet material.

[0021] Particularly preferably, the punching point is located outside the corner of the pressed drawbeam of the sheet metal.

[0022] Specifically, the stationary die is provided with a stop protrusion for defining the end point of the drawing stroke of the moving die; and / or the moving die is also provided with a waste collection device for collecting back punch waste.

[0023] Preferably, the drawbead clamping structure includes a blank holder of the sheet metal drawing equipment and a moving die. The moving die and the blank holder are mounted on a sliding seat of the sheet metal drawing equipment and are movable relative to each other and toward the stationary die. The blank holder and the moving die have corresponding flanges and grooves so that the moving die and the blank holder can press against each other and clamp the sheet metal through the flanges and grooves to form the drawbead.

[0024] Specifically, the pressure ring has a through hole for the punch to pass through.

[0025] More specifically, the punching punch and punching die are respectively disposed on the stationary die and the moving die at positions outside the flange and the groove, so as to align the punching set points around the pressed draw beads of the sheet metal during the drawing process.

[0026] In addition, the present invention also provides a drawing die, wherein the drawing die is a moving die or a stationary die used in the sheet metal drawing equipment of any of the above technical solutions.

[0027] Through the above-described technical solution of this invention, the sheet metal drawing process and its supporting sheet metal drawing equipment of this invention ingeniously analyze the staged and refined process of microscopic deformation during the sheet metal drawing process, and innovatively form a back-punching process. Utilizing the inherent characteristics and movement process of the moving die, stationary die, and clamping structure of the drawing equipment itself, a unique and universally applicable, simplified back-punching structure is formed. During the drawing process, positioning holes for subsequent processes are simultaneously processed. These positioning holes not only exhibit minimal deformation, meeting the positioning accuracy requirements of subsequent processes, but also feature a simple and convenient process. The corresponding back-punching structure is simplified and universally applicable, eliminating the need for redundant secondary positioning hole trimming processes or specialized positioning hole processing techniques. The positioning holes can be processed simultaneously with the completion of the normal drawing process. Furthermore, the drawing process and drawing equipment of this invention also have the following more specific advantages and technical effects:

[0028] First, this invention carefully analyzes the deformation characteristics of the sheet metal during the drawing process, performs detailed microscopic deformation analysis, and utilizes the structural characteristics and motion process of the drawing equipment itself. By integrating the invention's original reverse punching process, positioning holes are punched around the draw beads of the sheet metal drawing part (especially preferably at the outer corner). The material flow at this position is basically zero during the final drawing process of the part. By utilizing the clamping structure of the drawing equipment itself, the punching process environment is simulated at a specific time during the precise drawing process. It can be regarded as a hole punched in a static state. Therefore, the positioning hole itself is basically undeformed.

[0029] Secondly, the sheet metal drawing process and its supporting sheet metal drawing equipment of this invention cleverly integrate the punching components or punching structures into the moving and stationary dies of the drawing equipment. This not only does not affect the normal drawing process and is completely integrated into the drawing process, but also allows for the use of standard reverse punching parts for each part model according to the model of the drawn part. This facilitates installation, effectively improves processing efficiency, and has universal applicability and economic and technical value.

[0030] Third, the sheet metal drawing process and its supporting sheet metal drawing equipment of the present invention, due to the precision of the positioning hole process of the present invention, do not require the formation of special punching or flat surfaces, nor do they require special bushings or other supporting structures to prevent or alleviate sheet metal deformation. This saves more material usage for the drawn parts, and has higher feasibility and applicability. It has no requirements on the shape of the drawn sheet metal parts and can be effectively applied to the processing requirements of positioning holes for various product shapes such as deep drawing and shallow drawing.

[0031] Fourth, the sheet metal drawing process and its supporting sheet metal drawing equipment of the present invention provide great convenience and process feasibility for designing high-precision flexible fixtures for some subsequent processes, such as three-dimensional laser cutting and punching of products.

[0032] The drawing die of the present invention, specifically designed for the sheet metal drawing equipment of the present invention, also possesses the aforementioned advantages and technical effects. Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0033] The following figures are provided to further illustrate the invention and form part of the specification. They, together with the detailed embodiments described below, serve to explain the invention, but the scope of protection of the invention is not limited to the following figures and detailed embodiments. In the figures:

[0034] Figure 1 This is a schematic diagram of the punching device on a prior art drawing die;

[0035] Figure 2This is a flowchart illustrating the sheet metal drawing process according to a specific embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the material state analysis during the back punching process in the sheet metal drawing process of a specific embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the sheet metal drawing equipment according to a specific embodiment of the present invention, wherein the sheet metal is in a state before being drawn;

[0038] Figure 5 This is a schematic diagram of the sheet metal drawing equipment according to a specific embodiment of the present invention, wherein the sheet metal is in a state where draw beads are formed at the beginning of the drawing process;

[0039] Figure 6 This is a schematic diagram of the sheet metal drawing equipment according to a specific embodiment of the present invention, wherein the sheet metal is in a state where the drawing is completed and a positioning hole is formed through the back punch;

[0040] Explanation of reference numerals in the accompanying drawings of this invention:

[0041] 1. Moving mold 2. Sheet metal

[0042] 3. Pressure ring 4. Static mold

[0043] 5 Waste collection device 6 Punching die

[0044] 7. Punching punch; 8. Draw bead

[0045] 9 flanges 10 grooves

[0046] 11 Punching setting point 12 Through hole

[0047] 13 Stopping protrusions 14 Material drawing forming area Detailed Implementation

[0048] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention, and the scope of protection of the present invention is not limited to the specific embodiments described below.

[0049] As mentioned above, in sheet metal drawing processes, the development of technology in this field is actually at a technological bottleneck due to the prevalence of drawing deformation. For a long time, a consensus has been that the sheet metal, being in a state of deformation during the drawing process, is inherently unsuitable for punching. This conventional wisdom, coupled with the urgent need for positioning reference holes in subsequent production processes, has led to the forced addition of various punching structures during the drawing process, and even the artificial addition of large areas of waste material beyond the required shaping dimensions, to meet the needs of positioning hole processing. This results in exceptionally complex structures for drawing equipment with positioning hole processing capabilities. However, due to various drawing deformation factors, the processed positioning holes often fail to meet the accuracy requirements. This technological approach has gradually fallen into a difficult dilemma: the positioning requirements of actual production and the enormous technical difficulties in achieving them present an insurmountable technological gap.

[0050] Faced with this technological bottleneck in the field, the key technical challenge for breakthroughs in the research and development of this invention is to solve the critical point of drawing deformation. To this end, a large amount of research and design has been carried out, and a huge number of drawing deformation simulation experiments have been conducted. Simulation analysis and deformation trajectory simulation analysis (CAE) have been performed on a large number of drawing processes. However, the results of the experiments and analyses were not ideal for a long time. This is because the deformation of the sheet metal during the drawing process is actually a kind of plastic deformation within the material. During the drawing process, even if the sheet metal is pressed at the draw bead clamping structure (usually the blank holder) of the drawing equipment, there is internal material flow due to the plastic deformation of the sheet metal. This makes it almost impossible to simplify the drawing process with positioning hole processing function and ensure that the positioning holes are basically not deformed. However, technological breakthroughs often occur unexpectedly. After numerous failed simulation analyses in the early stages, the project team of this invention restarted the simulation analysis, expanding the scope of the sheet metal drawing process to include the entire drawing process from the formation of the draw beads to the unloading at the end of drawing. This led to a significant, unintentional, extremely small period in the drawing process that resulted in the technological breakthrough, which appeared in a large amount of statistical data from the simulation analysis of drawing deformation. To gain a deeper understanding of the technical concept of this invention, the following first explains the basis for establishing the technical concept of this invention and the process concept of "back punching" in this invention.

[0051] See Figure 3 As shown, Figure 3 This displays the normal process of the general sheet metal drawing process for sheet 1. (For reference only.) Figure 4 (Notice Figures 4 to 6(Only a partial view of the sheet metal drawing equipment corresponding to the end of sheet metal 2 is shown). Generally, during the drawing process of sheet metal 2, sheet metal 2 is placed on the blank holder 3, and the moving die 1 moves downward. Through the mutual compression between the moving die 1 and the blank holder 3, a draw bead 8 is formed on the sheet metal 2. The moving die 1 and the blank holder 3 continue to maintain a state of mutual compression, thereby compressing the draw bead 8 and its surrounding area. Then, the moving die 1 and the blank holder 3 move downward together toward the stationary die 4, and the sheet metal 2 is compressed and deformed by the drawing cavity structure on the stationary die 4. See also Figure 3 As mentioned above, during the drawing process of sheet metal 2, sheet metal 2 is subjected to extrusion by the drawing die and undergoes continuous plastic deformation. The internal material flow is relatively large even around the compressed draw beads 8. Figure 3 As indicated by the middle arrow, material continuously flows from the edge of sheet 2 towards the drawing center, and this flow process persists almost throughout the entire drawing process. However, as mentioned above, numerous simulations and analyses of the drawing process have revealed that when the part is nearing completion of the drawing (generally a period of 1-5 times the thickness of sheet 2 before the end of the drawing stroke), the material inflow around the draw bead 8 of sheet 2 (especially the local area near the outer corner is more stable) is almost zero. In other words, within this short, specific stroke period, this local area on sheet 2 is essentially stationary. This is very similar to the process environment of a normal standalone punching operation. Machining the positioning hole during this specific stroke period not only avoids significant deformation but also, since the drawing process is nearing completion, avoids additional deformation problems caused by the drawing process after the positioning hole is simultaneously formed. However, this breakthrough in technical approach and concept based on the microscopic analysis of drawing deformation has encountered significant technical difficulties in the punching hardware structure of the drawing die. Specifically, as is well known to those skilled in the art, a normal punching process involves the movement of the punching punch, with the workpiece clamped on the punching die, and punching performed using the impact motion of the punch (the drawing die with positioning hole processing function in the prior art analyzed above is also a similar forward punching process). This forward punching process mainly relies on the impact kinetic energy of the punching punch to perform punching. However, in the drawing process of sheet metal drawing equipment, since the sheet metal 2 follows the moving die 1 during the drawing process, it is not feasible to perform forward punching using the drawing motion of the moving die 1 itself. Therefore, the punching process in the prior art often requires a secondary punching motion in addition to the drawing motion to be specially designed for the punching punch 7, resulting in an extremely complex structure for the sheet metal drawing equipment.

[0052] To this end, the project team of this invention has delved into the existing drawing structures of sheet metal drawing equipment, and appropriately referenced... Figure 4During the drawing process, as the drawing process nears completion, the sheet metal 2 is clamped by the moving die 1 and the drawbead clamping structure (generally a blank holder 3) of the sheet metal drawing equipment. Typically, the drawbead clamping structure has a clamping surface for clamping the area around the drawbead 8 of the sheet metal 2, which mates with the clamping mating surface of the moving die 1 to clamp the drawbead 8 and its surrounding area. Although the sheet metal 2 is in the drawing motion following the moving die 1, the clamping of the area around the drawbead 8 of the sheet metal 2 by the moving die 1 and the drawbead clamping structure of the sheet metal drawing equipment is very similar to the state of the part to be punched being clamped on the punching die in a normal forward punching process. To address this issue, the project team of this invention broke through the traditional mindset of forward punching and proposed the concept of "reverse punching." "Reverse punching" refers to utilizing the passive die 1 and the draw bead clamping structure of the drawing equipment during the sheet metal drawing process. In this case, the punching groove structure is set on the moving die 1, while the punching punch is set on the stationary drawing die 4. Thus, through the drawing motion and impact of the moving die 1, a specific portion of the sheet metal 2 that is clamped (i.e., the area around the draw bead) collides with and impacts the stationary punching punch, completing the punching of the positioning hole simultaneously with the drawing motion. This "reverse punching" concept changes the design approach of normal forward punching and cleverly integrates into the existing general structure of sheet metal drawing equipment, greatly simplifying the structure of the sheet metal drawing equipment while simultaneously possessing a high-performance positioning hole processing function.

[0053] The basic embodiments and various preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0054] To aid in understanding the technical solution of this invention, the sheet metal drawing apparatus of this invention is first described below, and the sheet metal drawing process of this invention is introduced through the dynamic working process of the sheet metal drawing apparatus. It should be noted that although the drawing process of this invention can be conveniently and efficiently implemented using the sheet metal drawing apparatus of this invention, some operations of the sheet metal drawing process of this invention are not limited to forming on the drawing apparatus. For example, the formation of draw beads on the sheet metal, although generally formed at the beginning of the sheet metal drawing process on the drawing apparatus, can also be formed in the pre-setting process of the sheet metal preceding the drawing process, which will be explained below. Furthermore, although in this invention… Figures 2 to 6 In the drawing equipment shown, the upper die is the moving die 1, and the lower die is the stationary die 4. However, this invention is not limited to this. Various arrangements of moving and stationary dies are widely used in sheet metal drawing equipment, such as upper moving and lower stationary, upper stationary and lower moving, left moving and right stationary, or left stationary and right moving, etc. As long as they adopt the technical concept of this invention, they should all fall within the protection scope of this invention. At the same time, for this invention, the use of directional terms such as "inner" and "outer" is generally relative to the drawbead 8. Those within the range of the drawbead 8 can be called "inner," and those outside the range of the drawbead can be called "outer."

[0055] See Figures 3 to 6 The sheet metal drawing apparatus of the basic embodiment of the present invention includes a stationary die 4, a moving die 1, and a drawbead clamping structure for clamping and limiting the drawbeads 8 of the sheet metal 2. The stationary die 4 is provided with a punching punch 7, and the moving die 1 is provided with a punching die 6. The position and size of the punching punch 7 and the punching die 8 (especially the distance of the height of the punching punch 7 relative to the end of the drawing stroke) need to be carefully designed. Specifically, the position and size of the punching punch 7 and the punching die 6 are configured to cooperate with each other so that during the drawing process, when the moving die 1 reaches the back punching position at a set distance before the end of the drawing stroke, as the moving die 1 moves, the punching punch 7 contacts the sheet metal 2 clamped on the moving die 1, and simultaneously performs back punching on the punching setting point 11 around the clamped drawbeads 8 of the sheet metal 2, thereby forming a positioning hole when or before the moving die 1 reaches the end of the drawing stroke.

[0056] In the basic embodiment of the sheet metal drawing equipment described above, it is generally understood by those skilled in the art that the drawbead clamping structure has a clamping surface for clamping the area around the drawbead 8 of the sheet metal 2, and both the punching punch 7 and the punching die 8 can be arranged corresponding to the clamping surface. The drawbead clamping structure of the sheet metal drawing equipment can generally be a blank holder 3, but it is not limited to this. The drawbead clamping structure of the sheet metal drawing equipment can be of various types. For example, if the drawbead 8 on the sheet metal 2 is pre-formed, the drawbead clamping structure on the sheet metal drawing equipment can even be a sheet metal clamp attached to the moving die 1. Generally speaking, the drawbead clamping structure of the sheet metal drawing equipment only needs to be able to cooperate with the clamping surface of the moving die 1 to form a limiting groove that accommodates and limits the drawbead 8. At the same time, the clamping surface of the moving die 1 and the mating surface of the drawbead clamping structure press against each other to tighten the area around the drawbead 8 of the sheet metal 2, ensuring that the sheet metal 2 is fixed and does not slip during the drawing process.

[0057] In the aforementioned drawing equipment, the punching punch 7 is mounted on the upper die (which serves as the moving die 1), and the punching die 6 is mounted on the lower die (which serves as the stationary die 4). As a common structure in sheet metal drawing equipment, the upper die generally moves downwards along with the moving base of the drawing equipment, and the upper die and the blank holder 3 (usually equipped with a nitrogen cylinder or spring) press the sheet metal 2 together, thus cooperating with the lower die to draw the sheet metal during the movement. When it reaches the back-punching position near the end of the drawing stroke, the punching punch 7 and the punching die 6 enter the working state to punch. As analyzed in the deformation analysis of the sheet metal 2 during the drawing process, at this back-punching position, the sheet metal 2 is actually punched in a relatively static state. The punching position is selected as follows... Figure 3The punching setting point 11 around the compressed draw bead 8 of the sheet 2 shown (especially preferably the punching setting point 11 on the outer side of the corner of the draw bead 8) is located in the vicinity of the draw bead 8. When the sheet 2 is close to the end of the drawing process, the material flow at this specific location is almost zero. Punching of the sheet 2 starts from the back punching position at this specific location and from a set distance from the end of the drawing stroke, which is basically equivalent to the normal punching working environment.

[0058] As can be seen from the above-described technical route, the formation process of the technical concept, and the basic implementation method of the sheet metal drawing equipment of the present invention, the sheet metal drawing equipment of the present invention cleverly analyzes the staged and refined process of microscopic deformation in response to the deformation characteristics of sheet metal 2 during the drawing process, and innovatively forms a back-punching process. Utilizing the inherent characteristics and movement process of the moving die 1, stationary die 4, and clamping structure of the drawing equipment itself, a unique and universally applicable, simplified back-punching structure is formed. During the drawing process, positioning holes for subsequent processes are simultaneously processed. These positioning holes not only have basically no deformation and meet the positioning accuracy requirements of subsequent processes, but also have a simple and convenient process. The corresponding back-punching structure is simplified and has universal applicability. There is no need for a redundant secondary positioning hole trimming process or a special positioning hole processing process. The processing of positioning holes can be completed at the same time as the normal drawing process ends.

[0059] Based on the above basic implementation method, preferably, the starting point of the back punching is a back punching position set at a distance before the moving die 1 reaches the end of the drawing stroke. This back punching position is determined according to the thickness of the sheet 2. After repeated testing in the actual research and development process, the distance is set to 1-5 times the thickness of the sheet 2. This ensures that the punching can make full use of the kinetic energy of the drawing motion, and also ensures that the sheet 2 is in the stroke section that is close to the completion of the drawing. As mentioned above, at this time, the material inflow of the punching setting point 11 around the draw bead 8 is almost zero, which is basically equivalent to the punching process environment, ensuring that the positioning hole formed by synchronous processing is basically free from deformation and meets the positioning accuracy requirements.

[0060] See Figures 4 to 6 Typically, the moving die 1 is the upper die, and the stationary die 4 is the lower die. However, as mentioned above, the relative arrangement of the moving die 1 and stationary die 4 in the sheet metal drawing equipment is not limited to this. It can also be arranged such as the upper die being the stationary die 4 and the lower die being the moving die 1, depending on the process requirements. Furthermore, to limit the end point of the drawing stroke and prevent the moving die 1 and stationary die 4 from colliding and damaging the main shaping surface of the drawing die, the stationary die 4 can generally be provided with a stop protrusion 13 to limit the end point of the drawing stroke of the moving die 1. When the moving die 1 and the drawing bead clamping structure of the sheet metal drawing equipment, carrying the sheet metal 2, reach the end point of the drawing stroke, they will encounter the stop protrusion 13 and cannot continue moving, thus reaching the end point of the drawing stroke.

[0061] In addition, since the punching die 8 is set on the moving die 1, in order to prevent the waste material generated by punching from being discarded or splashed at will, a waste collection device 5 can be set on the moving die 1 corresponding to the punching die 6. In this way, the waste material punched in the positioning hole can be pushed into the waste collection device 5 by the punching punch 7, so as to prevent the waste material from splashing at will and affecting the safety of the drawing equipment or operators.

[0062] In a preferred embodiment of the present invention, adapted to commonly used sheet metal drawing equipment, the drawbead clamping structure of the sheet metal drawing equipment can be coupled with a blank holder 3 and a moving die 1 commonly used in sheet metal drawing equipment. The blank holder 3 generally has a clamping surface, and the moving die 1 has a clamping mating surface. As is well known to those skilled in the art, the moving die 1 and the blank holder 3 are generally mounted on a sliding seat of the sheet metal drawing equipment and can move relative to each other and toward the stationary die 4. The clamping surface of the blank holder 3 and the clamping mating surface of the moving die 1 have corresponding flanges 9 and grooves 10, so that the moving die 1 and the blank holder 3 can press against each other, and the sheet metal is clamped by the flanges 9 and the grooves 10 to form the drawbead 8. In this way, during the drawing process, the drawbead 8 of the sheet metal 2 is clamped and limited by the cooperation of the flanges 9 and the grooves 10, and at the same time, the part around the drawbead 8 is also pressed between the moving die 1 and the blank holder 3, ensuring that the sheet metal 2 will not shift during the drawing process.

[0063] When the blank holder 3 is used as the drawbead clamping structure, since the punching setting point 11 is located around the drawbead 8 (preferably the outer part of the corner of the drawbead 8), this outer part is generally clamped between the moving die 1 and the blank holder 3. When the blank holder 3 is a normal ring, in order to avoid the blank holder 3 affecting the passage of the punching punch 7 on the stationary die 4, the blank holder 3 can adaptively form a through hole 12 for the punching punch 7 to pass through. Of course, the drawbead clamping structure of the sheet metal drawing equipment used in practice varies, and there are also types where the blank holder 3 has a notch. If it does not interfere with the punching movement of the punching punch 7, the above-mentioned through hole 12 may not be provided. This is mainly determined according to the actual process.

[0064] Furthermore, as described above, in a typical sheet metal drawing machine, the draw bead 8 on the sheet metal 2 is formed by pressing the flange 9 and groove 10 on the moving die 1 and the blank holder 3 at the start of drawing. That is, the flange 9 and the groove 10 cooperate to form the draw bead 8. The flange 9 and the groove 10 correspond to the draw bead 8 on the sheet metal 2. The draw bead 8 has a corner, and the flange 9 and the groove 10 also have corners. Since the punching setting point 11 of the present invention is preferably located on the outer part of the corner of the draw bead 8, in order for the punching punch 7 and the punching die 6 to accurately punch at the punching setting point 11, the punching punch 7 and the punching die 6 need to be correspondingly set on the outer side of the flange 9 and the groove 10 (preferably on the outer side of the corner), and correspondingly set on the outer side of its corner, so that during the drawing process, the punching point 11 on the outer side of the corner of the pressed draw bead 8 of the sheet metal 2 can be punched.

[0065] From the above description of various embodiments of the sheet metal drawing equipment of the present invention, it can be seen that although the sheet metal drawing equipment of the present invention generally adopts various existing types of sheet metal drawing equipment, its drawing die still needs to be structurally improved, that is, it is necessary to set punching punch 7 and punching die 6 in specific positions. For this purpose, the present invention also provides a drawing die, wherein the drawing die is the moving die 1 or the stationary die 4 used in the above sheet metal drawing equipment. The moving die 1 and the stationary die 4 are molds dedicated to the drawing equipment of the present invention, and they also fall within the protection scope of the present invention.

[0066] The sheet metal drawing equipment and its matching molds of the present invention have been described above in a hierarchical manner. The following refers to... Figures 4 to 6 The preferred embodiment of the sheet metal drawing equipment of the present invention is shown, describing the working process and principle of the drawing equipment to achieve reverse punching in the drawing process: A punching punch 7 is installed on the lower die (stationary die 4), and a punching die 6 is installed on the upper die (moving die 1), corresponding to the outer corner of the groove 10 of the blank holder 3 of the drawing equipment. During the drawing process, starting from the feeding stage, after the sheet metal 2 is placed on the blank holder 3, the upper die begins to move downwards with the sliding seat of the sheet metal drawing equipment (i.e., the press). When the upper die contacts the blank holder 3, it presses the sheet metal 2 and forms a drawing bead 8, as shown... Figure 5 As shown. The sliding seat, upper die, sheet metal 2, and blank holder 3 continue to move downwards simultaneously. Then, sheet metal 2 contacts the cavity of the lower drawing die (the lower die is fixed on the lower base of the drawing equipment and remains stationary), and the lower die cavity draws sheet metal 2 into shape. When the drawing is nearly complete (i.e., the lower die reaches the back punch position at a set distance before the end of the drawing stroke), sheet metal 2 contacts the punching punch 7 installed on the lower drawing die. Then, under the pressure of the blank holder 3 and the upper die, sheet metal 2 is drawn downwards as shown. Figure 2 Punching is performed at the specified punching point 11. Back punching also ends at or slightly before the completion of the drawing process. Figure 6 As shown. The workpiece then enters the next process, and the positioning hole punched in the drawing process is used as the positioning hole for the next process to improve the dimensional accuracy of the workpiece. The subsequent process uses this positioning hole for positioning and achieves datum conversion by punching other holes on the part, which is beneficial to improving the overall dimensional accuracy of the part. In addition, since the amount of sheet material flowing into the corner of the drawing bead 8 of the sheet material 2 held between the blank holder 3 and the upper die is very small when the drawing is near completion, it can be regarded as a relatively static state. The blank holder 3 plays a pressing role in the punching process, which meets the normal conditions required for the punching process. The positioning hole is basically undeformed, and since the drawing is near completion, it will not have the effect of subsequent deformation. Furthermore, the part punching set point 11 is located in the blank holder scrap area, which has no impact on the drawing efficiency and quality of the part.

[0067] The sheet metal drawing equipment and its working process of the present invention have been described in detail above. However, it should be noted that the core technical concept of the present invention is not limited to... Figures 4 to 6 The drawing equipment shown in the specific preferred structure can be implemented, for example, the blank holder 3 can be implemented by an alternative type of fixture on another moving die 1, and the draw bead 8 of the sheet 2 is not necessarily formed by the sheet drawing equipment, but can be pre-formed on the sheet 2. For this purpose, see Figure 2 As shown, the present invention provides a sheet metal drawing process, which includes the following steps: First, a sheet metal 2 is drawn using a drawing device equipped with a moving die 1 and a stationary die 4. During the drawing process, the drawing bead 8 of the sheet metal 2 is pressed by the drawing bead pressing structure of the sheet metal drawing device. Second, when the moving die 1 reaches the back punch position at a set distance before the end of the drawing stroke, the punching punch 7 on the stationary die 4 and the punching die 6 on the moving die 1 simultaneously punch the punch setting point 11 around the pressed drawing bead 8 of the sheet metal 2, thereby forming a positioning hole when the moving die 1 reaches the end of the drawing stroke.

[0068] In the above sheet metal drawing process, specifically, the set distance can be 1-5 times the thickness of the sheet metal. Of course, the set distance can also be outside the above range according to the process requirements, as long as the punching can make full use of the kinetic energy of the drawing motion and ensure that the sheet metal 2 is in the stroke section that is close to the completion of the drawing.

[0069] Furthermore, as a general structure employing typical sheet metal drawing equipment, the drawbead clamping structure in the above-mentioned drawing process may include a blank holder 3 and a moving die 1 of the sheet metal drawing equipment. The blank holder 3 and the moving die 1 have corresponding flanges 9 and grooves 10. During the drawing process, the moving die 1 and the blank holder 3 press against each other to clamp and limit the drawbead 8 through the flanges 9 and grooves 10, and also to clamp the area surrounding the drawbead 8 through the moving die 1 and the blank holder 3. Further, before or at the start of drawing, the sheet metal 2 can also be formed by clamping the sheet metal 2 with the flanges 9 and grooves 10 on the moving die 1 and the blank holder 3.

[0070] As can be seen from the above description, the drawing process and its supporting sheet metal drawing equipment of the present invention analyze the staged and refined process of microscopic deformation during the drawing process of sheet metal 2, and innovatively develop a back-punching process by combining the structural specificity of the drawing equipment and the drawing process. Utilizing the inherent characteristics and movement process of the moving die, stationary die and clamping structure of the drawing equipment itself, a unique and universally applicable, simplified back-punching structure is formed. During the drawing process, positioning holes for subsequent processes are simultaneously processed. These positioning holes not only have basically no deformation and meet the positioning accuracy requirements of subsequent processes, but also have a simple and convenient process. The corresponding back-punching structure is simplified and has universal applicability, eliminating the need for redundant secondary positioning hole trimming processes or special positioning hole processing processes. The processing of positioning holes can be completed at the same time as the normal drawing process ends. First, this invention, through meticulous analysis of the deformation characteristics of the sheet metal 2 during the drawing process, conducts a refined microscopic deformation analysis. Utilizing the structural characteristics and motion of the drawing equipment itself, and integrating the invention's unique reverse punching process, positioning holes are punched around the draw beads 8 of the sheet metal 2 (especially preferably at the outer corner of the draw bead 8). At this location, the material inflow during the final drawing process is essentially zero. By utilizing the clamping structure of the drawing equipment itself, the punching process environment is simulated at a specific time point in the precise drawing process; it can essentially be considered a hole punched in a static state, therefore the positioning hole itself is essentially undeformed. Second, this invention's sheet metal drawing process and its supporting sheet metal drawing equipment cleverly integrate the punching components or structures into the moving and stationary dies of the drawing equipment without affecting the normal drawing process. It is completely integrated into the drawing process and can effectively utilize standard reverse punching parts for various part types, facilitating installation and effectively improving processing efficiency. It has universal applicability and economic and technical value. Third, the drawing process and its supporting sheet metal drawing equipment of this invention, due to the precision of the positioning hole process, do not require the formation of special punching or flat surfaces, nor do they require special bushings or other supporting structures to prevent or mitigate sheet metal deformation. This results in greater material savings for the drawn parts, higher feasibility and applicability. It has no requirements on the shape of the drawn sheet metal parts and can be effectively applied to the processing requirements of positioning holes for various product shapes, including deep drawing and shallow drawing. Fourth, the sheet metal drawing process and its supporting sheet metal drawing equipment of this invention, even for some subsequent replacement processes, such as three-dimensional laser cutting for trimming, greatly facilitate the design of high-precision flexible fixtures and improve process feasibility for these replacement processes.

[0071] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations.

[0072] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. Sheet metal drawing process, among which, Includes the following steps: First, the sheet metal (2) is drawn by a sheet metal drawing equipment equipped with a moving die (1) and a stationary die (4). During the drawing process, the drawing ribs (8) of the sheet metal (2) are pressed by the drawing rib pressing structure of the sheet metal drawing equipment. Second, when the moving die (1) reaches the back punch position at a set distance before the end of the drawing stroke, the punch punch (7) on the stationary die (4) and the punch die (6) on the moving die (1) simultaneously punch the punch setting point (11) around the pressed drawing bead (8) of the sheet (2) through the moving die (1), so that the positioning hole is formed when the moving die (1) reaches the end of the drawing stroke; The punching setting point (11) is located outside the corner of the pressed draw bead (8) of the sheet (2); The moving mold (1) is the upper mold, and the stationary mold (4) is the lower mold.

2. The sheet metal drawing process according to claim 1, wherein, The set distance is 1-5 times the thickness of the sheet material.

3. The sheet metal drawing process according to any one of claims 1 to 2, wherein the draw bead clamping structure includes a pressure ring (3) of the drawing equipment, the pressure ring (3) and the moving die (1) cooperating with each other to clamp the sheet metal, wherein the pressure ring (3) and the moving die (1) have corresponding flanges (9) and grooves (10), and during the drawing process, the moving die (1) and the pressure ring (3) press against each other to clamp and limit the draw bead (8) by the flanges (9) and grooves (10), and clamp the area around the draw bead (8).

4. The sheet metal drawing process according to claim 3, wherein, Before or at the start of drawing, the sheet metal (2) is clamped by the moving die (1) and the flange (9) and groove (10) on the blank holder (3) to form the draw bead (8).

5. The sheet metal drawing process according to claim 3, wherein, The pressure ring has a through hole (12) for the punch (7) to pass through.

6. Sheet metal drawing equipment, comprising a stationary die (4), a moving die (1), and a drawbead clamping structure for clamping and limiting the drawbeads (8) of the sheet metal (2), wherein, The stationary die (4) is provided with a punching punch (7), and the moving die (1) is provided with a punching die (6). The positions and dimensions of the punching punch (7) and the punching die (6) are configured to cooperate with each other: during the drawing process, when the moving die (1) reaches the back punching position at a set distance before the end of the drawing stroke, the punching set point (11) around the pressed drawing bead (8) of the sheet (2) is punched synchronously as the moving die (1) moves, so that a positioning hole is formed when the moving die (1) reaches the end of the drawing stroke. The punching setting point (11) is located outside the corner of the pressed draw bead (8) of the sheet (2); The moving mold (1) is the upper mold, and the stationary mold (4) is the lower mold.

7. The sheet metal drawing equipment according to claim 6, wherein, The set distance is 1-5 times the thickness of the sheet (2).

8. The sheet metal drawing equipment according to claim 6, wherein, The stationary die (4) is provided with a stop protrusion (13) for limiting the end point of the drawing stroke of the moving die (1); and / or the moving die (1) is also provided with a waste collection device (5) for collecting back punch waste.

9. The sheet metal drawing equipment according to any one of claims 6 to 8, wherein, The drawbead clamping structure includes a blank holder (3) of the sheet metal drawing equipment and a moving die (1). The moving die (1) and the blank holder (3) are mounted on a sliding seat of the sheet metal drawing equipment and can move relative to each other and toward the stationary die (4). The blank holder (3) and the moving die (1) have corresponding flanges (9) and grooves (10) so that the sheet metal can be formed by pressing the moving die (1) against the blank holder (3) and clamping the sheet metal through the flanges (9) and grooves (10).

10. The sheet metal drawing equipment according to claim 9, wherein, The pressure ring (3) has a through hole (12) for the punching punch (7) to pass through.

11. The sheet metal drawing equipment according to claim 9, wherein, The punching punch (7) and punching die (6) are respectively positioned on the stationary die (4) and the moving die (1) on the outside of the flange (9) and the groove (10) so that they can be aligned with the punching set point (11) around the pressed draw bead (8) of the sheet (2) during the drawing process.

12. Drawing die, wherein, The drawing die is a moving die (1) or a stationary die (4) used in the sheet metal drawing equipment according to any one of claims 6 to 11.

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