3D printing integrally formed shoe mold

Abstract

The utility model discloses a 3D prints integrated shoe mould, integrate and include: the side wall, the hollow accommodating cavity is provided with in the inside recessed setting of side wall top, the integrative frame is detachably installed to the side wall top, and the forming block is provided with to the outward protruding setting of outer frame bottom. The side wall of shoe mould in the utility model is made through laser selective melting process 3D printing, can realize the precision forming processing of metal material with the bite flower pattern, removes the repeated reverse mould and the process step of etching concave-convex texture on the metal mould through the acid etching method, effectively reduces the moulding cycle and mould overall weight, improves the heat dissipation performance.

Description

Technical Field

[0001] This utility model relates to the technical field of shoe mold forming equipment, specifically to a 3D printed one-piece shoe mold. Background Technology

[0002] Shoe molds are used for shaping and molding shoes during the production process. They are key tools in the shoe industry and are typically made of materials such as metal, wood, or plastic. The traditional shoe mold etching process involves several steps: first, computer-aided design (CAD) software is used to create a 3D model of the sole texture or pattern; then, a wooden master mold is machined using a computer numerical control (CNC) machine; next, silicone is injected into this wooden master mold to create a silicone film; then, plaster is injected into this silicone film to create a plaster mold; finally, metal is injected to create a metal mold; the etching texture is then created through polluting chemical etching; and finally, polishing and surface treatment are performed to improve durability. This process involves numerous steps, complex procedures, and multiple mold-making and casting operations. Not only is the molding cycle lengthy, but the chemical etching process also causes significant environmental pollution, contradicting current principles of cost reduction, efficiency improvement, and green production.

[0003] Currently, many shoe factories are using stereolithography (SLA) to replace the traditional machining process of wooden mold prototyping. This means that 3D printing technology can flexibly mass-produce these prototype molds, thereby reducing costs and improving production efficiency. However, printing technology only replaces the CNC machining of the master mold and the subsequent texturing process. It still requires the casting of metal molds. The molds are relatively heavy and have slow heat dissipation during high-frequency use, which affects the molding effect and causes problems such as dimensional deviations and surface defects. Utility Model Content

[0004] The purpose of this utility model is to provide a 3D printed one-piece shoe mold to solve the above problems.

[0005] To achieve the above objectives, this utility model specifically adopts the following technical solution, including:

[0006] The side wall is integrally formed, and the top of the side wall is recessed inward to provide a hollow receiving cavity;

[0007] The top of the side wall is detachably fitted with an integrally molded outer frame, and a molded block is provided protruding outward from the bottom of the outer frame.

[0008] As a further description of the above technical solution, a fixing seat is installed at one end of the side wall, and the side wall is detachably connected to the base at the bottom through the fixing seat.

[0009] As a further description of the above technical solution, a flip shaft is installed at the other end of the side wall, and the side wall is rotatably connected to the top outer frame through the flip shaft.

[0010] As a further description of the above technical solution, the wall thickness of the sidewall and the outer frame is 1-3cm.

[0011] As a further description of the above technical solution, the receiving cavity includes symmetrically arranged pressing cavities, and the top end face of the pressing cavity is provided with a first textured metal pattern.

[0012] As a further description of the above technical solution, the molding block includes symmetrically arranged pressing blocks, and the bottom end face of the pressing block is provided with a second textured metal pattern.

[0013] As a further description of the above technical solution, the gap thickness between the pressing chamber and the pressing block is 1-4 mm.

[0014] As a further description of the above technical solution, a fastening cavity is symmetrically arranged around the pressing cavity, and a fastening groove is symmetrically arranged on the outer side of the pressing cavity.

[0015] As a further description of the above technical solution, fastening blocks are symmetrically arranged around the pressing block, and fastening strips are symmetrically arranged on the outer side of the pressing cavity.

[0016] As a further description of the above technical solution, the inner contour of the fastening cavity fits with the outer contour of the fastening block, and the inner contour of the fastening groove fits with the outer contour of the fastening strip.

[0017] The beneficial effects of this utility model are as follows:

[0018] In this invention, the sidewalls of the shoe mold are 3D printed using a laser selective melting process, which enables precision forming of metal materials with textured patterns. This eliminates the need for repeated molding and etching of textures on metal molds using acid etching, effectively reducing the molding cycle and overall mold weight, and improving heat dissipation performance.

[0019] To more clearly illustrate the structural features and functions of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1 This is the front view of the 3D printed one-piece shoe mold proposed in this application;

[0021] Figure 2This is a side view of the 3D printed one-piece shoe mold proposed in this application. Figure 1 ;

[0022] Figure 3 This is a top view of the 3D printed one-piece shoe mold proposed in this application;

[0023] Figure 4 This is a side view of the 3D printed one-piece shoe mold proposed in this application. Figure 2 ;

[0024] Figure 5 This is the process flow of the 3D printing one-piece shoe mold manufacturing technology proposed in this application. Figure 1 ;

[0025] Figure 6 This is the process flow of the 3D printing one-piece shoe mold manufacturing technology proposed in this application. Figure 2 ;

[0026] Figure 7 This is the process flow of the 3D printing one-piece shoe mold manufacturing technology proposed in this application. Figure 3 ;

[0027] Figure 8 This is a schematic diagram of the shoe mold in Embodiment 1 of this application;

[0028] Figure 9 This is a schematic diagram of the shoe mold structure in Embodiment 2 of this application;

[0029] Figure 10 This is a schematic diagram of the shoe mold in Embodiment 3 of this application.

[0030] Figure label:

[0031] 1. Side wall; 11. Receiving cavity; 111. Pressing cavity; 112. First textured metal pattern; 12. Fastening cavity; 13. Fastening groove; 2. Outer frame; 21. Molding block; 211. Pressing block; 212. Second textured metal pattern; 22. Fastening block; 23. Fastening strip; 3. Fixing seat; 4. Flip shaft. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0033] The traditional shoe mold texturing process involves the following steps: First, computer-aided design (CAD) software is used to create a 3D model of the sole texture or pattern. Then, a wooden master mold is machined using a CNC machine tool. Next, silicone is injected into this wooden master mold to create a silicone film, and plaster is then injected through this silicone film to create a plaster mold. After the plaster mold is completed, aluminum or other metals are injected for casting to create a metal mold. At this stage, the metal mold does not yet have texturing features, so methods such as chemical etching are used to add texturing details to complete the texturing metal mold. Polishing and cleaning are often required to ensure a smooth surface. Finally, anodizing or a protective coating is applied to improve the durability and reduce wear of the shoe mold.

[0034] Understandably, this process involves many steps and complex procedures, including multiple mold making and casting. It not only has a long molding cycle but also causes significant environmental pollution due to the chemical etching process, which does not align with the current concepts of cost reduction, efficiency improvement, and green and environmentally friendly production.

[0035] Currently, many shoe factories are using stereolithography (SLA) to replace the traditional machining process of wooden mold prototyping. This means that 3D printing technology can flexibly mass-produce these prototype molds, thereby reducing costs and improving production efficiency. However, printing technology only replaces the CNC machining of the master mold and the subsequent texturing process. It still requires the casting of metal molds. The molds are relatively heavy and have slow heat dissipation during high-frequency use, which affects the molding effect and causes problems such as dimensional deviations and surface defects.

[0036] This application provides a 3D printed one-piece shoe mold and its manufacturing process, solving the problems of heavy overall molds and slow heat dissipation during high-frequency use in existing stereolithography processes, which affect the molding effect and cause dimensional deviations and surface defects. In this application, the sidewalls of the shoe mold are 3D printed using Selective Laser Melting (SLM) technology, enabling precise molding of metal materials with textured patterns. This eliminates the need for repeated casting and etching of textured surfaces on the metal mold using acid etching, effectively reducing the molding cycle and overall mold weight, and improving heat dissipation performance.

[0037] like Figures 1-4 As shown, in one embodiment, a 3D printed one-piece shoe mold includes: a one-piece sidewall 1 and an outer frame 2. The bottom of the sidewall 1 is flat and can be detachably installed on a base, while the outer frame 2 can be detachably installed on the top of the sidewall 1 to form a shoe mold for pressing the finished shoe sole.

[0038] Understandably, when the sole pressing operation is carried out, the outer frame 2 is pressed down by equipment such as hydraulic presses and stamping machines, so that the semi-finished sole located in the mold cavity is fully filled in the mold cavity space under high temperature and high pressure environment, and is finally pressed into a finished sole that meets the design requirements.

[0039] It should be explained in detail that the sidewall 1 is 3D printed using selective laser melting (SLM) technology. This process uses metal powder as raw material and selectively melts the metal powder layer by layer under the action of a high-energy-density laser beam according to the pre-designed three-dimensional model data, and then rapidly solidifies it into shape. Compared with traditional manufacturing methods, SLM technology can not only manufacture sidewall 1 parts with complex structures and extremely high precision, but also directly construct special structures such as internal hollows and gradient densities during the forming process, effectively reducing the weight of the parts while ensuring their mechanical properties. The outer frame 2 is manufactured by computer numerical control (CNC) machine tools, which can achieve precision forming of metal materials with textured patterns. This process eliminates the need for repeated molding and etching of textured surfaces on metal molds using acid etching methods, effectively reducing the molding cycle and processing costs.

[0040] Specifically, the sidewall 1 and outer frame 2 can be made of materials such as stainless steel, aluminum alloy, titanium alloy, and breathable steel. They have good breathability and do not require additional ventilation holes on the metal mold as in traditional manufacturing methods. This not only simplifies the mold manufacturing process but also significantly reduces the overall weight of the mold and optimizes its heat dissipation performance. This allows the heat in the mold cavity to be dissipated more quickly and evenly, effectively avoiding quality problems such as bubbles and deformation on the sole surface caused by local overheating, and significantly improving the quality and production efficiency of the finished sole.

[0041] For example, a fixing seat 3 is installed at one end of the side wall 1 by bolts or other connecting parts. The side wall 1 is detachably connected to the base at the bottom through the fixing seat 3, ensuring that the fixing seat 3 is tightly connected to the side wall 1. When transmitting the supporting force from the base and the pressure during the molding process, the stability of the structure can be maintained. Correspondingly, a flip shaft 4 is installed at the other end of the side wall 1 by hinges or other means. The side wall 1 is rotatably connected to the outer frame 2 at the top through the flip shaft 4, ensuring the flexibility of rotation and the structural strength, so that the outer frame 2 can open and close around the flip shaft 4.

[0042] Specifically, the wall thickness of the side wall 1 and the outer frame 2 is 1-3cm (preferably 1.5-2cm): if the wall thickness is too thin, it will be difficult to withstand the pressure load when the mold is subjected to a strong mold pressure of more than 20t during the later shoe sole pressing process. It is very easy for cracks to appear at the stress concentration points, resulting in mold damage. It will take time and cost to repair or replace, which will seriously affect the production progress and economic benefits. On the other hand, if the wall thickness is too thick, it will significantly increase the amount of metal material used, further increasing the processing cost.

[0043] Please continue reading. Figures 1-4 In this embodiment, the top of the side wall 1 is recessed inward to form a hollow receiving cavity 11, and the bottom of the corresponding outer frame 2 is protruding outward to form a molding block 21. This concave-convex fit effectively prevents material overflow during the shoe sole molding process, ensuring the neatness of the shoe sole edge. At the same time, through mutual limiting action, it improves the overall stability and sealing of the mold, ensuring the pressing accuracy of the shoe sole.

[0044] For example, the receiving cavity 11 includes symmetrically arranged pressing cavities 111, and the top end face of the pressing cavity 111 is provided with a first textured metal pattern 112; correspondingly, the molding block 21 includes symmetrically arranged pressing blocks 211, and the bottom end face of the pressing block 211 is provided with a second textured metal pattern 212. Through this bidirectional textured design, precisely matched texture patterns are simultaneously imprinted on the upper and lower surfaces of the sole, which can not only improve the aesthetics and recognizability of the sole, but also enhance the functionality of the sole, meeting the design needs of different footwear products.

[0045] Specifically, the gap thickness between the pressing cavity 111 and the pressing block 211 is 1-4mm, which is suitable for molding the midsole of shoes with a thickness of 1-4mm. Whether it is a thin midsole of 1cm or a thicker midsole of 4cm, this mold can be used for production.

[0046] Furthermore, a snap-fit ​​cavity 12 is symmetrically arranged around the pressing cavity 111, and a snap-fit ​​groove 13 is symmetrically arranged on the outside of the pressing cavity 111; correspondingly, a snap-fit ​​block 22 is symmetrically arranged around the pressing block 211, and a snap-fit ​​strip 23 is symmetrically arranged on the outside of the pressing cavity 111.

[0047] Specifically, the inner contour of the fastening cavity 12 fits with the outer contour of the fastening block 22, and the inner contour of the fastening groove 13 fits with the outer contour of the fastening strip 23, effectively limiting the displacement of the outer frame 2 in the horizontal and vertical directions, and avoiding shoe sole size deviation or surface defects caused by mold shaking.

[0048] Through the above technical solution, this application can realize the precision forming process of metal materials with textured patterns, eliminating the process steps of repeated casting and etching the textured surface on the metal mold by acid etching, effectively reducing the mold making cycle and the overall weight of the mold, and improving heat dissipation performance.

[0049] Reference Figures 5-7 The present invention also provides an embodiment of a manufacturing process for a 3D printed one-piece shoe mold, used to process the 3D printed one-piece shoe mold as described in the above embodiments. The manufacturing process includes:

[0050] S100: Establish an integrated shoe mold model, prepare metal powder for metal laser printing, and verify the manufacturability of metal surface texture construction.

[0051] S200, an integrated shoe mold assembly, is used to place the raw materials to be processed, adjust the gap, and conduct trial processing to verify the finished product.

[0052] Please continue reading. Figure 6 In this embodiment, S100 includes:

[0053] S110: Obtain shoe mold design parameters and establish an integrated shoe mold model;

[0054] S120 is based on an integrated shoe mold model to unfold the curved surface of the mold that requires the textured metal pattern, maps the textured metal pattern to the 3D model, adjusts the texture density of high curvature areas, and plans the cooling water channels and textured metal pattern in layers.

[0055] S130 generates a texture depth model based on a planar texture bitmap, and merges the texture depth model with the integrated shoe mold model to generate a 3D printed integrated shoe mold model.

[0056] S140, based on 3D printed one-piece shoe mold, performs slicing and layering, converts the three-dimensional model into a two-dimensional model output and plans the scanning path, and converts it into laser scanning information data;

[0057] S150, prepare metal powder, set printing parameters for metal laser printing, and perform post-processing to obtain shoe mold;

[0058] S160: Perform manufacturability verification of the texture of the metal surface and determine whether S140-S150 need to be repeated.

[0059] It should be explained in detail that the core principle of laser energy melting metal powder is to control the stability of the micro-melt pool through the interaction between laser energy and metal powder, so as to achieve precise forming of the textured pattern.

[0060] For example, after obtaining the shoe mold design parameters, surface modeling can be performed using 3D modeling software such as Rhino, and procedural texture processing can be performed using plugins such as ant3d. In specific operations, it is necessary to design a complete mold body structure based on the actual use scenario and product requirements of the shoe mold, such as the molding midsole, mold stability and demolding requirements, and finally establish an integrated shoe mold model.

[0061] Furthermore, traditional mold texturing often suffers from problems such as texture stretching in curved areas and blurring of edge textures. Mold cavities are mostly complex curved surfaces. For special parts such as the concave surface of the heel or the curved surface of the toe, if the flat texturing pattern is directly applied to the curved surface, stretching and deformation will occur. However, by first decomposing the curved surface of the mold that needs texturing into multiple planarizable UV blocks in the CAD software RizomUV VS, and then accurately mapping the customer's flat texturing pattern onto each UV block, and then restoring the UV blocks back to the curved surface shape after mapping, the texture will naturally fit the curved surface.

[0062] It is important to explain in detail that in the selective laser melting (SLM) process, high curvature areas such as the edges or concave corners of the mold can experience energy accumulation due to the concentrated laser scanning path. This can lead to problems such as excessively high edge temperatures causing blurred textures or low temperatures in concave corners resulting in incomplete texture formation. Therefore, texture density adjustment is necessary to prevent energy accumulation or loss during laser melting. It can be understood that reducing the texture density in edge areas corresponds to increasing the laser scanning interval, while increasing the texture density in concave corner areas corresponds to making the laser scanning more dense, thereby achieving consistent texture formation across the entire mold.

[0063] It should be explained in detail that the cooling channels used for cooling after molding in traditional molds are mostly straight holes, which often conflict with the textured area, causing damage to the textured pattern when drilling. However, in the digital design stage of SLM molds, the cooling channels and textured patterns are separated into different design layers: for example, the cooling channels are located inside the mold away from the surface, while the textured pattern is located on the surface of the mold, and the channel wall thickness is controlled to be ≥1mm. It can be understood that the layered design can ensure the strength of the channels, avoid cracking during molding, and ensure that there is a sufficient safety distance between the channels and the surface textured pattern, so that the surface texture will not melt and deform due to heat dissipation from the channels. In addition, the conformal cooling channels can effectively shorten the cooling time.

[0064] It should be explained in detail that when generating a texture depth model based on a planar texture bitmap, the process first involves receiving the texture bitmap provided by the customer and specifying the required texture size, including the width and depth of the texture. Then, the planar bitmap is converted into three-dimensional height field data using the ant3d plugin. This involves using digital algorithms to create height differences in the planar texture, thereby forming a digital model of the three-dimensional texture. Next, the three-dimensional texture model is digitally fused with the main structure of the mold built in Rhino, forming a complete digital model of the mold with the three-dimensional texture. It can be understood that the minimum width of the generated texture can reach 0.1mm, far exceeding the 0.3mm limit of traditional chemical etching. Furthermore, the three-dimensional texture is directly integrated into the mold digital model, allowing for one-time molding during subsequent SLM printing, eliminating the need for a mold first and then etching the texture as in traditional processes, effectively reducing process steps and texture errors.

[0065] For example, during laser printing, BLT's SLM and BLTBuild Processor software are used to slit and laser-integrate the mold. For different metal powder materials, different adjustments to the optical polarization and laser angle are required to accurately form the textured pattern and mold surface. Specifically, the texture detail must be ≥0.1mm to match the limits of the SLM process, and supports must be added when the angle is <45° to prevent the overhanging structure from collapsing during printing. The angle between the texture direction and the laser scanning direction must be ≥30° to reduce the step effect caused by layered printing and improve surface smoothness.

[0066] It's important to explain in detail that two molding methods can be used in actual printing: direct SLM molding or hybrid manufacturing. Direct SLM molding is suitable for highly complex molds, such as textured molds with irregularly shaped cooling channels, completing complex structures in one go without splicing errors. For this method, 316L stainless steel or aluminum alloy (AlSi10Mg) is required. Hybrid manufacturing using SLM molding and etching requires first printing the mold base. If the forming surface angle is greater than 45° and requires support, the support is removed after printing, and then fine-grained textures are refined in specific areas using chemical etching to ensure texture accuracy in those areas. Understandably, integrating the textured pattern with the mold structure through digital design and additive manufacturing can significantly shorten the development cycle and achieve fine textures unattainable by traditional processes, enabling clear forming of textures as narrow as 0.1mm.

[0067] Through the above technical solution, this application breaks through the traditional multi-process mode of CNC rough machining → manual / chemical etching texturing → post-processing. It can directly form texturing structures in one step through SLM process, thereby shortening the production cycle from 13 days to 8 days. At the same time, when the 3D printing equipment is directly controlled to build textures on the metal surface through digital modeling, since there is no need to use silicone molds for texture transfer, the sand mold preparation and silicone mold forming steps in sand casting can be omitted, and the release of organosilicon compounds (VOCs) and solid waste pollution from discarded molds can be eliminated. In addition, the waste generated by the SLM process is only recyclable metal. The powder is free from heavy metal acidic wastewater, waste acid mist, or waste silicone molds. The metal powder recovery rate is ≥95%, and no supporting wastewater treatment or VOCs purification facilities are required, thus effectively reducing production costs and environmental pollution. In addition, the one-piece molded shoe mold of this application is made by laser selective melting 3D printing, which can solve the technical barrier that traditional processes cannot achieve three-dimensional gradient textures. It supports micron-level complex curved surface texturing, with a minimum texture width of 0.1mm and texturing accuracy of ±0.05mm. It can eliminate human error through digital control and meet the highest standard of shoe mold texturing JISB0601~2013 Class 0.

[0068] It should be noted in detail that the special treatments in the SLM process chain include:

[0069] (1) Conical support technology: Conical supports with a contact point diameter of ≤0.2mm are designed for the overhanging area of ​​the textured surface, which can reduce the support residual rate to below 5%, while the residual rate of traditional block supports is >13%;

[0070] (2) Composite polishing process: By combining electrolytic polishing (EP) and magnetorheological polishing (MRF), the surface roughness Ra of the textured surface can be stably controlled at 0.6 to 0.8 μm;

[0071] (3) SLM direct forming texturing precision control: By controlling the minimum powder layer thickness to 30μm, variable layer thickness printing and partition modification of the model improve printing efficiency.

[0072] Table 1 Performance Comparison of Traditional Etching Processes and SLM Process Examples of this Application

[0073] Minimum bite mark width 0.3mm 0.1mm 67％ Surface roughness Ra 1.2μm 0.6μm 50％ Production cycle of a single mold 13 days 8 days 50％ Mold life (number of injection cycles) 60,000 times 100,000 times 67％

[0074] For example, the metal powder is any one of stainless steel, breathable steel, aluminum alloy, and titanium alloy; wherein:

[0075] (1) The composition of stainless steel (316L) is: the main body is an iron-based alloy, containing ≥16% chromium (Cr), ≥10% nickel (Ni) and ≥2% molybdenum (Mo) by mass; the strength is moderate, with a tensile strength of 500-700MPa, but the toughness is excellent; the wear resistance is average, but it can be improved by surface hardening such as nitriding; chromium can form a passivation film, thereby resisting oxidation and acid and alkali corrosion, so it does not rust or contaminate the product during production; and it contains molybdenum, which is resistant to chloride ion corrosion, high temperature resistance, and non-magnetic.

[0076] (2) Porous steel can be sintered through SLM process to form a porous structure with a porosity of 10-30%. After removing residual powder, it can achieve micron-level air permeability. Gas or liquid can permeate through the interconnected pores with a pore size of 5-100μm and a controllable air permeability rate. Due to the presence of pores, the tensile strength is about 200MPa, which is slightly lower than that of dense steel, but can meet the needs of injection molding production.

[0077] (3) The composition of aluminum alloy (AlSi10Mg) is: mainly aluminum, containing silicon (Si) with a mass fraction of ≥9% and magnesium (Mg) with a mass fraction of ≥0.2%; the tensile strength of ordinary aluminum alloy (e.g., 6061) is about 300MPa; the tensile strength of high-strength aluminum alloy (e.g., 7075~T6) can reach 500~700MPa, and the specific strength (strength / density) is better than that of steel; the hardness is HB 60~120, the wear resistance is average, and the density is only 2.7g / cm³.3 It is about 1 / 3 the weight of steel, making it suitable for weight reduction applications.

[0078] (4) The composition of titanium alloy is: the main component is titanium, containing 5% to 6% by mass of aluminum (Al) and 3% to 4% by mass of vanadium (V), etc.; the tensile strength of commercial titanium alloy is 900 to 1200 MPa, which is close to that of high-strength steel, and the density is only 4.5 g / cm³. 3 Excellent in terms of lightweighting; some alloys can be used for a long time at 500℃, with excellent high-temperature performance; hardness HRC 30~40, wear resistance is average, but can be improved by oxygen infiltration or coating; low coefficient of friction, easy product demolding, and easy to form a passivation film in the air, making it resistant to seawater and chloride ion corrosion, which is better than stainless steel.

[0079] Table 2. Comprehensive Comparison of Performance Characteristics of Metal Powder Products of Different Materials

[0080]

[0081]

[0082] To ensure the mold meets production needs, we selected these materials from various alloys. Our selection criteria included thermal conductivity, strength, durability, air permeability, as well as cost and processability in practical applications. We also provide stress test data for different materials during the molding process (e.g., deformation rate and cracking threshold under 20t pressure).

[0083] Table 3 Comparison of basic mechanical properties of metal powders of different materials

[0084]

[0085] Table 4. Comparison of Deformation Performance of Different Metal Powders under 20t Pressure (Contact Area 50cm²) 2 (Calculated stress σ = 40 MPa)

[0086]

[0087]

[0088] Table 5 Comparison of Cracking Threshold and Fatigue Performance of Metal Powders of Different Materials

[0089] It is necessary to explain in detail the comparison of key properties of metal powders of different materials:

[0090] (1) Stiffness ranking: Stainless steel (316L) > Titanium alloy (TC4) > Aluminum alloy (AlSi10Mg); (2) Strength ranking: Titanium alloy (TC4) > Stainless steel (316L) > Aluminum alloy (AlSi10Mg); (3) Toughness ranking: Stainless steel (316L) > Titanium alloy (TC4) > Aluminum alloy (AlSi10Mg).

[0091] Table 6 Comparison of basic parameters between traditional etching processes and SLM process examples of this application.

[0092]

[0093]

[0094] Table 6. Comparison of heat dissipation efficiency experimental results between traditional etching process and SLM process embodiment of this application. Mold temperature: 200℃ (simulated molding process); Cooling medium: air (natural convection).

[0095] Alternatively, water cooling (forced convection); pressure: 0.3 MPa (simulating the molding and holding pressure stage).

[0096]

[0097]

[0098] The above experiments show that breathable steel can dissipate heat evenly, and the microporous structure forms a three-dimensional heat dissipation network, avoiding localized overheating caused by uneven drilling in traditional methods. In thick-walled areas such as the heel, the temperature fluctuation of the breathable shoe mold is reduced by 60% compared to the perforated mold. At a porosity of 25%, the air permeability reaches 1.5 L / min·cm. 2 This design allows for rapid air removal from the foamed plastic filling cavity, reducing bubble defects. Traditional molds require additional venting channels. The porous structure reduces thermal stress concentration, lowering the risk of mold cracking by 70% compared to perforated molds. It is less prone to clogging, and the micropores have a self-cleaning effect, unlike traditional drilling which is easily clogged by plastic residue. Traditional perforated molds weaken structural strength through drilling, necessitating the avoidance of dense perforation; therefore, the porosity is typically <5%, requiring external cooling systems for heat dissipation and resulting in higher energy consumption. The secondary compression shoe mold production process operates at 160–180℃; using breathable steel molds reduces cooling time by 30%, and the product bubble defect rate drops from 5% to 0.3%. Traditional perforated molds require an increased number of cooling channels, leading to a 20% increase in mold cost.

[0099] For example, the shoe mold appearance pattern is constructed using the professional NURBS (Non-Uniform Rational B-Spline) surface modeling tool Rhino, and the constructed shoe mold 3D is decomposed according to the sole material, such as outsole rubber, midsole supercritical TPU foam, etc.

[0100] Subsequently, Rhino software was used to create an integrated design for the midsole mold, including the upper and lower molds, which are connected by a rotating pin in the middle, thus achieving a 180° opening and closing angle. The locking buckle at the opening point can prevent the mold from being popped open by the pressure of the shoe blank during molding.

[0101] In addition, based on the textured pattern provided by the customer, a three-dimensional textured pattern can be created using the Rhino software plugin ants3d. To meet the customer's requirements for the size and depth of the pattern, a small mold with textured patterns can be printed using SLM for adjustment and testing.

[0102] In addition, after the mold is designed, it must be made into a printable STL format using Materialise Magics software. When the angle between the mold pattern and the plane is less than 40 degrees, a grid support must be added in the MAGICS software to prevent the single layer from being disturbed by the scraper during laser printing, causing warping and deformation during sintering.

[0103] It should be explained in detail that, in order to improve printing efficiency and save printing costs, the honeycomb structure creation function of Magics software is used to hollow out a honeycomb structure at the bottom of the mold, and the shell extraction function is used to distinguish different sections to select different printing layer thicknesses, thereby saving printing time and improving printing efficiency.

[0104] For example, printing parameters include laser power, scanning speed, powder layer thickness, and forming temperature control. Specifically, when printing 316L stainless steel shoe molds using SLM technology, the laser power used is 180–220W, and the scanning speed is 900–1100 mm / s. This optimal energy density, combined with the laser power, ensures molten pool stability. Correspondingly, the powder layer thickness is 30–40 μm, balancing printing efficiency and surface quality, resulting in a surface roughness Ra of 6–8 μm. It is understood that a powder layer thickness of 30 μm is significantly lower than the conventional 50 μm, reducing the serration height of the texture by 62%, thus solving the texture distortion problem caused by the step effect. Furthermore, when the layer thickness is reduced to 30 μm, a clear forming of a 0.1 mm wide texture can be achieved, at which point the surface roughness Ra decreases from the traditional 1.2 μm to 0.6 μm.

[0105] It should be explained in detail that the substrate can be preheated during molding: the preheating temperature is 150-200℃, which can reduce the cooling rate and reduce thermal cracking; the oxygen content of the cavity is <0.1%, and high-purity argon (content >99.99%) is used as the protective gas. The laminar flow design of the protective gas flow field makes the flow velocity 1.5-2m / s, which can avoid dust adhesion caused by turbulence, thereby ensuring that the surface roughness Ra≤0.8μm.

[0106] Furthermore, the energy density ranges from 60 to 80 J / mm². 3 The scanning strategy employs a 67° interlayer rotation angle and combines light mesh support with conical support to handle the printing of textured surfaces with an angle of less than 40°. Understandably, the scanning strategy uses random island-shaped scanning with a 67° rotation in different areas, which can effectively reduce thermal stress concentration and thus prevent deformation of the textured structure.

[0107] It is important to explain in detail that after printing, the mold cracking problem needs to be addressed through post-processing optimization. This post-processing includes heat treatment and surface polishing: during heat treatment, annealing at 1100℃ for 2–4 hours eliminates residual stress, resulting in a density ≥99.7%, tensile strength ≥550MPa, and elongation ≥40%. After sandblasting, the surface roughness Ra is 3–5μm. Polishing uses a brown corundum fiber wheel with diamond paste (W40–W20), a pneumatic polishing machine with a speed of 2000–3000 RPM, a pneumatic pressure of 0.1–0.3MPa, and a linear speed of 15–25m / s, polishing the inner surface of the mold from the inside out. Before polishing, wax or a special sealant is used to temporarily fill the pores to prevent the polishing paste from seeping into the mold.

[0108] Furthermore, the porosity of the printed breathable steel is kept within the range of 15% to 25% by adjusting the printing parameters, i.e., porosity < 30, and the printing layer thickness is controlled within 20 to 40 μm, which can ensure density and pore uniformity.

[0109] It should be explained in detail that the flip shaft can be printed in one piece. Since there are no weak connection areas, the fatigue life can be improved by 3 to 5 times. Furthermore, weight reduction can be achieved through topology optimization, that is, by designing a hollow mesh structure through finite element analysis (such as ANSYS), thereby achieving a weight reduction of 20% to 40% while maintaining structural rigidity, so that the deformation is <0.02mm / 100N·m. In addition, the spiral oil passages inside the shaft can be printed directly, so that the minimum hole diameter is 0.8mm, thereby achieving self-lubrication. For example, a nylon composite material containing MoS2 can be used, which reduces the coefficient of friction to 0.08.

[0110] Furthermore, during production and processing, it is also necessary to control the fitting precision of the fastening cavity and the fastening block to improve the mold's sealing performance. First, the sealing performance needs to meet the anti-overflow requirements of more than 90% of shoe materials, and the thickness of the flash needs to be controlled within 0.3mm, thereby meeting the requirement of no edge trimming for most shoes. Second, it is necessary to control the processing efficiency and mold life to achieve the best balance of production costs, so it is necessary to control the critical value of material flow and thermal expansion compensation. Next, it is necessary to consider the stability of mass production. The tolerance of ±0.05mm can be consistently met by 95% of mold factories in the existing supply chain, so inspection only requires a conventional micrometer to meet the mass production requirements. In addition, because the size of the foamed preform is not completely uniform, this fitting gap is conducive to the discharge of excess material, thereby facilitating mold venting and the firing of finished products.

[0111] It should be noted in detail that the gap between the pressing cavity and the pressing block needs to match the molding requirements:

[0112] (1) Material flowability control: Expansion space needs to be reserved for supercritical foaming materials (such as EVA, TPU, TPE, PEBA, etc.) to prevent excessive compression from causing damage to the closed-cell structure;

[0113] (2) Pressure balance control: By adjusting the gap, the pressure distribution in the mold cavity can be optimized to avoid local underpressure (corresponding to uneven density) or overpressure (corresponding to flash thickening).

[0114] (3) Thickness adaptability control: By adjusting the gap, it can adapt to midsoles of different thicknesses: for thin midsoles (e.g., 3-6mm), the gap is 1-2mm to ensure that the material is fully filled; for thick midsoles (e.g., 8-25mm), the gap is 2-4mm to take into account both foam expansion and pressure transmission.

[0115] It is important to explain in detail that the research and development transformation from traditional steel shoe molds to SLM metal 3D printed one-piece shoe molds requires overcoming several technical challenges:

[0116] (1) Deformation of mold due to inadequate heat treatment process: When using a simple annealing process of 300℃×1h, the residual stress of printing was not fully eliminated, resulting in a mold gap of 0.5mm during the molding process, which is 9 times higher than the industry standard, and micro-cracks appeared on the mold surface after 200 cycles. Thermodynamic analysis revealed that this deformation was mainly due to uneven shrinkage of +0.25mm in the length direction and ~0.18mm in the width direction. Finally, by using an optimized process of solution treatment at 530℃×2h plus artificial aging, the deformation was successfully controlled within 0.03mm.

[0117] (2) Problem of insufficient reproduction of fine patterns due to improper setting of printing layer thickness parameters: In pursuit of production efficiency, a layer thickness parameter of 0.04mm was used for the pattern area, resulting in a serious lack of reproduction of fine patterns. The pattern with a designed depth of 0.5mm was actually formed to only 0.32mm, with a loss rate of 36%, while the surface roughness Ra value deteriorated from the expected 0.8μm to 2.5μm. Microscopic analysis showed that the excessive layer thickness produced a significant step effect, which not only affected the appearance quality but also increased the demolding force by 40%. By implementing a differentiated layer thickness strategy, 0.02mm fine printing was used in the key areas of the pattern, while 0.04mm was maintained in the non-critical areas. Although the overall printing time increased by 18%, the pattern reproduction rate was improved to 95%, which fully met the design requirements.

[0118] (3) The printing strategy that does not distinguish between finished product areas and non-finished product areas leads to a long printing time: When the printing parameters are uniform for the entire mold, the printing time is as long as 38 hours, which is 73% longer than the optimized solution. The support structure accounts for as much as 45%, and unnecessary heat-affected zones are generated in non-critical areas, increasing the risk of deformation by 25%. By establishing a functional area classification printing strategy: the cavity surface uses 250W laser power with a layer thickness of 0.02mm to ensure quality, the internal structure uses 180W power and a layer thickness of 0.04mm to improve efficiency, and the support area uses 150W power and a layer thickness of 0.05mm to optimize the removal. In the end, the printing time is shortened by 32% and the support ratio is reduced to below 30%.

[0119] (4) Problem of difficult post-processing due to improper support structure design: Directly using the software default support parameters leads to difficulties in post-processing. The support removal time is up to 6 hours, which is 140% longer than the optimized solution. During the removal process, 15% of the cavity surface is scratched, and the support residue in key parts reaches 0.12mm. By introducing a dot matrix support structure and contact point optimization technology, the support contact area is reduced by 60%. Combined with electrolytic polishing process, the support removal time is finally controlled within 2.5 hours, and the surface damage problem is completely eliminated.

[0120] Please continue reading. Figure 7 In this embodiment, S200 includes:

[0121] S210, integrated shoe mold assembly, integrated shoe mold preheating;

[0122] S220: Place the raw material to be processed into the mold, close the mold and initially adjust the gap, set the processing parameters and perform trial processing, and adjust the gap again after cooling.

[0123] S230: Open the mold, remove the product, verify whether the finished product is qualified, and determine whether S220 needs to be repeated.

[0124] For example, the processing parameters include pressure molding and pressure temperature.

[0125] Table 7 Comparison of Production Dimensions between Traditional Etching Process and the SLM Process of this Application

[0126]

[0127] For example, the following are specific application cases of midsole molds for different shoe types (sports shoes, leather shoes), and 3D model diagrams are attached.

[0128] Example 1:

[0129] Please continue reading. Figure 8 In this embodiment, taking the midsole of a high-performance running shoe from an international brand as an example, the mold needs to achieve a 35mm high sidewall structure and a 0.8mm pore diameter honeycomb cushioning system. The aluminum alloy mold printed using SLM technology, through a gradient conformal cooling channel and integrated honeycomb structure design, perfectly solves the problems of insufficient sidewall filling and low micropore forming accuracy of traditional shoe molds. The measured sidewall filling rate of the shoe mold has been increased from 87% to 99.5%, and the micropore forming accuracy has been increased from ±0.15mm to ±0.05mm.

[0130] It should be noted that the design of the 45° inclined reinforcing ribs inside the mold reduces weight by 20% while completely eliminating the risk of high sidewall collapse. Combined with the 0.6mm conical venting pin array, the venting efficiency is increased by 70%, which shortens the single molding cycle by 39% and extends the mold life by 133%.

[0131] Example 2:

[0132] Please continue reading. Figure 9 In this embodiment, taking the midsole of a leather shoe from an international brand as an example, a 2.5mm ultra-thin mold is used to simultaneously meet the requirements of precise molding of five different depth patterns with thicknesses ranging from 0.3 to 1.2mm and near-mirror polishing with Ra≤0.4μm. By using 0.015mm ultra-thin layer printing combined with laser remelting, the molding loss rate of shallow patterns was successfully reduced from 52% to 12%, and the clarity score (out of 5) of deep patterns was improved from 3.1 to 4.5. The specially designed honeycomb heat dissipation fins control the temperature uniformity of the mold core within ±2℃, and with the fine polishing process, the final surface roughness reaches 0.25μm. In this case, the 32% scrap rate problem that occurred when using aluminum alloy printing in the early stage can be perfectly solved by changing to an intermittent printing strategy of stopping cooling for 2 seconds every 5 layers.

[0133] Example 3:

[0134] Please continue reading. Figure 10In this embodiment, taking the midsole of an international brand's outdoor boot as an example, it needs to meet special requirements such as asymmetrical sidewalls with a height difference of 25mm and a gusset. The titanium alloy mold printed by SLM can achieve modularity, the dual-temperature zone temperature control system can accurately control the molding temperature of different materials, and the variable cross-section support can make the thickness consistency of the irregular sidewalls reach ±0.1mm, so that the deformation of the mold under extreme temperatures can be controlled within 0.04mm.

[0135] The above typical cases fully demonstrate the advantages of SLM metal 3D printing technology in shoe mold manufacturing: sports shoe molds demonstrate the ability to form complex structures with high sidewalls, leather shoe molds verify the processing precision of ultra-thin and fine features, and outdoor boot molds demonstrate the flexibility of multi-material adaptation; although the initial cost of SLM molds is relatively high, the significant improvement in overall yield and the substantial extension of mold life make it show obvious economic advantages in mass production.

[0136] These successful experiences can provide a clear technical roadmap for the shoe mold manufacturing industry: aluminum alloys are chosen for high thermal conductivity requirements, stainless steel is chosen for a balance between strength and lightness, and titanium alloys are given priority for corrosion resistance and temperature difference resistance scenarios. With targeted structural design and process optimization, it is entirely possible to achieve a quality breakthrough that far exceeds traditional processes.

[0137] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A 3D-printed one-piece shoe mold, characterized in that, include: The side wall is integrally formed, and the top of the side wall is recessed inward to provide a hollow receiving cavity; The top of the side wall is detachably fitted with an integrally molded outer frame, and a molded block is provided protruding outward from the bottom of the outer frame.

2. The 3D printed one-piece shoe mold according to claim 1, characterized in that, A fixing seat is installed at one end of the side wall, and the side wall is detachably connected to the base at the bottom through the fixing seat.

3. The 3D printed one-piece shoe mold according to claim 2, characterized in that, A flip shaft is installed at the other end of the side wall, and the side wall is rotatably connected to the top outer frame through the flip shaft.

4. The 3D printed one-piece shoe mold according to claim 1, characterized in that, The wall thickness of the sidewall and the outer frame is 1-3cm.

5. The 3D printed one-piece shoe mold according to claim 1, characterized in that, The receiving cavity includes symmetrically arranged pressing cavities, and the top end face of the pressing cavity is provided with a first textured metal pattern.

6. The 3D printed one-piece shoe mold according to claim 1, characterized in that, The molding block includes symmetrically arranged pressing blocks, and the bottom end face of the pressing block is provided with a second textured metal pattern.

7. The 3D printed one-piece shoe mold according to claim 5, characterized in that, The thickness of the gap between the pressing chamber and the pressing block is 1-4 mm.

8. The 3D printed one-piece shoe mold according to claim 5, characterized in that, The pressing cavity is symmetrically provided with fastening cavities around it, and fastening grooves are symmetrically provided on the outer side of the pressing cavity.

9. The 3D printed one-piece shoe mold according to claim 7, characterized in that, The pressing block is symmetrically surrounded by fastening blocks, and the pressing cavity is symmetrically surrounded by fastening strips.

10. The 3D printed one-piece shoe mold according to claim 8, characterized in that, The inner contour of the fastening cavity fits with the outer contour of the fastening block, and the inner contour of the fastening groove fits with the outer contour of the fastening strip.

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