Mold and preparation method thereof

Abstract

The invention provides a preparation method of a mold, and relates to the field of mold processing and production.The preparation method comprises the steps that a mold outer frame is built, and a pouring cavity is formed; spraying a release agent on the inner surface of the pouring cavity; and pouring the composite material into a pouring cavity, compacting, curing, and removing the outer frame to obtain the mold. The adhesive and the metal particles are used as main materials of the mold, and the materials can replace traditional metal and non-metal materials in mold processing production, so that the processing difficulty of the mold is reduced, the material cost and the processing cost are reduced, and the production efficiency of the mold is improved.

Description

Technical Field

[0001] This invention relates to the field of mold processing and production, and more specifically, to a mold and its preparation method. Background Technology

[0002] Currently, injection molds, vacuum forming molds, blow molding molds, and polymer solidification molds are mostly made of metal materials such as steel, iron, and aluminum, or non-metallic materials such as fiberglass and plastics. The advantages of metal materials are high strength, structural stability, and the ability to operate in high-temperature environments; while the advantages of non-metallic materials are lightweight, simple processing, and easy handling. However, both also have significant disadvantages.

[0003] The high density of metal materials makes handling and transportation difficult, which results in very few large and extra-large products being processed using molds in the injection molding, thermoforming, and forging industries. The high strength and hardness of metal materials make processing difficult and the processing cycle long, which is also a major pain point in the mold production process. Metal materials are valuable, and mold production must use drilling, milling, cutting, CNC and other processes to remove a large amount of scrap material according to the product structure, resulting in a lot of waste and seriously affecting the price of molds. The high price of metal materials themselves also drives up the price of molds.

[0004] Non-metallic materials have a narrow operating environment, especially in terms of temperature. Currently, most molds made of non-metallic materials can only be used between -10 and 80°C. The low strength of non-metallic materials means that these molds can only be used in industrial fields such as polymer condensation, manual or semi-mechanical, and low-strength thermoforming.

[0005] With the development of the polymer materials industry, epoxy resin products with a strength of 85MPa that can be used in a temperature range of -60℃ to 300℃ have been developed, making it possible to use composite materials in molds. However, pure epoxy resins and other polymers are brittle, especially on thin surfaces and at edges.

[0006] The published authorized patents (such as CN111300693) disclose several methods for modifying epoxy resin, which greatly contribute to rapid molding. However, their shortcomings are also very obvious. The modification process uses micron-level fine metal powder, and the overall connection still relies on epoxy resin. The metal powder films cannot form an effective interlocking, resulting in low overall strength and fragility of the material, which is particularly evident when the material is irregular or has abrupt thickness changes.

[0007] Therefore, there is an urgent need to develop a composite material that can be used in mold manufacturing to overcome the above-mentioned defects. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing a mold, using adhesives and metal particles as the main materials of the mold. These materials can replace traditional metal and non-metal materials in mold processing and production, thereby reducing the processing difficulty of the mold, reducing material and processing costs, and improving mold production efficiency.

[0009] The technical problem solved by this invention is achieved by the following technical solution.

[0010] On one hand, embodiments of the present invention provide a method for preparing a mold, comprising the following steps: mixing an adhesive and metal particles evenly, casting and molding, and curing to obtain a composite material blank; and machining a mold cavity on the composite material blank according to a designed mold, thereby obtaining the mold.

[0011] On the other hand, embodiments of the present invention provide another method for preparing a mold, comprising the following steps: Build the outer frame of the mold to form the casting cavity; The composite material is poured into the casting cavity, compacted, and cured to obtain the mold.

[0012] The mold produced by this method retains the outer frame, which can provide a certain degree of support for the mold, thereby improving the mechanical properties of the mold and extending its service life.

[0013] In some embodiments of the present invention, the method further includes spraying a release agent onto the inner surface of the casting cavity, and removing the outer frame after curing. The mold obtained by this method, with the release agent sprayed before casting, facilitates the removal of the outer frame after curing; the mold obtained by this method does not contain an outer frame.

[0014] In some embodiments of the present invention, the mold includes a support portion and a molding surface, wherein the composite material of the support portion includes an adhesive and metal particles with a particle size greater than 5 mm; and the composite material of the molding surface includes an adhesive and metal particles with a particle size of 0.4-1 mm.

[0015] In some embodiments of the present invention, the surface curing time is 2 hours at room temperature, and the internal complete curing time is 36-48 hours.

[0016] On one hand, embodiments of the present invention provide a mixture comprising an adhesive and metal particles, wherein the volume ratio of the adhesive to the metal particles and / or metal powder is 1:1 to 1:9. More preferably, the volume ratio of the adhesive to the metal particles and / or metal powder is 1:3 to 1:3.5.

[0017] In some embodiments of the present invention, the adhesive is a modified epoxy resin adhesive.

[0018] On the other hand, embodiments of the present invention provide a method for preparing a composite material, comprising: grinding metal particles, cleaning the metal particles, and drying them; mixing the dried metal particles with an adhesive and curing them to obtain the composite material. Cleaning the metal particles includes: cleaning the metal particles with an alkaline degreasing agent and then rinsing the metal particles with clean water.

[0019] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. Using metal particles larger than millimeters can effectively form an interlaced distribution, improve the stress performance of the material, and increase the overall strength of the material.

[0020] 2. Both metal granules and adhesives can be packaged separately, reducing transportation difficulties and costs. This is particularly evident in the application of large and extra-large molds.

[0021] 3. Composite materials formed by adhesives and metal particles can be molded according to requirements, reducing material usage and subsequent processing. This advantage is particularly evident for molds with large molding depths.

[0022] 4. The composite material uses a combination of metal particles and adhesives, and its thermal properties are similar to those of metal materials. This ensures that the expansion and deformation of the mold during use are compatible with existing processes, so that existing mold designs can be used without major modifications to the existing designs.

[0023] 5. Compared with existing non-metallic molds, molds made of composite materials have higher structural strength, more stable structure, and a wider applicable temperature range, making them suitable for injection molding, vacuum forming, blow molding and other processes, and thus have a wider range of applications.

[0024] 6. When using this composite material to prepare molds, it can directly form structures such as holes, grooves, and concave shapes, simplifying mold processing and making the preparation process simpler. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart illustrating the preparation of the mold according to an embodiment of the present invention; Figure 2 A photograph of the raw composite material prepared according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the relationship between the mold and the product prepared according to an embodiment of the present invention; Figure 4 This is a top view of the concave mold prepared in Example 1; Figure 5 This is a front view schematic diagram of the concave mold prepared in Example 1; Figure 6 This is a top view of the concave mold prepared in Example 2; Figure 7 for Figure 6 Cross-sectional view along the AA direction; Figure 8 This is the inspection report for the composite material in Example 1; Figure 9 This is the second inspection report for the composite material in Example 1; Figure 10 This is the third inspection report for the composite material in Example 1; Figure 11 This is the fourth inspection report for the composite material in Example 1.

[0027] Icons: 1-Metal shell, 2-Composite material mold core, 3-Guide sleeve, 4-Gate, 5-Gate sleeve, 6-Metal profile, 7-Water channel, 8-Punch, 9-Finished product, 10-Die, 11-Guide sleeve, 12-Guide pillar. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.

[0030] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0031] Example 1 Composite materials of suitable dimensions are produced using a template casting method. Templates can be made of wood, cardboard boxes, plastic boxes, or metal boxes for reuse. An oil-based release agent should be sprayed onto the inner wall of the box. When using a release agent, the composite material should not be stirred inside the box to prevent contamination. During casting, temperature and humidity must be controlled within the range suitable for the coagulant. Methods such as extrusion, vacuuming, and vibration should be used during casting to ensure the absence of cavities and air bubbles within the material. Then, mold components can be machined using a machining center and assembled into a finished mold. Alternatively, finished parts can be used as templates for direct molding during the material casting process. In the latter case, the template part is at the bottom during casting, allowing gravity to help more adhesive solidify at the contact surface, increasing surface smoothness. Figure 1 , 4 As shown in Figure 5 (the figure only illustrates the parts relevant to this invention and does not depict the mold details in detail, the same applies below). The specific steps are as follows: Steps M1-M5: Preparation of metal particles, including the following requirements and steps: Spherical metal particles are produced using a die-casting process, requiring a particle diameter of less than 5mm. The metal particles are then placed in a grinding mill to cause them to collide with each other, crushing hollow and incomplete particles while simultaneously removing surface rust and stains.

[0032] Screen and classify metal particles. Use 5-mesh, 10-mesh, 20-mesh, and 45-mesh sieves to separate the metal particles into several categories based on their diameter: larger than 5 mm, 1-2 mm, 0.4-1 mm, and smaller than 0.4 mm.

[0033] Clean the metal particles with an alkaline degreasing agent, rinse the metal particles with clean water, and dry the metal particles.

[0034] Step M6: Mix the adhesive and metal particles thoroughly. In this step, the higher the temperature of the epoxy resin at room temperature, the faster it cures. You can refer to the properties of the adhesive to lower the ambient temperature or freeze the metal particles appropriately to ensure that there is enough time to mix the adhesive and metal particles evenly.

[0035] The volume ratio of adhesive to metal particles can range from 1:1 to 1:9 depending on the requirements of different parts and the size of the metal spheres. According to the theory of closest packing, when the closest packing is FCC or HCP, the volume ratio of the small spheres is η=π / (3·√2) ≈0.74. Then the ratio of the space occupied by the cavity is: 1-η≈ 1-0.74 = 0.26. The volume ratio of the cavity to the small spheres is approximately 0.26 / 0.74≈ 0.35.

[0036] The conclusion is that, optimally, the volume ratio of the adhesive to the metal spheres should be greater than 1 / 3 to ensure that the adhesive completely fills the gaps between the metal spheres.

[0037] Table 1 shows the mechanical test results of a composite material with a metal particle (0.35 mm diameter) to binder (epoxy resin TS2111) volume ratio of 3:1 and dimensions of 300 mm (length), 200 mm (width), and 50 mm (thickness). The tests were conducted by Hefei Guangce Product Testing Institute at 24.7℃ and 52.4% humidity. The inspection report is as follows: Figure 8-11 As shown.

[0038] Table 1

[0039] Most common molds, especially injection and vacuum forming molds, focus on indicators such as hardness, compressive strength, and flexural strength. This analysis report shows that this composite material can meet the requirements of common molds.

[0040] Steps W1-W3: A simple mold frame can be selected. Design the mold frame according to the product's shape, and assemble it using wooden boards, cardboard, etc., to serve as the pouring container and forming mold. After cleaning, evenly spray a layer of release agent onto the frame. The release agent must be applied evenly and without dripping. All inner surfaces must be coated, leaving no gaps.

[0041] Step P1: Clean, deburr, and polish the finished material after the design has been verified.

[0042] Step P2: Since the material needs to be fixed in position, ensure that the moving and stationary molds move in the same direction, reasonably separate the moving and stationary molds, and add positioning base points and direction references to the finished material.

[0043] Steps P3-4: Clean the finished material and spray the release agent evenly.

[0044] Step O: After the outer frame is formed, fix the auxiliary materials on the formed blank, and fix the finished material to the frame according to the positioning requirements.

[0045] Steps L1-L3: Based on cost and mold structure, select composite materials with different proportions of spheres and adhesive for different locations on the mold, and cast the main body of the mold. If cost and mold requirements allow for casting with a uniform material, these three steps can be combined into one. The casting process must ensure a tight seal, free of cavities, air bubbles, or other issues that could affect material properties. The composite material can be compacted using methods such as vacuuming, vibratory rods, vibratory mills, or hammering. Before proceeding with this step, if necessary, prepare and secure heating, temperature control, and rapid cooling systems.

[0046] Step L4: After the mold is poured, refer to the adhesive instructions and allow it to cure at a suitable temperature and humidity for a sufficient amount of time, paying attention to the difference in curing time between the inside and outside. Do not move or vibrate the mold blank before it is fully cured. After curing, remove the outer frame to obtain the mold body.

[0047] Step L5: Based on the mold requirements and the actual mold body cast, if necessary, use CNC or other tools to modify and finish the surface of the mold, install guide pillars and ejector pins, and adjust or process the gate and runner according to the fluid requirements.

[0048] L6: Adjust the mold fit and assemble all parts. Complete the mold processing.

[0049] Example 2 For molds requiring high strength and with low allowable structural deformation, a metal shell combined with internal composite material filling can be used, such as... Figure 6 and 7 As shown. Select suitable metal shell material, metal particles, and adhesive, ensuring compatibility among the three and guaranteeing good adhesion between the adhesive and the first two. Cut and process the metal frame; for high strength requirements, consider using steel. Secure the frame using welding, screws, or other methods, and then mix the composite material according to the specified ratio for casting. For the supporting parts, use a composite material with a coarse metal particle and adhesive ratio; for the molding surface, use a composite material with fine particles and adhesive. This combination balances strength, cost, and surface smoothness requirements. For large and extra-large molds, consider reinforcing the metal shell with through-through connecting ribs. This process uses a molded shell, making it easier to control the parting surface; the mold closing guide pillars and guide sleeves are designed on the metal shell to ensure smooth mold closing and facilitate mold alignment. The steps are as follows: Step S1: Based on the mold design, use steel with a thickness of 3mm or more to process metal sheets. If necessary, process and reserve openings for guide pillars, gates, water pipe interfaces, etc., as well as installation nodes for heating, temperature control systems, water pipes, water valves, etc.

[0050] Steps S2-S3: Assemble the outer frame. Assemble the processed steel plates using methods such as studs and welding, and clean the outer frame to ensure effective adhesion between the outer frame and the composite material.

[0051] The subsequent process is the same as step O to step L6 in Example 1, but the outer frame is not removed, and the metal outer frame and the composite material are a whole.

[0052] Example 3 As attached Figure 5As shown. For molds requiring high surface smoothness, the mold surface is machined from thin metal sheets, manufactured using the methods described in Example 1 or Example 2. To ensure reliable bonding between the mold surface and the composite material, the metal used for the mold surface must correspond to the adhesive, ensuring a strong bond between the metal mold surface and the composite material. For example, if aluminum adhesive is used, both the metal particles and the mold surface metal should be made of aluminum. The mold surface is cleaned using acid or alkali cleaning agents. The position of the mold surface and the outer template or shell is fixed. The adhesive and metal particles are mixed and stirred evenly according to the ratio, poured into the mold, and cured by heating or natural placement. After the composite material has completely cured, the mold is precision machined to form the final shape. Specifically: Step F1: While preparing the metal particles and outer frame, machine the metal profile blank. Positioning and fixing points also need to be machined in this step.

[0053] Step F2: According to the finished product requirements, the metal mold mirror surface is processed by EDM, polishing, grinding and other processes to ensure the surface flatness and smoothness of the product produced by the mold.

[0054] Step F3: After cleaning the mold surface, fix the mold surface to the outer frame. The subsequent processes are the same as steps O to L6 in Example 1.

[0055] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method of producing a mold, characterized by, The method comprises the following steps: mixing the binder, metal powder or / and metal particles uniformly, casting, curing to obtain a composite material blank; processing a cavity of the mold on the composite material blank according to the designed mold shape to obtain the mold.

2. A method of producing a mold, characterized by, The method comprises the following steps: building a mold frame to form a pouring cavity; pouring the composite material into the pouring cavity, compacting, curing to obtain the mold.

3. The method of producing a mold according to claim 2, wherein The method further comprises spraying a release agent on the inner surface of the pouring cavity, and removing the frame after curing.

4. The method of producing a mold according to claim 1 or 2, characterized by, The mold comprises a support part and a forming surface, the composite material of the support part comprises a binder and metal particles with a particle size greater than 5 mm; the composite material of the forming surface comprises a binder and metal particles with a particle size of 0.4-1 mm.

5. The method of producing a mold according to claim 1 or 2, characterized by, The volume ratio of the binder to the metal particles or / and metal powder is 1:1-1:

9.

6. The method of producing a mold according to claim 1 or 2, characterized by, The volume ratio of the binder to the metal particles or / and metal powder is 1:3-1:3.

5.

7. A mold characterized in that, The mold is prepared by the method of any one of claims 1-6.

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