A molding die and method for a thin keycap

Abstract

A kind of forming die of thin key cap, including fixed mould core, movable mould core, the top surface of the fixed mould core is equipped with recessed cavity, the bottom surface of the movable mould core is equipped with two-stage step, movable mould core, fixed mould core, through two-stage step, recessed cavity form key cap cavity, the bottom surface area of movable mould core located two-stage step long side two sides is respectively provided with glue inlet horn, the gate of glue inlet horn is waist-shaped hole, and it is communicated with key cap cavity, the long axis length of gate is 1.8mm, and the short axis length is 0.3mm.The present application is modular design, and the cost of opening mould is low, and it is suitable for batch processing production thin modeling.

Description

Technical Field

[0001] This invention relates to the field of keyboard manufacturing, and in particular to a molding die and method for thin keycaps. Background Technology

[0002] See Figure 1 This is a schematic diagram of a thin keycap structure. This thin keycap has a length of 16.25±0.05mm, a width of 15.25±0.05mm, and a wall thickness of 2mm. The top and bottom surfaces are two-tiered, and the thickness of the middle area needs to be designed to reach 0.1±0.02mm to accommodate light-emitting devices and meet the requirements of local light transmittance.

[0003] Currently, the use of injection molding to process thin keycaps of this structure results in serious defects on the top surface, leading to a low product yield and failing to meet the quality requirements of enterprises.

[0004] Therefore, designing a high-yield processing method for this type of keycap structure is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] One of the objectives of this invention is to address the shortcomings of existing technologies by providing a molding die for thin keycaps. This die features a modular design, low mold opening costs, and is suitable for mass production of thin keycaps.

[0006] The second objective of this invention is to provide a method for processing thin keycaps using the above-mentioned molding die, which can efficiently process the target thin keycaps with a pass rate of over 98.5%.

[0007] One of the technical solutions to achieve the objective of this invention is: a molding die for a thin keycap, comprising a fixed mold core and a moving mold core. The top surface of the fixed mold core is provided with a cavity, and the bottom surface of the moving mold core is provided with a two-stage step. The moving mold core and the fixed mold core are closed, forming a keycap cavity through the two-stage step and the cavity. The bottom surface area of ​​the moving mold core on both sides of the long side of the two-stage step is provided with a gating horn. The gating horn has a waist-shaped hole and is connected to the keycap cavity. The long axis of the gating horn is 1.8 mm and the short axis is 0.3 mm.

[0008] The fixed mold core is provided with a cooling channel surrounding the keycap cavity.

[0009] The moving mold core is fitted with multiple moving modules with a gap and moves along the mold closing direction. The extension surfaces of the multiple moving modules combine to form the second step surface of the second step. There is a gap between two adjacent moving modules to form a vent hole.

[0010] The gap width is 0.025mm.

[0011] The number of gates for the glue-injecting horn is two, which are spaced apart along the length of the second-level step.

[0012] The two long sides of the first step of the second-level step are provided with clearance grooves. These two clearance grooves are staggered along the length of the second-level step. Each clearance groove is equipped with a horn gate module. The horn gate module has three steps. The first step surface of the horn gate module is flush with the bottom surface of the moving mold core, and the third step surface is flush with the first step surface of the moving mold core. The second step surface of the horn gate module is inclined and extends 0.1mm above the bottom surface of the moving mold core. The gate of the horn is located on the second step surface of the horn gate module.

[0013] Two relief grooves are symmetrically distributed along the center of the second-level step. The outer wall of the third-level step surface of the horn-shaped gating module is located inside the relief groove, and the outer wall of the second-level step surface extends beyond the opening of the relief groove.

[0014] The second technical solution to achieve the objective of this invention is: a method for processing thin keycaps using any of the above-mentioned molding dies, comprising the following steps: 1) Drying treatment of injection molding raw materials; 2) After the molding die is closed, control the mold temperature to 95℃, and the temperature of the injection molding machine's feed tube to 330-340℃; 3) The injection molding process consists of four stages: the injection pressure for each stage is 1600±5 kgf / cm², the injection time for each stage is 0.7±0.07 s, and the initial position of the injection screw is 36 mm, with an end position of 15.6 mm. Stage 1: The injection screw moves to 30 mm, and the injection speed is 260±5 mm / s; Phase 2: The injection screw moves to 21 mm, and the injection speed is 300±5 mm / s; Phase 3: The injection screw moves to 16 mm, and the injection speed is 265±5 mm / s; Phase 4: The injection screw moves to its end point, and the injection speed is 220±5 mm / s; 4) After the third stage of injection molding, pressure holding begins, which consists of two stages: Stage 1: The holding pressure is 190±5 kgf / cm², the holding speed is 55±5 mm / s, and the holding time is 0.5±0.05 s; Stage 2: The holding pressure is 450±5 kgf / cm², the holding speed is 55±5 mm / s, and the holding time is 1±0.1s; 5) After the pressure holding is completed, the mold is opened and the product is ejected to obtain the molded product.

[0015] Step 1) The drying temperature is 120±5℃, the time is 4h, and the injection molding material is LCP.

[0016] The above technical solution has the following beneficial effects: 1. The molding die for thin keycaps includes a fixed mold core and a moving mold core. The top surface of the fixed mold core has a cavity, and the bottom surface of the moving mold core has two levels of steps. When the moving mold core and the fixed mold core are closed, the keycap cavity is formed by the two levels of steps and the cavity, which is used to inject molten material and form a thin keycap. The bottom surface of the moving mold core on both sides of the long side of the two levels of steps has injection horns. The gates of the injection horns are oblong holes and communicate with the keycap cavity. The major axis of the gate is 1.8 mm and the minor axis is 0.3 mm, which extends the effective injection coverage area, allowing the melt to spread smoothly along the length of the product. Simultaneously, the symmetrically arranged injection positions on both sides effectively balance the pressure field inside the cavity, avoiding molding defects such as product displacement, uneven filling, and stress concentration caused by unilateral injection. Conventional point-type gates, on the other hand, result in concentrated injection, which is prone to problems such as melt jetting, scorching, and localized missing material.

[0017] 2. The moving mold core is fitted with multiple moving modules with a gap, and they move along the mold closing direction. The extended surfaces of the multiple moving modules combine to form the second-level step surface of the second-level step. Through the coordinated movement of the multiple moving modules, the mold cavity wall is formed, which facilitates the adjustment and modification of the cavity. There is a gap between two adjacent moving modules, forming a vent hole, eliminating the need for additional vent hole design. This has the advantages of simple structure and low processing cost, and also avoids residual air bubbles in the molded thin keycaps, ensuring the quality of the molded thin keycaps.

[0018] 3. The two long sides of the first step of the second-level step are provided with relief grooves. These two relief grooves are staggered along the length of the second-level step, and each relief groove is equipped with a horn-shaped gate module. Glue is injected from both sides of the cavity along the width direction, and the injection positions are staggered (the two relief grooves are symmetrically distributed along the center of the second-level step). This optimizes the melt flow path and eliminates weld line defects. Specifically, the staggered injection of glue from both sides can change the confluence position of the two plastic melts, avoiding weld lines from concentrated in key areas such as the appearance surface of the keycap and the assembly stress surface; at the same time, it extends the melt fusion stroke, improves the bonding strength at the weld, and prevents problems such as cracking, whitening, and insufficient strength caused by weld lines, thus ensuring the appearance and structural performance of the product. In addition, it can balance cavity pressure and flow rate, and improve filling consistency. Specifically, the staggered double-sided injection breaks the problems of flow rate superposition and excessive local pressure caused by the symmetrical flow field, so that the melt fills in an orderly manner in the length and width of the cavity, and the overall pressure distribution is more uniform. It effectively solves the problems of insufficient glue at the far end and uneven density in the narrow cavity of thin keycaps, and improves the consistency of the size and weight of the whole product. In addition, it can also avoid the superposition of gate marks and improve the appearance quality. Specifically, the two gates are staggered, and the tiny marks left after the glue breaks are staggered, so that the marks will not be superimposed in the same area of ​​the product, ensuring that the appearance of the keycap is clean and uniform, and further improving the appearance yield. The horn-shaped gate module has three steps. The first step surface of the horn-shaped gate module is flush with the bottom surface of the moving mold core, and the third step surface is flush with the first step surface of the moving mold core. The second step surface of the horn-shaped gate module is inclined and protrudes 0.1mm above the bottom surface of the moving mold core. The gate for the glue-injecting horn is located on the second step surface of the horn-shaped gate module. By designing the second step surface to protrude above the bottom surface of the moving mold core, the molded thin keycap forms a compensation gap at the corresponding position, so that the sprue head formed after the gate breaks does not exceed the reference surface of the keycap. Under the premise of meeting quality requirements, the process is omitted, effectively reducing the processing cost.

[0019] 4. The outer wall of the third-level stepped surface of the horn-shaped gate module is located in the relief groove, and the outer wall of the second-level stepped surface extends beyond the opening of the relief groove. This expands the feed channel space and improves the melt flow capacity. Specifically, the outer wall of the second-level stepped surface extends outward and beyond the opening of the relief groove, effectively widening the local flow cross section of the gate and increasing the volume of the glue inlet channel. Designed for thin-walled, elongated cavities of thin keycaps, this design reduces molten plastic flow resistance, increases mold filling speed, and avoids problems such as poor feeding, slow filling, and insufficient fill at distant ends caused by narrow runner spaces. This ensures rapid and complete cavity filling. Furthermore, it improves melt turning, reducing eddies and stagnation. Specifically, the horn-shaped gate features a runner turning structure. This outward expansion design provides more space for the melt to move in the transition area between turning and entering the cavity, resulting in a smoother flow transition. This effectively suppresses melt eddies and localized stagnation, reducing defects such as material accumulation, decomposition, scorching, and air bubbles, thus improving product surface quality. Additionally, it optimizes pressure transfer, ensuring product density. The expanded injection space facilitates the smooth transfer of injection pressure to all parts of the cavity, resulting in more even shrinkage compensation. It effectively compensates for melt cooling and shrinkage in thin keycaps and secondary step areas, reducing defects such as shrinkage, depressions, and internal porosity, and stabilizing product dimensions and structural density.

[0020] 5. The molding method of this invention first dries the raw material to remove moisture, preventing cavity defects during the molding process. By controlling the barrel temperature at 330-340℃, the raw material can be completely melted, achieving optimal melt flow. This is suitable for the narrow, thin-walled cavities of thin keycaps, ensuring smooth mold filling and avoiding insufficient filling and short shots. It prevents insufficient melting, excessive melt viscosity, and increased flow resistance caused by excessively low temperatures; and avoids thermal decomposition of LCP material, performance degradation, yellowing of products, and degradation streaks caused by excessively high temperatures. The stable material temperature also ensures uniform melt viscosity, consistent molding conditions between batches, and improved product dimensional and appearance consistency. A mold temperature of 95℃ slows down the cooling rate of the melt on the cavity surface, preventing rapid condensation and flow interruption in thin-walled areas, ensuring complete filling of the cavity end. It also improves the melt bonding state, weakens weld lines, and enhances the strength and appearance quality of welded areas. This results in more uniform cooling and shrinkage rates for the entire plastic part, effectively reducing problems such as warping, deformation, and excessive internal stress in thin keycaps, and stabilizing the secondary step and overall dimensional accuracy. After preparation, the injection molding process is divided into four stages: the injection pressure in each stage is 1600±5 kgf / cm², and the injection time in each stage is 0.7±0.07 s. This injection pressure is suitable for molding thin keycaps with a large aspect ratio and thin-walled cavities. The pressure is sufficient and the allowance is reasonable, overcoming the flow resistance of runners, micro-gauges, and narrow cavities, ensuring stable melt propulsion throughout the process. Strict pressure tolerance is maintained to ensure consistent molding pressure in each mold, achieving uniform quality in batches. If the injection pressure is below 1595 kgf / cm²: insufficient propulsion force makes it difficult for the melt to penetrate narrow cavities and micro-gauges, easily leading to short shots, localized missing material, and incomplete filling at the cavity end; simultaneously, weak material flow propulsion reduces the bonding strength at the weld joint. If the injection pressure is above 1605 kgf / cm²: kgf / cm²: Pressure overload can easily cause burrs and flash in thin cavities, exacerbating wear on the mold parting surface, relief grooves, and gate modules. Excessive pressure significantly increases the melt shear heat, causing localized overheating and degradation of LCP, resulting in yellowing, air bubbles, and brittleness in the product. It also increases internal stress and exacerbates warping. The injection screw has an initial position of 36mm and an end position of 15.6mm. The segment duration of 0.7±0.07s and the total stroke range (36mm→15.6mm) are combined with four-stage speed control logic to achieve a uniform and controllable overall mold filling cycle. This ensures that the cavity is completely filled within the specified cycle while avoiding a series of defects caused by excessively fast or slow overall mold filling. It is suitable for automated mass production cycles. If the duration is too short, the action will stop before the material flow reaches the target, resulting in insufficient glue. If the duration is too long, the melt will remain in the pipe and runner for too long, causing material decomposition and reducing production efficiency.

[0021] Phase 1: The injection screw moves to 30 mm, and the injection speed is 260±5 mm / s. This phase is the initial melt delivery and pre-filling stage of the runners and gates. The melt flows through the main runner and branch runners, and is about to enter the area between the horn gate and the waist-shaped gate. A medium-low injection speed of 260±5 mm / s is used for the following reasons: The screw advances smoothly at low speed, avoiding high-speed impact from the melt at startup and preventing jetting, which can cause LCP melt to impact the mold wall and create defects such as splashes, flow marks, and spray marks; the low speed minimizes the melt shear temperature rise, preventing premature thermal degradation of LCP and preserving the original material properties; and it smoothly delivers the melt to the front of the two staggered horn gates, ensuring consistent material pressure and flow on both sides of the runners, laying the foundation for subsequent synchronous mold filling. If the injection speed is >265 mm / s: the initial flow rate is too fast, and the melt is injected into the gate at high speed, resulting in obvious spray marks, haze, and flow marks on the cavity surface; the intense shearing causes a sudden increase in local temperature, and LCP decomposes to produce fumes and bubbles. If the injection speed is <255 mm / s: the feed starts slowly, and the melt is prone to cooling in the runner to form cold material, causing gate blockage and poor feeding, directly leading to poor subsequent filling.

[0022] Stage 2: The injection screw moves to 21 mm, and the injection speed is 300±5 mm / s; Stage 3: The injection screw moves to 16 mm, and the injection speed is 265±5 mm / s; Stage 4: The injection screw moves to the end point, and the injection speed is 220±5 mm / s; This stage is the rapid filling stage of the cavity body. The melt has entered the main cavity of the keycap through the waist-shaped gate, corresponding to the narrow and thin-walled main body area of ​​the product, which is the core area of ​​mold filling. Increasing the injection speed to a maximum of 300±5 mm / s offers the following technical advantages: LCP melt has low viscosity and rapid cooling, allowing for quick and easy solidification of the melt surface in thin-walled cavities. Increasing the injection speed shortens mold filling time, preventing premature solidification of the melt front and ensuring complete filling of the narrow cavity to the middle section, eliminating cold weld lines caused by mid-process stagnation. Combined with a double-sided staggered injection structure, the high-speed and stable propulsion of two melt streams ensures that the convergence points are distributed according to the designed trajectory, preventing weld lines from concentrating on the appearance and stress surfaces. The high flow rate ensures uniform melt density throughout the cavity, improving the overall compactness of the product. However, if the injection speed is >305 mm / s: excessive flow rate prevents timely airflow from escaping the cavity, leading to trapped air, scorching, and bubbles; increased melt flow disturbance results in wavy patterns and turbulent flow marks on the surface; and excessive shear force further increases internal stress in the product. If the injection speed is less than 295 mm / s: the main body filling speed is insufficient, the melt in the thin-walled area cools and solidifies rapidly, resulting in filling interruption and missing glue at the far end; the two material streams are not fully fused, the weld lines are obvious, the bonding strength is greatly reduced, and the product is prone to breakage.

[0023] Phase 3: The injection screw moves to 16 mm, and the injection speed is 265±5 mm / s. This phase is the transition section between cavity end filling and secondary step structure filling. The melt is about to reach the tail of the cavity and the precision structure area of ​​the secondary step. The injection speed is slightly reduced from the highest speed to 265±5 mm / s, which is a slow and stable pressure transition: reducing the flow rate reduces the impact of the material flow on the cavity end and the sidewalls of the secondary step, preventing the high-speed material flow from hitting the mold wall and causing rebound and eddies, avoiding air marks and pitting at the end; slowing down the filling rhythm allows the internal pressure of the cavity to gradually become more balanced, alleviating the local high pressure formed by the high-speed filling in the early stage and reducing the accumulation of internal stress in the product; for the thickness transition area of ​​the secondary step, the material is fed smoothly to ensure the complete forming of the step edges and sidewalls, avoiding dimensional defects such as missing material in the contour and excessively large rounded corners. If the injection speed is >270 mm / s: the flow rate at the end is still too fast, the air trapping in the cavity is aggravated, and the secondary step position is prone to scorching and surface defects; the impact of the material flow causes uneven local pressure, and the step dimensional accuracy exceeds the tolerance. If the injection speed is less than 260 mm / s: the speed reduction is excessive, the material flow thrust is insufficient, and material shortage and unclear outline are likely to occur at the end of the cavity and the corners of the secondary step; the fusion of the two material flows is delayed, and the welding defects are aggravated.

[0024] Phase Four: The injection screw reaches its endpoint at an injection speed of 220±5 mm / s. This phase is the final filling and sealing stage of the cavity, the closing step of the entire injection molding process. It utilizes the lowest injection speed of 220±5 mm / s: this extremely low flow rate ensures slow sealing, guaranteeing 100% complete filling of the cavity and eliminating any remaining gaps. Simultaneously, it thoroughly smooths out internal pressure fluctuations, resulting in uniform overall pressure distribution. At low speeds, it avoids impacting the molded part's walls and gate location, protecting the micro-gated gate and compensation notch structure, preventing gate deformation and backflow. It also establishes a stable initial pressure field for subsequent holding pressure processes, achieving seamless integration between injection and holding pressure. If the injection speed > 225 mm / s: the closing flow rate is too fast, causing a sudden increase in cavity pressure, resulting in flash and mold bulging on thin products; excess melt is squeezed to the gate, causing gate deformation and abnormal compensation notch dimensions. If the firing rate is less than 215 mm / s: the tail thrust is insufficient, the cavity cannot be completely filled, resulting in hidden shrinkage cavities and local low-density areas, and the product's appearance and strength do not meet the standards.

[0025] The above four-stage variable speed injection molding forms a complete rhythm of "medium speed start → high speed mold filling → slow speed transition → low speed finish", which perfectly matches the whole process structure of runner → main cavity → precision step → cavity finish. It is the core design to ensure complete mold filling, excellent appearance and controllable stress.

[0026] After the third stage of the injection molding process is completed, the pressure holding process begins, which is controlled in two stages: Phase 1: Holding pressure is 190±5 kgf / cm², holding speed is 55±5 mm / s, and holding time is 0.5±0.05 s. This phase is a low-pressure stabilization buffer section. Injection molding is not yet complete, and the melt inside the cavity is still in a flowing state. Low pressure, constant low speed, and short-term holding pressure are adopted: slow low-pressure material replenishment gradually takes over the pressure of the injection molding stage, avoiding sudden pressure changes that impact the plastic part and mold, and preventing deformation and displacement of thin-walled structures under pressure. Low-speed material replenishment can smooth out the small pressure difference inside the cavity, allowing the melt to be evenly distributed in the cavity, initially compensating for the slight shrinkage caused by the initial cooling of the melt; stabilizing the material state in key areas such as misaligned gates and secondary steps, preventing melt backflow, and transitioning to high-pressure holding. If the pressure is >195 kgf / cm²: the initial holding pressure is too high, and the sudden pressure change squeezes the thin-walled plastic part, causing product deformation and out-of-tolerance flatness; at the same time, it forces the melt to backflow into the runner and gate. If the pressure is less than 185 kgf / cm²: the pressure stabilization effect is insufficient, the melt backflow occurs, the cavity pressure drops rapidly, and the shrinkage risk is generated prematurely; if the duration exceeds the tolerance: if the duration is too short, the buffer is insufficient; if the duration is too long, the melt cooling is accelerated, and the subsequent high-pressure compensation fails.

[0027] Phase Two: Holding pressure is 450±5 kgf / cm², holding speed is 55±5 mm / s, and holding time is 1±0.1s. This phase is the main high-pressure reinforcement and shrinkage stage, and is the core process for controlling product shrinkage, density, and dimensional accuracy. During the rapid cooling and shrinkage phase of the melt, the holding pressure is increased and the holding time is extended: LCP material will shrink to a certain extent during cooling, and the uneven wall thickness of structures such as thin keycaps, secondary steps, and gate compensation notches will result in differences in shrinkage. High-pressure continuous feeding replenishes the mold cavity with melt, completely eliminating shrinkage cavities, depressions, and surface shrinkage marks. High-pressure holding improves the overall density of the plastic part, strengthens the bonding strength at weld lines, and enhances the product's structural toughness and service life. Constant low-speed feeding ensures that pressure is evenly distributed to all corners of the cavity, especially for areas prone to shrinkage such as secondary steps and misaligned gates, stabilizing overall dimensions, flatness, and geometric tolerances. Continuous pressure acting on the gate area causes the melt at the gate to cool slowly, ensuring a flat sprue after demolding. Combined with the 0.1mm compensation notch design mentioned earlier, this ensures that the sprue does not exceed the product's reference surface, eliminating the need for post-processing steps. If the pressure > 455 kgf / cm²: Excessive holding pressure leads to over-compacting of the plastic part, causing a sharp increase in internal stress, resulting in severe warping, bending, and twisting deformation after demolding. It also exacerbates mold wear, causing flash on the parting surface and clearance grooves. If the pressure is <445 kgf / cm²: Insufficient shrinkage pressure results in incomplete compensation for melt cooling and shrinkage, leading to noticeable shrinkage depressions and internal shrinkage cavities on the product surface, smaller dimensions, and exceeding tolerances; the weld joint is loose, lacking strength and prone to breakage. If the duration exceeds tolerance: Insufficient duration results in incomplete shrinkage compensation, leaving shrinkage defects; excessive duration causes complete solidification of the melt in the gate and runner, forming large areas of cold material, increasing demolding resistance, and easily damaging the product surface and causing sticking to the mold. A low, constant holding speed is used throughout the process to ensure static and uniform pressure transmission, rather than dynamic impact. Excessive holding speed causes localized pressure concentration and melt disturbance, damaging the already formed appearance and dimensions; excessively slow speed results in delayed material replenishment, preventing timely compensation for shrinkage defects.

[0028] This solution adopts a combination of four-stage variable speed injection molding and two-stage gradient holding pressure process parameters. Combined with the refined control of constant pressure, precise stroke, and strict time tolerance, it is a core process solution tailored for LCP material, thin keycap thin-wall structure, two-stage step, and staggered horn waist-shaped gate mold. The injection molding stage employs a variable speed logic of "stable start, fast mid-stage, gentle transition, and slow finish" to adapt to the filling points of runners, narrow cavities, and precision steps, eliminating appearance and structural defects such as jetting, trapped air, scorching, material shortage, and poor welding from the source. The holding pressure stage adopts a gradient pressure design of "low-pressure buffering and high-pressure compensation" to accurately compensate for the cooling and shrinkage of LCP melt, completely solving the problems of shrinkage and cavities, balancing the internal stress of the product, suppressing warpage, and ensuring the dimensional accuracy of key structures such as secondary steps and gate compensation gaps. All parameter settings strictly limit the tolerance range to ensure a high degree of consistency in the molding state of each mold, greatly improving product yield and mass production stability. The entire process is deeply integrated with the modular structure of the mold, staggered injection, gate compensation gaps, and other structural designs, eliminating the need for subsequent trimming, grinding, and other secondary processing, simplifying production processes and reducing overall manufacturing costs while ensuring product quality.

[0029] According to the applicant's batch testing, the yield rate of thin keycaps produced using the method of this invention is 98.5%, and the unit cost is reduced by 23%.

[0030] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a thin keycap in the background art; Figure 2 This is a schematic diagram of the moving mold core of the molding die in Example 1; Figure 3 This is a schematic diagram of the structure of the fixed mold core of the molding die in Example 1; Figure 4 for Figure 2 Enlarged view of point M in the middle.

[0032] In the attached diagram, 1 is the fixed mold core, 101 is the cavity, 2 is the moving mold core, 201 is the secondary step, 202 is the moving module, 203 is the clearance groove, 3 is the gate, 4 is the cooling channel, and 5 is the horn gate module. Detailed Implementation

[0033] In this invention, the structures or arrangements not described in detail are conventional structures or arrangements in the mold industry. Example 1

[0034] See Figures 2 to 4The molding die for the thin keycap includes a fixed mold core 1 and a moving mold core 2. Obviously, the fixed mold core needs to be assembled on a fixed template and the moving mold core needs to be assembled on a moving template, which is conventional technology in this field. The top surface of the fixed mold core 1 is provided with a cavity 101, and the bottom surface of the moving mold core 2 is provided with a secondary step 201. The moving mold core 2 and the fixed mold core 1 are closed, and the secondary step 201 and the cavity 101 form the keycap cavity. Typically, the fixed mold core 1 is provided with a cooling channel 4 surrounding the keycap cavity. In this embodiment, the fixed mold core is provided with two cavities and the moving mold core is provided with two secondary steps, which can simultaneously injection mold two thin keycaps. The moving mold core 2 has multiple moving modules 202 with clearance fit, and they move along the mold closing direction. The extension surfaces of the multiple moving modules 202 are combined to form the second step surface of the secondary step 201. There is a gap between two adjacent moving modules 202 to form a vent hole. Specifically, the width of the gap is 0.025mm. Obviously, the molding die is also equipped with an ejection mechanism. Specifically, the ejection mechanism has six ejector blocks, four of which are located at the four corners of the first step of the second-level step, and the other two are located on the two short sides of the first step of the second-level step. Obviously, these six ejector blocks remain integrated with the second-level step during injection molding, forming part of the keycap cavity. After injection molding is completed and the mold is opened, the six ejector blocks eject, pushing out the formed thin keycap. The moving mold core 2 is provided with injection horns on the bottom surface areas of both sides of the long side of the second-level step 201. The gates 3 of the injection horns are waist-shaped holes and communicate with the keycap cavity. The major axis length of the gate 3 is 1.8 mm and the minor axis length is 0.3 mm. In this embodiment, the side walls of the two long sides of the first step of the second-level step 201 are provided with relief grooves 203. These two relief grooves 203 are staggered along the length direction of the second-level step 201. Specifically, the two relief grooves 203 are symmetrically distributed along the center of the second-level step 201. Each relief groove 203 is equipped with a horn-shaped gate module 5. The horn-shaped gate module 5 has three steps. The first step surface of the horn-shaped gate module 5 is flush with the bottom surface of the moving mold core 2, and the third step surface is flush with the first step surface of the moving mold core. The second step surface of the horn-shaped gate module 5 is inclined and extends 0.1mm above the bottom surface of the moving mold core. The gate 3 for the glue-injecting horn is located on the second step surface of the horn-shaped gate module 5, and there are two gates 3 for the glue-injecting horn, which are spaced apart along the length of the second step 201. In order to expand the injection space of the gate and prevent the residual sprue from exceeding the reference surface of the thin keycap, the outer wall of the third step surface of the horn-shaped gate module 5 is located inside the relief groove 203, and the outer wall of the second step surface extends beyond the opening of the relief groove 203. Example 2

[0035] The method for processing thin keycaps using the molding die of Example 1 includes the following steps: 1) Take the injection molding raw material LCP and dry it at 120℃ for 4 hours; 2) After the molding die is closed, the mold temperature is controlled at 95℃, and the temperature of the injection molding machine's feed tube is 330-340℃. The injection molding material LCP is in a molten state. 3) Injection molding is divided into four stages: the injection pressure in all four stages is 1600 kgf / cm², the injection time in all four stages is 0.7 s, the initial position of the injection screw is 36 mm, and the final position is 15.6 mm. Phase 1: The injection screw moves to 30 mm, and the injection speed is 260 mm / s; Phase 2: The injection screw moves to 21 mm, and the injection speed is 300 mm / s; Phase 3: The injection screw moves to 16 mm, and the injection speed is 265 mm / s; Phase 4: The injection screw moves to its end point, with an injection speed of 220 mm / s; 4) After the third stage of injection molding, pressure holding begins, which consists of two stages: Stage 1: The holding pressure is 190 kgf / cm², the holding speed is 55 mm / s, and the holding time is 0.5 s; Phase 2: The holding pressure is 450 kgf / cm², the holding speed is 55 mm / s, and the holding time is 1 s; 5) After the pressure holding is completed, the mold is opened and the product is ejected to obtain the molded product.

[0036] A batch injection molding production of 10,000 units was completed, with a pass rate of 98.85%.

[0037] Compare with Example 1 Using conventional injection molding processes with industry-standard integrated molds, ordinary straight-through gates, and single pressure and injection speed, the overall pass rate for producing 10,000 units of the same specification continuously under the same raw materials, equipment, and production environment is only 92.0%. Traditional processes are prone to problems such as short shots, insufficient material, obvious weld lines, product warping and deformation, gate flash, and protruding sprue from the reference surface. These issues require additional post-processing steps such as gate trimming, burr removal, and visual inspection, resulting in low production efficiency and high overall costs. This invention, by optimizing the mold structure and molding process, significantly reduces the percentage of defective products, eliminates secondary processing steps, and significantly improves molding stability and economic benefits.

Claims

1. A molding die for a thin keycap, comprising a fixed mold core (1) and a moving mold core (2), characterized in that: The top surface of the fixed mold core (1) is provided with a cavity (101), and the bottom surface of the moving mold core (2) is provided with a two-stage step (201). When the moving mold core (2) and the fixed mold core (1) are closed, a keycap cavity is formed by the two-stage step (201) and the cavity (101). The moving mold core (2) is provided with a gating horn on the bottom surface area on both sides of the long side of the secondary step (201). The gating horn has a girdle-shaped hole (3) and is connected to the keycap cavity. The long axis of the gating horn (3) is 1.8 mm and the short axis is 0.3 mm.

2. The molding die according to claim 1, characterized in that: The fixed mold core (1) is provided with a cooling channel (4) surrounding the keycap cavity.

3. The molding die according to claim 1, characterized in that: The moving mold core (2) is fitted with multiple moving modules (202) with a gap and moves along the mold closing direction. The extension surfaces of the multiple moving modules (202) are combined to form the second step surface of the second step (201). There is a gap between two adjacent moving modules (202) to form a vent hole.

4. The molding die according to claim 3, characterized in that: The gap width is 0.025mm.

5. The molding die according to claim 1, characterized in that: The number of gates (3) for the glue-injecting horn is two, which are distributed at intervals along the length of the secondary step (201).

6. The molding die according to claim 1 or 5, characterized in that: The two long sides of the first step of the second-level step (201) are provided with relief grooves (203). These two relief grooves (203) are staggered along the length of the second-level step (201). Each relief groove (203) is equipped with a horn gate module (5). The horn gate module (5) is a three-level step. The first level step surface of the horn gate module (5) is flush with the bottom surface of the moving mold core (2), and the third level step surface is flush with the first level step surface of the moving mold core. The second level step surface of the horn gate module (5) is an inclined surface and is 0.1mm higher than the bottom surface of the moving mold core. The gate (3) of the horn is located on the second level step surface of the horn gate module (5).

7. The molding die according to claim 6, characterized in that: Two relief grooves (203) are symmetrically distributed along the center of the second step (201). The outer wall of the third step surface of the horn gate module (5) is located in the relief groove (203), and the outer wall of the second step surface extends beyond the groove opening of the relief groove (203).

8. A method for processing thin keycaps using any one of the forming molds according to claims 1-7, characterized in that, Includes the following steps: 1) Drying treatment of injection molding raw materials; 2) After the molding die is closed, control the mold temperature to 95℃, and the temperature of the injection molding machine's feed tube to 330-340℃; 3) The injection molding process consists of four stages: the injection pressure for each stage is 1600±5 kgf / cm², the injection time for each stage is 0.7±0.07 s, and the initial position of the injection screw is 36 mm, with an end position of 15.6 mm. Stage 1: The injection screw moves to 30 mm, and the injection speed is 260±5 mm / s; Phase 2: The injection screw moves to 21 mm, and the injection speed is 300±5 mm / s; Phase 3: The injection screw moves to 16 mm, and the injection speed is 265±5 mm / s; Phase 4: The injection screw moves to its end point, and the injection speed is 220±5 mm / s; 4) After the third stage of injection molding, pressure holding begins, which consists of two stages: Stage 1: The holding pressure is 190±5 kgf / cm², the holding speed is 55±5 mm / s, and the holding time is 0.5±0.05s; Phase 2: The holding pressure is 450±5 kgf / cm², the holding speed is 55±5 mm / s, and the holding time is 1±0.1 s; 5) After the pressure holding is completed, the mold is opened and the product is ejected to obtain the molded product.

9. The method according to claim 8, characterized in that, Step 1) The drying temperature is 120±5℃, the time is 4h, and the injection molding material is LCP.

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