High-precision lens barrel forming die

Abstract

The utility model provides a kind of high-precision lens barrel forming die, belong to injection mould technical field.It solves the filling demand of the traditional cold runner structure in the existing injection mould under the condition of multiple hole number, long runner, easily lead to filling shortage, precision decline and other problems.The utility model includes from top to bottom the upper fixed plate, fixed template, runner plate, movable template and lower fixed plate, the die is equipped with multiple for the forming cavity of product main body, cavity extends downward from runner plate, penetrates movable template and forms the forming part of product main body in lower fixed plate;Hot runner system is provided in the upper fixed plate, and cold runner is formed in common with hot runner system in runner plate and movable template;Heat insulation mechanism is equipped on the contact surface of fixed template and upper fixed plate.The utility model is characterized in that by optimizing runner structure and heat insulation design, realize stable filling and efficient stripping.

Description

Technical Field

[0001] This utility model relates to the field of injection mold technology, and in particular to a high-precision mirror barrel forming mold. Background Technology

[0002] With the development of automotive intelligence, automotive lenses are increasingly widely used in systems such as autonomous driving, driver fatigue monitoring, and driving recording. As the core supporting structure of the lens, the dimensional accuracy, shape stability, and high-temperature resistance of the lens barrel directly determine the image quality and long-term reliability of the lens. Currently, high-end automotive lens barrels are generally made of polyphenylene sulfide (PPS) engineering plastic injection molding because PPS has excellent high-temperature resistance, dimensional stability, and mechanical strength.

[0003] However, the narrow molding process window of PPS material poses a significant challenge to precision injection molding. Firstly, PPS requires extremely high molding temperatures, typically exceeding 300°C. Furthermore, to promote the orderly arrangement of PPS molecular chains and the formation of stable crystals for optimal performance, the mold temperature must also be maintained at a high level of around 150°C. Under these stringent process conditions, traditional pure cold runner mold systems encounter significant problems when dealing with multi-cavity (to improve production efficiency) and long runner layouts: as the high-temperature melt flows through the unheated cold runner, heat dissipates rapidly, leading to a decrease in the flow front temperature and a sharp increase in viscosity. This ultimately results in defects such as incomplete filling and obvious weld lines, severely impacting product dimensional accuracy and mechanical properties.

[0004] Secondly, PPS is prone to sticking to the mold and localized carbonization at high temperatures. Sticking to the mold leads to difficulty in demolding, damages the product surface, and reduces demolding efficiency; while impurities produced by carbonization contaminate the mold cavity, causing defects on the product surface and significantly reducing the product qualification rate. Utility Model Content

[0005] The main purpose of this invention is to overcome the shortcomings of the existing technology and provide a high-precision injection mold suitable for PPS material lens barrels. By optimizing the flow channel structure and heat insulation design, stable filling and efficient demolding are achieved.

[0006] The objective of this utility model can be achieved through the following technical solutions: A high-precision mirror barrel forming mold includes an upper fixed plate, a fixed template, a runner plate, a moving template, and a lower fixed plate arranged from top to bottom. The mold has multiple cavities for forming the main body of the product. The cavities extend downward from the runner plate, pass through the moving template, and form the forming part of the main body of the product in the lower fixed plate. The upper fixed plate is characterized by having a hot runner system, and the runner plate and the moving template together form a cold runner that communicates with the hot runner system. The cold runner includes a main runner connected to the outlet of the hot runner system and branch runners that communicate with the main runner and extend to each forming part. A heat insulation mechanism is provided on the contact surface between the fixed template and the upper fixed plate.

[0007] In the aforementioned high-precision lens barrel forming mold, the heat insulation mechanism includes several heat insulation grooves formed on the upper surface of the fixed template, with one end of the heat insulation groove extending outward through the fixed template to make the inside and outside of the fixed template connected.

[0008] In the aforementioned high-precision lens barrel forming mold, the heat insulation mechanism includes several grid-like structures disposed on the upper surface of the fixed template, the grid-like structures being composed of several crisscrossing grooves.

[0009] In the aforementioned high-precision lens barrel forming mold, a heat insulation plate is also provided on the upper surface of the upper fixing plate.

[0010] In the aforementioned high-precision mirror barrel forming mold, the main runner is divided into multiple segments along its length, and the heights of adjacent segments are different.

[0011] In the aforementioned high-precision mirror barrel forming mold, each cavity is filled by three branch runners.

[0012] In the aforementioned high-precision lens barrel forming mold, a glue injection head is provided within the hot runner system, and the glue injection head is made of titanium alloy.

[0013] In the aforementioned high-precision mirror barrel forming mold, a heating device is provided within the hot runner system.

[0014] In the aforementioned high-precision lens barrel forming mold, the heating device includes a heating coil.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Innovative hot runner and cold runner composite system: The system adopts a combined layout of hot runner and cold runner. The hot runner system ensures the temperature and fluidity of the melt before entering the mold, effectively solving the problem of heat loss during long-distance transport. The part near the cavity uses a cold runner. This composite design perfectly balances the filling performance and solves the problem of difficult filling of long runners with multiple cavities. 2. Precise temperature zone control: By strictly controlling the melt temperature at 300℃-340℃ and the mold temperature at 140℃-160℃, the PPS melt is guaranteed to have good fluidity for perfect filling, and the optimal crystallization temperature environment is provided for PPS, ensuring that the product obtains high dimensional stability and mechanical properties. 3. Solving the problems of sticking and carbonization: Reasonable mold temperature and efficient heat insulation mechanism avoid local overheating in the mold, reduce the risk of adhesion and thermal degradation (carbonization) caused by PPS melt staying on the surface of the cavity for a long time, thereby improving the smoothness of demolding and the surface quality of the product, and significantly improving the product qualification rate. 4. Improved production efficiency and product precision: This process supports multi-cavity production, has strong flow channel filling capability, and effectively avoids the problem of precision degradation caused by insufficient filling. Through pressure holding and temperature-controlled crystallization, the product has low internal stress, low deformation, and good consistency, making it very suitable for large-scale mass production of high-precision lens barrels; 5. The flow channel structure can balance the flow of hot and cold materials and avoid molding defects caused by uneven temperature. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the injection mold of the present invention; Figure 2 This is a schematic diagram of the structure of the main body of the product and the flow channel condensate of the present invention; Figure 3 This is a schematic diagram of the heat insulation mechanism of the present invention; In the diagram, 1 is the upper fixed plate; 2 is the fixed template; 3 is the runner plate; 4 is the moving template; 5 is the lower fixed plate; 6 is the molding part; 7 is the main runner; 8 is the branch runner; 9 is the heat insulation groove; 10 is the groove; 11 is the heat insulation plate; and 12 is the runner solidified material. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0018] like Figure 1As shown, the high-precision lens barrel forming mold of this utility model includes an upper fixed plate 1, a fixed template 2, a runner plate 3, a moving template 4, and a lower fixed plate 5 arranged from top to bottom. The mold has multiple cavities for forming the main body 6 of the product. The cavities extend downward from the runner plate 3, pass through the moving template 4, and form the forming part of the main body 6 of the product in the lower fixed plate 5. A hot runner system is provided in the upper fixed plate 1. The runner plate 3 and the moving template 4 together form a cold runner that communicates with the hot runner system. The cold runner includes a main runner 7 connected to the outlet of the hot runner system and branch runners 8 that communicate with the main runner 7 and extend to each forming part. A heat insulation mechanism is provided on the contact surface between the fixed template 2 and the upper fixed plate 1.

[0019] like Figure 3 As shown, the heat insulation mechanism includes several heat insulation grooves 9 formed on the upper surface of the fixed template 2, with one end of each groove extending outward through the fixed template 2 to allow communication between the inside and outside of the fixed template 2. The heat insulation mechanism also includes several grid-like structures on the upper surface of the fixed template 2, each grid-like structure consisting of several intersecting grooves 10. A heat insulation plate 11 is also provided on the upper surface of the upper fixed plate 1. The core function of the heat insulation plate 11 is to isolate the mold (especially the hot runner system) from heat transfer to the injection molding machine, reducing heat loss, saving energy, and assisting in stabilizing the hot runner process.

[0020] The primary pathway for heat transfer is direct contact between solids. On a flat contact surface without the insulating grooves 9, heat can be directly conducted over a large area from the upper fixed plate 1 (close to the hot runner system, where the temperature is higher) to the fixed platen 2. With the dense insulating grooves 9 or grids, only raised "ribs" or "islands" remain in contact between the fixed platen 2 and the upper fixed plate 1, resulting in a very small actual thermal conductivity cross-sectional area. Most of the area is separated by air. Since air is a poor conductor of heat, with a thermal conductivity far lower than that of metal (mold steel), the air filling the insulating grooves 9 and grids forms an effective air insulation layer. Heat must then be transferred via a path of "contact point (metal) – air (low thermal conductivity) – contact point (metal)," which significantly increases thermal resistance, making rapid heat conduction difficult.

[0021] The main gating system 7 is divided into multiple segments along its length, with adjacent segments having different heights. When the molten material flows through a step or changes direction, the drastic change in flow direction and magnitude disrupts the original laminar flow state. The high-temperature molten material at the center is forced towards the outer wall of the channel or the step surface, while the low-temperature molten material on the periphery is carried into the main flow region. This process generates strong shearing and mixing effects, similar to a static mixer, causing the molten material at the center and the outer edges to continuously exchange and mix, thereby leveling out the overall temperature difference and forming a more uniformly sized melt.

[0022] In traditional straight-through runners, when high-speed, high-pressure molten material rushes directly from a narrow runner opening into a wide cavity or channel, a "jetting" phenomenon occurs. The molten material flies out like a jet, first contacting the cavity wall, then folding and tangling together, leading to problems such as flow marks (serpentine patterns), gas lines, and uneven molecular orientation. The design of a flip-up runner, by setting steps of varying heights, forces a change in the flow direction of the molten material. Instead of being ejected in a straight line, the molten material must "flip over" a step and impact the runner wall. This impact causes the molten material to spread out, transforming the "jet flow" into a smooth, orderly "expanding flow," thus smoothly filling the cavity.

[0023] Each cavity is filled by three branch runners 8. For complex plastic parts, if there is only one injection point, the molten plastic needs to flow a long path to fill the cavity, which leads to a drop in the temperature at the front end and the formation of obvious and weak weld marks when they meet at the ends. Using three injection points shortens the flow path of the molten material, allowing the plastic to fill the cavity simultaneously from different directions, effectively avoiding weld marks caused by long flow paths. With single-point injection, the plastic molecules are highly stretched and oriented in the flow direction, resulting in uneven internal stress after cooling and solidification, causing product warping and deformation. Multi-point injection makes the plastic flow smoother and more symmetrical, and the molecular orientation more uniform, thereby significantly reducing internal stress, improving the dimensional stability and flatness of the product, and reducing the risk of warping and deformation. During the holding pressure stage, plastic shrinkage requires continuous replenishment. Multi-point injection allows the holding pressure to be transmitted more evenly to all areas of the product, ensuring consistent overall shrinkage and uniform density, thereby achieving better dimensional accuracy and mechanical properties.

[0024] The hot runner system includes a dispensing head made of titanium alloy. Titanium alloy maintains its mechanical properties at high temperatures (typically 400-600℃), ensuring structural integrity and stability under high temperature and pressure conditions. Titanium alloy also has low thermal conductivity, meaning heat is less likely to dissipate from the dispensing head into the mold at the rear. This is highly advantageous for processes requiring high temperatures to prevent premature solidification of the melt, effectively reducing drooling and cold material blockage, making it particularly suitable for hot runner systems.

[0025] The hot runner system is equipped with a heating device, which includes a heating coil.

[0026] The injection molding process of the high-precision lens barrel described in this utility model is as follows: S1. The PPS melt flowing through the hot runner system is heated and maintained at an injection temperature of 300°C to 340°C by the heating device in the hot runner system; at the same time, the mold temperature controller is started to introduce high temperature oil or hot water into the cooling / heating pipes in the fixed mold plate 2, runner plate 3, moving mold plate 4 and lower fixed plate 5, so that the working temperature of the entire mold is stabilized at 140°C to 160°C. S2. The pre-plasticized PPS melt is injected into the hot runner system. The melt remains in a high-temperature flowing state within the hot runner and is then pushed into the cold runner. Driven by injection pressure, the melt rapidly fills the main runner 7 and is simultaneously injected into the molding sections of all cavities via the branch runners 8; as shown... Figure 2 As shown, the melt forms the main product 6 in the cavity and the runner solid 12 in the cold runner; S3. After the melt fills the mold cavity, the process transitions to the holding pressure stage. The holding pressure continues to act on the still-molten PPS to compensate for material shortages caused by cooling shrinkage, ensuring product density and dimensions. During this process, the mold is maintained at a high temperature of 140℃ to 160℃, providing sufficient crystallization conditions for the PPS material, allowing its molecular chains to arrange regularly and form a stable crystal structure, thus giving the product body excellent heat resistance and dimensional stability. S4. After the pressure holding period, the product is allowed to cool naturally within the cavity for a period of time to allow its surface layer to solidify sufficiently. Upon mold opening, the solidified runner material 12 in the cold runner remains at the interface between the runner plate 3 and the moving mold plate 4, while the main body of the product 6 remains on the moving mold side. During mold opening, the brittle gate will be pulled apart at the connection point between the branch runner 8 and the main body of the product 6, achieving automatic separation. S5. Remove the product body 6 and the runner solidified material 12. In step S5, the product body 6 and the runner solidified material 12 can be automatically removed from the mold by a transfer device. The transfer device includes a clamping assembly and a driving component that drives the clamping assembly to move. The clamping assembly includes clamping component one and clamping component two. After the mold is opened, the driving component drives the clamping assembly to move. Clamping component one clamps the product body 6, and clamping component two clamps the runner solidified material 12. The driving component moves the product body 6 and the runner solidified material 12 out of the mold. Through two collection boxes set outside the mold, the driving component moves to the top of the collection boxes, clamping component one and clamping component two are released, and the product body 6 and the runner solidified material 12 fall into the corresponding collection boxes respectively.

[0027] It should be understood that in the claims and description of this utility model, all instances of "comprising..." should be understood as having an open meaning, that is, their meaning is equivalent to "containing at least...", and should not be understood as having a closed meaning, that is, their meaning should not be understood as "containing only...".

[0028] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A high-precision lens barrel forming mold, comprising an upper fixed plate (1), a fixed template (2), a flow channel plate (3), a moving template (4), and a lower fixed plate (5) arranged from top to bottom, wherein the mold is provided with a plurality of cavities for forming a product body (6), the cavities extending downward from the flow channel plate (3), penetrating the moving template (4), and forming the forming part of the product body (6) in the lower fixed plate (5); characterized in that, A hot runner system is provided in the upper fixed plate (1), and a cold runner is formed in the runner plate (3) and the moving template (4) together, which is connected to the hot runner system. The cold runner includes a main runner (7) connected to the outlet of the hot runner system and a branch runner (8) connected to the main runner (7) and extending to each molding part. A heat insulation mechanism is provided on the contact surface between the fixed template (2) and the upper fixed plate (1).

2. The high-precision lens barrel forming mold according to claim 1, characterized in that, The heat insulation mechanism includes several heat insulation grooves (9) formed on the upper surface of the fixed template (2), with one end of the heat insulation groove (9) extending outward through the fixed template (2) to make the fixed template (2) connected inside and out.

3. The high-precision lens barrel forming mold according to claim 1, characterized in that, The heat insulation mechanism includes several grid-like structures set on the upper surface of the fixed template (2), and the grid-like structures are composed of several crisscrossing grooves (10).

4. The high-precision lens barrel forming mold according to claim 1, characterized in that, The upper surface of the upper fixing plate (1) is also provided with a heat insulation plate (11).

5. The high-precision lens barrel forming mold according to claim 1, characterized in that, The main gating channel (7) is divided into multiple segments along its length, and the heights of adjacent segments are different.

6. The high-precision lens barrel forming mold according to claim 1, characterized in that, Each cavity is filled by three branch runners (8).

7. The high-precision lens barrel forming mold according to claim 1, characterized in that, The hot runner system is equipped with a dispensing head, which is made of titanium alloy.

8. The high-precision lens barrel forming mold according to claim 1, characterized in that, The hot runner system is equipped with a heating device; the heating device includes a heating coil.

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