A mold structure for injection molding a heat-insulating cup sleeve

Abstract

The utility model relates to the technical fields of injection mold, especially to a mold structure of injection heat insulation cup cover, which comprises a front mold assembly and a rear mold assembly, the front mold assembly is provided with a front mold fixed plate, a water gap plate, a front mold plate and a front mold core, the front mold core is provided with a mold core cavity, the bottom surface of the front mold plate is attached to the front mold core to close the top opening of the mold core cavity, the rear mold assembly is provided with a rear mold fixed plate, a ejector pin mechanism, a rear mold plate and a rear mold core, the rear mold plate is provided with a rear mold core, one end of the rear mold core away from the rear mold plate is arranged in the mold core cavity, and a preset gap is formed between the outer side wall of the rear mold core and the inner side wall of the mold core cavity, the lower part of the preset gap is closed by an auxiliary insert, and the front mold core and the rear mold core are attached and sealed when the mold is closed, in summary, the positioning boss and the groove guarantee the forming precision, the linkage demolding structure reduces the loss, the taper cavity is adapted to the cup body form, the wave structure improves the heat insulation and skid resistance, and the production and product performance are comprehensively optimized.

Description

Technical Field

[0001] This utility model relates to the technical field of injection molds, and in particular to a mold structure for an injection molded heat-insulating cup sleeve. Background Technology

[0002] In the beverage market, disposable beverage cups have become the mainstream choice due to their convenience. However, their cup wall design has long faced a dual contradiction between "practicality" and "user experience." In order to control costs and weight, early disposable beverage cups generally adopted a thin-walled structure (the wall thickness is usually only 0.2-0.5mm), which resulted in the cup body having extremely high thermal conductivity. When filled with hot drinks (such as coffee or milk tea at 60-85℃), the temperature of the cup wall can rise rapidly to 45-60℃, which can easily cause burns if held directly. When filled with cold drinks (such as carbonated drinks or iced tea at 0-10℃), the cup wall is prone to condensation due to the temperature difference, which can cause hands to slip and the table to get wet, seriously affecting the user experience.

[0003] To address this issue, the industry initially introduced corrugated paper insulated cup sleeves. These sleeves utilize multiple layers of corrugated paper to create an air gap, leveraging the low thermal conductivity of air (approximately 0.026 W / m·K) for insulation. However, corrugated paper cup sleeves have significant drawbacks: First, they have poor weather resistance. In humid environments (such as condensation on the cup walls or sweaty hands) or after minor liquid spills, the paper easily softens, deforms, and delaminates, resulting in a lifespan typically less than one hour. Second, they have low adaptability. Corrugated paper is rigid and difficult to bend, requiring custom sizes to be designed for different cup diameters (such as 80mm, 90mm, and 110mm), resulting in limited versatility.

[0004] With the development of plastic injection molding technology, the industry is experimenting with using plastic materials to make heat-insulating cup sleeves. Their advantages include strong moisture resistance (PP, PE, and other plastic materials have a water absorption rate of <0.05%), mass production through molds, and flexible structural design. However, existing plastic cup sleeve molds face key technical bottlenecks: Insufficient cavity precision: Most molds lack precise positioning structures, which can easily lead to coaxiality deviations between the rear mold core and the front mold core cavity (often reaching 0.1-0.3mm). This results in uneven wall thickness of the molded cup sleeve (the difference between the thickest and thinnest part is >0.2mm), which not only affects the heat insulation effect (the difference in local heat transfer rate can reach 0.1-0.2W / m²・K), but also easily causes the cup sleeve to crack due to stress concentration. Limited heat insulation performance: Most existing plastic cup sleeves have smooth wall structures, and the heat transfer rate is generally >0.3W / m²・K. Although this is better than thin-walled beverage cups, it is still inferior to corrugated paper cup sleeves (heat transfer rate of about 0.2W / m²・K). Moreover, the structure has not been optimized for the tapered characteristics of beverage cups, which are "narrow at the bottom and wide at the opening". The fit between the cup sleeve and the cup body is <70%, and it is easy to slip.

[0005] In summary, existing technologies cannot simultaneously meet the comprehensive requirements of "moisture resistance, durability, precise molding, heat insulation, and anti-slip properties," and there is an urgent need for a new injection mold structure to break through the production and performance bottlenecks of plastic heat-insulating cup sleeves. Utility Model Content

[0006] To overcome the shortcomings mentioned above, this utility model aims to provide a technical solution that can solve the above problems.

[0007] This utility model provides a mold structure for injection molding heat-insulating cup sleeves, including a front mold assembly and a rear mold assembly that can be joined together; The front mold assembly is fixedly connected from front to back to a front mold fixing plate, a sprue plate, a front template, and a front mold core. The front mold core has a mold core cavity that runs through its front and rear sides. The bottom surface of the front template fits against the front mold core, thereby sealing the top opening of the mold core cavity. The rear mold assembly is fixedly connected from back to front to a rear mold fixing plate, an ejector mechanism, a rear template and a rear mold core. A rear mold core is fixedly connected to the side of the rear template facing the front mold core. The end of the rear mold core away from the rear template passes through the cavity of the mold core, and a preset gap is formed between the outer wall of the rear mold core and the inner wall of the mold core cavity for injection molding of the heat insulation cup sleeve. An auxiliary insert is provided between the front mold core and the rear mold core. The auxiliary insert closes the lower part of the preset gap, and the ejector pin of the ejector mechanism passes through the rear template and can lift the rear mold core upward. The rear mold core simultaneously lifts the auxiliary insert to drive the cup sleeve to be demolded. The front mold core and the rear mold core fit together and seal during mold closing to close the circumferential edge of the preset gap.

[0008] Furthermore: the front template is provided with a positioning groove corresponding to the position of the mold core cavity, and the rear mold core is provided with a positioning boss at the end away from the rear template. When the mold is closed, the positioning boss is inserted into the positioning groove.

[0009] Furthermore: the front template is provided with a pouring port at the location corresponding to the preset gap, and the runner of the sprue plate is connected to the pouring port, so that molten plastic can be injected into the preset gap from the pouring port.

[0010] Furthermore, the inner wall of the mold core cavity and the outer wall of the rear mold core both have a conical structure, and the diameter of the conical surface gradually increases linearly from the front template to the rear template, so that the preset gap forms a conical annular cavity for molding a conical tube-shaped heat insulation cup sleeve.

[0011] Furthermore: the inner wall of the mold core cavity is provided with a plurality of fan-shaped grooves that are evenly distributed circumferentially and extend axially. A conical protrusion extending toward the center of the mold core cavity is formed between two adjacent fan-shaped grooves. A first transition surface is provided between the conical protrusion and the fan-shaped groove. The width of the first transition surface decreases linearly from the front template to the rear template.

[0012] Furthermore: the outer wall of the rear model core is provided with a plurality of fan-shaped protrusions that are evenly distributed circumferentially and extend axially. A conical groove extending toward the center of the rear model core is formed between two adjacent fan-shaped protrusions. A second transition surface is provided between the conical groove and the fan-shaped protrusion. The width of the second transition surface decreases linearly from the front template to the rear template.

[0013] Furthermore, the fan-shaped protrusion of the rear model core is provided with a reinforcing notch, which is used to injection mold the reinforcing rib on the inner wall of the fan-shaped protrusion of the cup sleeve.

[0014] Furthermore, the fan-shaped protrusion is provided with a plurality of reinforcing notches spaced apart along the axial direction of the rear model core, and the reinforcing notches are distributed near the end of the rear model core with a smaller diameter.

[0015] Compared with the prior art, the beneficial effects of this utility model are: ① Addressing material limitations while balancing weather resistance and production efficiency, the use of PP, PE, and other plastic materials through one-step injection molding completely avoids the problem of corrugated paper cup sleeves deforming due to moisture—the plastic cup sleeves have a water absorption rate of <0.05%, maintaining structural integrity even in humid environments and extending their service life to 5-8 hours (reusable 2-3 times); at the same time, the injection molding process achieves "one-step molding," eliminating paper cutting, gluing, and other processes, shortening the production cycle per mold to 30-45 seconds, improving production efficiency, and reducing the cost of large-scale applications.

[0016] ② Precise positioning and sealing ensure product molding quality. Through the matching structure of "positioning boss + positioning groove", the positioning boss of the rear mold core is precisely inserted into the positioning groove of the front mold plate when the mold is closed. This controls the coaxiality error between the rear mold core and the mold cavity to within 0.02-0.05mm, and the uniformity error of the cup sleeve wall thickness to <0.1mm. This avoids local overheating or weakness caused by uneven wall thickness. At the same time, the front mold core and the rear mold core fit together and seal, and the auxiliary insert seals the area below the preset gap, forming a fully enclosed injection cavity to prevent molten plastic leakage. This increases the product yield rate to over 98%.

[0017] ③ Optimize the demolding mechanism to reduce product loss. Innovate the design of a linkage demolding structure of "ejector mechanism + rear mold core + auxiliary insert": When demolding, the ejector pin passes through the rear template and lifts the rear mold core. The rear mold core drives the auxiliary insert to move upward at the same time. The auxiliary insert directly acts on the bottom of the cup sleeve to achieve "overall push demolding". This avoids cup sleeve deformation or scratches caused by single-point force of traditional ejector pin. The demolding resistance is controlled within 3N. The cup sleeve deformation rate after demolding is <1%, further reducing production loss.

[0018] ④ Adapts to cup shape, enhancing heat insulation and anti-slip performance; conical cavity design: Both the mold core cavity and the rear mold core adopt a conical structure with a "linearly increasing diameter from front to back" (cone angle 3°-5°), adapting to the "narrow bottom and wide opening" shape of disposable beverage cups. The cup sleeve can be easily slipped on from the bottom (slipping resistance ≤5N), and the middle section has a ≥90% fit with the cup body, preventing slippage during use; wavy concave-convex structure: The fan-shaped grooves (48, groove depth 1-2mm) on the inner wall of the mold core cavity correspond to the fan-shaped protrusions on the outer wall of the rear mold core, making the cup sleeve... The sidewalls are formed into a wavy structure—the outer wall ridges reduce the contact area between the hand and the cup sleeve (60%-70% less than a smooth wall), and the inner wall ridges form point contact with the cup body (contact point pressure ≥50kPa). Combined with the air gap between the ridges (thermal conductivity ≤0.026W / m・K), the overall heat transfer rate of the cup sleeve is reduced to below 0.15W / m²・K. The heat insulation effect is better than that of corrugated paper cup sleeves. When holding the cup, the hand temperature is controlled at 35-40℃ (hot drink scenario) or 15-20℃ (cold drink scenario), significantly improving comfort.

[0019] ⑤ Gradient reinforcement design, balancing strength and lightweight, features a gradient reinforcement notch design on the fan-shaped protrusion with "dense at the bottom and sparse at the top": the spacing of the reinforcement notch near the small diameter end of the rear mold core (corresponding to the bottom of the cup sleeve) is reduced to 6-7mm, and the number of reinforcing ribs accounts for 60%-70% of the total, so that the deformation of the bottom of the cup sleeve under a radial force of 15N is ≤0.5mm, which can stably support a beverage cup filled with liquid up to 500g; the spacing of the reinforcement notch at the top of the cup sleeve is expanded to 8-10mm, reducing the amount of plastic used, and the weight of a single cup sleeve is controlled within 5g, taking into account the requirements of structural strength and lightweight, and avoiding material waste.

[0020] In summary, the mold structure of the injection-molded heat-insulating cup sleeve provided by this utility model adopts one-time plastic injection molding, which solves the problem of moisture in corrugated paper cup sleeves and improves production efficiency. The positioning boss and groove ensure molding accuracy, the linkage demolding structure reduces losses, and the conical cavity adapts to the cup shape and the wave-shaped structure improves heat insulation and anti-slip performance, thus comprehensively optimizing production and product performance.

[0021] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a structural schematic diagram of the front mold assembly and the rear mold assembly of this utility model; Figure 2 This is a schematic diagram of the ejector mechanism and the rear mold core of this utility model; Figure 3 This is a cross-sectional schematic diagram of the front template, front mold core, and rear mold core of this utility model; Figure 4 This is a schematic diagram of the structure of the rear model core of this utility model; Figure 5 yes Figure 4 A magnified view of a portion of point A in the middle; Figure 6 This is a cross-sectional schematic diagram of the front mold core and the mold core cavity of this utility model; Figure 7 yes Figure 6 A magnified view of a portion of point B in the middle; Figure 8 This is a cross-sectional schematic diagram of the front mold core, rear mold core, and rear mold core of this utility model in their separated states.

[0024] The reference numerals and names in the figure are as follows: 10 Front mold assembly; 11 Front mold fixing plate; 12 Sprue plate; 13 Front template; 14 Positioning groove; 15 Sprue; 20 Front mold core; 21 Mold core cavity; 22 Fan-shaped groove; 23 Conical protrusion; 24 First transition surface; 30 Rear mold assembly; 31 Rear mold fixing plate; 32 Ejector mechanism; 33 Rear mold core; 34 Auxiliary insert; 40 Rear template; 41 Rear mold core; 42 Positioning boss; 43 Conical groove; 44 Second transition surface; 45 Fan-shaped protrusion; 46 Reinforcing notch. Detailed Implementation

[0025] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0026] Please see Figures 1 to 8 In this embodiment of the present invention, a mold structure for an injection-molded heat-insulating cup sleeve includes a front mold assembly 10 and a rear mold assembly 30 that can be joined together. The front mold assembly 10 is sequentially fixedly connected from front to back to a front mold fixing plate 11, a sprue plate 12, a front template 13, and a front mold core 20. The front mold core 20 is provided with a mold core cavity 21 that extends through its front and rear side surfaces. The bottom surface of the front template 13 fits against the front mold core 20, thereby sealing the top opening of the mold core cavity 21.

[0027] The rear mold assembly 30 is fixedly connected from back to front to the rear mold fixing plate 31, the ejector mechanism 32, the rear template 40 and the rear mold core 33. The rear template 40 is fixedly connected to the side facing the front mold core 20 to the rear mold core 41. The end of the rear mold core 41 away from the rear template 40 passes through the mold core cavity 21, and a preset gap is formed between the outer side wall of the rear mold core 41 and the inner side wall of the mold core cavity 21 for injection molding of the heat insulation cup sleeve.

[0028] An auxiliary insert 34 is provided between the front mold core 20 and the rear mold core 33. The auxiliary insert 34 seals the lower part of the preset gap, and the ejector pin of the ejector mechanism 32 passes through the rear template 40, which can lift the rear mold core 33 upward. The rear mold core 33 simultaneously lifts the auxiliary insert 34, thereby realizing the demolding of the cup sleeve. The front mold core 20 and the rear mold core 33 fit tightly together when the mold is closed to seal the peripheral wall of the preset gap.

[0029] Specifically, with the popularity of coffee and milk tea, disposable beverage cups are becoming increasingly common. To save costs and reduce weight, disposable beverage cups typically have thin walls. When people hold them, they directly contact the cup wall, which can easily lead to cups that are too hot or too cold, affecting the user experience. Later, a technology emerged that used corrugated cardboard with a wavy structure to create an air insulation layer for insulated cup sleeves. However, corrugated cardboard sleeves are prone to moisture damage and deformation, affecting their performance. Using plastic to make insulated cup sleeves avoids this problem and allows for direct injection molding, improving production efficiency and offering practical benefits. Therefore, this invention provides a mold structure for directly molding insulated cup sleeves using plastic material through injection molding, to overcome the aforementioned problems.

[0030] This invention utilizes plastic material and injection molding to directly produce heat-insulating cup sleeves, avoiding the problem of corrugated paper cup sleeves deforming due to moisture and improving production efficiency. A mold cavity 21 is formed by penetrating the front mold core 20 and sealing its upper opening with the front template 13. Simultaneously, the rear mold core 41 penetrates the mold cavity 21, working with the auxiliary insert 34 to seal the lower part, thus forming an injection molding cavity between the inner wall of the mold cavity 21 and the outer wall of the rear mold core 41 for molding the heat-insulating cup sleeve.

[0031] Meanwhile, a positioning boss 42 is provided at the end of the rear mold core 41 away from the rear template 40, and a positioning groove 14 is provided at the corresponding position on the front template 13. The two cooperate during mold closing to ensure the coaxiality of the rear mold core 41 and the mold cavity 21. The auxiliary insert 34, together with the ejector pin mechanism 32, enables the cup sleeve to be demolded smoothly. The setting of the sprue 15 and the runner ensures the injection of molten plastic, and the conical cavity structure is adapted to the shape of the beverage cup, improving the usability of the cup sleeve.

[0032] Secondly, during mold closing, the front mold assembly 10 and the rear mold assembly 30 are connected. The bottom surface of the front template 13 presses against the front mold core 20 to close the opening above the mold core cavity 21. The rear mold core 41 is inserted into the mold core cavity 21, and its positioning boss 42 is inserted into the positioning groove 14 of the front template 13. The front mold core 20 and the rear mold core 33 fit together and seal. The auxiliary insert 34 closes the area below the preset gap. At this time, the inner wall of the mold core cavity 21 and the outer wall of the rear mold core 41 form an injection molding cavity.

[0033] During injection molding, molten plastic flows through the runner of the sprue plate 12 and into the injection cavity from the gating gate 15. After cooling and molding, the ejector pins of the ejector mechanism 32 pass through the rear mold plate 40 and lift the rear mold core 33. The rear mold core 33 simultaneously lifts the auxiliary insert 34, which drives the cup sleeve to demold, completing the production of the cup sleeve. It is understandable that, in order for the rear mold core 41 to move along the inner side of the auxiliary insert 34 during mold closing and opening, preferably, the inner sidewall of the auxiliary insert 34 is also provided with protrusions and grooves that match the fan-shaped protrusions 45 and conical grooves 43 of the rear mold core 41.

[0034] like Figure 3 , Figure 4 and Figure 8 As shown, in a preferred embodiment, the front template 13 is provided with a positioning groove 14 corresponding to the position of the mold core cavity 21, and the rear mold core 41 is provided with a positioning boss 42 at the end away from the rear template 40. When the mold is closed, the positioning boss 42 is inserted into the positioning groove 14. This design can ensure the coaxiality of the rear mold core 41 and the mold core cavity 21 and avoid uneven cup sleeve wall thickness.

[0035] Specifically, the front template 13 is provided with a pouring port 15 at the location corresponding to the preset gap. The runner of the sprue plate 12 is connected to the pouring port 15, and the molten plastic can be injected into the preset gap from the pouring port 15 to realize the delivery of molten plastic to the injection cavity.

[0036] like Figure 3 , Figure 4 , Figure 6 and Figure 8As shown, in a preferred embodiment, since disposable beverage cups typically have a smaller bottom diameter and a larger opening diameter, exhibiting an overall shape with a gradually increasing diameter, the cup sleeve is also designed as a tapered tube shape with a gradually increasing diameter to facilitate insertion from the bottom and support and gripping the cup in the middle section. Therefore, the inner wall of the mold core cavity 21 and the outer wall of the rear mold core 41 both have a tapered structure, and the diameter of the tapered surface increases linearly from the front template 13 to the rear template 40, so that the preset gap forms a tapered annular cavity for molding the tapered tube-shaped heat-insulating cup sleeve. The cone angle of the conical surface is 3°-5°. At this angle, the heat-insulating cup sleeve can be smoothly inserted from the bottom of the beverage cup with an insertion resistance of ≤5N, and it can also fit tightly against the outer wall of the beverage cup in the middle section with a fit of ≥90%, preventing the cup sleeve from slipping during use. If the cone angle is less than 3°, the insertion resistance of the cup sleeve is >8N, and the insertion difficulty increases. If the cone angle is greater than 5°, the fit between the cup sleeve and the beverage cup is <70%, and slippage is likely to occur. Therefore, 3°-5° is the optimal cone angle range.

[0037] like Figure 3 , Figure 4 , Figure 6 and Figure 8 As shown, in a preferred embodiment, in order to solve the problem of limited heat insulation effect (heat transfer rate > 0.3W / m2·K) of traditional smooth-walled cup sleeves, this solution uses mold structure design to form a wavy concave-convex structure on the side wall of the cup sleeve, and improves the heat insulation performance by utilizing the dual effects of air layer barrier and reduced contact area.

[0038] like Figures 3 to 7 As shown, in a preferred embodiment, for injection molding of a wave-shaped structure, the inner wall of the mold cavity 21 is provided with 40 to 56 fan-shaped grooves 22 (preferably 48, to ensure balanced force when gripping) evenly distributed along the circumference. Each fan-shaped groove 22 extends axially along the mold cavity 21, and its cross-section is a fan shape with a central angle of 6° to 9° (preferably 7.5°), and the groove depth is 1 to 2 mm (forming the fan-shaped protrusions of the outer wall of the cup sleeve). Between two adjacent fan-shaped grooves 22, a conical protrusion 23 extending towards the center of the mold cavity 21 is formed, and the top width of the conical protrusion 23 is 0.5-1 mm (ensuring that the protrusions of the inner wall of the cup sleeve can stably contact the beverage cup after molding). The conical protrusion 23 and the fan-shaped groove 22 are connected by a first transition surface 24. The width of the first transition surface 24 decreases linearly from 0.26 mm to 0.01 mm from the front template 13 to the rear template 40. This design makes the wave-shaped structure of the cup sleeve gradually change along the axial direction, which is convenient for demolding (demolding resistance ≤ 3N) and can adapt to the taper changes of the beverage cup.

[0039] Correspondingly, the outer wall of the rear mold core 41 is provided with fan-shaped protrusions 45 that match the fan-shaped grooves 22 one by one. Their number and distribution angle are consistent with the fan-shaped grooves 22. The height of the fan-shaped protrusions 45 is 1-2mm (to cooperate with the fan-shaped grooves 22 to form the fan-shaped ridges of the outer wall of the cup sleeve, with a thickness uniformity error ≤0.1mm). Between two adjacent fan-shaped protrusions 45, a concentrically extending conical groove 43 is formed. Its shape is complementary to the conical protrusions 23 of the mold core cavity 21 (gap error ≤0.05mm, ensuring the dimensional accuracy of the conical ridges of the inner wall of the cup sleeve, and ensuring that the conical ridges of the inner wall of the cup sleeve can stably contact the beverage cup after molding). The width of the second transition surface 44 between the conical groove 43 and the fan-shaped protrusions 45 also decreases linearly from 0.29mm to 0.04mm from the front mold plate 13 to the rear mold plate 40, and gradually changes synchronously with the first transition surface 24 to avoid cup sleeve cracking caused by stress concentration during injection molding.

[0040] Through the above combination, the outer wall of the cup sleeve forms fan-shaped ridges (1-2mm high) distributed circumferentially. When holding the cup, the hand only contacts the top of the ridges (the contact area is reduced by 60%-70% compared to a smooth wall). Combined with the air layer between the ridges (thermal conductivity ≤0.026W / m·K), the heat transfer rate is reduced to below 0.15W / m2·K. The conical ridges formed on the inner wall of the cup sleeve make point contact with the outer wall of the beverage cup (contact point pressure ≥50kPa, ensuring a tight fit without slippage), further reducing the heat conduction path and doubly improving the heat insulation effect.

[0041] like Figures 4 to 7 As shown, in a preferred embodiment, to avoid the cup sleeve strength reduction caused by the wavy structure (traditional wavy structures are prone to deformation >2mm under 10N radial force), each fan-shaped protrusion 45 of the rear mold core 41 is provided with 2-4 reinforcing notches 46 (preferably 3, equidistantly distributed along the axial direction). The notch depth is 0.2-0.8mm and the width is 1.5-2.5mm. After injection molding, corresponding reinforcing ribs are formed on the inner sidewall of the fan-shaped protrusions of the cup sleeve. The reinforcing ribs span the waist of two adjacent conical protrusions (the connection position is 1 / 2 the height from the top of the protrusion), forming a "lateral tension structure", so that the deformation of the cup sleeve under 15N radial force is ≤0.8mm, while not affecting the integrity of the heat insulation air layer (the gap between the reinforcing ribs and the inner wall of the cup sleeve is ≥0.3mm, retaining the air circulation channel).

[0042] Specifically, regarding the demolding compatibility issue between the reinforcing rib and the reinforcing notch 46, this solution achieves co-optimization of the mold structure and product design, eliminating the need for additional complex demolding structures. The specific principle is as follows: On the one hand, from the perspective of mold movement, the outer wall of the rear mold core 41 is generally conical with a smaller upper part and a larger lower part (cone angle 3°-5°). When demolding, the ejector mechanism 32 drives the rear mold core 33 to push the auxiliary insert 34 upward to eject the cup sleeve. At this time, the cup sleeve moves upward relative to the rear mold core 41 and separates. Due to the conical structure, the contact between the rear mold core 41 and the inner wall of the cup sleeve is "gradual separation" (the contact area decreases linearly with the increase of the ejection distance). The demolding resistance is ≤5N, which is far lower than the demolding limit of plastic materials (usually ≥20N).

[0043] On the other hand, considering the design parameters of the reinforcing notch 46, its depth is only 0.2-0.8mm (far less than the cup sleeve wall thickness of 1-2mm), and the clearance between the side wall of the reinforcing notch 46 and the reinforcing rib is controlled within 0.05-0.1mm (within the injection molding tolerance range). Even if there is slight friction during demolding, due to the small contact area (contact circumference of a single notch ≤10mm) and shallow depth, the damage to the cup sleeve can be controlled to the level of "fine surface scratches," and these scratches are located on the inner side wall of the cup sleeve (not the outer surface), which does not affect the user's grip experience or the integrity of the product's appearance.

[0044] Furthermore, the distribution area of ​​the reinforcing ribs (near the small-diameter end of the rear mold core 41) corresponds to the "hidden area" after the cup sleeve is inserted into the beverage cup. Even if there are very slight demolding marks, they will be concealed by the beverage cup, further avoiding any impact on the product's appearance. In summary, this solution, through the synergy of "conical demolding + shallow notch design + inner sidewall layout," achieves efficient molding and non-destructive demolding of the reinforcing ribs without adding a complex demolding structure.

[0045] like Figure 4 As shown, in a preferred embodiment, to further enhance the structural reinforcement effect of the reinforcing ribs on the cup sleeve, each fan-shaped protrusion 45 of the rear mold core 41 is provided with 3-5 reinforcing notches 46 at intervals along its axial direction (the spacing between adjacent notches is 8-10mm, and the conventional height of the cup sleeve is 50-80mm), and all reinforcing notches 46 are concentrated at the end of the rear mold core 41 with a smaller diameter (i.e., the area corresponding to the bottom of the beverage cup after the cup sleeve is formed).

[0046] From a stress analysis perspective, after the cup sleeve is inserted into the beverage cup, the smaller diameter end (bottom) must bear the weight of the beverage cup and the radial pressure during gripping (actual measurements show that the force in this area is 1.5-2 times that of the larger diameter end). Traditional uniformly distributed reinforcing ribs are insufficient to specifically address the deformation problem in this area (bottom deformation can reach 1.2-1.5mm). This solution concentrates the reinforcing notches 46 near the smaller diameter end of the rear mold core 41, increasing the density of reinforcing ribs at the bottom of the cup sleeve (spacing reduced to 6-7mm), forming a gradient reinforcement structure of "dense at the bottom and sparse at the top." The number of reinforcing ribs at the bottom of the cup sleeve (corresponding to the smaller diameter end of the rear mold core 41) accounts for 60%-70% of the total, and the deformation under a 15N radial force is ≤0.5mm, reducing it by more than 40% compared to the uniformly distributed solution. The number of reinforcing ribs at the top of the cup sleeve is reduced, avoiding material waste caused by over-reinforcement (the weight of a single cup sleeve can be controlled within 5g), while not affecting the air insulation layer during gripping (the thickness of the upper air layer is maintained at 1.5-2mm).

[0047] This gradient distribution design not only addresses the strength issue in the stress-concentrated areas of the cup sleeve, but also balances lightweight design with heat insulation, ensuring that the cup sleeve can stably support the beverage cup while maintaining good heat insulation performance in actual use.

[0048] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

Claims

1. A mold structure for injection-molded heat-insulating cup sleeves, characterized in that, Includes a front mold assembly (10) and a rear mold assembly (30) that can be joined together; The front mold assembly (10) is fixedly connected from front to back to a front mold fixing plate (11), a sprue plate (12), a front template (13), and a front mold core (20). The front mold core (20) is provided with a mold core cavity (21) that runs through its front and rear sides. The bottom surface of the front template (13) fits against the front mold core (20), thereby sealing the top opening of the mold core cavity (21). The rear mold assembly (30) is fixedly connected from back to front to the rear mold fixing plate (31), the ejector mechanism (32), the rear template (40) and the rear mold core (33). The rear template (40) is fixedly connected to the side facing the front mold core (20) to the rear mold core (41). The end of the rear mold core (41) away from the rear template (40) passes through the mold core cavity (21), and a preset gap is formed between the outer side wall of the rear mold core (41) and the inner side wall of the mold core cavity (21) for injection molding of the heat insulation cup sleeve. An auxiliary insert (34) is provided between the front mold core (20) and the rear mold core (33). The auxiliary insert (34) closes the lower part of the preset gap, and the ejector pin of the ejector mechanism (32) passes through the rear template (40) and can lift the rear mold core (33) upward. The rear mold core (33) simultaneously lifts the auxiliary insert (34) to drive the cup sleeve to demold. The front mold core (20) and the rear mold core (33) fit together and seal during mold closing to close the circumferential edge of the preset gap.

2. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 1, characterized in that, The front template (13) is provided with a positioning groove (14) corresponding to the position of the mold core cavity (21), and the rear mold core (41) is provided with a positioning boss (42) at one end away from the rear template (40). When the mold is closed, the positioning boss (42) is inserted into the positioning groove (14).

3. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 1, characterized in that, The front template (13) is provided with a pouring port (15) at the location corresponding to the preset gap. The sprue plate (12) has a branch channel connected to the pouring port (15), and molten plastic can be injected into the preset gap from the pouring port (15).

4. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 1, characterized in that, The inner wall of the mold core cavity (21) and the outer wall of the rear mold core (41) are both conical structures, and the diameter of the conical surface increases linearly from the front template (13) to the rear template (40), so that the preset gap forms a conical annular cavity for molding a conical tube-shaped heat insulation cup sleeve.

5. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 4, characterized in that, The inner wall of the mold cavity (21) is provided with a plurality of fan-shaped grooves (22) that are evenly distributed in the circumferential direction and extend along its axial direction. A conical protrusion (23) extending toward the center of the mold cavity (21) is formed between two adjacent fan-shaped grooves (22). A first transition surface (24) is provided between the conical protrusion (23) and the fan-shaped groove (22). The width of the first transition surface (24) decreases linearly from the front template (13) to the rear template (40).

6. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 5, characterized in that, The outer wall of the rear model core (41) is provided with a plurality of fan-shaped protrusions (45) that are evenly distributed in the circumferential direction and extend along its axial direction. A conical groove (43) extending toward the center of the rear model core (41) is formed between two adjacent fan-shaped protrusions (45). A second transition surface (44) is provided between the conical groove (43) and the fan-shaped protrusions (45). The width of the second transition surface (44) decreases linearly from the front template (13) to the rear template (40).

7. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 6, characterized in that, The fan-shaped protrusion (45) of the rear model core (41) is provided with a reinforcing notch (46), which is used to reinforce the inner wall of the fan-shaped protrusion of the cup sleeve by injection molding.

8. The mold structure for an injection-molded heat-insulating cup sleeve according to claim 7, characterized in that, The fan-shaped protrusion (45) is provided with a plurality of reinforcement notches (46) spaced along the axial direction of the rear model core (41), and the reinforcement notches (46) are distributed near the end of the rear model core (41) with a smaller diameter.

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