Injection mold for inversely buckling inner sides of four edges of product

Abstract

The invention relates to the technical field of molds, in particular to an injection mold for inversely buckling the inner sides of four edges of a product. According to the technical scheme, the device comprises a base, a hydraulic cylinder, an upper injection mold, a lower injection mold, an angle mold and an inner mold block, a lifting plate is arranged at the lower end of a telescopic rod of the hydraulic cylinder, the upper injection mold is arranged below the lifting plate, and first mounting rods are arranged at the upper ends of the upper injection mold; corner molds are arranged at the four corners of the lower injection mold, inner mold blocks are arranged in the corner molds, the lower injection mold, the corner molds and the inner mold blocks are of a separated structure, and the lower injection mold, the corner molds and the inner mold blocks are automatically unfolded outwards through the lower injection mold after the upper injection mold and the corner molds are lifted. According to the mold, the separated linkage structure driven by the hydraulic cylinder is arranged and matched with the torsional spring, the guide cone and the pressing rod to achieve automatic gathering and dispersing of the upper injection mold, the lower injection mold, the angle mold and the inner mold block, synchronous movement is guaranteed through gear linkage, demolding is assisted through the spring and the ejector block, and accurate molding and smooth demolding of four inner side inverted buckles are achieved.

Description

Technical Field

[0001] This invention relates to the field of plastic molding die technology, and in particular to an injection mold for undercutting the inner sides of a product. Background Technology

[0002] Recycled plastics refer to the reprocessing of waste plastic products or plastic scraps into reusable plastic materials. Recycled plastics exhibit significant characteristics and differences compared to virgin plastics in injection molding. These differences primarily stem from their origin, the degradation process they undergo, and the recycling process itself. These differences directly impact the injection molding process parameters, the performance of the final product, and its cost. The plastic shell / frame of a laptop monitor is a thin-walled structure made of PC / ABS material, serving as the core for screen protection and assembly. The frame requires snap-fit ​​assembly with inverted edges on all four sides. The recessed snap-fit / slot structure on the four inner walls of the monitor frame is the core assembly point between the frame and the screen / back cover. The molding surface is located inside the mold cavity; the part must first be removed from this recessed structure during demolding.

[0003] Because the undercut surface is hidden inside the mold, demolding can easily interfere with the mold cavity; manual removal can easily lead to undercut breakage, frame warping, and scratches on the appearance, and is extremely inefficient. Traditional molds are mostly multi-drive split types, using a lot of electrical equipment, with complex structures, large space occupation, poor opening and closing synchronization, and easy to cause product scrap. Therefore, those skilled in the art have provided an injection mold for undercutting the inner sides of the product to solve the problems mentioned in the background art. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the background art by proposing an injection mold for undercutting the inner sides of a product.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an injection mold for undercutting the inner sides of a product, comprising a base, a hydraulic cylinder, an upper injection mold, a lower injection mold, corner molds, and inner modules. A hydraulic cylinder is positioned above the base, and a lifting plate is positioned at the lower end of the hydraulic cylinder's telescopic rod. The upper injection mold is positioned below the lifting plate. The upper injection mold consists of four modules and flips outwards when lifted longitudinally. Each upper end of the upper injection mold is equipped with a mounting rod. The lower injection mold is located below the upper injection mold, and corner molds are positioned at its four corners to engage with it. The corner molds contain inner modules for undercutting. The lower injection mold, corner molds, and inner modules are separate structures. After the upper and corner molds are lifted, the lower injection mold automatically unfolds outwards, and the inner modules automatically retract inwards after the upper injection mold is lifted. When the upper injection mold descends for mold docking, the lower injection mold, corner molds, and inner modules automatically converge to form a mold for undercutting the inner sides.

[0006] Preferably, a bracket is provided on one side above the base, which is sleeved on the outside of the upper and lower injection molds and fixes the hydraulic cylinder. The bracket is connected to the cylinder body of the hydraulic cylinder. A ring frame is sleeved on the outer wall of the hydraulic cylinder. A guide sleeve is provided at the lower end of the ring frame, which is sleeved on the outside of the mounting rod.

[0007] Preferably, the thickness of the inner wall of the guide sleeve gradually increases from top to bottom, the outer wall of the mounting rod is sleeved with a guide cone, the outer wall thickness of the guide cone gradually decreases from top to bottom, and the upper end of the injection mold is connected to an injection tube, which is a flexible tube.

[0008] Preferably, the upper end of the mounting rod is provided with a rotating shaft, and the lower end of the lifting plate is provided with four sets of symmetrically distributed bearing seats. The rotating shaft is rotatably installed inside the bearing seats, and a torsion spring is sleeved on the outside of the rotating shaft, with its two ends respectively connected to the bearing seats and the mounting rod.

[0009] Preferably, the lower end of the injection mold is provided with a second mounting rod, the upper end of the base is provided with four sets of symmetrically distributed second bearing seats, the lower end of the second mounting rod is provided with a second rotating shaft that is rotatably installed inside the second bearing seat, and the outer side of the second rotating shaft is sleeved with a second torsion spring that is connected to the bearing seat and the second mounting rod at both ends respectively.

[0010] Preferably, the outer wall of the second mounting rod is fitted with a second guide cone whose outer wall thickness gradually increases from top to bottom. The upper end of the lifting plate is provided with an arched pressure rod that is fitted on the outer side of the ring frame and located on one side of the second mounting rod. The lower end of the pressure rod is rotatably fitted with a ball bearing that rolls and fits against the outer wall of the first guide cone.

[0011] Preferably, the lower end of the corner mold is provided with an installation rod three, and four sets of symmetrically distributed bearing seats three are provided above the base. The lower end of the installation rod three is provided with a rotating shaft three rotatably installed inside the bearing seat three. The outer side of the rotating shaft three is sleeved with a torsion spring three whose two ends are respectively connected to the bearing seat three and the installation rod three. The rotation angle of the installation rod two is 45° with the rotation angle of the installation rod three, and the rotation angle of two adjacent installation rod twos is 90°. The outer wall of the installation rod three is sleeved with a guide cone three whose outer wall thickness gradually increases from top to bottom. The outer wall of the lifting plate is provided with a pressure rod two sleeved on the outside of the upper injection mold and the lower injection mold and located on one side of the installation rod three. The lower end of the pressure rod two is rotatably installed with a ball three that rolls against the outer wall of the guide cone three.

[0012] Preferably, the inner wall of the corner mold is provided with a mating groove, the lower end of the inner module is provided with a mounting rod four adapted to the mating groove, the bearing seat four is provided on one side of the bearing seat three, the lower end of the mounting rod four is provided with a rotating shaft four rotatably installed inside the bearing seat four, and a torsion spring four with both ends connected to the bearing seat four and the mounting rod four respectively is sleeved on the outside of the rotating shaft four.

[0013] Preferably, the outer wall of the mounting rod four is sleeved with a guide cone four whose outer wall thickness gradually increases from top to bottom. The lower end of the lifting plate is provided with a pressure rod three located at the center of the upper injection mold and the lower injection mold, with one side of the lower end located on one side of the mounting rod four. The lower end of the pressure rod three is rotatably mounted with a ball bearing two that rolls and fits against the outer wall of the guide cone four. The mounting rod three is opposite to or rotates relative to the mounting rod four.

[0014] Preferably, the lower end of the bearing seat three is provided with a positioning cylinder two, the upper inner wall of the positioning cylinder two is provided with a spring two, the lower end of the spring two is provided with a limiting block connected to the base, the upper end of the base is provided with a positioning rod two located inside the spring two and the upper part of the positioning cylinder two, the lower end of the pressure rod two is provided with a toothed plate one, the positioning cylinder two is provided with a toothed plate two at one end, the upper end of the base is provided with a bearing seat five at each of the four corners, the bearing seat five is rotatably mounted with a rotating shaft five inside, the outer wall of the rotating shaft five is sleeved with a gear that meshes with the toothed plate one and the toothed plate two, the upper end of the inner module is provided with an inner groove, the inner wall of the inner groove is provided with a spring one, the upper end of the spring one is provided with a top block, the lower end of the top block is provided with a positioning rod one located inside the spring one and the lower part of the top block is located at the center of the inner groove.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, four sets of upper injection molds move longitudinally via hydraulic cylinder telescopic rods. When rising, the upper injection mold expands outwards under the elastic support of torsion spring one. When descending, it gradually converges and closes under the constraint of guide sleeve on guide cone one. The lifting plate guides cone one (and the lower injection mold linked with it, expanding or closing outwards), guide cone two (and the corner mold linked with it, expanding or closing outwards), and guide cone three (and the inner module linked with it, expanding or closing outwards) through pressure rod one, pressure rod two, and pressure rod three. The expansion actions in different directions make demolding of the plastic shell frame of the laptop display convenient and avoids obstruction. At the same time, the inner undercut structure of the plastic shell frame of the laptop display is not pulled, and it separates smoothly from the mold, avoiding pulling and scratching damage, and ensuring the safety of the demolded product. The mold adopts a linkage expansion result, and the hydraulic cylinder telescopic rod is used as the driving force to achieve automatic closing and expansion. The structure is concentrated to reduce the space occupied, and the rapid demolding improves production efficiency. Attached Figure Description

[0016] Figure 1 This is a front-view three-dimensional structural schematic diagram of the present invention; Figure 2 This is a front-view three-dimensional structural diagram of the ring frame of the present invention; Figure 3 This is a side sectional perspective view of the three-dimensional structure of the ring frame of the present invention; Figure 4 This is a schematic diagram of the three-dimensional structure of the guide sleeve of the present invention in main cross-section; Figure 5 This is a front-view perspective three-dimensional structural diagram of the lifting plate and base of the present invention; Figure 6 This is a side-view perspective view of the three-dimensional structure of the injection mold lower die of the present invention; Figure 7 This is a front-view three-dimensional structural diagram of pressure rod one, pressure rod two, and pressure rod three of the present invention; Figure 8 This is a bottom-view three-dimensional structural diagram of the pressure rod one, pressure rod two, and pressure rod three of the present invention; Figure 9 This is a front-view perspective view of the injection mold and base structure of the present invention; Figure 10 This is a top view of the upper and lower injection molds of the present invention from a first angle. Figure 11 This is a top-view three-dimensional structural diagram of the upper and lower injection molds of the present invention. Figure 12 This is a top-view three-dimensional structural diagram of the injection molding lower mold, corner mold, and inner module of the present invention; Figure 13 This is a side perspective three-dimensional structural diagram of the first and second pressure rods of the present invention; Figure 14 For the present invention Figure 13 Enlarged 3D schematic diagram of the central guide cone 1 and guide cone 2 from the main view; Figure 15 For the present invention Figure 14 A magnified 3D structural diagram of the inner module from the side view; Figure 16 For the present invention Figure 14 A magnified side view of the three-dimensional structure of the mid-angle module; Figure 17 For the present invention Figure 14 Enlarged front view of the three-dimensional structure of toothed plate one and toothed plate two.

[0017] Reference numerals: 1. Base; 2. Hydraulic cylinder; 3. Bracket; 4. Lifting plate; 5. Upper injection mold; 6. Lower injection mold; 7. Corner mold; 8. Ring frame; 9. Guide sleeve; 11. Mounting rod one; 12. Guide cone one; 13. Bearing seat one; 14. Torsion spring one; 15. Rotating shaft one; 16. Pressure rod one; 17. Ball bearing one; 18. Mounting rod two; 19. Guide cone two; 20. Bearing seat two; 21. Rotating shaft two; 22. Torsion spring two; 23. Pressure rod two; 24. Pressure rod three; 25. Toothed plate one; 26. Ball bearing two; 27. 28. Injection tube; 29. ​​Mounting rod three; 30. Mounting rod four; 31. Inner module; 32. Guide cone three; 33. Guide cone four; 34. Top block; 35. Toothed plate two; 36. Inner groove; 37. Positioning rod one; 38. Spring one; 39. Connecting groove; 40. Bearing seat three; 41. Torsion spring three; 42. Rotating shaft three; 43. Positioning rod two; 44. Spring two; 45. Limiting block; 46. Rotating shaft four; 47. Bearing seat four; 48. Torsion spring four; 49. Ball three; 50. Bearing seat five; 51. Rotating shaft five; 52. Gear. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figures 1 to 17 The present invention provides three embodiments: Example 1: An injection mold for undercutting the inner sides of a product includes a base 1, a hydraulic cylinder 2, an upper injection mold 5, a lower injection mold 6, corner molds 7, and an inner module 30. The hydraulic cylinder 2 is positioned above the base 1, and a lifting plate 4 is located at the lower end of the extension rod of the hydraulic cylinder 2. The upper injection mold 5 is positioned below the lifting plate 4. The upper injection mold 5 consists of four modules and flips outwards when lifted longitudinally. Each module of the upper injection mold 5 has a mounting rod 11 at its upper end. The lower injection mold 6 is located below the upper injection mold 5. 6. Corner molds 7 are provided at the four corners to dock with them. The corner molds 7 have inner modules 30 for undercut molding inside. The injection mold 6, corner molds 7 and inner modules 30 are separate structures. After the injection mold 5 and corner molds 7 are raised, they automatically unfold outward through the injection mold 6. The inner modules 30 automatically retract inward after the injection mold 5 is raised. When the injection mold 5 is lowered to dock the molds, the injection mold 6, corner molds 7 and inner modules 30 automatically assemble to form a mold for undercutting the inner sides.

[0020] In this embodiment, the hydraulic cylinder 2 telescopic rod drives the lifting plate 4 to move longitudinally. When it descends, the guide sleeve 9 constrains the guide cone 12 of the upper injection mold 5, so that the four sets of upper injection molds 5 overcome the elastic force of the torsion spring 14 and close together. At the same time, the pressure rod 16, pressure rod 23, and pressure rod 34 of the lifting plate 4 fit with the corresponding guide cone through the ball bearing structure, pushing the lower injection mold 6 and corner mold 7 to converge inward. The pressure rod 324 is linked to the inner module 30 to unfold outward. The lower injection mold 6, corner mold 7, and inner module 30 are precisely connected to form a complete mold cavity, and the injection is completed through the injection tube 27 of the upper injection mold 5.

[0021] When the mold opens, the hydraulic cylinder 2 drives the lifting plate 4 to rise, and the torsion spring 14 resets, causing the upper injection mold 5 to flip and unfold outward. After the pressure rod assembly and the guide cone assembly separate, the torsion spring 22 and the torsion spring 30 drive the lower injection mold 6 and the corner mold 7 to unfold outward automatically. The torsion spring 48 drives the inner module 30 to retract inward, sequentially disengaging from the inner buckles of the four sides and corners of the product. The inner module 30 and the top block 33 assist in ejecting the product under the action of the spring 37, completing the demolding. During production, the synchronous and precise movement of each component is ensured by the gear 52, the toothed plate 25 and the toothed plate meshing, and the cooperation of the positioning rod 36 and the spring 37, realizing automated mold closing and opening.

[0022] The mold utilizes a single hydraulic cylinder (2-cylinder) to achieve full component linkage. The upper injection mold (5), lower injection mold (6), corner mold (7), and inner module (30) are separated. Through the cooperation of torsion springs, guide cones, and pressure rods, automatic assembly during mold closing and orderly multi-directional unfolding during mold opening are achieved. This perfectly solves the demolding problem of the four inner edges of the plastic casing for laptop monitors being undercut, preventing tearing and scratching of the product and ensuring the appearance and structural precision of the molded parts. The integrated mold design allows for the centralized arrangement of all moving structures, significantly reducing the space occupied by the equipment and eliminating the need for multiple drive units, thus simplifying the operation process. Automated mold closing, injection, and demolding actions significantly shorten the production cycle, improve demolding efficiency, and adapt to the large-scale production needs of monitor plastic casings and frames. Simultaneously, the positioning and buffering structures of each component extend the mold's lifespan and reduce production and maintenance costs.

[0023] Example 2: A bracket 3 is provided on one side above the base 1, which is sleeved on the outside of the upper injection mold 5 and the lower injection mold 6 and fixed to the hydraulic cylinder 2. The bracket 3 is connected to the cylinder body of the hydraulic cylinder 2. A ring frame 8 is sleeved on the outer wall of the cylinder body of the hydraulic cylinder 2. A guide sleeve 9 is provided at the lower end of the ring frame 8, which is sleeved on the outside of the mounting rod 11. The inner wall thickness of the guide sleeve 9 gradually increases from top to bottom. A guide cone 12 is sleeved on the outer wall of the mounting rod 11. The outer wall thickness of the guide cone 12 gradually decreases from top to bottom. The upper end of the upper injection mold 5 is connected to an injection tube 27, which is a flexible tube. A rotating shaft 15 is provided at the upper end of the mounting rod 11. Four sets of symmetrically distributed bearing seats 13 are provided at the lower end of the lifting plate 4. The rotating shaft 15 is rotatably installed inside the bearing seats 13. A torsion spring 14 is sleeved on the outside of the rotating shaft 15, with its two ends connected to the bearing seats 13 and the mounting rod 11 respectively.

[0024] The lower end of the injection mold 6 is provided with a mounting rod 2 18, and the upper end of the base 1 is provided with four sets of symmetrically distributed bearing seats 20. The lower end of the mounting rod 2 18 is provided with a rotating shaft 21 rotatably installed inside the bearing seat 20. The outer side of the rotating shaft 21 is fitted with a torsion spring 22, the two ends of which are respectively connected to the bearing seat and the mounting rod 2 18. The outer wall of the mounting rod 2 18 is fitted with a guide cone 2 19 whose outer wall thickness gradually increases from top to bottom. The upper end of the lifting plate 4 is provided with an arched pressure rod 16 that is fitted above the ring frame 8 and located on one side of the mounting rod 2 18. The lower end of the pressure rod 16 is rotatably fitted with a ball bearing 17 that rolls against the outer wall of the guide cone 12.

[0025] The lower end of the corner mold 7 is provided with a mounting rod 28. The upper part of the base 1 is provided with four sets of symmetrically distributed bearing seats 39. The lower end of the mounting rod 28 is provided with a rotating shaft 41 that is rotatably installed inside the bearing seat 39. The outer side of the rotating shaft 41 is fitted with a torsion spring 40 that is connected to the bearing seat 39 and the mounting rod 28 at both ends respectively. The rotation angle of the mounting rod 18 is 45° with the rotation angle of the mounting rod 28. The rotation angle of two adjacent mounting rods 18 is 90°. The outer wall of the mounting rod 28 is fitted with a guide cone 31 whose outer wall thickness gradually increases from top to bottom. The outer wall of the lifting plate 4 is provided with a pressure rod 23 that is fitted on the outside of the upper injection mold 5 and the lower injection mold 6 and located on one side of the mounting rod 28. The lower end of the pressure rod 23 is rotatably installed with a ball bearing 49 that rolls against the outer wall of the guide cone 31.

[0026] The inner wall of the corner mold 7 is provided with a mating groove 38. The lower end of the inner module 30 is provided with a mounting rod 29 adapted to the mating groove 38. Bearing seats 47 are provided on one side of the bearing seats 39. The lower end of the mounting rod 29 is provided with a rotating shaft 46 rotatably installed inside the bearing seat 47. A torsion spring 48 is sleeved on the outside of the rotating shaft 46, with its two ends connected to the bearing seat 47 and the mounting rod 29 respectively.

[0027] The outer wall of the mounting rod 4 29 is fitted with a guide cone 4 32 whose outer wall thickness gradually increases from top to bottom. The lower end of the lifting plate 4 is provided with a pressure rod 3 24 located at the center of the upper injection mold 5 and the lower injection mold 6, with one side of the lower end located on the side of the mounting rod 4 29. The lower end of the pressure rod 3 24 is rotatably mounted with a ball bearing 2 26 that rolls and fits against the outer wall of the guide cone 4 32. The mounting rod 3 28 is opposite to or rotates relative to the mounting rod 4 29.

[0028] In this embodiment, the principle of the injection upper mold 5 is as follows: The injection upper mold 5 is composed of four independent modules. The core is opened and closed by hydraulic cylinder 2 driving, torsion spring reset and conical guide. It is the core component for mold closing, sealing and injection. The upper mounting rod 11 is connected to the bearing seat 13 of the lifting plate 4 through the rotating shaft 15 and torsion spring 14. Under normal conditions, the elastic force of torsion spring 14 causes the four modules to be in an outward flipped unfolded state. When the mold is closed, the extension rod of hydraulic cylinder 2 drives the lifting plate 4 to move downward. The guide cone 12 on the mounting rod 11 fits against the conical surface of the guide sleeve 9 at the lower end of the ring frame 8. The gradually thickening inner wall of the guide sleeve 9 forms a radial constraint on the guide cone 12, forcing the four injection upper molds 5 to overcome the torsion spring force and converge towards the center, accurately closing to form a complete injection upper mold cavity 5. The upper injection mold 5 is internally connected to a flexible injection tube 27, which can directly inject into the mold cavity after closing. When the mold is opened, the hydraulic cylinder 2 drives the lifting plate 4 to rise, the guide cone 12 is released from the constraint of the guide sleeve 9, and the torsion spring 14 is reset, causing the four sets of upper injection molds 5 to flip and unfold outward, separating from the upper surface of the product, making room for subsequent demolding.

[0029] Principle of injection mold lower mold: The lower injection mold 6 has a four-unit symmetrical structure. It opens and closes through the linkage of pressure rods, ball bearings 17, guide cones, and torsion springs 22. It forms the foundation for the bottom and four straight sides of the product and works with the upper injection mold 5 to form the basic mold cavity. The lower end of the lower injection mold 6 is connected to the bearing seat 20 of the base 1 via the rotating shaft 21 and torsion spring 22. The adjacent mounting rods 18 rotate at a 90° angle. Under normal conditions, the torsion spring 22 supports the lower injection mold 6 in an outward-opening state. When the mold is closed, the lifting plate 4 moves down, causing the pressure rod 16 to move down. The ball bearings 17 at the end of the pressure rod 16 roll and fit against the gradually thickening outer wall of the guide cone 19 of the mounting rod 18. The cone thrust pushes the mounting rod 18 to rotate around the rotating shaft 21, causing the four sets of lower injection molds 6 to converge towards the center and precisely align with the upper injection mold 5 to form the bottom molding surface of the product. When the mold opens, the lifting plate 4 is raised, the pressure rod 16 and the ball 17 are separated from the guide cone 19, and the torsion spring 22 is reset to drive the injection mold 6 to unfold outward, separating from the four sides of the product and avoiding interference with the side wall of the product.

[0030] Principle of angle mold 7: There are four sets of corner molds 7, corresponding to the four corners of the product. They are opened and closed by 45° angle linkage, pressure rod 23, ball bearing 3 49 cooperation, and torsion spring 3 40 reset. They are the forming parts of the transition surface of the four corners of the product, and at the same time provide the installation and positioning foundation for the inner module 30. The lower end of the corner mold 7 is connected to the bearing seat 39 of the base 1 via the rotating shaft 31 and the torsion spring 30. The rotation angle of the mounting rod 328 is 45° with that of the mounting rod 18 of the lower injection mold 6, which is adapted to the structural features of the four corners of the product. Under normal conditions, the torsion spring 340 keeps the corner mold 7 in an outward unfolded state. When the mold is closed, the lifting plate 4 moves downward, which drives the pressure rod 23 to move downward synchronously. The ball bearing 349 at the end of the pressure rod 23 rolls and fits against the conical surface of the guide cone 31 of the mounting rod 28, pushing the mounting rod 28 to rotate around the rotating shaft 341, which drives the four sets of corner molds 7 to converge towards the center and precisely align with the four corners of the lower injection mold 6, forming a complete molding surface of the four corners of the product in cooperation with the lower injection mold 6 and the upper injection mold 5. When the mold is opened, the lifting plate 4 is raised, the pressure rod 223 and the ball bearing 349 disengage from the guide cone 31, and the torsion spring 340 resets, driving the corner mold 7 to unfold outward and separate from the four corners of the product, completing the demolding separation of the four corner molding surfaces.

[0031] Principle of Inner Module 30: The inner module 30 is embedded in the mating groove 38 on the inner wall of the corner mold 7. It achieves its action through the central drive of the pressure rod 24, the linkage of the gear 52 and the toothed plates (toothed plate 1 25 and toothed plate 2 34), the reset of the torsion spring 48, and the spring ejection. It is the core forming component of the inverted inner side of the product and the key structure for demolding. The lower mounting rod 29 of the inner module 30 is connected to the bearing seat 47 of the base 1 via the rotating shaft 46 and the torsion spring 48. It has a linkage relationship with the mounting rod 28 of the corner mold 7, which is opposite to each other / rotates relative to each other. When the mold is closed, the lifting plate 4 moves downward, causing the central pressure rod 24 to move downward. The ball bearing 26 at the end of the pressure rod 24 fits against the conical surface of the guide cone 32 of the mounting rod 29, pushing the mounting rod 29 to rotate. This causes the inner module 30 to extend outward and fit against the inner side of the corner mold 7 and the injection mold 6, forming the undercut molding surface on the inner side of the four sides of the product. At the same time, the gear 52 of the base 1 ensures the synchronicity and accuracy of the movement of the inner module 30. When the mold is opened, the lifting plate 4 rises, causing the pressure rod 24 to disengage from the guide cone 32. The torsion spring 48 resets and drives the inner module 30 to retract inward, quickly disengaging from the undercut structure on the inner side of the product, avoiding damage to the undercut.

[0032] Example 3: A positioning cylinder 42 is provided at the lower end of bearing housing 39. A spring 44 is provided on the inner wall of the upper end of positioning cylinder 42. A limiting block 45 connected to the base 1 is provided at the lower end of spring 44. A positioning rod 43 is provided at the upper end of the base 1, located inside spring 44 with its upper part inside positioning cylinder 42. A toothed plate 25 is provided on one side of the lower end of pressure rod 23. A toothed plate 34 is provided at one end of positioning cylinder 42. Bearing housing 50 is provided at each of the four corners of the upper end of the base 1. A rotating shaft 51 is rotatably installed inside bearing housing 50. A gear 52 that meshes with toothed plate 25 and toothed plate 34 is sleeved on the outer wall of rotating shaft 51. An inner groove 35 is opened inside the upper end of inner module 30. A spring 37 is provided on the inner wall of inner groove 35. A top block 33 is provided at the upper end of spring 37. A positioning rod 36 located inside spring 37 with its lower part at the center of inner groove 35 is provided at the lower end of top block 33.

[0033] In this embodiment, the linkage structure of top block 33, gear 52, spring 1 37, and spring 2 44 are the core auxiliary components of the four-sided inner undercut mold. The four work together to precisely link with the opening and closing actions of the main structures such as injection upper mold 5 and injection lower mold 6, which not only ensures the synchronization of mold movement and the accuracy of molding, but also provides key assistance for demolding, thus optimizing the overall automated operation of the mold and adapting to the high-precision molding requirements of plastic shells / frames for laptop displays.

[0034] The ejector block 33 is embedded in the inner groove 35 at the upper end of the inner module 30. Together with spring 37 and positioning rod 36, it forms an auxiliary ejection structure. Spring 37 connects the inner wall of the inner groove 35 and the ejector block 33. When the mold is closed for injection molding, the ejector block 33 is compressed by the pressure of the inner wall of the upper mold 5 and the spring 37 is housed in the inner groove 35. This does not interfere with the undercut molding of the inner side of the product. At the same time, spring 37 buffers the pressure of the mold cavity and reduces hard contact wear of the parts. When the mold is opened, the pressure of the mold cavity is released, and spring 37 resets and releases its elastic potential energy, pushing the ejector block 33 upward to push the non-undercut area of ​​the inner side of the product. This helps the main structure to demold and avoids the product sticking to the mold. Positioning rod 36 restricts the movement direction of the ejector block 33 to prevent offset and jamming.

[0035] The gear 52 linkage structure consists of gear plate 1 25, gear plate 2 34, rotating shaft 51, and meshing gear 52. During mold closing and opening, gear plate 1 25, which moves synchronously with pressure rod 2 23, drives gear 52 to rotate. Gear plate 2 34 then pulls the corner mold 7 to move in linkage, causing the corner mold 7 to descend under the elastic force of spring 2 44, thus assisting in the mold's release. Spring 2 44 is installed between positioning cylinder 2 42 and base 1 limiting block 45. During mold closing, it is stretched upward with the movement of inner module 30, storing elastic potential energy while pulling positioning cylinder 2 42 to prevent the components from shifting due to inertia and ensuring mold closing accuracy. During mold opening, the stretched spring 2 44 contracts and releases potential energy, generating a downward pulling force. This causes the corner mold 7 to descend slightly synchronously during the rotation of the outer side driven by the torsion spring, creating a gap between the injection mold 6 and the bottom of the product, completely separating it from the molding surface, significantly reducing demolding resistance, and facilitating smooth demolding of the injection mold 6.

[0036] The above specific embodiments are merely several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An injection mold for undercutting the inner sides of a product, comprising a base (1), a hydraulic cylinder (2), an upper injection mold (5), a lower injection mold (6), a corner mold (7), and an inner module (30), characterized in that: A hydraulic cylinder (2) is provided above the base (1). A lifting plate (4) is provided at the lower end of the telescopic rod of the hydraulic cylinder (2). An upper injection mold (5) is provided below the lifting plate (4). The upper injection mold (5) is composed of four modules and flips outward when lifted longitudinally. Each upper injection mold (5) is provided with a mounting rod (11). The lower injection mold (6) is located below the upper injection mold (5). Corner molds (7) are provided at the four corners of the lower injection mold (6) to connect with it. The interior is provided with an inner module (30) for undercut molding. The injection mold (6), corner mold (7) and inner module (30) are separate structures. After the injection mold (5) and corner mold (7) are raised, they automatically unfold outward through the injection mold (6). The inner module (30) automatically retracts inward after the injection mold (5) is raised. When the injection mold (5) descends to dock the mold, the injection mold (6), corner mold (7) and inner module (30) automatically aggregate to form a mold for undercutting on the four sides.

2. The injection mold for undercutting the inner sides of a product according to claim 1, characterized in that: A bracket (3) is provided on one side above the base (1) and is sleeved on the outside of the upper injection mold (5) and the lower injection mold (6) and fixed to the hydraulic cylinder (2). The bracket (3) is connected to the cylinder body of the hydraulic cylinder (2). A ring frame (8) is sleeved on the outer wall of the cylinder body of the hydraulic cylinder (2). A guide sleeve (9) is provided at the lower end of the ring frame (8) and sleeved on the outside of the mounting rod (11).

3. The injection mold for undercutting the inner sides of a product according to claim 2, characterized in that: The thickness of the inner wall of the guide sleeve (9) gradually increases from top to bottom. The outer wall of the mounting rod (11) is fitted with a guide cone (12). The thickness of the outer wall of the guide cone (12) gradually decreases from top to bottom. The upper end of the injection mold (5) is connected to an injection tube (27), and the injection tube (27) is a flexible tube.

4. The injection mold for undercutting the inner sides of a product according to claim 3, characterized in that: The upper end of the mounting rod (11) is provided with a rotating shaft (15), and the lower end of the lifting plate (4) is provided with four sets of symmetrically distributed bearing seats (13). The rotating shaft (15) is rotatably installed inside the bearing seat (13), and a torsion spring (14) is sleeved on the outside of the rotating shaft (15) and its two ends are respectively connected to the bearing seat (13) and the mounting rod (11).

5. The injection mold for undercutting the inner sides of a product according to claim 1, characterized in that: The lower end of the injection mold (6) is provided with a mounting rod 2 (18), the upper end of the base (1) is provided with four sets of symmetrically distributed bearing seats 2 (20), the lower end of the mounting rod 2 (18) is provided with a rotating shaft 2 (21) rotatably installed inside the bearing seat 2 (20), and the outer side of the rotating shaft 2 (21) is sleeved with a torsion spring 2 (22) whose two ends are respectively connected to the bearing seat and the mounting rod 2 (18).

6. The injection mold for undercutting the inner sides of a product according to claim 5, characterized in that: The outer wall of the second mounting rod (18) is fitted with a guide cone (19) whose outer wall thickness gradually increases from top to bottom. The upper end of the lifting plate (4) is provided with an arched pressure rod (16) that is fitted on the outer side of the ring frame (8) and located on one side of the second mounting rod (18). The lower end of the pressure rod (16) is rotatably fitted with a ball bearing (17) that rolls against the outer wall of the guide cone (12).

7. An injection mold for undercutting the inner sides of a product according to claim 6, characterized in that: The lower end of the corner mold (7) is provided with a mounting rod three (28), and four sets of symmetrically distributed bearing seats three (39) are provided above the base (1). The lower end of the mounting rod three (28) is provided with a rotating shaft three (41) rotatably installed inside the bearing seat three (39). The outer side of the rotating shaft three (41) is sleeved with a torsion spring three (40) whose two ends are respectively connected to the bearing seat three (39) and the mounting rod three (28). The rotation angle of the mounting rod two (18) is the same as the rotation angle of the mounting rod three (28). The angle is 45°, and the rotation angle of two adjacent mounting rods (18) is 90°. The outer wall of the mounting rod (28) is fitted with a guide cone (31) whose outer wall thickness gradually increases from top to bottom. The outer wall of the lifting plate (4) is provided with a pressure rod (23) that is fitted on the outside of the upper injection mold (5) and the lower injection mold (6) and located on one side of the mounting rod (28). The lower end of the pressure rod (23) is rotatably fitted with a ball bearing (49) that rolls against the outer wall of the guide cone (31).

8. An injection mold for undercutting the inner sides of a product according to claim 7, characterized in that: The inner wall of the corner mold (7) is provided with a mating groove (38). The lower end of the inner module (30) is provided with a mounting rod four (29) adapted to the mating groove (38). The bearing seat three (39) is provided with a bearing seat four (47) on one side. The lower end of the mounting rod four (29) is provided with a rotating shaft four (46) rotatably installed inside the bearing seat four (47). The outer side of the rotating shaft four (46) is fitted with a torsion spring four (48) whose two ends are respectively connected to the bearing seat four (47) and the mounting rod four (29).

9. An injection mold for undercutting the inner sides of a product according to claim 8, characterized in that: The outer wall of the mounting rod four (29) is fitted with a guide cone four (32) whose outer wall thickness gradually increases from top to bottom. The lower end of the lifting plate (4) is provided with a pressure rod three (24) located at the center of the upper injection mold (5) and the lower injection mold (6) and with one side of the lower end located on the side of the mounting rod four (29). The lower end of the pressure rod three (24) is rotatably mounted with a ball two (26) that rolls against the outer wall of the guide cone four (32). The mounting rod three (28) is opposite to or rotates relative to the mounting rod four (29).

10. An injection mold for undercutting the inner sides of a product according to claim 9, characterized in that: The lower end of the bearing housing three (39) is provided with a positioning cylinder two (42), the upper inner wall of the positioning cylinder two (42) is provided with a spring two (44), the lower end of the spring two (44) is provided with a limiting block (45) connected to the base (1), the upper end of the base (1) is provided with a positioning rod two (43) located inside the spring two (44) and the upper part is located inside the positioning cylinder two (42), the lower end of the pressure rod two (23) is provided with a toothed plate one (25), the positioning cylinder two (42) is provided with a toothed plate two (34) at one end, and the upper end of the base (1) is provided with four corners. A bearing seat five (50) is provided, and a rotating shaft five (51) is rotatably installed inside the bearing seat five (50). A gear (52) that meshes with a toothed plate one (25) and a toothed plate two (34) is sleeved on the outer wall of the rotating shaft five (51). An inner groove (35) is opened inside the upper end of the inner module (30). A spring one (37) is provided on the inner wall of the inner groove (35). A top block (33) is provided on the upper end of the spring one (37). A positioning rod one (36) is provided on the lower end of the top block (33) and is located inside the spring one (37) with its lower end located at the center of the inner groove (35).

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