Core-pulling structure of outer thread of injection mold

Abstract

This invention provides an external thread core-pulling structure for injection molds, including a moving mold, a fixed mold, and several molding components. The moving mold includes a power source, and the molding components include molding inserts, which include a first molding insert and a second molding insert. Each molding insert has an external thread for molding the outer wall of the injection molded part and several undercut molding cavities with protruding rings. The molding cavities are located on the first and second molding inserts. The power source drives the first and second molding inserts to move in opposite directions, gradually separating them from the injection molded part for core pulling. Compared with existing technologies, this external thread core-pulling structure for injection molds uses a top plate as a power source to drive ball bearings to move within the first and second guide slides, causing the first and second molding inserts to move in opposite directions for core pulling. This eliminates the need for an additional power source, resulting in a simple structure, low cost, small footprint, stable core pulling, and applicability to various undercuts such as external threads, protruding rings, and grooves, thus having a wide range of applications.

Description

Technical Field

[0001] This invention belongs to the field of injection mold technology and relates to an external thread core-pulling structure for injection molds. Background Technology

[0002] Injection molded parts typically have external threads for connection with other components. However, pulling the core out of these threads is difficult, and forced demolding can easily deform the external threads, resulting in a high scrap rate. Existing technologies for pulling the core out of external threads usually employ a rotational demolding method, such as the external thread injection mold described in Chinese Patent No. "202120093584.7". The specific structure of this external thread injection mold is as follows: it includes a fixed mold and a moving mold. The moving mold includes a rear mold plate, on which multiple core-pulling inserts are provided. Each core-pulling insert has a first cavity for forming the external thread. One end of each core-pulling insert is connected to a driven gear, which is driven by a driving gear. An ejector pin is also provided on the axis of the core-pulling insert for ejecting the external thread. A hydraulic motor drives a sprocket via chain drive, which in turn rotates the driving gear. The rotation of the driving gear drives the driven gear, simultaneously rotating multiple core-pulling inserts to extract the formed external thread, and then ejects the ejector pin to remove any remaining external thread.

[0003] However, the core-pulling method described above, which involves rotating the core-pulling insert to remove the formed external threaded part, is only suitable for injection molded parts with only external threaded structures on their outer walls. Most injection molded parts also have several grooves or raised rings on their outer walls. For example, the bottle neck of a beverage bottle usually has external threads that mate with the bottle cap, as well as a raised ring structure that positions the bottle cap. Grooves or raised rings cannot be removed by rotating the core-pulling insert, otherwise it will cause deformation of the injection molded part. The core-pulling method using the rotation of the core-pulling insert is only suitable for external threaded structures, and its applicability is limited. At the same time, the core-pulling structure driven by gear transmission to rotate the core-pulling insert is complex, costly, bulky, and has poor core-pulling stability. In addition, after the core-pulling insert has rotated and removed the core, an ejector pin is needed to eject the remaining external threaded part. This demolding process involves many steps, takes a long time, and has low production efficiency. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing an external thread core-pulling structure for injection molds that is applicable to various undercuts such as external threads and protruding rings, and has a wide range of core-pulling applications.

[0005] The objective of this invention can be achieved through the following technical solution: an external thread core-pulling structure for an injection mold, comprising a moving mold, a fixed mold, and several molding components. The moving mold includes a power source, and the molding components include molding inserts. The molding inserts include a first molding insert and a second molding insert. The molding inserts are provided with external threads for molding the outer wall of the injection molded part and several protruding rings with undercut molding cavities. The molding cavities are located on the first molding insert and the second molding insert. The power source drives the first molding insert and the second molding insert to move in opposite directions, so that the first molding insert, the second molding insert, and the injection molded part gradually separate to perform core pulling.

[0006] In the aforementioned external thread core-pulling structure of the injection mold, the moving mold further includes a base plate, a top plate, a core-pulling drive assembly, and a transmission assembly. When the mold is opened, the top plate can move relative to the base plate to eject the core. The transmission assembly is located on the top plate, and the top plate serves as the power source to drive the transmission assembly to move.

[0007] In the aforementioned external thread core-pulling structure of the injection mold, the transmission assembly includes a first transmission rod, a second transmission rod, and several sets of push plates. The push plate includes push plate one and push plate two. Push plate one is mounted on the first transmission rod, and push plate two is mounted on the second transmission rod. Several sets of molding components are provided on the push plate. The first molding insert is mounted on push plate one, and the second molding insert is mounted on push plate two.

[0008] In the aforementioned external thread core-pulling structure of the injection mold, the core-pulling drive assembly is provided in two sets and is located at both ends of the moving mold. The core-pulling drive assembly includes a guide plate and two rollers. A through hole is formed on the top plate. One end of the guide plate is mounted on the bottom plate, and the other end of the guide plate passes through the through hole. A first guide slide and a second guide slide are formed on the guide plate. The first guide slide and the second guide slide are symmetrically arranged. The first guide slide includes a first guide section, a first connecting section, and a second guide section in sequence. Correspondingly, the second guide slide includes a fourth guide section, a second connecting section, and a fifth guide section in sequence. The first connecting section and the second connecting section are relatively curved, such that the distance d2 between the second guide section and the fifth guide section is less than the distance d1 between the first guide section and the fourth guide section.

[0009] In the above-mentioned external thread core-pulling structure of the injection mold, the two rollers are respectively located in the first guide slide and the second guide slide, and the two rollers are respectively fixed to the adjacent push plate one and push plate two in different sets of push plates.

[0010] In the above-mentioned external thread core-pulling structure of the injection mold, when the mold is closed, the two rollers are respectively located on the first guide section and the fourth guide section; after the mold is opened, when the top plate is ejected, it drives the transmission assembly to move synchronously, and the first push plate and the second push plate drive the two rollers to move relative to the guide plate. When the rollers pass through the first connecting section and the second connecting section, the two rollers move towards each other. The two rollers drive the first molding insert and the second molding insert to move in opposite directions through the transmission assembly to pull the core. When the two rollers move to the second guide section and the fifth guide section, the first molding insert and the second molding insert stop moving in opposite directions.

[0011] In the above-mentioned external thread core-pulling structure of the injection mold, the first guide slide further includes a third guide section connected to the second guide section, and the second guide slide further includes a sixth guide section connected to the fifth guide section. The third guide section and the sixth guide section are bent relative to each other, such that the distance d3 between the end of the third guide section and the end of the sixth guide section is less than the distance d2 between the second guide section and the fifth guide section.

[0012] In the above-described external thread core-pulling structure of the injection mold, the two rollers continue to move to the third guide section and the sixth guide section, and the first molding insert and the second molding insert are driven to move in opposite directions again. When the two rollers move to the end of the third guide section and the end of the sixth guide section, the first molding insert and the second molding insert stop moving in opposite directions, and the core-pulling is completed.

[0013] In the external thread core-pulling structure of the above injection mold, the difference between d2 and d3 is greater than the difference between d1 and d2.

[0014] In the aforementioned external thread core-pulling structure of the injection mold, a slide rail is installed on the top plate. Two guide grooves are formed on the slide rail, making the slide rail approximately T-shaped. Guide protrusions are formed on both the first and second transmission rods. The first and second transmission rods are respectively located on both sides of the slide rail, and the guide protrusions are located in the grooves. The first and second transmission rods can move relative to the slide rail.

[0015] In the aforementioned external thread core-pulling structure of the injection mold, the molding assembly further includes a mandrel located on the moving mold and a mandrel sleeve located on the fixed mold. The mandrel is fixed on the base plate, and the push plate has a through hole for the mandrel to pass through. The first molding insert and the second molding insert are respectively located on both sides of the mandrel. When the mold is closed, the first molding insert and the second molding insert contact each other to form the molding cavity. The mandrel is located inside the molding cavity, and the mandrel sleeve is fitted on the mandrel, with the end face of the mandrel sleeve tightly against the molding insert.

[0016] Compared with existing technologies, the core-pulling structure of this injection mold, during the ejection of the injection part by the top plate, simultaneously completes the core-pulling movement of the injection part through the core-pulling drive assembly and transmission assembly, ensuring smooth demolding of the injection part. Furthermore, because ejection and core-pulling occur simultaneously, demolding time is significantly shortened, resulting in high production efficiency. The top plate acts as a power source, driving rollers to move within the first and second guide slides, causing the first and second molding inserts to move in opposite directions for core-pulling. No additional power source is required, resulting in a simple structure, low cost, small footprint, and stable core-pulling. It is applicable to various undercuts such as external threads, protruding rings, and grooves, offering a wide range of applications. There are two core-pulling processes: the first core-pulling distance is small, allowing some undercuts to demold first, and the second core-pulling ensures complete demolding of the injection part, preventing undercuts from sticking to the molding inserts and ensuring a high yield. The slide rails guide the movement of the first and second transmission rods, preventing skew during their movement. Attached Figure Description

[0017] Figure 1 This is a cross-sectional schematic diagram of the external thread core-pulling structure of this injection mold.

[0018] Figure 2 This is a three-dimensional structural diagram of the moving mold in the external thread core-pulling structure of this injection mold.

[0019] Figure 3 This is a schematic diagram of the guide plate and rollers in the external thread core-pulling structure of this injection mold.

[0020] In the diagram, 1. Base plate; 2. Top plate; 20. Through hole; 3. Core pulling drive assembly; 31. First guide section; 32. Second guide section; 33. Third guide section; 34. Fourth guide section; 35. Fifth guide section; 36. Sixth guide section; 37. First connecting section; 38. Second connecting section; 39. Guide plate; 310. Roller; 4. Transmission assembly; 41. First transmission rod; 42. Second transmission rod; 43. Push plate one; 44. Push plate two; 45. Slide rail; 5. Molding assembly; 51. Core rod; 52. First molding insert; 53. Second molding insert; 54. Core rod sleeve. Detailed Implementation

[0021] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0022] like Figure 1-3 As shown, the external thread core-pulling structure of this injection mold includes a moving mold, a fixed mold, and several molding components 5. The moving mold includes a base plate 1, a top plate 2, a core-pulling drive component 3, and a transmission component 4. When the mold is opened, the top plate 2 can move relative to the base plate 1 to eject the core.

[0023] In the above technical solution: the transmission assembly 4 is located on the top plate 2, and the top plate 2 serves as a power source to drive the transmission assembly 4 to move. The transmission assembly 4 includes a first transmission rod 41, a second transmission rod 42, and four sets of push plates, including push plate one 43 and push plate two 44. Push plate one 43 is mounted on the first transmission rod 41, and push plate two 44 is mounted on the second transmission rod 42. A slide rail 45 is installed on the top plate 2. The slide rail 45 has two guide grooves, making it approximately T-shaped. Guide protrusions are formed on both the first transmission rod 41 and the second transmission rod 42. The first transmission rod 41 and the second transmission rod 42 are located on both sides of the slide rail 45, and the guide protrusions are located in the guide grooves. The first transmission rod 41 and the second transmission rod 42 can move relative to the slide rail 45. The slide rail 45 guides the movement of the first transmission rod 41 and the second transmission rod 42, preventing them from tilting during movement. An arc-shaped groove is also formed at the bottom of the guide groove.

[0024] In the above technical solution: a plurality of molding components 5 are provided on the push plate. The molding components 5 include a mandrel 51 located on the moving mold, molding inserts, and a mandrel sleeve 54 located on the fixed mold. The molding inserts include a first molding insert 52 and a second molding insert 53. The molding inserts are provided with molding cavities for molding external threads and several protruding rings on the outer wall of the injection molded part. The molding cavities are located on the first molding insert 52 and the second molding insert 53. The mandrel 51 is fixed on the base plate 1. The push plate has a through hole for the mandrel 51 to pass through. The first molding insert 52 and the second molding insert 53 are located on both sides of the mandrel 51, respectively. The first molding insert 52 is installed on the first push plate 43, and the second molding insert 53 is installed on the second push plate 44. The mandrel 51 is located in the molding cavity. When the mold is closed, the first molding insert 52 and the second molding insert 53 come into contact to form the molding cavity. The mandrel sleeve 54 is fitted on the mandrel 51, and the end face of the mandrel sleeve 54 is in close contact with the molding insert.

[0025] In the above technical solution: the core-pulling drive assembly 3 has two sets, located at both ends of the moving mold respectively. The core-pulling drive assembly includes a guide plate 39 and a roller 310. A through hole 20 is formed on the top plate 2. One end of the guide plate 39 is mounted on the bottom plate 1, and the other end of the guide plate 39 passes through the through hole 20. A first guide slide and a second guide slide are formed on the guide plate 39. The first guide slide and the second guide slide are symmetrically arranged with the center line of the guide plate 39 as the axis. The first guide slide includes a first guide section 31, a first connecting section 37, a second guide section 32, and a third guide section 33 in sequence. The corresponding second guide slide includes a fourth guide section 34, a second connecting section 38, a fifth guide section 35, and a sixth guide section 36 in sequence. The first connecting section 37 and the second connecting section 38 are curved relative to each other, so that the distance d2 between the second guide section 32 and the fifth guide section 35 is less than the distance d1 between the first guide section 31 and the fourth guide section 34. The third guide segment 33 and the sixth guide segment 36 are arranged with relative curvature, such that the distance d3 between the end of the third guide segment 33 and the end of the sixth guide segment 36 is less than the distance d2 between the second guide segment 32 and the fifth guide segment 35. Furthermore, the difference between d2 and d3 is much greater than the difference between d1 and d2.

[0026] In the above technical solution: two rollers 310 are provided, and the two rollers 310 are respectively located in the first guide slide and the second guide slide, and can move within the first guide slide and the second guide slide. The two rollers 310 are respectively fixed to adjacent push plates 43 and 44 in different sets of push plates, that is, the two rollers 310 are respectively connected to the first transmission rod 41 and the second transmission rod 42.

[0027] During mold closing, the two rollers 310 are located on the first guide section 31 and the fourth guide section 34, respectively. After mold opening, the moving and fixed molds separate. The fixed mold drives the mandrel sleeve 54 to move, causing the mandrel sleeve 54 to detach from the injection molded part. Then, the ejector plate 2 ejects the injection molded part, causing it to move relative to the mandrel 51 for demolding. At the same time, the ejector plate 2 drives the transmission assembly 4 and the molding insert to be ejected synchronously. The push plate 1 43 and the push plate 2 44 drive the two rollers 310 to move relative to the guide plate 39. The two rollers 310 move synchronously. When the rollers 310 pass through the first connecting section 37 and the second connecting section 38, the two rollers 310 move towards each other, and the distance between the two rollers 310 decreases. Roller 310 drives adjacent push plates 43 and 44 in different groups connected to roller 310 to move towards each other. Simultaneously, push plates 43 and 44 drive the first transmission rod 41 and the second transmission rod 42 to move, respectively. The first transmission rod 41 and the second transmission rod 42 transmit the movement to other groups of push plates, enabling push plates 43 and 44 in the same group to move in opposite directions. The first molding insert 52 and the second molding insert 53 are also driven to move in opposite directions, initiating one core-pulling process for the first molding insert 52 and the second molding insert 53. When the two rollers 310 move to the second guide section 32 and the fifth guide section 35, the first molding insert 52 and the second molding insert 53 stop moving in opposite directions, and one core-pulling process ends. The distance of one core-pulling process is the difference between d1 and d2. If the distance is smaller, the undercut on the outer wall of the injection molded part is still located within the first molding insert 52 and the second molding insert 53.

[0028] The two rollers 310 continue to move onto the third guide section 33 and the sixth guide section 36, and the first molding insert 52 and the second molding insert 53 are again driven to move in opposite directions, starting the second core-pulling process for the first molding insert 52 and the second molding insert 53. When the two rollers 310 move to the end of the third guide section 33 and the end of the sixth guide section 36, the second core-pulling process ends. The distance of the second core-pulling is the difference between d2 and d3. The larger distance of the second core-pulling ensures that the first molding insert 52 and the second molding insert 53 can completely detach from the injection molded part, completing the core-pulling. Because there are usually many undercuts on the injection molded part, if the core-pulling is completed in one go, the undercuts may stick to the molding insert 53, resulting in demolding failure. Therefore, this invention has two core-pulling processes. The first core-pulling distance is small, allowing some undercuts to detach first. The second core-pulling ensures that the injection molded part is completely demolded, preventing the undercuts from sticking to the molding insert 53 and ensuring the yield rate.

[0029] In the external thread core-pulling structure of this injection mold, during the ejection of the injection part by the top plate 2, the core-pulling motion of the injection part is completed simultaneously by the core-pulling drive assembly 3 and the transmission assembly 4, ensuring smooth demolding of the injection part. Since ejection and core-pulling are carried out simultaneously, the demolding time is greatly shortened, resulting in high production efficiency. The top plate 2 acts as a power source to drive the roller 310 to move within the first and second guide slides, causing the first molding insert 52 and the second molding insert 53 to move in opposite directions for core-pulling. No additional power source is required, resulting in a simple structure, low cost, small footprint, and stable core-pulling. It is also suitable for core-pulling of various undercuts such as external threads, convex rings, and grooves, making it applicable to a wide range of applications. There are two core-pulling processes. The first core-pulling distance is small, allowing some undercuts to be demolded first. The second core-pulling ensures that the injection part is completely demolded, preventing undercuts from sticking to the molding insert 53 and ensuring a high yield. The slide rail 45 guides the movement of the first transmission rod 41 and the second transmission rod 42, preventing the first transmission rod 41 and the second transmission rod 42 from tilting during movement.

[0030] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention 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 the invention or exceeding the scope defined by the appended claims.

[0031] Although this document frequently uses terms such as base plate 1, top plate 2, through hole 20, core-pulling drive assembly 3, first guide section 31, second guide section 32, third guide section 33, fourth guide section 34, fifth guide section 35, sixth guide section 36, first connecting section 37, second connecting section 38, guide plate 39, roller 310, transmission assembly 4, first transmission rod 41, second transmission rod 42, push plate one 43, push plate two 44, slide rail 45, forming assembly 5, mandrel 51, first forming insert 52, second forming insert 53, and mandrel sleeve 54, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

[0032] Contents not described in detail herein are existing technologies known to those skilled in the art. The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. An external threaded core-pulling structure for injection molds, characterized in that... The system includes a moving mold, a fixed mold, and several molding components (5). The moving mold includes a power source. The molding components (5) include molding inserts. The molding inserts include a first molding insert (52) and a second molding insert (53). The molding inserts are provided with external threads for molding the outer wall of the injection molded part and several protruding rings with undercut molding cavities. The molding cavities are located on the first molding insert (52) and the second molding insert (53). The power source drives the first molding insert (52) and the second molding insert (53) to move in opposite directions, so that the first molding insert (52) and the second molding insert (53) gradually separate from the injection molded part for core pulling. The moving mold also includes a base plate (1), a top plate (2), a core-pulling drive assembly (3), and a transmission assembly (4). When the mold is opened, the top plate (2) can move relative to the base plate (1) to eject the mold. The transmission assembly (4) is located on the top plate (2), and the top plate (2) serves as the power source to drive the transmission assembly (4) to move. The transmission assembly (4) includes a first transmission rod (41), a second transmission rod (42), and several sets of push plates. The push plates include push plate one (43) and push plate two (44). Push plate one (43) is installed on the first transmission rod (41), and push plate two (44) is installed on the second transmission rod (42). Several sets of forming assemblies (5) are provided on the push plates. The first forming insert (52) is installed on push plate one (43), and the second forming insert (53) is installed on push plate two (44). The core-pulling drive assembly (3) has two sets located at both ends of the moving mold. The core-pulling drive assembly (3) includes a guide plate (39) and two rollers (310). The top plate (2) has a through hole (20). One end of the guide plate (39) is mounted on the bottom plate (1), and the other end of the guide plate (39) passes through the through hole (20). The guide plate (39) has a first guide slide and a second guide slide. The first guide slide and the second guide slide are symmetrically arranged. The first guide slide includes a first guide section (31), a first connecting section (37), and a second guide section (32) in sequence. Correspondingly, the second guide slide includes a fourth guide section (34), a second connecting section (38), and a fifth guide section (35) in sequence. The first connecting section (37) and the second connecting section (38) are bent relative to each other, so that the distance d2 between the second guide section (32) and the fifth guide section (35) is less than the distance d1 between the first guide section (31) and the fourth guide section (34). The two rollers (310) are located in the first guide slide and the second guide slide respectively, and the two rollers (310) are fixed to the adjacent push plate one (43) and push plate two (44) in different sets of push plates respectively; When the mold is closed, the two rollers (310) are located on the first guide section (31) and the fourth guide section (34) respectively. After the mold is opened, when the top plate (2) is ejected, it drives the transmission component (4) to move synchronously. The first push plate (43) and the second push plate (44) drive the two rollers (310) to move relative to the guide plate (39). When the rollers (310) pass through the first connecting section (37) and the second connecting section (38), the two rollers (310) move towards each other. The two rollers (310) drive the first molding insert (52) and the second molding insert (53) to move in opposite directions through the transmission component (4) to perform core pulling. When the two rollers (310) move to the second guide section (32) and the fifth guide section (35), the first molding insert (52) and the second molding insert (53) stop moving in opposite directions.

2. The external thread core-pulling structure of the injection mold according to claim 1, characterized in that... The first guide slide also includes a third guide section (33) connected to the second guide section (32), and the second guide slide also includes a sixth guide section (36) connected to the fifth guide section (35). The third guide section (33) and the sixth guide section (36) are curved relative to each other, such that the distance d3 between the end of the third guide section (33) and the end of the sixth guide section (36) is less than the distance d2 between the second guide section (32) and the fifth guide section (35). The two rollers (310) continue to move onto the third guide section (33) and the sixth guide section (36), and the first molding insert (52) and the second molding insert (53) are driven to move in opposite directions again. When the two rollers (310) move to the end of the third guide section (33) and the end of the sixth guide section (36), the first molding insert (52) and the second molding insert (53) stop moving in opposite directions, and the core pulling is completed.

3. The external thread core-pulling structure of the injection mold according to claim 2, characterized in that... The difference between d2 and d3 is greater than the difference between d1 and d2.

4. The external thread core-pulling structure of the injection mold according to claim 1, characterized in that... A slide rail (45) is installed on the top plate (2). Two guide grooves are made on the slide rail (45) so that the slide rail (45) is approximately T-shaped. Guide protrusions are made on the first transmission rod (41) and the second transmission rod (42). The first transmission rod (41) and the second transmission rod (42) are located on both sides of the slide rail (45). The guide protrusions are located in the grooves. The first transmission rod (41) and the second transmission rod (42) can move relative to the slide rail (45).

5. The external thread core-pulling structure of the injection mold according to claim 1, characterized in that... The molding assembly (5) further includes a mandrel (51) located on the moving mold and a mandrel sleeve (54) located on the fixed mold. The mandrel (51) is fixed on the base plate (1). The push plate has a through hole for the mandrel (51) to pass through. The first molding insert (52) and the second molding insert (53) are located on both sides of the mandrel (51). When the mold is closed, the first molding insert (52) and the second molding insert (53) contact each other to form the molding cavity. The mandrel (51) is located in the molding cavity. The mandrel sleeve (54) is sleeved on the mandrel (51), and the end face of the mandrel sleeve (54) is in close contact with the molding insert.

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