A sectional core-pulling structure of a bridge elbow pipe

Abstract

This invention provides a segmented core-pulling structure for a bridge elbow pipe fitting, belonging to the field of mold technology. It solves the problem of reducing scrap rate. The segmented core-pulling structure of this bridge elbow pipe fitting includes a mold base, on which a core-pulling seat is slidably connected along the core-pulling direction. The core-pulling seat has a main core and a secondary core extending into the cavity. The main core is fixed to the core-pulling seat, and the secondary core passes through the core-pulling seat. The core-pulling seat has a spring that elastically acts between the core-pulling seat and the outer end of the secondary core along the core-pulling direction. Under the elastic action of the spring, the inner end of the secondary core extends into the cavity, and the core-pulling seat can move outward to pull the main core out of the cavity. The secondary core has a transmission component, and the inner end of the secondary core is tilted to the side away from the main core to form a demolding part. When the core-pulling seat drives the main core to slide out of the cavity, the core-pulling seat can pull the secondary core through the transmission component, causing the secondary core to overcome the elastic force of the spring and exit the cavity. This segmented core-pulling structure of the bridge elbow pipe fitting can reduce the scrap rate.

Description

Technical Field

[0001] This invention belongs to the field of mold technology and relates to a segmented core-pulling structure for a bridge elbow pipe fitting. Background Technology

[0002] In the existing technology, the production of bridge elbow pipe fittings is generally achieved by injection molding, and after the product cools, it is demolded by core pulling in the mold open state. For example, a PPR bridge bend inverted injection molding demolding device disclosed in Chinese Patent (Authorization Announcement No.: CN223573741U) includes a moving mold group, a fixed mold group, a first core, a second core, a first core-pulling assembly, and a second core-pulling assembly. The moving mold group has a first cavity, and the fixed mold group has a second cavity. The first cavity and the second cavity are arranged opposite to each other to form a mold cavity for forming the external shape of the bridge bend. The two ends in the mold cavity corresponding to the two outlets of the bridge bend are defined as the left and right ends of the mold cavity. The first core and the second core are respectively inserted into the mold cavity from the left and right sides of the mold cavity. The first core and the second core are spliced ​​to form a mold core that matches the shape of the inner cavity of the bridge bend. An injection cavity is formed between the outer wall of the mold core and the inner wall of the mold cavity. The first core-pulling assembly and the second core-pulling assembly are respectively connected to the first core and the second core and are used to pull the first core and the second core away from each other.

[0003] The prior art discloses a mold core that is formed by mating a first core and a second core to match the shape of the inner cavity of the bridge bend. During injection molding, a complete bridge bend can be formed inside the cavity and outside the mold core. During subsequent demolding, the first core and the second core are pulled out and demolded by the first core-pulling assembly and the second core-pulling assembly, respectively.

[0004] However, due to the shape limitations of products like bridge bends, there will inevitably be interference between the end where the first and second cores are joined and the inner wall of the formed pipe. Although the material of the bridge bend itself has a certain elastic deformation capability, there will still be cases where the inner wall of the pipe is damaged or even cracked due to severe interference during the core pulling process, resulting in a high scrap rate. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a segmented core-pulling structure for bridge elbow pipe fittings. The technical problem to be solved by this invention is: how to reduce the scrap rate.

[0006] The objective of this invention can be achieved through the following technical solution: A segmented core-pulling structure for a bridge elbow pipe fitting, comprising a mold base, a core-pulling seat slidably connected to the mold base along the core-pulling direction, a main core and a secondary core extending into a cavity on the core-pulling seat, the main core being fixed on the core-pulling seat, the secondary core being inserted into the core-pulling seat, a spring on the core-pulling seat, the spring elastically acting between the outer end of the core-pulling seat and the secondary core along the core-pulling direction, and under the elastic action of the spring, the inner end of the secondary core extending into the cavity, the core-pulling seat being able to move outward and pull the main core out of the cavity, the secondary core having a transmission component, and the inner end of the secondary core tilting to the side away from the main core to form a demolding part, when the core-pulling seat drives the main core to slide out of the cavity, the core-pulling seat being able to pull the secondary core through the transmission component, causing the secondary core to overcome the elastic force of the spring and exit the cavity.

[0007] This application divides the mold core into a main core and a secondary core. The main core is fixed to a core-pulling seat, and the secondary core passes through the core-pulling seat. During core-pulling, an external drive source drives the core-pulling seat to slide outward along the core-pulling direction. The core-pulling seat moves the main core outward together, thus pulling out the main core. The secondary core, constrained by the elastic force of a spring, is held in place by the spring during the initial outward movement of the core-pulling seat, remaining stationary relative to the main core. After the core-pulling seat has completely pulled the main core out of the mold cavity, the core-pulling seat continues to move outward and simultaneously contacts the transmission component on the secondary core. The transmission component applies an outward pulling force to the secondary core, causing it to overcome the elastic force of the spring and be pulled out of the mold cavity. This achieves sequential core-pulling of the main core and secondary core. This segmented core-pulling method allows the main core to be pulled out first, providing sufficient clearance for the secondary core. When the secondary core is pulled out subsequently, it avoids severe interference with the inner wall of the pipe, effectively preventing damage or cracking of the pipe due to interference during core pulling, as is common in existing technologies. This significantly reduces the scrap rate. Notably, the secondary core, as the later-pulled part, has its inner end tilted to the side, facing away from the main core, forming a demolding section. This structure allows the pipe greater freedom in the mold opening direction when the secondary core is pulled out of the cavity, as the main core has already been removed. When the secondary core is pulled out, the demolding section pushes the formed pipe along the mold opening direction, simultaneously pulling out the secondary core and assisting in demolding the product from the cavity.

[0008] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, a positioning plate is fixed to the inner end of the core-pulling seat by bolts. The positioning plate has a first stepped hole with its stepped surface facing away from the cavity. The main core body passes through the first stepped hole, with its outer end abutting against its stepped surface. The positioning plate presses the outer end of the main core body tightly against the core-pulling seat. Through the engagement of the first stepped hole on the positioning plate with the stepped surface of the main core body's outer end, the positioning plate presses the main core body firmly against the inner sidewall of the core-pulling seat, ensuring a secure connection between the main core body and the core-pulling seat. The stepped surface of the stepped hole is positioned facing away from the cavity, ensuring that when the main core body is subjected to outward tension during the core-pulling process, its outer stepped surface closely abuts against the stepped surface of the first stepped hole, ensuring that the main core body and the core-pulling seat move synchronously.

[0009] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, the main core includes a U-shaped fixed section and a long strip-shaped forming section. The fixed section is embedded in the first stepped hole and pressed against the core-pulling seat. The forming section passes through the first stepped hole and extends into the cavity. A through-hole is provided on the fixed section, and the secondary core passes through the through-hole and extends into the cavity, with the outer wall of the secondary core fitting against the outer wall of the forming section. The main core is engaged with the first stepped hole on the positioning plate using the fixed section. The fixed section is U-shaped, meaning its outer end has a protruding stepped surface. After being embedded in the first stepped hole, it is axially limited by the stepped surface, thereby achieving axial positioning of the main core on the core-pulling seat. The through hole on the fixed section allows the inner end of the sub-core to pass through, enabling the sub-core to pass through the main core and extend into the cavity. The outer wall of the inner end of the sub-core fits into the outer wall of the forming section, thus combining the main core and the sub-core into a complete core shape that matches the inner cavity shape of the bridge bend.

[0010] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, the core-pulling seat is equipped with a retaining rod, and a second stepped hole with a stepped surface facing the cavity is opened on the core-pulling seat along the core-pulling direction. The outer end of the sub-core extends into the second stepped hole and abuts against its stepped surface. A fixing plate is fixed to the outer end of the core-pulling seat, and a through-rod hole is opened on the fixing plate. One end of the retaining rod extends into the second stepped hole and abuts against the outer end of the sub-core, while the other end slides through the through-rod hole. A spring is sleeved on the retaining rod and elastically acts between the core-pulling seat and the retaining rod along the core-pulling direction. By setting the second stepped hole, the outer end of the sub-core passes through the second stepped hole and abuts against its stepped surface, ensuring the positioning of the sub-core in the initial state. One end of the retaining rod extends into the second step hole and abuts against the outer end of the sub-core, while the other end slides through the rod hole on the fixing plate. The retaining rod is double-limited by the hole wall of the second step hole and the hole wall of the rod hole, ensuring that the retaining rod can always act in the core-pulling direction when subjected to the elastic force of the spring, and accurately transmit the spring force to the outer end of the sub-core.

[0011] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, the middle part of the retaining rod has an outwardly protruding abutment along the circumferential direction. Both ends of the spring are respectively pressed against the fixing plate and the abutment. Specifically, the spring acts elastically between the fixing plate and the abutment in the middle of the retaining rod; one end of the spring is pressed against the fixing plate, and the other end is pressed against the abutment. Under the elastic action of the spring, the abutment is pushed outward, causing the retaining rod to move outward. The inner end of the retaining rod then pushes the sub-core towards the cavity, thus keeping the inner end of the sub-core extended into the cavity.

[0012] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, the transmission component is rod-shaped and fixed to the outer end sidewall of the secondary core facing away from the main core. The core-pulling seat has a notch along the mold opening direction that connects to the second step hole, and the notch extends along the core-pulling direction. The transmission component slides through the notch. During the process of the core-pulling seat sliding outward under the drive of an external driving source, pulling out the main core, the transmission component, along with the secondary core, is held in place by a spring, and simultaneously slides relative to the core-pulling seat from one end of the notch to the other. When the core-pulling seat has completely pulled the main core out of the cavity, the transmission component slides to and contacts the inner wall of the other end of the notch. At this point, as the core-pulling seat continues to slide outward, the transmission component is pushed outward by the inner wall of the notch, causing the secondary core to overcome the elastic force of the spring and move outward, thus realizing the core-pulling of the secondary core. Through the cooperation of the notch and the transmission component, only one set of driving sources is needed to achieve the sequential core-pulling of the main core and the secondary core, resulting in a compact structure and precise control.

[0013] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, the notch is U-shaped and penetrates the inner end face of the core-pulling seat. The U-shaped notch penetrating the inner end face of the core-pulling seat ensures that the transmission component can slide freely within the notch along the core-pulling direction while minimizing the machining difficulty of the mold. Simultaneously, because the notch penetrates the inner end face of the core-pulling seat, the positioning plate can move outwards along with the core-pulling seat when it slides outwards. When the transmission component slides to the end of the notch, the positioning plate can abut against the transmission component and apply a pushing force, thereby ensuring that the transmission component is reliably pulled outwards, driving the secondary core to complete the core-pulling process.

[0014] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, a snap-fit ​​hole is provided on the side wall of the secondary core, and the transmission component snaps into the snap-fit ​​hole. The transmission component is fixed to the side wall of the secondary core by snap-fit ​​and is detachable from the secondary core. When the transmission component wears out during long-term use, only the transmission component needs to be replaced, without replacing the entire secondary core, which facilitates maintenance and reduces operating costs. At the same time, the snap-fit ​​structure also facilitates the quick assembly of the transmission component.

[0015] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, a guide groove is formed along the length direction on the side wall of the forming section, and a guide block is formed along the length direction on the side wall of the secondary core. The guide block is slidably connected in the guide groove. Through the cooperation of the guide block and the guide groove, it is ensured that the main core and the secondary core remain in close contact during the assembly state and the core-pulling process. The guide block slides along the guide groove, guiding and constraining the movement path of the secondary core, causing it to move along a predetermined trajectory during the core-pulling process, preventing the secondary core from skewing or deviating and affecting the core-pulling accuracy.

[0016] In the segmented core-pulling structure of the aforementioned bridge elbow pipe fitting, the guide groove is a wedge-shaped groove, and the guide block is a wedge-shaped block. By setting the guide groove and guide block as a mutually cooperating wedge structure (i.e., the cross-section of the guide groove is trapezoidal or dovetail-shaped, and the cross-section of the guide block is adapted to it), the wedge fit can constrain the degree of freedom of the secondary core in the direction perpendicular to the core-pulling process, preventing the secondary core from detaching from the main core during sliding, ensuring that the two always remain in a close fit, and improving the stability and reliability of the core-pulling process.

[0017] Compared with existing technologies, the segmented core-pulling structure of this bridge elbow pipe fitting has the following advantages:

[0018] 1. By splitting the core into a main core and a secondary core, and using a spring to keep the secondary core stationary during the initial core-pulling stage, the main core and secondary core are pulled out sequentially. The main core exits the cavity first to provide clearance for the secondary core, effectively avoiding severe interference between the core and the inner wall of the fitting during the core-pulling process, reducing the risk of fitting damage and cracking, and significantly reducing the scrap rate.

[0019] 2. The inner end of the secondary core is inclined to the side, facing away from the main core. When the secondary core is pulled out, the inclined surface can be used to push the formed tube. At the same time as the core is pulled out, it helps the product to be demolded from the cavity, achieving two goals at once.

[0020] 3. Through the cooperation of the notch and the transmission components, only one set of drive source is needed to complete the sequential core pulling of the main core and the secondary core. The structure is compact and the control is precise, which reduces the manufacturing cost and complexity of the mold.

[0021] 4. The wedge-shaped guide groove and the wedge-shaped guide block work together to guide and constrain the sub-core during the core pulling process, preventing the sub-core from deviating or detaching from the main core, thus ensuring the stability and accuracy of the core pulling process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the segmented core-pulling structure of the bridge elbow pipe fitting.

[0023] Figure 2This is a front view of the segmented core-pulling structure of this bridge elbow pipe fitting.

[0024] Figure 3 yes Figure 2 A sectional view taken along the AA direction.

[0025] Figure 4 This is a schematic diagram of the core-pulling seat.

[0026] Figure 5 This is a structural diagram of the positioning plate.

[0027] Figure 6 This is a schematic diagram of the retaining rod.

[0028] Figure 7 This is a structural diagram of the main core.

[0029] Figure 8 This is a schematic diagram of the sub-core structure.

[0030] In the picture,

[0031] 1. Mold base;

[0032] 2. Core puller; 21. Second step hole; 22. Notch;

[0033] 3. Main core; 31. Fixing section; 311. Through hole; 32. Forming section; 321. Guide groove;

[0034] 4. Sub-core; 41. Guide block; 42. Snap-fit ​​hole; 43. Demolding part;

[0035] 5. Holding rod; 51. Abutment part;

[0036] 6. Spring;

[0037] 7. Transmission components;

[0038] 8. Positioning plate; 81. First step hole;

[0039] 9. Fixing plate; 91. Through hole. Detailed Implementation

[0040] 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.

[0041] like Figure 1-3As shown, the segmented core-pulling structure of this bridge elbow pipe fitting mainly consists of a mold base 1, a core-pulling seat 2, a main core 3, a secondary core 4, a retaining rod 5, a spring 6, a transmission component 7, a positioning plate 8, and a fixing plate 9. The mold base 1 is the fixed part of the injection mold, and its interior forms a cavity for molding the bridge elbow pipe fitting. The core-pulling seat 2 is slidably connected to the mold base 1 along the core-pulling direction via a slide rail. An external drive source (such as a hydraulic cylinder or pneumatic cylinder) is connected to the core-pulling seat 2, driving the core-pulling seat 2 to slide back and forth along the core-pulling direction. In this embodiment, the external drive source is not shown in the figure. As prior art, its specific structure can be found in CN223573741U.

[0042] Combination Figure 4 The core-pulling seat 2 has a block-shaped structure. A second stepped hole 21 with a stepped surface facing the cavity is opened on the inner end (the end closest to the cavity). The second stepped hole 21 extends along the core-pulling direction. A notch 22 communicating with the second stepped hole 21 is also opened on the core-pulling seat 2. The notch 22 extends along the core-pulling direction and penetrates the inner end face of the core-pulling seat 2. The notch 22 is U-shaped.

[0043] A positioning plate 8 is fixed to the inner end of the core pull holder 2 by bolts. For example... Figure 3 As shown, the positioning plate 8 has a first stepped hole 81 with the stepped surface facing away from the cavity. The main core 3 passes through the first stepped hole 81, and its outer end abuts against the stepped surface of the first stepped hole 81. The positioning plate 8 presses the outer end of the main core 3 against the inner side wall of the core-pulling seat 2, thereby achieving a fixed connection between the main core 3 and the core-pulling seat 2.

[0044] Combination Figure 7 The main core 3 includes a U-shaped fixing section 31 and a long strip-shaped molding section 32. The fixing section 31 is embedded in the first stepped hole 81 and pressed against the core-pulling seat 2, while the molding section 32 passes through the first stepped hole 81 and extends into the cavity. A through core-pulling hole 311 is provided on the fixing section 31, extending along the core-pulling direction. A guide groove 321, which is a wedge-shaped groove, is provided on the side wall of the molding section 32 along its length.

[0045] Combination Figure 8 The secondary core 4 is elongated, with its inner end facing away from the main core 3 and inclined to the side to form a demolding section 43, used to form the curved inner cavity of the bridge elbow pipe fitting. A guide block 41 is provided along the length of the side wall of the secondary core 4. The cross-section of the guide block 41 is wedge-shaped and matches the guide groove 321 on the main core 3. A snap-fit ​​hole 42 is also provided on the side wall of the secondary core 4.

[0046] The secondary core 4 is inserted into the core-pulling seat 2, with its inner end passing through the core-through hole 311 on the fixing section 31 of the main core 3 and extending into the cavity. The outer wall of the secondary core 4 fits against the outer wall of the forming section 32 of the main core 3, and the two are joined together to form a complete core shape. A snap-fit ​​hole 42 is provided on the side wall of the outer end of the secondary core 4. The transmission component 7 is rod-shaped, with one end snapped and fixed in the snap-fit ​​hole 42, and the other end extending along the core-pulling direction and sliding through the notch 22 on the core-pulling seat 2.

[0047] Combination Figure 6 The retaining rod 5 is inserted into the core-pulling seat 2 and extends along the core-pulling direction. One end of the retaining rod 5 extends into the second step hole 21 and abuts against the outer end of the sub-core 4, while the other end slides through the rod hole 91 on the fixing plate 9. The fixing plate 9 is fixed to the outer end face of the core-pulling seat 2. The middle part of the retaining rod 5 has an outwardly protruding abutment part 51 along the circumferential direction. The spring 6 is sleeved on the outside of the retaining rod 5, with one end abutting against the fixing plate 9 and the other end abutting against the abutment part 51. The spring 6 elastically acts between the core-pulling seat 2 and the sub-core 4 along the core-pulling direction.

[0048] The complete working process of this segmented core-pulling structure for the bridge elbow pipe fitting is divided into the injection molding stage, the first core-pulling stage, and the second core-pulling stage:

[0049] Injection Molding Stage: After mold closing, the main core 3 and the secondary core 4 assemble to form a complete core that extends into the mold cavity. The elastic force of the spring 6 is transmitted to the outer end of the secondary core 4 through the retaining rod 5, keeping the inner end of the secondary core 4 extended into the mold cavity. Molten plastic is injected into the mold cavity, forming a bridge elbow fitting in the space between the mold cavity and the core. After cooling and solidification, the core-pulling operation begins.

[0050] The first stage of core pulling: An external drive source drives the core pulling seat 2 to slide outward along the core pulling direction. The core pulling seat 2 drives the positioning plate 8 and the main core 3 to slide outward together, with the main core 3 being pulled out of the cavity first. During this process, the secondary core 4 remains stationary under the elastic force of the spring 6, and the transmission component 7 remains in its original position with the secondary core 4, while sliding relative to the core pulling seat 2 from the inner end to the outer end of the notch 22. When the core pulling seat 2 drives the main core 3 to completely exit the cavity, the first stage of core pulling is completed.

[0051] The second stage of core pulling: The core pulling seat 2 continues to slide outward, and the transmission component 7 slides to the outer end of the notch 22 and abuts against the side wall of the positioning plate 8. The transmission component 7 is pushed outward by the side wall of the positioning plate 8, and the transmission component 7 drives the secondary core 4 to slide outward against the elastic force of the spring 6. The inner end of the secondary core 4 is pulled out of the cavity. Since the main core 3 has now been removed from the cavity, the tube has gained greater freedom in the mold opening direction. During the extraction process, the demolding part 43 of the secondary core 4 pushes the formed tube along the mold opening direction, assisting the product in demolding from the cavity while completing the core pulling of the secondary core 4. When the secondary core 4 is completely removed from the cavity, the second stage of core pulling is completed, and the entire core pulling process ends.

[0052] During the core-pulling process, the guide groove 321 on the main core 3 and the guide block 41 on the secondary core 4 always maintain a sliding fit to guide the movement path of the secondary core 4. The wedge structure ensures that the secondary core 4 will not detach from the main core 3 during the sliding process, thus ensuring the stability and accuracy of the core-pulling process.

[0053] 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.

[0054] Although this document frequently uses terms such as mold base 1, core-pulling base 2, second step hole 21, notch 22, main core 3, fixing section 31, through hole 311, forming section 32, guide groove 321, secondary core 4, guide block 41, snap-fit ​​hole 42, demolding part 43, retaining rod 5, abutment part 51, spring 6, transmission component 7, positioning plate 8, first step hole 81, fixing plate 9, and through hole 91, 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.

Claims

1. A segmented core-pulling structure for a bridge elbow pipe fitting, comprising a mold base (1), wherein a core-pulling seat (2) is slidably connected to the mold base (1) along the core-pulling direction, characterized in that, The core-pulling seat (2) is provided with a main core (3) and a secondary core (4) extending into the mold cavity. The main core (3) is fixed on the core-pulling seat (2), and the secondary core (4) passes through the core-pulling seat (2). The core-pulling seat (2) is provided with a spring (6). The spring (6) acts elastically between the outer ends of the core-pulling seat (2) and the secondary core (4) along the core-pulling direction. Under the elastic action of the spring (6), the inner end of the secondary core (4) extends into the mold cavity. (2) It can move outward and pull the main core (3) out of the cavity. The secondary core (4) has a transmission member (7), and the inner end of the secondary core (4) is tilted to the side away from the main core (3) to form a demolding part (43). When the core-pulling seat (2) drives the main core (3) to slide out of the cavity, the core-pulling seat (2) can pull the secondary core (4) through the transmission member (7) so that the secondary core (4) overcomes the elastic force of the spring (6) and exits the cavity.

2. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 1, characterized in that, The inner end of the core-pulling seat (2) is fixed with a positioning plate (8) by bolts. The positioning plate (8) has a first step hole (81) with the stepped surface facing away from the cavity. The main core (3) passes through the first step hole (81) and its outer end abuts against its stepped surface. The positioning plate (8) presses the outer end of the main core (3) onto the core-pulling seat (2).

3. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 2, characterized in that, The main core (3) includes a fixed section (31) in the shape of a convex shape and a molding section (32) in the shape of a long strip. The fixed section (31) is embedded in the first stepped hole (81) and pressed on the core-pulling seat (2). The molding section (32) passes through the first stepped hole (81) and extends into the cavity. The fixed section (31) has a core-penetrating hole (311). The secondary core (4) passes through the core-penetrating hole (311) and extends into the cavity. The outer wall of the secondary core (4) is in contact with the outer wall of the molding section (32).

4. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 2 or 3, characterized in that, The core-pulling seat (2) is provided with a retaining rod (5). The core-pulling seat (2) is provided with a second stepped hole (21) with the stepped surface facing the cavity along the core-pulling direction. The outer end of the sub-core (4) extends into the second stepped hole (21) and abuts against its stepped surface. The outer end of the core-pulling seat (2) is fixed with a fixing plate (9), and the fixing plate (9) is provided with a rod-through hole (91). One end of the retaining rod (5) extends into the second stepped hole (21) and abuts against the outer end of the sub-core (4), and the other end slides through the rod-through hole (91). The spring (6) is sleeved on the retaining rod (5) and acts elastically between the core-pulling seat (2) and the retaining rod (5) along the core-pulling direction.

5. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 4, characterized in that, The middle part of the retaining rod (5) has an outwardly protruding abutment (51) along the circumferential direction, and the two ends of the spring (6) abut against the fixing plate (9) and the abutment (51) respectively.

6. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 5, characterized in that, The transmission component (7) is rod-shaped and fixed on the outer side wall of the secondary core (4) facing away from the main core (3). The core-pulling seat (2) has a notch (22) that connects to the second step hole (21) along the mold opening direction, and the notch (22) extends along the core-pulling direction. The transmission component (7) slides through the notch (22).

7. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 6, characterized in that, The notch (22) is U-shaped and extends through the inner end face of the core-pulling seat (2).

8. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 7, characterized in that, The secondary core (4) has a snap-fit ​​hole (42) on its side wall, and the transmission component (7) is snapped into the snap-fit ​​hole (42).

9. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 3, characterized in that, The sidewall of the forming section (32) is provided with a guide groove (321) along the length direction, and the sidewall of the sub-core (4) is provided with a guide block (41) along the length direction. The guide block (41) is slidably connected in the guide groove (321).

10. The segmented core-pulling structure of the bridge elbow pipe fitting according to claim 9, characterized in that, The guide groove (321) is a wedge-shaped groove, and the guide block (41) is a wedge-shaped block.

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