Demolding structure of rubber expansion joint for special pipeline

Abstract

The utility model discloses a demoulding structure of a rubber expansion joint for a special pipeline, which comprises an upper mould cavity, a middle mould cavity, a lower mould cavity and a cavity core, the middle mould cavity is provided with a hollow forming frame, the demoulding structure is characterized in that the cavity core consists of an upper cavity core and a lower cavity core which can be separated along the axial direction, the upper cavity core is connected to the bottom of the upper mould cavity through a guide sliding structure I, and the lower cavity core is connected to the bottom of the lower mould cavity through a guide sliding structure II; the upper cavity core can axially translate up and down through a guide sliding structure I, the lower cavity core is connected to the top of the lower die cavity through a guide sliding structure II, the lower cavity core can axially translate up and down through the guide sliding structure II, and a positioning structure is arranged between the upper cavity core and the lower cavity core. The rubber expansion joint demolding device solves the problems that in the prior art, automatic demolding of a rubber expansion joint for a special pipeline is difficult to achieve, especially automatic demolding of the rubber expansion joint for the special pipeline with chamfering structures arranged on the upper outer edge and the lower outer edge of the inner wall cannot be achieved, working efficiency is low, and large-batch production and manufacturing cannot be achieved. The device has the characteristics of low cost, simple structure and easiness in maintenance.

Description

TECHNICAL FIELD

[0001] The utility model relates to rubber mould pressing vulcanization technical field especially relates to a special pipeline rubber expansion joint's stripping structure. BACKGROUND

[0002] The rubber expansion joint is the soft connector that pump, valve, pipeline equipment and pipeline connect, has high compression resistance, good ductility, big deflection, equalizes pipeline error, absorbs kinetic energy, reduces noise effect is good, installation is convenient and so on, it is widely applied in the pipeline accessory field.

[0003] The rubber expansion joint mainly adopts the rubber mould pressing vulcanization method to produce, that is, the rubber material is placed in the mold made in advance, and a method of vulcanization forming under high temperature and high pressure, different molds can quickly complete the mass production of different rubber expansion joints.

[0004] A stripping device is disclosed in patent document CN101648420A, which comprises a stripping frame, a stripping cover plate, a mold core lifting rod, an outer mold lifting rod and a stripping drive device. The stripping drive device can drive the mold core lifting rod and the outer mold lifting rod to reciprocate up and down. The cover plate is provided with a mold core through hole with a size larger than the outer diameter of the mold core and smaller than the inner diameter of the outer mold. The stripping frame is arranged on the transversely extending part in the same sliding direction as the mold moving base and the mold moving drag plate. The mold moving base and the stripping frame are both provided with passages for the mold core lifting rod and the outer mold lifting rod to reciprocate up and down. The mold moving drag plate is provided with a mold core lifting rod hole and an outer mold lifting rod hole corresponding to the mold core lifting rod and the outer mold lifting rod respectively. During stripping, the mold and the mold moving drag plate are located between the stripping frame and the stripping cover plate. The stripping drive device drives the mold core lifting rod and the outer mold lifting rod to pass through the stripping frame, the mold moving base and the mold moving drag plate in turn, and then pushes against the mold core and the lower end of the outer mold respectively. The upper end of the mold core lifting rod is higher than the upper end surface of the outer mold lifting rod, and the stripping drive device is controlled by an automatic control system. As described in the patent document, the existing stripping method uses the top stripping method, which first pushes out the mold core and then pushes out the outer mold. The outer mold and the inner mold core move relative to each other, which forms a reverse friction force on the inner and outer edges of the product during this process, thereby pulling the product out of the outer mold and the mold core.

[0005] However, with the wide application of rubber expansion joints in special pipelines, the inner wall shape of such special pipeline rubber expansion joints becomes more and more complex. When the product is pulled out by the top stripping method, the friction force between the complex inner surface and the cavity core is large, and the friction force generated by pulling out cannot guarantee that the product is separated from the cavity core, making it difficult to complete stripping smoothly. Especially when the upper and lower inner edges of the rubber expansion joint are provided with chamfer structures, most of the products are still completely covered on the cavity core after stripping, and the products cannot be effectively separated. Therefore, the existing technology cannot complete the automatic stripping of such special pipeline rubber expansion joints, and the work efficiency is low, and mass production cannot be carried out. UTILITY MODEL CONTENT

[0006] The utility model discloses a special pipeline rubber expansion joint's stripping structure, solved the automatic stripping of special pipeline rubber expansion joint in prior art, especially the automatic stripping of special pipeline rubber expansion joint that the inner wall upper and lower outer edge all is provided with chamfer structure, and the problem of low work efficiency, unable to carry out mass production is made.

[0007] In order to realize the above object, the utility model provides the following technical scheme:

[0008] A special pipeline rubber expansion joint's stripping structure, including upper die cavity, middle die cavity, lower die cavity and cavity core, the hollow forming frame is equipped in middle die cavity, the cavity core is composed of the upper cavity core and lower cavity core that can be separated along the axial direction, the upper cavity core is connected in the upper die cavity bottom through guiding sliding structure one, the upper cavity core can be axially up and down translation through guiding sliding structure one, the lower cavity core is connected in the lower die cavity top through guiding sliding structure two, the lower cavity core can be axially up and down translation through guiding sliding structure two, and the positioning structure is arranged between the upper cavity core and the lower cavity core.

[0009] Further, guiding sliding structure one is composed of a plurality of through holes one and guiding tension rod one located in through hole one, through hole one is arranged on the upper cavity core and is distributed along the axial symmetry, and limiting ring one is arranged at the upper surface of the upper cavity core; guiding tension rod one is detachably fixedly connected to the bottom of the upper die cavity, the top end of guiding tension rod one is provided with a limiting block one, the outer diameter of the limiting block one is same with the inner diameter of the through hole one, and the limiting block one can slide axially along the inner wall of the through hole one.

[0010] Guiding sliding structure two is composed of a plurality of through holes two and guiding tension rod two located in through hole two, and through hole two is arranged on the lower cavity core and is distributed along the axial symmetry, and limiting ring two is arranged at the lower surface of the lower cavity core; guiding tension rod two is detachably fixedly connected to the top of the lower die cavity, the top end of guiding tension rod two is provided with a limiting block two, the outer diameter of the limiting block two is same with the inner diameter of the through hole two, and the limiting block two can slide axially along the inner wall of the through hole two.

[0011] Further, the through hole one is 2, the through hole two is 2, and the through hole one and the through hole two are distributed along the axial symmetry. This structure is simple and has good guiding stability.

[0012] Further, the upper cavity core is also provided with through hole three, the through hole three is coaxial and has the same aperture with the through hole two, when the upper cavity core and the lower cavity core are in the closed state, guiding tension rod two is located in the through hole two and the through hole three, and the limiting block two can slide axially along the inner wall of the through hole two and the through hole three. This structure uses guiding tension rod two to improve the guiding stability of the upper cavity core, which helps the accurate positioning of the upper cavity core and the lower cavity core in the clamping process, and the structure is simple.

[0013] Further, the lower surface of the upper die cavity is provided with a limiting hole two, the limiting hole two is in one-to-one correspondence with the through hole three in position and coaxial and has the same aperture, when in the die closing state, the limiting block two at the top end of the guide tension rod two is located in the limiting hole two. This structure helps the accurate positioning between the upper die cavity, the upper cavity core, the lower cavity core and the lower die cavity during the die closing process.

[0014] Further, the closing surface of the upper cavity core and the lower cavity core is located at the minimum inner diameter of the cavity core, which is beneficial to the separation of the cavity core from the product.

[0015] Further, the length ratio of the upper cavity core and the lower cavity core along the axial direction is 2:1, which is beneficial to the effective demolding of the product.

[0016] Further, the upper surface of the lower cavity core is provided with a limiting hole one, the limiting hole one is in one-to-one correspondence with the through hole one in position and coaxial and has the same aperture, when in the die closing state, the limiting block one at the top end of the guide tension rod one is located in the limiting hole one. It is helpful to accurately position the upper die cavity, the upper cavity core and the lower cavity core during the die closing process.

[0017] Further, the positioning structure includes an inner recess and an outer convex part, the inner recess is arranged at the bottom of the upper cavity core, and the outer convex part is arranged at the top of the lower cavity core, when the upper cavity core and the lower cavity core are closed, the inner recess and the outer convex part are closed, this structure is simple and has good positioning effect.

[0018] Compared with the prior art, the beneficial effects of the utility model are:

[0019] 1. The cavity core is divided into two parts of the upper cavity core and the lower cavity core which can be separated axially, so that the structure of the product inner edge upper and lower chamfer covered on the same cavity core is divided into two automatic demolding structures of the product inner edge upper chamfer covered on the upper cavity core and the product inner edge lower chamfer covered on the lower cavity core, and two-section demolding operation is adopted, so that the product is effectively separated from the mold, and the problem that the rubber expansion joint product cannot be automatically demolded when the upper and lower inner edges of the product are provided with chamfer structures is solved.

[0020] 2. The guide sliding structure one and the guide sliding structure two are used for guiding, so that the upper cavity core and the lower cavity core move up and down along the defined axial path stably, avoiding the influence of accidental stress such as shaking or deviation caused by movement on the product demolding operation, and ensuring the effective demolding of the product.

[0021] 3. The guide tension rod one and the guide tension rod two are detachably fixed and connected, which is beneficial to quickly adapt to the mold pressing vulcanization operation of different products by replacing the cavity core, and has the characteristics of low cost, simple structure and easy maintenance.

[0022] 4、Adopt the positioning structure, the through hole one, the through hole two, the through hole three along the axial symmetry arrangement, the limit block one and the limit hole one, the limit block two and the limit hole two and so on structure carry out multiple positioning, ensure in the repeated operation process of the mold clamping demolding, always accurate positioning between each structure. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and serve to explain the present application, and do not constitute a limitation of the present application.

[0024] In the drawings:

[0025] Figure 1 It is a kind of special pipeline rubber expansion joint demolding structure in the mold clamping state under the front view;

[0026] Figure 2 It is a kind of special pipeline rubber expansion joint demolding structure in the mold clamping state under the front view;

[0027] Figure 3 It is a kind of special pipeline rubber expansion joint demolding structure in the mold clamping state under the front view;

[0028] Figure 4 It is a kind of special pipeline rubber expansion joint demolding structure in the mold clamping state under the front view;

[0029] Figure 5 It is the enlarged schematic diagram of A point;

[0030] Figure 6 It is Figure 5 Structure split schematic diagram;

[0031] Figure 7 It is Figure 5 The bottom view schematic diagram of;

[0032] Figure 8 It is Figure 7 Structure split schematic diagram.

[0033] Figure mark annotation:

[0034] 1, upper die cavity;2, middle die cavity;3, lower die cavity;4, cavity core;5, guide sliding structure one;6, guide sliding structure two;11, limit hole two;21, forming frame;41, upper cavity core;411, through hole one;412, limit ring one;413, through hole three;42, lower cavity core;421, through hole two;422, limit ring two;423, limit hole one;43, positioning structure;431, inner recess;432, outer convex part;51, guide tension rod one;52, limit block one;61, guide tension rod two;62, limit block two; DETAILED DESCRIPTION

[0035] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, like reference numerals refer to like elements throughout the description. The following exemplary embodiments are not representative of all embodiments consistent with the present disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present embodiments as detailed in the appended claims.

[0036] It should be noted that all directional directions (such as up, down, left, right, front, back, etc.) in the embodiments are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional directions also change accordingly.

[0037] In addition, the description such as "first", "second" and the like in the embodiments is only for the purpose of description, and is not intended to specifically indicate the order or sequence, nor to limit the present application. It is merely to distinguish components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0038] It should be noted that the structure of mold locking, material injection, heating and the like in the mold is related to the existing technology of mold pressing vulcanization process, and the drawings and technical description in the specification are not marked and described in detail.

[0039] In order to further understand the content, characteristics and effects of the present application, the following embodiments are listed and described in detail as follows in conjunction with the drawings:

[0040] As shown in a special rubber expansion joint for pipeline demolding structure, there are 4 sets of demolding structure, which can produce 4 products at a time. Figures 1 to 4

[0041] As shown in a special rubber expansion joint for pipeline demolding structure, there are 4 sets of demolding structure, which can produce 4 products at a time. Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 ​As shown in the drawing, a special rubber expansion joint for pipeline demolding structure, including the upper die cavity 1, the middle die cavity 2, the lower die cavity 3 and the cavity core 4, the middle die cavity 2 is provided with a hollow forming frame 21, the cavity core 4 is composed of an upper cavity core 41 and a lower cavity core 42 which can be separated along the axial direction, the upper cavity core 41 is connected to the bottom of the upper die cavity 1 through the guiding sliding structure 5, the upper cavity core 41 can be translated up and down along the axial direction through the guiding sliding structure 5, the lower cavity core 42 is connected to the top of the lower die cavity 3 through the guiding sliding structure 6, the lower cavity core 42 can be translated up and down along the axial direction through the guiding sliding structure 6, and the positioning structure 43 is arranged between the upper cavity core 41 and the lower cavity core 42.

[0042] As shown in the drawing, Figure 5 , Figure 6 , Figure 7 , Figure 8 As shown in the drawing, the guiding sliding structure 5 is composed of two through holes 411 and guiding tension rods 51 located in the through holes 411; the two through holes 411 are arranged on the upper cavity core 41 and symmetrically distributed along the axial center, the through holes 411 are provided with limiting rings 412 at the upper surface of the upper cavity core 41; the two guiding tension rods 51 are detachably fixedly connected to the bottom of the upper die cavity 1, the guiding tension rods 51 are provided with limiting blocks 52 at the top ends, the outer diameter of the limiting blocks 52 is the same as the inner diameter of the through holes 411, and the limiting blocks 52 can be axially slid along the inner wall of the through holes 411. That is, this structure makes the upper cavity core 41 be able to translate up and down along the axial direction of the guiding tension rods 51 between the bottom of the upper die cavity 1 and the limiting blocks 52.

[0043] The guiding sliding structure 6 is composed of two through holes 421 and guiding tension rods 61 located in the through holes 421; the two through holes 421 are arranged on the lower cavity core 42 and symmetrically distributed along the axial center, the through holes 421 are provided with limiting rings 422 at the lower surface of the lower cavity core 42; the two guiding tension rods 61 are detachably fixedly connected to the top of the lower die cavity 3, the guiding tension rods 61 are provided with limiting blocks 62 at the top ends, the outer diameter of the limiting blocks 62 is the same as the inner diameter of the through holes 421, and the limiting blocks 62 can be axially slid along the inner wall of the through holes 421. That is, this structure makes the lower cavity core 42 be able to translate up and down along the axial direction of the guiding tension rods 61 between the top of the lower die cavity 3 and the limiting blocks 62.

[0044] As shown in the drawing, Figure 5 The two through holes 411 and the two through holes 421 are symmetrically distributed along the axial center.

[0045] As shown in the drawing, Figure 5 , Figure 6As shown in the drawings, the upper cavity core 41 is also provided with a through hole three 413, which is coaxial and has the same aperture as the through hole two 421, that is, the through hole one 411 and the through hole three 413 are also symmetrically distributed along the axis on the upper cavity core 41, and when the upper cavity core 41 and the lower cavity core 42 are in the closed state, the guide tension rod two 6 is located in the through hole two 421 and the through hole three 413, and the limiting block two 62 can axially slide along the inner wall of the through hole two 421 and the through hole three 413.

[0046] As shown in the drawings, Figure 3 , Figure 5 , Figure 6 As shown in the drawings, the lower surface of the upper die cavity 1 is provided with a limiting hole two 11, which is coaxial and has the same aperture as the through hole three 413, and when in the closed state, the guide tension rod two 61 is located in the through hole two 421 and the through hole three 413, and the limiting block two 62 at the top of the guide tension rod two 61 is located in the limiting hole two 11.

[0047] As shown in the drawings, Figure 5 , Figure 6 , Figure 8 As shown in the drawings, the upper surface of the lower cavity core 42 is provided with a limiting hole one 423, which is coaxial and has the same aperture as the through hole one 411, and when in the closed state, the limiting block one 52 at the top of the guide tension rod one 51 is located in the limiting hole one 423.

[0048] As shown in the drawings, Figure 3 The closed surface of the upper cavity core 41 and the lower cavity core 42 is located at the smallest inner diameter of the cavity core 4.

[0049] The length ratio of the upper cavity core 41 and the lower cavity core 42 along the axial direction is 2:1.

[0050] As shown in the drawings, Figure 3 , Figure 6 and Figure 8 The positioning structure 43 is composed of an inner recess 431 at the bottom of the upper cavity core 41 and an outer protrusion 432 at the top of the lower cavity core 42.

[0051] The working principle of the utility model is as follows:

[0052] 1, the initial state before demolding: in this state, the product has completed the mold pressing vulcanization forming process, the upper die cavity 1, the middle die cavity 2 and the lower die cavity 3 are in the closed state, the cavity core 4 is located in the forming frame 21, the product is located between the forming frame 21 and the cavity core 4, and the product and the upper die cavity 1, the middle die cavity 2, the lower die cavity 3, the cavity core 4 and other structures are in airtight and gapless close contact state.

[0053] 2, the first demolding process: after the initial state before demolding, the driving device on the vulcanizing machine pushes the upper die cavity 1 upward.

[0054] The guiding tension rod one 51 moves upward with the upper mold cavity 1, and the upper mold cavity 1 is separated from the middle mold cavity 2.

[0055] When the limiting block one 52 reaches the position of the limiting ring one 412, the limiting block one 52 pulls the upper cavity core 41 out of the forming frame 21 of the middle mold cavity 2, and the upper part of the product is wrapped on the upper cavity core 41 and is pulled out of the forming frame 21, at this time, the lower cavity core 42 is also pulled to move upward.

[0056] When the lower cavity core 42 moves upward along the guiding tension rod two 61, the limiting block two 62 reaches the position of the limiting ring two 422, the lower cavity core 42 no longer moves upward, at this time, the lower end of the product is limited in the forming frame 21 by the lower cavity core 42 and the forming frame 21, when the upper cavity core 41 continues to move upward along the guiding tension rod one 51, the upper end of the product continues to be pulled out of the forming frame 21, the formed elastic force makes the product separate from the upper cavity core 41, and the product falls into the forming frame 21, realizing the automatic separation of the product from the upper cavity core 41.

[0057] 3, the second demolding process: after the first demolding process, the driving device on the vulcanizing machine pushes the middle mold cavity 2 to move upward.

[0058] The middle mold cavity 2 is separated from the lower mold cavity 3, when the middle mold cavity 2 continues to move upward after passing the contact position of the limiting block two 62 and the limiting ring two 422, the product is pulled out from below the forming frame 21 along with the lower cavity core 42, at this time, the product part attached to the lower cavity core 42 after being pulled out of the forming frame 21, the product part tightly limited by the lower cavity core 42 in the forming frame 21, and the product part in a relaxed state with the upper end separated from the upper cavity core 41, the three parts produce different tensile elastic deformations, when the middle mold cavity 2 moves upward to the moment when the upper cavity core 41 completely separates from the forming frame 21, the rebound force applied to the product makes the product quickly separate from the upper cavity core 41 and fall on the lower end of the guiding tension rod two 61 or the lower mold cavity 3, at this time, the product can be conveniently taken down manually, and the automatic demolding of the product is completed.

[0059] 4, the clamping process: after the second demolding process, the driving device on the vulcanizing machine first pushes the middle mold cavity 2 to descend and fall back onto the lower mold cavity 3, at this time, the lower cavity core 42 is located in the forming frame 21.

[0060] The driving device on the vulcanizing machine then pushes the upper mold cavity 1 to descend and fall back onto the middle mold cavity, the upper mold cavity 1 drives the upper cavity core 41 and the guiding tension rod one 51 to descend, in the process of descending:

[0061] The upper cavity core 41 returns to the forming frame 21 with the descent of the upper mold cavity 1, the guiding tension rod two 61 enters the through hole three 413 from the bottom of the upper cavity core 41, guiding the upper cavity core 41 to descend more stably and accurately onto the lower cavity core 42, the positioning structure 43 makes the upper cavity core 41 and the lower cavity core 42 accurately positioned, and the upper cavity core 41 and the lower cavity core 42 return to the closed state.

[0062] With the upper die cavity 1 continues to drop, the guide tension rod one 51 continues to slide in the through hole one 411, until the limiting block 52 reaches the positioning hole one 423 on the top of the lower cavity core 42; the guide tension rod two 61 slides in the through hole three 413, until the top limiting block two 62 reaches the positioning hole two 11 on the bottom of the upper die cavity 1, by which the upper die cavity 1 falls on the middle die cavity 2, the upper die cavity 1, the middle die cavity 2, the lower die cavity 3 complete the closure. The product forming space formed by the lower surface of the upper die cavity 1, the inner surface of the forming frame 21, the upper surface of the lower die cavity 3 and the outer surface of the cavity core 4 is in a closed state, completing the entire mold closing process.

[0063] After that, the mold can be pushed into the vulcanizing machine again for production operation.

[0064] In this embodiment, multiple positioning designs such as the positioning device 43, the limiting hole one 423, the limiting hole two 11 are adopted, which ensures that the positions between the upper die cavity 1, the middle die cavity 2, the lower die cavity 3, the cavity core 4 and other structures can be accurately positioned after repeated mold opening and closing operations, and ensures that the product forming space in the mold pressing vulcanization process is in the correct closed state.

[0065] Finally, it should be noted that: the above disclosure is only the preferred embodiment of the utility model, and is not used to limit the utility model, although the utility model is described in detail with reference to the foregoing embodiments, for those skilled in the art, it still can modify the technical scheme recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model. The scope of the present application is only limited by the appended claims.

Claims

1. A demolding structure for a special rubber expansion joint for pipelines, comprising an upper mold cavity (1), a middle mold cavity (2), a lower mold cavity (3), and a core (4), wherein the middle mold cavity (2) is provided with a hollow forming frame (21), characterized in that: The cavity core (4) is composed of an axially separable upper cavity core (41) and a lower cavity core (42). The upper cavity core (41) is connected to the bottom of the upper mold cavity (1) through a guide sliding structure (5). The upper cavity core (41) can be axially moved up and down through the guide sliding structure (5). The lower cavity core (42) is connected to the top of the lower mold cavity (3) through a guide sliding structure (6). The lower cavity core (42) can be axially moved up and down through the guide sliding structure (6). A positioning structure (43) is provided between the upper cavity core (41) and the lower cavity core (42).

2. The demolding structure of a special rubber expansion joint for pipelines according to claim 1, characterized in that: The guide sliding structure (5) consists of several through holes (411) and a guide tension rod (51) located in the through holes (411); the through holes (411) are provided on the upper cavity core (41) and symmetrically distributed along the axis, and a limit ring (412) is provided on the upper surface of the upper cavity core (41) of the through holes (411); the guide tension rod (51) is detachably fixed to the bottom of the upper mold cavity (1), and a limit block (52) is provided at the top of the guide tension rod (51). The outer diameter of the limit block (52) is the same as the inner diameter of the through hole (411), and the limit block (52) can slide axially along the inner wall of the through hole (411); The second guide sliding structure (6) consists of several through holes (421) and a second guide pull rod (61) located in the through holes (421); the through holes (421) are arranged on the lower cavity core (42) and symmetrically distributed along the axis, and the through holes (421) are provided with a limit ring (422) on the lower surface of the lower cavity core (42); the second guide pull rod (61) is detachably fixed to the top of the lower mold cavity (3), and the top of the second guide pull rod (61) is provided with a limit block (62), the outer diameter of the limit block (62) is the same as the inner diameter of the through hole (421), and the limit block (62) can slide axially along the inner wall of the through hole (421).

3. The demolding structure of a special rubber expansion joint for pipelines according to claim 2, characterized in that: There are two through holes (411) and two through holes (421), and the through holes (411) and the through holes (421) are symmetrically distributed along the axis.

4. The demolding structure of a special rubber expansion joint for pipelines according to claim 2 or 3, characterized in that: The upper cavity core (41) is also provided with a through hole three (413), which is a through hole that corresponds one-to-one with the position of the through hole two (421) and is coaxial with the same diameter. When the upper cavity core (41) and the lower cavity core (42) are in a closed state, the guide pull rod two (61) is located in the through hole two (421) and the through hole three (413), and the limiting block two (62) can slide axially along the inner wall of the through hole two (421) and the through hole three (413).

5. The demolding structure of a special rubber expansion joint for pipelines according to claim 4, characterized in that: The lower surface of the upper mold cavity (1) is provided with a limiting hole two (11). The limiting hole two (11) and the through hole three (413) are in one-to-one correspondence and are coaxial with the same diameter. When the mold is closed, the limiting block two (62) at the top of the guide pull rod two (61) is located in the limiting hole two (11).

6. The demolding structure of a special rubber expansion joint for pipelines according to claim 1, 2, or 3, characterized in that: The closed surface of the upper cavity core (41) and the lower cavity core (42) is located at the minimum inner diameter of the cavity core (4).

7. The demolding structure of a special rubber expansion joint for pipelines according to claim 1, 2, or 3, characterized in that: The length ratio of the upper cavity core (41) and the lower cavity core (42) along the axial direction is 2:

1.

8. The demolding structure of a special rubber expansion joint for pipelines according to claim 2 or 3, characterized in that: The upper surface of the lower cavity core (42) is provided with a limiting hole (423). The limiting hole (423) and the through hole (411) are in a one-to-one correspondence and are coaxial with the same diameter. When the mold is closed, the limiting block (52) at the top of the guide tension rod (51) is located in the limiting hole (423).

9. The demolding structure of a special rubber expansion joint for pipelines according to claim 1 or 2, characterized in that: The positioning structure (43) includes an inner recess (431) at the bottom of the upper cavity core (41) and an outer protrusion (432) at the top of the lower cavity core (42).

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