A pipe bending die

Abstract

The application provides a bent pipe mold and belongs to the technical field of molds. The bent pipe mold can improve the yield of the bent pipe. The bent pipe mold comprises a body, a feeding channel and a core arranged in the vertical direction are arranged in the body, a mold cavity is formed between the body and the core, a plurality of flow channels in the form of rings are arranged around the core and are arranged in the circumferential direction below the mold cavity in the body, the plurality of flow channels are arranged at intervals along the length direction of the mold cavity, a material passing groove is arranged between every two adjacent flow channels in the body, every two adjacent flow channels are communicated through the material passing groove, the lowermost flow channel is communicated with the feeding channel, and the uppermost flow channel is communicated with the lower end of the mold cavity.

Description

Technical Field

[0001] This invention belongs to the field of mold technology and relates to a pipe bending mold. Background Technology

[0002] Pipe bends, also known as pipe joints, are a very important part of modern piping systems. They serve to connect two pipes and change the pipe path.

[0003] As disclosed in Chinese Patent (Authorization Announcement No.: CN205270765U), a casting mold for a 90° elbow of a large-diameter ductile iron pipe has a mold base plate. On the mold base plate, there are two symmetrically arranged half molds. The structure of each half mold is the same as that of half of the 90° elbow pipe and they are assembled into a semi-circular structure. Each half mold has a built-in sand core and joint blocks spliced ​​at both ends of the half mold. Both spliced ​​and non-spliced ​​ends of the two half molds are provided with core heads of matching joint blocks. Each half mold, together with the corresponding sand core, joint block and core head, forms a casting cavity. The joint block at the non-spliced ​​end of each half mold has a direct sprue that connects to the corresponding casting cavity.

[0004] Combined with appendix Figure 1 It is known that the injection molding process for the bent pipe is achieved through the direct sprue 5. However, in actual production, this injection molding method has significant defects. Specifically, liquid polyethylene, as the raw material, has relatively unstable fluidity. Coupled with interference from factors such as the pressure inside the mold cavity, it is impossible to guarantee that the raw material will fill the mold cavity during the injection molding process. This results in defects such as uneven wall thickness, uneven surface pits, and excessive non-roundness of the molded bent pipe joint. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a pipe bending mold. The technical problem this invention aims to solve is: how to improve the yield of bent pipes.

[0006] The objective of this invention can be achieved through the following technical solution: A pipe bending mold, comprising a body, wherein the body has a feeding channel and a core arranged vertically, and a cavity is formed between the body and the core, characterized in that a plurality of annular flow channels are provided circumferentially below the cavity in the body and surrounding the core, and the plurality of flow channels are spaced apart along the length direction of the cavity, a material passage groove is provided between every two adjacent flow channels in the body, and every two adjacent flow channels are connected through the material passage groove, the lowermost flow channel is connected to the feeding channel, and the uppermost flow channel is connected to the lower end of the cavity.

[0007] The working principle of this pipe bending mold is as follows: liquid raw material is supplied to the mold from an external pipe through the feeding channel, and the raw material is fed into the flow channel through the feeding channel. During this process, because there are several flow channels arranged at intervals along the length of the cavity, the liquid raw material can be fed into each flow channel sequentially from bottom to top through the material passage between every two adjacent flow channels, and finally fed into the cavity circumferentially from the uppermost flow channel. Compared with existing technologies, the advantage of this pipe bending mold is that, through the arrangement of several flow channels and the cooperation of each material passage, the liquid raw material can flow from bottom to top into each flow channel sequentially, allowing the liquid raw material to... The impact force inherent in the material itself is fully released as it flows through each channel, ensuring that the liquid material is in a relatively stable state when it is finally output from the top channel and enters the cavity. At the same time, since the top channel is circumferentially connected to the bottom of the cavity, the liquid material is evenly distributed in the circumferential direction and completely fills the cavity from bottom to top. This effectively avoids unstable liquid material flow and many interference factors in the cavity, ensuring the saturation of liquid plastic injection in the cavity. This prevents defects such as uneven wall thickness, uneven surface pits, and excessive non-roundness in the processed bent tubes, effectively improving the yield of bent tube forming.

[0008] In the above-mentioned bending die, the flow channels are arranged sequentially from top to bottom as primary flow channels, secondary flow channels and tertiary flow channels. A transition channel connecting the primary flow channels and the feed channel is provided in the body. The number of material passages located between the primary flow channels and the secondary flow channels in the body is less than the number of material passages located between the secondary flow channels and the tertiary flow channels, and the material passages are arranged at intervals along the circumference of the cavity. Specifically, the flow channels formed in the body have at least three, namely a primary flow channel, a secondary flow channel, and a tertiary flow channel. In addition, due to the setting of the transition channel, the delivery of liquid raw materials between the feed channel and the primary flow channel can be ensured. Since the number of material passages between the primary flow channel and the secondary flow channel is less than the number of material passages between the secondary flow channel and the tertiary flow channel, the liquid raw materials can achieve the purpose of gradually reducing and stabilizing pressure when being delivered from the primary flow channel to the secondary flow channel and the tertiary flow channel. This ensures that the liquid raw materials output from the tertiary flow channel into the cavity can remain in a relatively stable state, ensuring the saturation of the liquid plastic injection in the cavity. This prevents defects such as uneven wall thickness, uneven surface pits, and excessive product roundness in the processed bent tubes, effectively improving the yield of bent tube forming.

[0009] In the aforementioned pipe bending mold, the main body has at least two material passages located between the primary flow channel and the secondary flow channel, and at least four material passages located between the secondary flow channel and the tertiary flow channel. The material passages located between the primary and secondary flow channels and between the secondary and tertiary flow channels are staggered. This arrangement prevents liquid raw materials from being directly fed into the tertiary flow channel via the material passages between the secondary and tertiary flow channels after entering the secondary flow channel from the primary flow channel. This effectively utilizes each flow channel, maximizes the release of internal pressure of the liquid raw material, and ensures the flow stability of the liquid raw material.

[0010] In the aforementioned pipe bending mold, the cross-sectional area of ​​each of the feed channels located between the primary and secondary flow channels and between the secondary and tertiary flow channels is the same. This ensures that the liquid raw material is adequately depressurized when it enters the secondary flow channel from the primary flow channel and from the secondary flow channel into the tertiary flow channel, thus ensuring a more stable flow of the liquid raw material.

[0011] In the aforementioned bending mold, the cavity has an inwardly protruding gate edge along the circumferential direction above the three-stage runner, and the width of the gate edge gradually decreases from the inner bend side to the outer bend side. This arrangement makes the gate formed above the three-stage runner eccentrically positioned relative to the centerline of the cavity. Specifically, the gate edge has a wider width corresponding to the inner bend and a smaller width corresponding to the outer bend. In other words, the space near the gate is smaller near the inner bend and larger near the outer bend. This arrangement alters the flow rate of the liquid material, causing the liquid material to flow into the inner bend more slowly and into the outer bend more quickly. This balances the injection time of the inner and outer bends during the injection process, effectively solving the problem of unequal injection times for the inner and outer bends during the injection process.

[0012] In the aforementioned bending die, the feed channel is bent close to the inner cavity, and the transition channel is curved in an arc shape. The feed channel's proximity to the inner cavity helps reduce heat loss from the liquid material, thus ensuring its fluidity. Simultaneously, the curved transition channel prevents the liquid material from impacting the inner wall of the transition channel during its transition from the feed channel to the primary flow channel, thus avoiding turbulence.

[0013] In the aforementioned bending die, the feed channel is elongated and vertically arranged. A feed hole is formed on the inner wall of the feed channel near its upper end, and the inlet end of the transition channel is located near the lower end of the feed channel. During the input process, the liquid raw material enters through the feed hole and impacts the inner wall of the upper end of the feed channel. Then, under the influence of gravity, it impacts the inner wall of the lower end of the feed channel. This achieves pre-buffering and pressure reduction of the liquid raw material before it enters the primary flow channel. Simultaneously, the impact during this process also allows air bubbles in the liquid raw material to be fully expelled within the feed channel.

[0014] In the aforementioned bending die, the inner walls at both ends of the feed channel are curved. This structure buffers the liquid material as it flows through the feed channel, preventing turbulence.

[0015] In the aforementioned pipe bending mold, a ring-shaped reinforcing groove is provided circumferentially at the upper end of the cavity. This creates a ring-shaped reinforcing edge at the upper end of the pipe formed in the cavity, preventing deformation due to thermal expansion and contraction after demolding and cooling, and thus preventing defects such as excessive out-of-roundness in the pipe.

[0016] In the aforementioned pipe bending mold, two auxiliary grooves are formed on the inner wall of the reinforcing groove, and the two auxiliary grooves are symmetrically arranged circumferentially along the reinforcing groove. The presence of the auxiliary grooves enables the re-forming of the protrusion structure on the outside of the reinforcing groove, ensuring that the ejector pin has a supporting position during the subsequent demolding process, and avoiding damage to the pipe during the ejection and demolding process.

[0017] Compared with existing technologies, this pipe bending mold has the following advantages:

[0018] 1. By setting up multiple flow channels and the material passage between each flow channel, the liquid raw material is fed into the feed channel and then gradually buffered and depressurized before filling the cavity from bottom to top, ensuring the saturation of the liquid plastic injection in the cavity and effectively improving the yield of bent tube forming.

[0019] 2. The material passages between the secondary and tertiary flow channels are more numerous and staggered than those between the primary and secondary flow channels. This maximizes the utilization of each flow channel, provides sufficient buffering for the liquid raw materials, and ensures the flow stability of the liquid raw materials.

[0020] 3. The gate edge is set eccentrically to ensure that the filling speed of liquid raw material in the inner and outer bends of the cavity is consistent. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this pipe bending mold.

[0022] Figure 2 This is a side view of the pipe bending mold.

[0023] Figure 3 yes Figure 2 A sectional view taken along the AA direction.

[0024] Figure 4 yes Figure 3 A magnified view of a section at point E in the middle.

[0025] Figure 5 yes Figure 2 A cross-sectional view of the mold cavity with the core removed after being cut along the AA direction.

[0026] Figure 6 yes Figure 2 A sectional view taken along the BB direction.

[0027] Figure 7 yes Figure 2 A sectional view taken along the CC direction.

[0028] Figure 8 yes Figure 2 A sectional view taken along the DD direction.

[0029] Figure 9 yes Figure 8 A magnified view of a section at point F.

[0030] In the diagram, 1. Body; 11. Feed channel; 111. Feed hole; 12. Cavity; 121. Reinforcing groove; 1211. Auxiliary groove; 13. Runner; 131. Primary runner; 132. Secondary runner; 133. Tertiary runner; 14. Material passage groove; 15. Transition channel; 16. Gate edge; 2. Core. Detailed Implementation

[0031] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0032] like Figure 1-2 As shown, this pipe bending mold includes a body 1, combined with... Figure 3 and Figure 5The main body 1 has a vertically arranged feed channel 11 and a cavity 12. The feed channel 11 is specifically located on one side of the cavity 12 and is curved close to the inside of the cavity 12. Several flow channels 13 are arranged at intervals along the length of the cavity 12 below the cavity 12 within the main body 1. These flow channels 13 are arranged from bottom to top as a primary flow channel 131, a secondary flow channel 132, and a tertiary flow channel 133. A transition channel 15 is provided within the main body 1, specifically located between the feed channel 11 and the primary flow channel 131. The feed channel 11 has a feed hole 111 on its inner wall near the upper end, communicating with an external pipe. The inlet end of the transition channel 15 penetrates the inner wall of the lower end of the feed channel 11, and the outlet end of the transition channel 15 penetrates a... The inner wall of the primary flow channel 131 is configured such that the transition channel 15 is curved in an arc shape. During the feeding process, the liquid raw material is input into the feed channel 11 through the feed hole 111. After entering the feed channel 11, the liquid raw material can first impact the inner wall of the upper end of the feed channel 11. Then, under the action of gravity, the liquid raw material impacts the inner wall of the lower end of the feed channel 11, thereby achieving pre-depressurization of the liquid raw material and the precipitation of internal bubbles. It is worth mentioning that both the upper and lower ends of the feed channel 11 are arc-shaped, thereby preventing turbulence when the liquid raw material impacts the inner wall of the end of the feed channel 11. Subsequently, the pre-depressurized liquid raw material is stably input into the primary flow channel 131 under the guidance of the transition channel 15.

[0033] Combination Figure 6 and Figure 7 At least two material passages 14 are provided between the primary flow channel 131 and the secondary flow channel 132 within the body 1, and at least four material passages 14 are provided between the secondary flow channel 132 and the tertiary flow channel 133. The primary flow channel 131 and the secondary flow channel 132, as well as the secondary flow channel 132 and the tertiary flow channel 133, are all connected by the material passages 14. Specifically, the two material passages 14 between the primary flow channel 131 and the secondary flow channel 132, and the four material passages 14 between the secondary flow channel 132 and the tertiary flow channel 133, are all along the circumference of the cavity 12. The two feed troughs 14 located between the primary flow channel 131 and the secondary flow channel 132 and the four feed troughs 14 located between the secondary flow channel 132 and the tertiary flow channel 133 are staggered. During the flow of liquid raw materials, the liquid raw materials enter the secondary flow channel 132 through the two feed troughs 14 located between the primary flow channel 131 and the secondary flow channel 132 to achieve initial pressure reduction, and then enter the tertiary flow channel 133 through the four feed troughs 14 located between the secondary flow channel 132 and the tertiary flow channel 133 to achieve secondary pressure reduction, thereby ensuring the flow stability of liquid raw materials.

[0034] Combination Figure 8 and Figure 9The body 1 has a ring-shaped gate edge 16 at the lower end of the cavity 12, which is located directly above the three-stage runner 133 and forms a gate that is circumferentially connected to the three-stage runner 133 at the lower end of the cavity 12. In addition, the width of the gate edge 16 gradually decreases from the side of the inner bend of the cavity 12 to the side of the outer bend of the cavity 12. That is to say, the gate formed at the lower end of the cavity 12 is eccentrically set relative to the center line of the cavity 12. This setting makes the gate gap at the inner bend smaller and the gate gap at the outer bend larger. When the liquid material transitions from the three-stage runner 133 into the cavity 12, the liquid material can be regarded as two parts. The liquid material corresponding to the inner bend of the cavity 12 flows slowly and the liquid material corresponding to the outer bend of the cavity 12 flows faster. This makes the overall filling speed of the cavity 12 consistent and avoids the problem of uneven outer wall thickness of the tube after molding.

[0035] Combination Figure 5 A ring-shaped reinforcing groove 121 is provided circumferentially at the upper end of the cavity 12, and two symmetrically arranged auxiliary grooves 1211 are provided on the inner wall of the reinforcing groove 121. During injection molding, the liquid material flowing into the reinforcing groove 121 can form a reinforcing edge at the upper end of the tube after cooling, so as to avoid the tube from deforming during the cooling process. At the same time, the setting of the reinforcing groove 121 can form a protrusion structure on the reinforcing edge, so that the ejector pin can abut against the protrusion structure during the subsequent demolding process, so as to avoid the tube body from being damaged by force.

[0036] Furthermore, it is worth mentioning that the main body 1 of this pipe bending mold specifically includes two vertically arranged modules, each module having a groove. The two modules can move along the horizontal direction to open or close the mold. In the closed state, the grooves on the two modules can close together to form a mold cavity. The mold also includes a core 2 that is detachably connected to the mold cavity. The core 2 is detachably connected to the inside of the mold cavity and forms a cavity 12 with the inner wall of the mold cavity.

[0037] Working principle: Liquid raw material is fed into the feed channel 11 through the feed hole 111 via an external pipe and impacts the upper inner wall of the feed channel 11. Then, under the action of gravity, it impacts the lower inner wall of the feed channel 11, thereby completing the pre-pressure reduction of the liquid raw material and allowing air bubbles in the liquid raw material to be released. Then, the liquid raw material enters the primary flow channel 131 along the transition channel 15, and enters the secondary flow channel 132 and the tertiary flow channel 133 in sequence with the cooperation of each feed groove 14, realizing multiple stages of pressure reduction of the liquid raw material. Then, under the action of the gate edge 16, the liquid raw material enters the lower end of the cavity 12 through the gate and fills the cavity 12 simultaneously with different filling rates of the inner and outer bends, thereby completing the injection molding process.

[0038] 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.

[0039] Although this document frequently uses terms such as body 1, feed channel 11, feed hole 111, cavity 12, reinforcing groove 121, auxiliary groove 1211, runner 13, primary runner 131, secondary runner 132, tertiary runner 133, material passage groove 14, transition channel 15, gate edge 16, and core 2, the possibility of using other terms is not excluded. These terms are used 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 pipe bending mold, comprising a body (1), wherein the body (1) has a feeding channel (11) and a core (2) arranged vertically, and a cavity (12) is formed between the body (1) and the core (2), characterized in that, The main body (1) has several annular flow channels (13) arranged around the core (2) below the cavity (12) in a circumferential direction. The flow channels (13) are spaced apart along the length of the cavity (12). A feed groove (14) is provided between every two adjacent flow channels (13) in the main body (1). Every two adjacent flow channels (13) are connected through the feed groove (14). The flow channel (13) at the bottom is connected to the feed channel (11). The uppermost flow channel (13) is connected to the lower end of the cavity (12). The flow channels (13) are arranged sequentially from bottom to top as a first-level flow channel (131), a second-level flow channel (132), and a third-level flow channel (133). The cavity (12) has an inwardly protruding gate edge (16) above the third-level flow channel (133) along the circumferential direction. The width of the gate edge (16) gradually decreases from the side that bends inward in the cavity (12) to the side that bends outward in the cavity (12).

2. The pipe bending mold according to claim 1, characterized in that, The body (1) has a transition channel (15) that connects the primary flow channel (131) and the feed channel (11). The number of material passages (14) located between the primary flow channel (131) and the secondary flow channel (132) in the body (1) is less than the number of material passages (14) located between the secondary flow channel (132) and the tertiary flow channel (133). A number of material passages (14) are arranged at intervals along the circumference of the cavity (12).

3. The pipe bending mold according to claim 2, characterized in that, The body (1) has at least two material passages (14) located between the primary flow channel (131) and the secondary flow channel (132), and the body (1) has at least four material passages (14) located between the secondary flow channel (132) and the tertiary flow channel (133). The material passages (14) located between the primary flow channel (131) and the secondary flow channel (132) and the material passages (14) located between the secondary flow channel (132) and the tertiary flow channel (133) are staggered.

4. The pipe bending mold according to claim 2 or 3, characterized in that, The cross-sectional area of ​​each of the material passages (14) located between the primary flow channel (131) and the secondary flow channel (132) and the material passages (14) located between the secondary flow channel (132) and the tertiary flow channel (133) is the same.

5. The pipe bending mold according to claim 4, characterized in that, The feed channel (11) is bent close to the cavity (12) and the transition channel (15) is curved in an arc shape.

6. The pipe bending mold according to claim 5, characterized in that, The feeding channel (11) is long and vertically arranged. The feeding channel (11) has a feeding hole (111) on its inner side wall near the upper end. The entrance end of the transition channel (15) is located near the lower end of the feeding channel (11).

7. The pipe bending mold according to claim 6, characterized in that, The inner walls at both ends of the feed channel (11) are curved.

8. The pipe bending mold according to claim 1, 2, or 3, characterized in that, The upper end of the cavity (12) is provided with a ring-shaped reinforcing groove (121) along the circumferential direction.

9. The pipe bending mold according to claim 8, characterized in that, Two auxiliary grooves (1211) are provided on the inner wall of the reinforcing groove (121), and the two auxiliary grooves (1211) are symmetrically arranged around the reinforcing groove (121).

Images