Moulding die for inner pipe of double-wall corrugated pipe
By designing the double-wall corrugated inner tube molding die, the pipe quality problems caused by the accumulation of impurities in the melt are solved, and more efficient production and more uniform pipe wall thickness are achieved.
Patent Information
- Application Number
- CN202421526137.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-28
- Publication Date
- 2025-06-13
- Estimated Expiration
- 2034-06-28
AI Technical Summary
In the process of forming HDPE double-wall corrugated pipes, impurities in the melt accumulate at the outlet position, resulting in quality problems such as marking and holes on the inner wall of the pipe, affecting the use effect and safety of the product.
A double-wall corrugated inner tube molding die is designed, including a mold body in the shape of a round table, with an outer diameter gradually decreasing from the discharge part to the flow part, and an angle between the discharge part and the outer wall of the flow part. The slope of the outer wall of the discharge part is smaller than the slope of the outer wall of the flow part, which increases the discharge gap, promotes the flow of the melt and effectively takes away the precipitate.
By increasing the discharge gap and providing sufficient expansion space, the accumulation of precipitates is reduced, the quality of pipe walls is reduced, the quality of pipes is improved, the downtime cleaning time is reduced, and the production efficiency is improved.
Smart Images
Figure CN222972726U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of double-wall corrugated pipe forming dies, and more specifically, to an inner pipe forming die for double-wall corrugated pipes. Background Art
[0002] HDPE double-wall corrugated pipes are formed by extruding plasticized materials through two extruders. The materials are formed into two concentric pipes with uniform wall thicknesses through a composite head, and then enter the forming machine to be combined with the module forming cavity. Vacuum is drawn in the outer layer module cavity to make the outer layer closely adhere to the module. At the same time, compressed air is injected between the inner and outer layers to separate the inner and outer layers at the wave peaks. Under the action of the sizing mandrel and the module, the inner and outer layers are pressed together at the wave valleys to form a corrugated pipe with a smooth inner wall and uneven outer wall.
[0003] Currently, the raw materials of PE double-wall corrugated pipes generally consist of polyethylene, reinforced modified masterbatch, color masterbatch, etc. To improve the physical properties and production efficiency of the pipes, steel-filled masterbatch, defoaming agents, etc. are appropriately added to the formula. However, in the production, storage, transportation, and processing links of the raw materials and filling functional masterbatch, if the screening and detection work are not rigorous, various impurities may penetrate, including inorganic and organic components. Inorganic impurities are mostly environmental pollutants such as metal oxides, dust, and soil; while organic impurities may cover unreacted raw materials, residual solvents, additives, and low molecular weight polymer fragments. During the extrusion process of heating and pressurizing in the extruder, the impurities in the materials will undergo physical sublimation. When the sublimated substances gradually accumulate to a certain amount, insoluble precipitates will adhere and remain at the discharge port position. Under long-term high-temperature heating, these precipitates will form carbides, which will cause quality problems such as scoring and perforation on the inner wall of the pipes, seriously affecting the use effect and safety of the products.
[0004] The prior art discloses an HDPE double-wall corrugated pipe forming die, including an outer die body, an outer layer spiral body, and an inner layer spiral body. The outer die body and the outer layer spiral body form a first outer wall material channel for the outer layer melt to flow, and the outer layer spiral body and the inner layer spiral body form a first inner wall material channel for the inner layer melt to flow. Both the first outer wall material channel and the first inner wall material channel are spiral structures with continuously decreasing spiral radii. It also includes an outer layer die head, a die head flow splitter core, and an inner layer die head. The outer layer die head and the die head flow splitter core form a second outer wall material channel, and the inner layer die head and the die head flow splitter core form a second inner wall material channel. In this solution, in order to eliminate the flow line, the sizes of the second outer wall material channel and the second inner wall material channel both decrease from large to small, further compressing and densifying the melt to further plasticize the melt. However, the organic impurities in the melt will undergo physical sublimation, and the sublimated substances will accumulate and remain insoluble precipitates at the discharge port position, affecting the wall surface quality of the pipes during the production process. Summary of the Utility Model
[0005] The purpose of the present utility model is to overcome the deficiencies of the prior art and provide an inner tube forming die for double-wall corrugated pipes, so that the precipitates generated by the melt are not easily adhered, the accumulation of precipitates is reduced, the quality problems such as scribing and perforation on the pipe wall are reduced, and the quality of the pipes is improved.
[0006] To solve the above technical problems, the technical solution adopted by the present utility model is:
[0007] Provide an inner tube forming die for double-wall corrugated pipes, including a die body in the shape of a frustum of a cone. The die body is coaxially provided with a through cavity. The die body includes a material flow part and a discharging part connected. The outer diameter of the die body gradually decreases from the discharging part at one end of the die body to the material flow part at the other end of the die body; the outer wall of the discharging part forms a first included angle with the outer wall of the material flow part, and the slope of the outer wall of the discharging part is less than the slope of the outer wall of the material flow part.
[0008] The inner tube forming die for double-wall corrugated pipes of the present utility model is used in a double-wall corrugated pipe forming die. The melt flows through the outer walls of the material flow part and the discharging part and discharges to form an inner tube. The outer diameter of the die body gradually decreases from the discharging part at one end of the die body to the material flow part at the other end of the die body. The melt is compressed and compacted during the discharging process, so that the melt is further plasticized; the outer wall of the discharging part forms a first included angle with the outer wall of the material flow part, and the slope of the outer wall of the discharging part is less than the slope of the outer wall of the material flow part, increasing the discharging gap, making the discharging smoother, and the precipitates are not easily accumulated. At the same time, it also provides enough space for the melt to expand, and can effectively carry away the precipitates, avoiding the quality problems such as scribing and perforation on the pipe wall caused by the accumulation of precipitates affecting the pipe production, improving the quality of the pipes, and reducing the shutdown cleaning time, thereby improving the production efficiency.
[0009] Further, the die body is also provided with a flat flow part at the end of the discharging part away from the material flow part. The outer wall of the flat flow part forms a second included angle with the outer wall of the discharging part. The flat flow part is in the shape of a cylinder coaxial with the die body. The melt flows along the outer walls of the material flow part and the discharging part to the flat flow part, so that the finally discharged and formed pipe is a uniform round pipe.
[0010] Further, an air ring is provided on the outer wall at one end of the die body. The die body is provided with a flow channel structure connected to an external vacuum device. The flow channel structure is communicated with the air ring. The vacuum device is used to evacuate the air ring through the flow channel structure. Using the vacuum device to evacuate the air ring through the flow channel structure, the circumferential wall of the melt is vacuum adsorbed when extruding the inner layer die, preventing the melt from sagging and piling up and wrinkling, and at the same time solving the problem that the melt at the top of the pipe sags and makes the wall thickness thinner. The inner wall of the pipe can be more stably attached to the water jacket transition section, and the wall thickness of the inner tube of the pipe is more uniform, improving the qualified rate of the product.
[0011] Further, the flow channel structure includes a vacuum channel, a bypass channel, and an air duct. The vacuum channel is opened in the die body. The bypass channel and the air duct are respectively arranged at one end of the die body. The air ring is communicated with the bypass channel through the air duct. One end of the vacuum channel is communicated with the bypass channel, and the other end of the vacuum channel is communicated with the cavity. The vacuum channel is used to connect the vacuum device. The vacuum device evacuates the bypass channel through the vacuum channel. After being pressurized by the bypass channel, it is divided into the air ring at one end of the die body through the air duct, so that when the melt is extruded from the die body, an adsorption force can be obtained on the circumferential wall of the inner tube, preventing the melt from sagging and stacking at the bottom and preventing the top of the pipe from thinning.
[0012] Further, the bypass channel is spiral. The bypass channel includes connected spiral coils. The air duct communicates with each spiral coil of the bypass channel. One end of the vacuum channel is located on the spiral coil close to the central axis of the die body in the bypass channel. After the vacuum is pressurized by the spiral coil, it is divided into the air ring through the air duct to adsorb the inner wall circumference of the inner tube, making the wall thickness of the inner tube more uniform.
[0013] Further, the bypass channel is circular. One ends of multiple vacuum channels are evenly arranged at intervals on the bypass channel. Multiple shunt channels are arranged offset from the vacuum channels, making the vacuum pressure in the bypass channel uniform. The air ring is evacuated through the bypass channel and the air duct, and then the vacuum adsorption force in the air ring is made uniform.
[0014] Further, there are multiple vacuum channels, and the multiple vacuum channels are evenly arranged along the circumferential direction of the die body.
[0015] Further, there are multiple air ducts, and the multiple air ducts are evenly arranged along the circumferential direction of the die body.
[0016] Further, it further includes an air path pressing plate. The air path pressing plate is arranged at one end of the die body, and the air path pressing plate covers the bypass channel, the air duct, and the vacuum channel. The bypass channel, the air duct, and the vacuum channel are covered at one end of the die body through the air path pressing plate, so that the air duct and the vacuum channel are only communicated through the bypass channel, ensuring the vacuum pumping effect and ensuring sufficient adsorption force on the inner tube.
[0017] Further, the vacuum device includes a shunt pipe, an air extraction seat, an air extraction pipe, and a vacuum pump. One end of the shunt pipe is installed in the vacuum channel, the other end of the shunt pipe is communicated with the air extraction seat, one end of the air extraction pipe is communicated with the air extraction seat, and the other end of the air extraction pipe is communicated with the vacuum pump. The vacuum pump evacuates the air extraction seat through the air extraction pipe, and then uses the shunt pipe to evacuate the air ring through the flow channel structure to generate an adsorption force on the inner tube.
[0018] Compared with the prior art, the beneficial effects produced by the inner tube forming die of the double-wall corrugated pipe of the present utility model are as follows:
[0019] Increase the discharge gap to make the discharge smoother and prevent the precipitates from accumulating easily.
[0020] Meanwhile, it also provides enough space for melt expansion, which can effectively carry away the precipitates, avoid the accumulation of precipitates affecting the pipe production and causing quality problems such as scribing and perforation on the pipe wall surface, improve the pipe quality, and reduce the downtime for cleaning, thus improving the production efficiency.
[0021] Use a vacuum device to evacuate the air ring through the flow channel structure, so that the circumferential wall of the melt is vacuum adsorbed when extruding the inner layer die, preventing the melt from sagging and wrinkling, and at the same time avoiding the melt at the top of the inner pipe from sagging and thinning the wall thickness, making the wall thickness of the inner pipe more uniform and improving the qualified rate of the product. Description of the Drawings
[0022] Figure 1 It is a schematic structural diagram of the inner pipe forming die of the double-wall corrugated pipe in the embodiment of the present utility model;
[0023] Figure 2 is Figure 1 an enlarged view of the partial A in
[0024] Figure 3 It is a perspective view of the inner pipe forming die of the double-wall corrugated pipe in the embodiment of the present utility model;
[0025] Figure 4 It is an installation schematic diagram of the vacuum device in the embodiment of the present utility model.
[0026] In the drawings: 1 - die body; 11 - material flow part; 12 - discharge part; 13 - flat flow part; 2 - air ring; 3 - vacuum channel; 4 - bypass channel; 5 - air duct; 6 - air path pressing plate; 7 - shunt pipe; 8 - air extraction seat; 9 - air extraction pipe;
[0027] Figure 2 In it, α represents the first included angle; β represents the second included angle. Detailed Embodiments
[0028] The following further describes the present utility model in conjunction with the specific embodiments. Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to this patent; in order to better illustrate the embodiments of the present utility model, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.
[0029] In the drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.
[0030] Embodiment 1
[0031] A forming die for the inner tube of a double-wall corrugated pipe, as Figure 1 、 Figure 2 shown, includes a die body 1 in the shape of a frustum of a cone. The die body 1 is coaxially provided with a through cavity. The die body 1 includes a material flow part 11 and a discharge part 12 which are connected. The outer diameter of the die body 1 gradually decreases from the discharge part 12 at one end of the die body 1 to the material flow part 11 at the other end of the die body 1; the outer wall of the discharge part 12 and the outer wall of the material flow part 11 form a first included angle α, and the slope of the outer wall of the discharge part 12 is less than the slope of the outer wall of the material flow part 11.
[0032] The above-mentioned forming die for the inner tube of a double-wall corrugated pipe is used in a double-wall corrugated pipe forming die. The melt flows through the outer walls of the material flow part 11 and the discharge part 12 and discharges to form an inner tube. The outer diameter of the die body 1 gradually decreases from the discharge part 12 at one end of the die body 1 to the material flow part 11 at the other end of the die body 1. The melt is compressed and compacted during the discharging process, so that the melt is further plasticized; the outer wall of the discharge part 12 and the outer wall of the material flow part 11 form a first included angle α, and the slope of the outer wall of the discharge part 12 is less than the slope of the outer wall of the material flow part 11, which increases the discharge gap, makes the discharge smoother, and the precipitates are not easy to accumulate. At the same time, it also provides enough space for the melt to expand, can effectively carry away the precipitates, avoids the quality problems such as wall surface scribing and hole punching of the pipe caused by the accumulation of precipitates, improves the quality of the pipe, and can reduce the shutdown cleaning time, thereby improving the production efficiency.
[0033] As Figure 2 shown, the die body 1 is further provided with a flat flow part 13 at the end of the discharge part 12 away from the material flow part 11. The outer wall of the flat flow part 13 and the outer wall of the discharge part 12 form a second included angle β. The flat flow part 13 is in the shape of a cylinder coaxial with the die body 1. During implementation, the melt flows along the outer walls of the material flow part 11 and the discharge part 12 to the flat flow part 13, so that the finally discharged and formed pipe is a uniform circular tube.
[0034] Specifically, as Figure 2As shown, on the same cross-section, the angle between the outer wall surface of the material flow part 11 and the central axis of the die body 1 is 45°. The first angle α is 35°, and the second angle β is 15°. By increasing the discharge gap through the first angle α, the discharge becomes smoother, and sufficient space is provided for melt expansion, which can effectively carry away the precipitates. Through the second angle β, the pipe can be extruded in a uniform circular tubular shape.
[0035] Embodiment 2
[0036] This embodiment is similar to Embodiment 1, the difference is that, as Figure 3 shown, an air ring 2 is provided on the outer wall at one end of the die body 1. The die body 1 is provided with a flow channel structure connected to an external vacuum device, and the flow channel structure is communicated with the air ring 2. The vacuum device is used to evacuate the air ring 2 through the flow channel structure. During implementation, the vacuum device evacuates the air ring 2 through the flow channel structure, so that the circumferential wall of the melt is vacuum-adsorbed when extruding the inner layer die, preventing the melt from sagging and stacking and wrinkling. At the same time, the problem that the melt at the top of the pipe sags and the wall thickness becomes thinner is solved. The inner wall of the pipe can fit more stably with the water jacket transition section, and the inner wall thickness of the pipe is more uniform, improving the qualified rate of the product.
[0037] As Figure 3 shown, the flow channel structure includes a vacuum channel 3, a bypass channel 4 and an air duct 5. The vacuum channel 3 is opened on the die body 1. The bypass channel 4 and the air duct 5 are respectively arranged at one end of the die body 1. The air ring 2 is communicated with the bypass channel 4 through the air duct 5. One end of the vacuum channel 3 is communicated with the bypass channel 4, and the other end of the vacuum channel 3 is communicated with the cavity. The vacuum channel 3 is used to connect the vacuum device. During implementation, the vacuum device evacuates the bypass channel 4 through the vacuum channel 3. After being pressurized by the bypass channel 4, it is split through the air duct 5 to the air ring 2 at one end of the die body 1, so that when the melt is extruded from the die body 1, the inner circumferential wall of the inner pipe can obtain an adsorption force, preventing the melt from sagging and stacking at the bottom and preventing the top of the pipe from thinning.
[0038] As Figure 3 shown, the bypass channel 4 is spiral. The bypass channel 4 includes a plurality of connected spiral coils. The air duct 5 is communicated with each spiral coil of the bypass channel 4. Specifically, one end of the vacuum channel 3 is located in any spiral coil. In this embodiment, one end of the vacuum channel 3 is located in the spiral coil of the bypass channel 4 close to the central axis of the die body 1. After the vacuum is pressurized by the spiral coil, it is split through the air duct 5 to the air ring 2 to adsorb the inner circumferential wall of the inner pipe, making the inner wall thickness of the inner pipe more uniform.
[0039] Specifically, there are multiple vacuum channels 3, and the multiple vacuum channels 3 are evenly arranged along the circumferential direction of the die body 1. There are multiple air channels 5, and the multiple air channels 5 are evenly arranged along the circumferential direction of the die body 1. By means of the multiple vacuum channels 3, vacuum can be pumped from different positions of the bypass channel 4, improving the vacuum pumping efficiency. By means of the multiple evenly distributed air channels 5, the uniformity of the vacuum adsorption force can be improved, and further the uniformity of the adsorption force at each position of the circumferential wall of the inner tube can be improved.
[0040] As Figure 1 , Figure 4 shown, it further includes an air path pressing plate 6. The air path pressing plate 6 is arranged at one end of the die body 1, and the air path pressing plate 6 covers the bypass channel 4, the air channel 5 and the vacuum channel 3. During implementation, the bypass channel 4, the air channel 5 and the vacuum channel 3 are covered at one end of the die body 1 through the air path pressing plate 6, so that the air channel 5 and the vacuum channel 3 are only connected through the bypass channel 4, ensuring the vacuum pumping effect and guaranteeing sufficient adsorption force on the inner tube.
[0041] As Figure 4 shown, the vacuum device includes a shunt pipe 7, an air extraction seat 8, an air extraction pipe 9 and a vacuum pump. One end of the shunt pipe 7 is installed in the vacuum channel 3, the other end of the shunt pipe 7 is connected to the air extraction seat 8, one end of the air extraction pipe 9 is connected to the air extraction seat 8, and the other end of the air extraction pipe 9 is connected to the vacuum pump. During implementation, multiple shunt pipes 7 are respectively installed in the vacuum channels 3, and the multiple shunt pipes 7 are respectively connected to the air extraction seat 8. The air extraction seat 8 is located in the cavity of the die body 1. The vacuum pump pumps vacuum for the air extraction seat 8 through the air extraction pipe 9, and then uses the shunt pipe 7 to pump vacuum for the air ring 2 through the flow channel structure, generating an adsorption force on the inner tube.
[0042] Specifically, a vacuum gauge is provided on the air extraction pipe 9, and the vacuum degree or air pressure can be measured through the vacuum gauge, so as to adjust an appropriate vacuum degree for adsorbing the inner tube.
[0043] Embodiment III
[0044] This embodiment is similar to Embodiment II, the difference being that the bypass channel 4 is in a circular ring shape. One ends of the multiple vacuum channels 3 are evenly spaced and arranged on the bypass channel 4, and the multiple shunt channels are arranged in a staggered manner with the vacuum channels 3, so that the vacuum pressure in the bypass channel 4 is uniform. The air ring 2 is pumped with vacuum through the bypass channel 4 and the air channel 5, and further the vacuum adsorption force in the air ring 2 is uniform.
[0045] It should be noted that the bypass channel 4 can be a ring-shaped structure such as a rectangle or a triangle, which satisfies that the multiple air channels 5 are evenly spaced on the circumference of the air ring 2. The vacuum of the bypass channel 4 is led out to the circumference of the air ring 2 through the air channels 5, so that each position of the circumferential wall of the inner tube obtains an adsorption force, preventing the melt from sagging or stacking.
[0046] In the specific content of the above specific embodiments, the technical features can be combined arbitrarily without contradiction. For the sake of concise description, not all possible combinations of the above technical features are described. However, as long as the combinations of these technical features do not exist in contradiction, they should all be considered as within the scope described in this specification.
[0047] Obviously, the above embodiments of the present invention are merely examples given to clearly illustrate the present invention, rather than limitations on the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to enumerate all the embodiments here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.
Claims
1. A double-wall corrugated pipe inner tube forming die, comprising a truncated cone-shaped die body (1), the die body (1) being coaxially provided with a through cavity, the die body (1) comprising a material flow portion (11) and a material discharge portion (12) connected to each other, the outer diameter of the die body (1) gradually decreasing from the material discharge portion (12) at one end of the die body (1) to the material flow portion (11) at the other end of the die body (1); characterized in that: The outer wall of the discharge portion (12) forms a first angle with the outer wall of the material flow portion (11), and the slope of the outer wall of the discharge portion (12) is smaller than the slope of the outer wall of the material flow portion (11).
2. The double-wall corrugated pipe inner tube forming die according to claim 1, characterized in that: The die body (1) is further provided with a flat flow portion (13) at one end of the discharge portion (12) away from the material flow portion (11); the outer wall of the flat flow portion (13) forms a second angle with the outer wall of the discharge portion (12); and the flat flow portion (13) is in a cylindrical shape coaxial with the die body (1).
3. The double-wall corrugated pipe inner tube forming die according to claim 1, characterized in that: An air ring (2) is provided on an outer wall at one end of the die body (1); the die body (1) is provided with a flow channel structure connected to an external vacuum device; the flow channel structure is in communication with the air ring (2); and the vacuum device is used to evacuate the air ring (2) through the flow channel structure.
4. The double-wall corrugated pipe inner tube forming die according to claim 3, characterized in that: The flow channel structure comprises a vacuum channel (3), a bypass channel (4) and an air channel (5); the vacuum channel (3) is opened on the die body (1); the bypass channel (4) and the air channel (5) are respectively arranged at one end of the die body (1); the air ring (2) is connected to the bypass channel (4) through the air channel (5); one end of the vacuum channel (3) is connected to the bypass channel (4); the other end of the vacuum channel (3) is connected to the cavity; the vacuum channel (3) is used to connect the vacuum device.
5. The double-wall corrugated pipe inner tube forming die according to claim 4, characterized in that: The bypass channel (4) is spiral-shaped, the bypass channel (4) comprises connected spiral turns, and the air duct (5) is connected to each spiral turn of the bypass channel (4).
6. The double-wall corrugated pipe inner tube forming die according to claim 4, characterized in that: The bypass channel (4) is in the shape of a circular ring.
7. The double-wall corrugated pipe inner tube forming die according to claim 4, characterized in that: A plurality of vacuum channels (3) are provided, and the plurality of vacuum channels (3) are evenly arranged along the circumference of the die body (1).
8. The double-wall corrugated pipe inner tube forming die according to claim 4, characterized in that: A plurality of the air ducts (5) are provided, and the plurality of the air ducts (5) are evenly arranged along the circumference of the die body (1).
9. The double-wall corrugated pipe inner tube forming die according to claim 4, characterized in that: It also comprises an air circuit pressure plate (6), wherein the air circuit pressure plate (6) is arranged at one end of the die body (1), and the air circuit pressure plate (6) covers the bypass channel (4), the air channel (5) and the vacuum channel (3).
10. The double-wall corrugated pipe inner tube forming die according to any one of claims 4 to 9, characterized in that: The vacuum device comprises a shunt pipe (7), an exhaust seat (8), an exhaust pipe (9) and a vacuum pump; one end of the shunt pipe (7) is installed in the vacuum channel (3), the other end of the shunt pipe (7) is connected to the exhaust seat (8), one end of the exhaust pipe (9) is connected to the exhaust seat (8), and the other end of the exhaust pipe (9) is connected to the vacuum pump.