Large-diameter plastic pipe extrusion die

Abstract

The present application relates to the technical fields of plastic extrusion forming, in particular to a large-diameter plastic pipe extrusion die connected to the discharge port of an extruder, comprising a spiral body, a die body, an expansion sleeve, a die, and an adjusting screw, the rear end surface of the spiral body is connected to the discharge port, the die body, the expansion sleeve, and the die are wrapped outside the spiral body from back to front, the spiral body, the die body, and the expansion sleeve are connected as a whole, the die is tightly fixed at the front end opening of the expansion sleeve, a plurality of threaded through holes are uniformly arranged at the front end opening of the expansion sleeve along the circumference, the adjusting screw is installed in the threaded through hole, the front end of the adjusting screw passes through the threaded through hole and contacts the die, the expansion sleeve contacts the rear end of the die, and the contact surface of the expansion sleeve and the die is spherical surface I. The extrusion die can quickly adjust the position of the die and reduce the material leakage.

Description

Technical Field

[0001] The invention relates to the technical field of plastic extrusion molding, in particular to a large-diameter plastic pipe extrusion die. Background Art

[0002] During plastic pipe production, raw material enters the die head from the extruder, flows through the flow channel between the die and the core, enters the sizing sleeve for final shaping, and then cools to produce a plastic pipe of the desired diameter. During the plastic pipe production process, uniformity of the pipe wall thickness is a key indicator of pipe quality. Therefore, during production, the gap between the die and the core in the die head must be adjusted to ensure uniform pipe wall thickness.

[0003] In the prior art, there are several ways to achieve uniform pipe wall thickness: 1. The invention patent with authorization announcement number CN111745934B provides a mold for producing thick-walled pipes with uniform wall thickness, comprising a die base, a spiral body and an outer die body connected to the die base, a shrinking core connected to the spiral body, a die core connected to the shrinking core, and a die disposed outside the die core. A flow channel is formed between the spiral body, the shrinking core, and the outer die body, and an extrusion channel is formed between the die core and the die base. The flow channel is connected to the extrusion channel, and a drive mechanism is mounted on the die base to drive the die core to rotate. The rotation of the die core generates a circumferential motion force on the inner wall of the melt in the extrusion channel. This reverse force creates conditions for melt accumulation by disrupting melt sagging, thereby avoiding the problem of thin upper end and thick lower end pipes caused by melt sagging during production, thereby improving the yield rate and product quality of thick-walled pipes. 2. Traditional equipment adjusts the pipe wall thickness by turning an adjustment bolt to change the die position.

[0004] In the process of realizing the present invention, the inventors found that there are at least the following problems in the prior art: the method of making the pipe wall thickness uniform by rotating the mold core has a high degree of equipment structure complexity and high equipment cost; the method of adjusting the position of the die has a low equipment manufacturing cost, but leakage is likely to occur between the die and the expansion sleeve, which wastes raw materials, and when adjusting, each adjusting bolt needs to be readjusted to a new tightness, which is inconvenient to operate. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention develops a large-diameter plastic pipe extrusion die, which can quickly adjust the die position and reduce material leakage.

[0006] The technical solution to the technical problem solved by the present invention is as follows: an embodiment of the present invention provides a large-diameter plastic pipe extrusion die, which is connected to the discharge port of the extruder, and includes a spiral body, a die body, an expansion sleeve, a die, and an adjusting screw. The rear end face of the spiral body is connected to the discharge port, and the die body, the expansion sleeve, and the die are wrapped around the outside of the spiral body from back to front. The spiral body, the die body, and the expansion sleeve are connected as one. The die is pressed and fixed at the front end opening of the expansion sleeve. The front end opening of the expansion sleeve is evenly provided with multiple threaded through holes along the circumference. The adjusting screw is installed in the threaded through hole. The front end of the adjusting screw contacts the die after passing through the threaded through hole. The expansion sleeve contacts the rear end of the die, and the contact surface between the expansion sleeve and the die is a spherical surface.

[0007] As an optimization, the extrusion die also includes a pressure plate, which is fixed to the front end face of the expansion sleeve by a tightening screw. The die is arranged between the pressure plate and the expansion sleeve. The pressure plate fixes the die on the expansion sleeve. The pressure plate is block-shaped, and a spherical protrusion is provided on the surface opposite to the die.

[0008] As an optimization, the adjusting screw contacts the side or end face of the die. The center of the spherical surface 1 in the large-diameter extrusion die is located at the front end of the front end face of the expansion sleeve, and the die can be rotated by applying force to the side or end face of the die.

[0009] As an optimization, three pressing plates and three adjusting screws are respectively arranged uniformly along the circumference of the central axis of the expansion sleeve, and the pressing plates and the adjusting screws are distributed at intervals.

[0010] As an optimization, the extrusion die is arranged horizontally, and an adjusting screw is arranged on the top of the expansion sleeve.

[0011] As an optimization, the extrusion die also includes a splint, which is in a circular ring shape and connected to the die. The splint contacts the front end of the die, and the contact surface between the die and the splint is spherical surface 2, and spherical surface 1 and spherical surface 2 are concentric and have the same diameter.

[0012] As an optimization, the extrusion die also includes a tie rod and a pin. The tie rod and pin are evenly distributed around the center of the clamping plate and the expansion sleeve, and are spaced apart from each other. The tie rod and pin connect the clamping plate and the expansion sleeve. The tie rod is a long bolt, and the clamping plate and the expansion sleeve are provided with connection ports and pin holes corresponding to the tie rod and pin.

[0013] As an optimization, the extrusion die also includes a support plate, an adjustment rod, and a cap seat. The cap seat is in the shape of an open spherical cover and is fixed to the front end side of the die. The support plate is arranged at the front end of the splint. A threaded hole is provided on the support plate. The adjustment rod is a screw rod. The adjustment rod passes through the threaded hole on the support plate. The lower end of the adjustment rod passes through the cap seat and is connected to a ball. The support plate, adjustment rod, and cap seat are evenly arranged in at least three groups along the circumference of the center line of the die.

[0014] As an optimization, the discharge port is arranged vertically downward, and the extrusion die is arranged vertically downward.

[0015] The effects provided in the summary of the invention are only the effects of the embodiments, rather than all the effects of the present invention. The above technical solution has the following advantages or beneficial effects:

[0016] 1. By rotating the adjustment screw, the die can be rotated along the center of spherical surface 1 to adjust the die position, thereby adjusting the shape of the flow channel outlet at the front end of the spiral and adjusting the thickness of the plastic tube. By setting the contact surface between the expansion sleeve and the die to a spherical surface, the sealing between the expansion sleeve and the die is improved, which can reduce leakage.

[0017] 2. By arranging spherical protrusions on the surfaces opposite to the die, the spherical protrusions of the pressing plate and the die are in point contact, so that the rotating die can be pressed and fixed.

[0018] 3. By setting three pressure plates and adjusting screws at intervals, the number of clamping screws and adjusting screws is reduced to the greatest extent, and the adjustment speed of the die position is improved.

[0019] 4. By setting a splint, which presses and fixes the die on the expansion sleeve, the contact surfaces of the die, the splint and the expansion sleeve are the same spherical surface. The pressing force applied by the fixed die does not need to be too large to ensure sealing. When rotating the adjusting screw, there is no need to loosen the connection between the splint and the expansion sleeve, and the die position can be adjusted quickly.

[0020] 5. By setting at least three groups of support plates, adjustment rods and cap seats, the front end of the die can be stretched and squeezed, the shape of the die can be changed, the adjustment method is increased, and the thickness of the plastic pipe can be adjusted more flexibly.

[0021] 6. By setting the discharge port and extrusion die vertically downward, the raw materials in the radial direction of the plastic pipe are evenly stressed, avoiding the influence of gravity and further improving the uniformity of the thickness of the plastic pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a left view of the first embodiment of the present invention.

[0023] Figure 2 This is a general structural diagram of the first embodiment of the present invention.

[0024] Figure 3 It is a left view of the second embodiment of the present invention.

[0025] Figure 4 This is a general structural diagram of the second embodiment of the present invention.

[0026] Among them: spiral body 1, mold body 2, expansion sleeve 3, die 4, adjustment screw 5, pressure plate 6, clamping plate 7, support plate 8, adjustment rod 9, cap seat 10, pull rod 11, pin 12, discharge port 20, spherical surface 1 41, spherical surface 2 42. DETAILED DESCRIPTION

[0027] In order to clearly illustrate the technical features of this solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0028] Figure 1 、 Figure 2 As an embodiment of the present invention, Figure 2 As shown, a large-diameter plastic pipe extrusion die is connected to the discharge port 20 of the extruder, including a spiral body 1, a die body 2, an expansion sleeve 3, a die 4, an adjusting screw 5, and a pressing plate 6. The rear end face of the spiral body 1 is connected to the discharge port 20, and the die body 2, the expansion sleeve 3, and the die 4 are wrapped around the outside of the spiral body 1 from back to front. The spiral body 1, the die body 2, and the expansion sleeve 3 are connected as a whole. The die 4 is pressed and fixed at the front end opening of the expansion sleeve 3. The front end opening of the expansion sleeve 3 is evenly provided with a plurality of threaded through holes along the circumference. The adjusting screw 5 is installed in the threaded through hole. The front end of the adjusting screw 5 contacts the die 4 after passing through the threaded through hole. The expansion sleeve 3 contacts the rear end of the die 4, and the contact surface between the expansion sleeve 3 and the die 4 is a spherical surface 41. The pressure plate 6 is fixed to the front end of the expansion sleeve 3 by a tightening screw. The die 4 is disposed between the pressure plate 6 and the expansion sleeve 3, securing the die 4 to the expansion sleeve 3. The pressure plate 6 is block-shaped, and a spherical protrusion is provided on the surface of the pressure plate 6 facing the die 4. By providing the spherical protrusion on the surface of the pressure plate 6 facing the die 4, the spherical protrusion of the pressure plate 6 and the die 4 form a point contact, thereby compressing and securing the rotating die 4. The adjusting screw 5 contacts the side of the die 4. The center of the spherical surface 41 in the large-diameter extrusion die is located at the front end of the front end of the expansion sleeve 3. Applying force to the side or end of the die 4 can rotate the die 4.

[0029] like Figure 1 As shown, three pressure plates 6 and three adjusting screws 5 are arranged evenly around the central axis of the expansion sleeve 3, with the pressure plates 6 and adjusting screws 5 spaced apart. By spacing the pressure plates 6 and adjusting screws 5 apart, the number of pressure screws and adjusting screws 5 is greatly reduced, improving the speed of adjusting the position of the die 4. The extrusion die is arranged horizontally, with one adjusting screw 5 positioned at the top of the expansion sleeve 3. By positioning one adjusting screw 5 at the top of the expansion sleeve 3, when the extrusion die is arranged horizontally, loosening the adjusting screws 5 on both sides of the lower end of the expansion sleeve 3 and tightening the adjusting screws 5 at the top of the expansion sleeve 3 can reduce the thickness of the upper end of the plastic tube. Conversely, loosening the adjusting screws 5 at the top of the expansion sleeve 3 and tightening the adjusting screws 5 on both sides of the lower end of the expansion sleeve 3 can increase the thickness of the upper end of the plastic tube.

[0030] Figure 3 、 Figure 4 For the second embodiment of the present invention, Figure 4 As shown, a large-diameter plastic pipe extrusion die is connected to the discharge port 20 of the extruder, including a spiral body 1, a die body 2, an expansion sleeve 3, a die 4, an adjusting screw 5, and a splint 7. The rear end face of the spiral body 1 is connected to the discharge port 20, and the die body 2, the expansion sleeve 3, and the die 4 are wrapped around the outside of the spiral body 1 from back to front. The spiral body 1, the die body 2, and the expansion sleeve 3 are connected as a whole. The die 4 is pressed and fixed at the front end opening of the expansion sleeve 3. The front end opening of the expansion sleeve 3 is evenly provided with a plurality of threaded through holes along the circumference. The adjusting screw 5 is installed in the threaded through hole. The front end of the adjusting screw 5 contacts the die 4 after passing through the threaded through hole. The expansion sleeve 3 contacts the rear end of the die 4, and the contact surface between the expansion sleeve 3 and the die 4 is a spherical surface 41. The splint 7 is annular and connected to the die 4. The splint 7 contacts the front end of the die 4. The contact surface between the die 4 and the splint 7 is spherical surface 2 42. Spherical surface 1 41 is concentric and has the same diameter as spherical surface 2 42. By setting the splint 7 and pressing the die 4 to the expansion sleeve 3, the contact surfaces of the die 4, the splint 7, and the expansion sleeve 3 are the same spherical surface. The pressing force applied to the fixed die 4 does not need to be too large to ensure sealing. When rotating the adjustment screw 5, there is no need to loosen the connection between the splint 7 and the expansion sleeve 3, and the position of the die 4 can be quickly adjusted. The extrusion die also includes a pull rod 11 and a pin 12. The pull rod 11 and the pin 12 are evenly distributed along the center of the splint 7 and the expansion sleeve 3. The pull rod 11 and the pin 12 are spaced apart. The pull rod 11 and the pin 12 connect the splint 7 and the expansion sleeve 3. The pull rod 11 is a long bolt, and the clamping plate 7 and the expansion sleeve 3 are provided with connection ports and pin holes corresponding to the pull rod 11 and the pin shaft 12. The extrusion die also includes a support plate 8, an adjustment rod 9, and a cap seat 10. The cap seat 10 is in the shape of an open spherical cover and is fixed to the front side of the die 4. The support plate 8 is arranged at the front end of the clamping plate 7 and is provided with a threaded hole extending therethrough. The adjustment rod 9 is a screw rod that extends through the threaded hole in the support plate 8. The lower end of the adjustment rod 9 passes through the cap seat 10 and connects to a ball. The support plates 8, adjustment rods 9, and cap seat 10 are evenly arranged in four groups along the centerline circumference of the die 4. By providing at least three groups of support plates 8, adjustment rods 9, and cap seats 10, the front end of the die 4 can be stretched and squeezed, the shape of the die 4 can be changed, and the adjustment method is increased, allowing for more flexible adjustment of the thickness of the plastic tube.

[0031] The plastic material flows out of the extruder's discharge port 20 and sequentially enters the flow channel at the rear end of the spiral 1, the spiral flow channel between the die 2 and the spiral 1, the flow channel between the expansion sleeve 3 and the spiral 1, and the flow channel between the die 4 and the spiral 1. Finally, it flows out of the front end of the spiral 1 and forms a plastic tube after cooling. By rotating the adjustment screw 5, the die 4 can be rotated along the center of the spherical surface 41 to adjust the position of the die 4, thereby adjusting the shape of the flow channel outlet at the front end of the spiral 1 and adjusting the thickness of the plastic tube. By setting the contact surface between the expansion sleeve 3 and the die 4 as a spherical surface, the sealing between the expansion sleeve 3 and the die 4 is improved, which can reduce material leakage.

[0032] When in use, the discharge port 20 and the extrusion die can also be arranged vertically downward. By arranging the discharge port 20 and the extrusion die vertically downward, the raw material in the radial direction of the plastic pipe is uniformly stressed, avoiding the influence of gravity, and further improving the uniformity of the thickness of the plastic pipe.

[0033] Although the above describes the specific implementation methods of the invention in conjunction with the accompanying drawings, it does not limit the scope of protection of the invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A large-diameter plastic pipe extrusion die, connected to the discharge port (20) of an extruder, comprising a spiral body (1), a die body (2), an expansion sleeve (3), a die (4), and an adjusting screw (5), wherein the rear end face of the spiral body (1) is connected to the discharge port (20), the die body (2), the expansion sleeve (3), and the die (4) are wrapped around the outside of the spiral body (1) from back to front, the spiral body (1), the die body (2), and the expansion sleeve (3) are connected as a whole, the die (4) is pressed and fixed at the front end opening of the expansion sleeve (3), the front end opening of the expansion sleeve (3) is uniformly provided with a plurality of threaded through holes along the circumference, the adjusting screw (5) is installed in the threaded through hole, and the front end of the adjusting screw (5) contacts the die (4) after passing through the threaded through hole, wherein the characteristics are: The expansion sleeve (3) contacts the rear end of the die (4), and the contact surface between the expansion sleeve (3) and the die (4) is a spherical surface (41); The adjusting screw (5) contacts the side surface or end surface of the die (4); The extrusion die is arranged horizontally, and an adjusting screw (5) is arranged on the top of the expansion sleeve (3); The extrusion die further comprises a clamping plate (7), which is in the shape of a circular ring and is connected to the die (4). The clamping plate (7) contacts the front end of the die (4). The contact surface between the die (4) and the clamping plate (7) is a second spherical surface (42). The first spherical surface (41) and the second spherical surface (42) are concentric and have the same diameter. The extrusion die further comprises a pull rod (11) and a pin (12). The pull rod (11) and the pin (12) are evenly distributed along the center of the splint (7) and the expansion sleeve (3). The pull rod (11) and the pin (12) are spaced apart. The pull rod (11) and the pin (12) connect the splint (7) and the expansion sleeve (3).

2. A large-diameter plastic pipe extrusion die according to claim 1, characterized in that: The extrusion die further comprises a pressing plate (6), which is fixed to the front end face of the expansion sleeve (3) by a tightening screw, and the die (4) is arranged between the pressing plate (6) and the expansion sleeve (3), and the pressing plate (6) fixes the die (4) on the expansion sleeve (3). The pressing plate (6) is block-shaped, and a spherical protrusion is provided on the surface of the pressing plate (6) opposite to the die (4).

3. A large-diameter plastic pipe extrusion die according to claim 2, characterized in that: The pressure plates (6) and the adjusting screws (5) are respectively arranged three uniformly along the circumference of the central axis of the expansion sleeve (3), and the pressure plates (6) and the adjusting screws (5) are spaced apart.

4. A large-diameter plastic pipe extrusion die according to claim 1, characterized in that: The extrusion die further comprises a support plate (8), an adjusting rod (9), and a cap seat (10). The cap seat (10) is in the shape of an open spherical cover. The cap seat (10) is fixed to the front end side of the die (4). The support plate (8) is arranged at the front end of the clamping plate (7). A threaded hole is provided on the support plate (8). The adjusting rod (9) is a screw rod. The adjusting rod (9) passes through the threaded hole on the support plate (8). The lower end of the adjusting rod (9) passes through the cap seat (10) and is connected to a ball. The support plate (8), the adjusting rod (9), and the cap seat (10) are evenly arranged in at least three groups along the circumference of the center line of the die (4).

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