Extruding machine for preparation process of high-hardness plastic grains

Abstract

The utility model discloses an extruder for a high-hardness plastic grain preparation process, which relates to the technical field of extruders, and comprises an extruder shell, one side of the extruder shell is connected with servo motors which are symmetrically arranged, and the output ends of the servo motors are connected with two groups of screw extrusion components which are symmetrically arranged. The screw extrusion assembly is used for carrying out three-section type conveying, compression, melting and plasticizing treatment on plastic rice raw materials; the screw extrusion assembly comprises a variable-pitch screw connected to the output end of the servo motor, one end of the variable-pitch screw is connected with a variable-diameter screw, and one end of the variable-diameter screw is connected with an equal-pitch equal-diameter screw. According to the utility model, the screw extrusion assembly is arranged and comprises the variable-pitch screw, the variable-diameter screw and the equal-pitch and equal-diameter screw, and gradient propulsion and preliminary loosening pretreatment of plastic rice raw materials are realized by utilizing a gradually-expanded conveying structure of the variable-pitch screw; the problems of raw material slipping, local overheating degradation and insufficient plasticizing caused by a single screw structure of traditional equipment can be solved.

Description

Technical Field

[0001] This utility model relates to the field of extrusion technology, specifically to an extrusion machine used in the preparation process of high-hardness plastic pellets. Background Technology

[0002] The extruder used in the high-hardness plastic pellet preparation process uses the extrusion pressure generated by the rotation of the internal screw and the temperature provided by the heating device to melt and plasticize the uniformly mixed high-hardness plastic raw material in the barrel, making it a melt with good fluidity. Then, it is extruded and shaped through a specific die to finally obtain high-hardness plastic pellets that meet the specifications. This process realizes the key processing transformation from raw material to molded plastic pellets, ensuring the smooth progress of the preparation process and product quality.

[0003] Patent document CN222587674U discloses an extruder. This document mainly considers that the debris generated during the cutting of aluminum strips may splash onto the conveyor belt. When the aluminum profile is just processed from the extruder, the surface has not yet hardened and is more susceptible to scratches from metal debris on the conveyor belt, which can damage the surface of the aluminum profile and affect product quality. However, it does not take into account the problems of raw material slippage, local overheating degradation, and insufficient plasticization caused by the simple screw structure of traditional equipment. Utility Model Content

[0004] The purpose of this invention is to provide an extruder for the preparation of high-hardness plastic pellets, in order to solve the problems of raw material slippage, local overheating degradation and insufficient plasticization caused by the simple screw structure of traditional equipment mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an extruder for the preparation process of high-hardness plastic rice, including an extruder shell, one side of which is connected to symmetrically arranged servo motors, and the output end of the servo motors is connected to two sets of symmetrically arranged screw extrusion assemblies, which are used to perform three-stage conveying, compression, melting and plasticizing treatment on the plastic rice raw material;

[0006] The screw extrusion assembly includes a variable pitch screw connected to the output end of a servo motor, one end of which is connected to a variable diameter screw, and the other end of which is connected to a constant pitch, constant diameter screw.

[0007] Preferably, the variable pitch screw has a screw diameter of 50 mm, an initial pitch of 40 mm, and the pitch increases linearly to 70 mm along the axial direction of the variable pitch screw.

[0008] The pitch of the variable diameter screw is 30mm, the initial screw diameter is 50mm, and the screw diameter increases linearly to 100mm along the axial direction of the variable diameter screw.

[0009] The pitch of the equal pitch and equal diameter screw is 30mm, and the screw diameter is 100mm.

[0010] Preferably, the surfaces of the variable pitch screw and the variable diameter screw are provided with staggered raised ribs, the height of which is 2mm and the width of which is 3mm, arranged along the helical direction of the variable pitch screw and the variable diameter screw.

[0011] Preferably, the outer surface of the extruder housing is connected to a melt cooling assembly, which is used to control the temperature of the plastic pellet raw material during compression, melting and plasticizing processes;

[0012] The melt cooling assembly includes a heating and plasticizing layer disposed on the outer surface of the extruder housing, and uniformly arranged resistance wires are disposed inside the heating and plasticizing layer;

[0013] A cooling circulation layer is provided on the outer surface of the heated plasticized layer, and a spiral cooling channel is provided inside the cooling circulation layer.

[0014] Preferably, the cooling channel is provided with uniformly arranged baffles, which are right-angled triangles with a height of 5mm and a base length of 10mm.

[0015] Preferably, one end of the cooling channel is connected to a coolant inlet, which penetrates the top of the cooling circulation layer, and the other end of the cooling channel is connected to a coolant outlet, which penetrates the bottom of the cooling circulation layer.

[0016] Preferably, the top of the extruder housing is provided with a feed inlet, and the feed inlet is located above the variable pitch screw;

[0017] The other side of the extruder housing is connected to a discharge port, which is located on one side of the screw with equal pitch and equal diameter.

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

[0019] 1. This utility model utilizes a symmetrical servo motor driven by two sets of three-section screw extrusion components, including a variable pitch screw, a variable diameter screw, and a constant pitch, constant diameter screw, to drive two sets of three-section screw extrusion components on one side of the extruder shell. The variable pitch screw's gradually expanding conveying structure enables gradient propulsion and initial loosening pretreatment of the plastic pellet raw material. The variable diameter screw creates a cavity environment with progressively increasing compression ratios, forcing the raw material particles to shear and rub against each other to generate heat. Finally, the constant pitch, constant diameter screw's stable plasticizing section achieves uniform melting. Compared to the fixed pitch structure of traditional single-screw extruders, this segmented screw assembly can precisely match process parameters to the differentiated needs of the raw material in the conveying, compression, and plasticizing sections, improving the uniformity of raw material plasticization. Simultaneously, the reverse meshing motion of the symmetrical twin screws eliminates unilateral pressure deviations, solving the problems of raw material slippage, localized overheating and degradation, and insufficient plasticization caused by the single screw structure in traditional equipment.

[0020] 2. This utility model, by setting a melt cooling component on the outside of the extruder shell, and combining a spiral cooling channel in the cooling circulation layer with right-angled triangular baffles, increases the heat exchange efficiency by increasing the turbulence of the coolant. It can quickly stabilize the melt temperature in the target range after the plasticizing section. Compared with the single outer wall heating or simple water cooling structure of traditional extruders, this composite temperature control system avoids the overheating and decomposition of the melt caused by temperature lag or the internal stress concentration caused by uneven cooling through a dynamic regulation mechanism of segmented heating and gradient cooling. It can solve the problems of poor hardness consistency and high scrap rate caused by the rough temperature control of traditional equipment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0022] Figure 2 This is a side view of the present invention.

[0023] Figure 3 This is a cross-sectional structural diagram of the present invention;

[0024] Figure 4 This is a schematic diagram of the melt cooling assembly structure of this utility model;

[0025] Figure 5 This is a schematic diagram of the variable pitch screw structure of this utility model.

[0026] In the diagram: 1. Extruder housing; 2. Servo motor; 3. Variable pitch screw; 4. Variable diameter screw; 5. Equal pitch and equal diameter screw; 6. Heating and plasticizing layer; 7. Cooling circulation layer; 8. Cooling channel; 9. Coolant inlet; 10. Coolant outlet; 11. Feed inlet; 12. Discharge outlet. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 An embodiment of this utility model is provided: an extruder for the preparation process of high-hardness plastic rice, including an extruder shell 1, a servo motor 2 symmetrically arranged connected to one side of the extruder shell 1, and two sets of symmetrically arranged screw extrusion assemblies connected to the output end of the servo motor 2. The screw extrusion assemblies are used to perform three-stage conveying, compression, melting and plasticizing treatment on the plastic rice raw material.

[0030] The screw extrusion assembly includes a variable pitch screw 3 connected to the output end of the servo motor 2, a variable diameter screw 4 connected to one end of the variable pitch screw 3, and a constant pitch, constant diameter screw 5 connected to one end of the variable diameter screw 4.

[0031] The screw diameter of the variable pitch screw 3 is 50mm, the initial pitch is 40mm, and the pitch increases linearly to 70mm along the axial direction of the variable pitch screw 3.

[0032] The pitch of the variable diameter screw 4 is 30mm, the initial screw diameter is 50mm, and the screw diameter increases linearly to 100mm along the axial direction of the variable diameter screw 4.

[0033] The pitch of the equal pitch and equal diameter screw 5 is 30mm, and the screw diameter is 100mm.

[0034] The surfaces of the variable pitch screw 3 and the variable diameter screw 4 are provided with staggered raised ribs, the height of which is 2mm and the width of which is 3mm, and they are arranged along the helical direction of the variable pitch screw 3 and the variable diameter screw 4.

[0035] Furthermore, the extruder housing 1 serves as the main support structure, with two servo motors 2 symmetrically installed on one side. The servo motors 2 are directly connected to the screw extrusion assembly via a coupling, which can precisely control the screw speed adjustment range of 50 to 300 r / min. The symmetrically arranged servo motors 2 achieve consistent speed through a synchronous control system, ensuring that the two sets of screw extrusion assemblies operate synchronously, offsetting the radial force generated when the screw rotates, reducing wear on the inner wall of the housing 1, and simultaneously forming a cross shear field through the reverse rotation of the twin screws, thereby improving the raw material mixing effect.

[0036] The diameter of the variable pitch screw 3 is fixed at 50mm, with an initial pitch of 40mm, which increases linearly along the axial direction to 70mm. When the raw material falls into the variable pitch screw 3 area from the feed port 11 at the top of the outer shell 1, the smaller initial pitch can densely grab the raw material particles. As the pitch gradually increases, the volume of the spiral channel expands, and the raw material is gradually pushed and loosely distributed to avoid feed accumulation. The staggered raised ribs on the screw surface extend along the spiral direction, breaking the air film between the raw material particles during rotation, and simultaneously performing preliminary shearing on the raw material, dispersing the agglomerated blocky material into particles with uniform particle size, providing a loose and uniform material base for the subsequent compression and melting section.

[0037] The variable diameter screw 4 has a constant pitch of 30mm, and the screw diameter increases linearly from 50mm to 100mm, causing the spiral channel volume to gradually decrease. When the raw material enters the area of ​​the variable diameter screw 4, the increased screw diameter leads to a shallower spiral channel depth, and the raw material is forcibly compressed. The frictional heat generated by the mutual squeezing between particles, combined with the heating of the plasticizing layer 6 on the outer surface of the outer shell 1 by the resistance wire, gradually raises the temperature of the raw material to a molten state. The raised ribs on the screw surface play a further role in this area, radially cutting the softened raw material through the gap between the ribs and the inner wall of the outer shell, breaking up the incompletely melted particles. At the same time, the ribs are distributed in an interlaced manner to form a turbulent area, promoting the uniform mixing of resin and filler and improving the homogeneity of the molten material.

[0038] The constant pitch and diameter screw 5 has a constant pitch of 30mm and diameter of 100mm, forming a stable spiral channel. After the molten material processed by the variable pitch screw 3 and the variable diameter screw 4 enters this area, it is subjected to uniform shearing. The constant screw structure ensures that the melt moves forward at a stable flow rate, eliminating pressure fluctuations caused by changes in screw structure. The two sets of symmetrically arranged screw extrusion assemblies form a conjugate extrusion effect in this area. The meshing gap generated by the counter-rotation of the twin screws can filter impurities in the melt and accumulate pressure. The uniformly plasticized melt is pushed to the subsequent molding die through the discharge port 12 on the other side of the outer shell 1, ensuring the dimensional accuracy of the extruded plastic pellets.

[0039] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4One embodiment of this utility model is an extruder for the preparation process of high-hardness plastic pellets. The outer surface of the extruder housing 1 is connected to a melt cooling component, which is used to control the temperature of the plastic pellet raw material during compression, melting and plasticizing processes.

[0040] The melt cooling assembly includes a heating and plasticizing layer 6 disposed on the outer surface of the extruder housing 1, and uniformly arranged resistance wires are disposed inside the heating and plasticizing layer 6;

[0041] A cooling circulation layer 7 is provided on the outer surface of the heated plasticizing layer 6, and a spiral cooling channel 8 is provided inside the cooling circulation layer 7.

[0042] The interior of the cooling channel 8 is equipped with uniformly arranged baffles. The baffles are right-angled triangles with a height of 5mm and a base length of 10mm.

[0043] One end of the cooling channel 8 is connected to a coolant inlet 9, which penetrates the top of the cooling circulation layer 7. The other end of the cooling channel 8 is connected to a coolant outlet 10, which penetrates the bottom of the cooling circulation layer 7.

[0044] The top of the extruder housing 1 is provided with a feed inlet 11, and the feed inlet 11 is located above the variable pitch screw 3;

[0045] The other side of the extruder housing 1 is connected to the discharge port 12, and the discharge port 12 is located on one side of the screw 5 with equal pitch and equal diameter.

[0046] Furthermore, the heating and plasticizing layer 6 is wrapped around the outer surface of the extruder shell 1, with resistance wires evenly embedded inside. The temperature control module enables segmented temperature control. In the variable pitch screw 3 area, the resistance wires can heat up quickly to compensate for insufficient shear heat generation in the early stage of raw material feeding, and avoid low-temperature retention leading to raw material degradation. In the variable diameter screw 4 area, the heating power is dynamically adjusted according to the raw material compression heat generation, so that the melt temperature deviation is controlled within ±1.5℃, ensuring that the raw material is fully melted in a viscous flow state. The segmented temperature control design of the heating and plasticizing layer 6 can flexibly adjust the temperature curve according to the melting characteristics of different raw materials, improving the equipment's adaptability to various high-hardness plastic pellet raw materials.

[0047] The cooling circulation layer 7 is located on the outer surface of the heating and plasticizing layer 6. The internal spiral cooling channel 8 is arranged in a right-handed manner, consistent with the screw rotation direction. The inner diameter of the channel is adjusted according to the screw diameter, with an adjustment range of 15-20 mm. The coolant flows in from the inlet 9 at the top of the cooling channel 8 and flows downward along the spiral channel, forming a counter-current with the melt flow direction, thus prolonging the heat exchange time.

[0048] The right-angled triangular baffles evenly arranged inside the channel form a 45° angle with the flow direction of the coolant, forcing the coolant to generate turbulence, breaking the laminar boundary layer on the inner wall of the channel, and increasing the heat exchange efficiency to 2.3 times that of traditional bare tubes. At the end of the equal pitch and equal diameter screw 5, the cooling channel 8 can quickly reduce the melt temperature, realize the gradient cooling and shaping of the melt, avoid internal stress concentration caused by sudden cooling, and ensure the high hardness and appearance quality of the plastic granules.

[0049] Working principle: The raw material falls into the variable pitch screw 3 area through the feed port 11 at the top of the extruder shell 1. The initial pitch of the variable pitch screw 3 is 40mm. As the axial extension progresses, the pitch increases linearly to 70mm. The raised ribs on its surface are distributed in an alternating manner as the screw rotates. First, the raw material particles are densely gripped with a smaller pitch to avoid feed accumulation. Then, the pitch gradually increases, which increases the volume of the spiral channel, gradually pushing and loosely distributing the raw material. At the same time, the ribs break the air film between the particles and perform preliminary shearing, dispersing the agglomerated material into uniform particles, providing a loose material basis for subsequent processing.

[0050] Symmetrically arranged servo motors 2 drive two sets of variable pitch screws 3 to rotate synchronously, forming a cross shear field through reverse meshing motion, which further improves the pre-dispersion effect of raw materials.

[0051] The raw material conveyed by the variable-pitch screw 3 enters the area of ​​the variable-diameter screw 4. The pitch of the variable-diameter screw 4 is constant at 30mm, and the screw diameter linearly increases from 50mm to 100mm, causing the screw channel depth to gradually become shallower. The raw material is forcibly compressed, and frictional heat is generated by the mutual extrusion of particles. At the same time, the resistance wire in the heating and plasticizing layer 6 on the outer surface of the extruder shell 1 provides external heating to this area. The combined effect of internal and external heat sources gradually raises the temperature of the raw material to a molten state. The raised ribs on the surface of the variable-diameter screw 4 form a gap of 1-2mm with the inner wall of the shell, which radially cuts the softened raw material and breaks up unmelted particles. The turbulent area formed by the interlaced distribution of the ribs promotes uniform mixing of resin and filler, improving the homogeneity of the molten material. The heating and plasticizing layer 6 achieves segmented temperature control through a temperature control module, dynamically adjusting the heating power in the area of ​​the variable-diameter screw 4 to keep the melt temperature deviation within ±1.5℃, ensuring that the raw material is fully melted.

[0052] The molten material enters the region of the equal-pitch, equal-diameter screw 5. The screw has a constant pitch of 30 mm and a diameter of 100 mm, forming a stable spiral channel. This allows the melt to be uniformly sheared and propelled at a stable flow rate, eliminating pressure fluctuations caused by structural changes. In this region, two sets of symmetrical screw extrusion assemblies generate a conjugate extrusion effect through the counter-rotation of twin screws. The meshing gap filters impurities in the melt and accumulates pressure. Finally, the uniformly plasticized melt is pushed to the forming die through the discharge port 12 on the other side of the extruder shell 1 under pressure.

[0053] The heating plastic layer 6 resistance wire rapidly heats up to compensate for insufficient shear heat generation in the early stage of feeding and avoids raw material degradation. In the variable diameter screw 4 area, the power is dynamically adjusted according to the heat generation of compression to achieve gradient heating.

[0054] The cooling channels 8 inside the cooling circulation layer 7 are arranged in a spiral right-handed manner, consistent with the screw rotation direction. The coolant flows in from the top inlet 9 and flows downward along the channel in a spiral. It counter-convects with the melt to prolong the heat exchange time. The right-angled triangular baffles inside the channel form a 45° angle with the flow direction, forcing the coolant to generate turbulence and increasing the heat exchange efficiency to 2.3 times that of traditional bare tubes. At the end of the equal pitch and equal diameter screw 5, the cooling channels 8 reduce the melt temperature. Gradient cooling avoids sudden cooling stress and ensures that the hardness of the plastic Mivicat fluctuates within ±3HV, achieving stable shaping.

[0055] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0056] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An extruder for preparing high-hardness plastic pellets, comprising an extruder housing (1), characterized in that: One side of the extruder housing (1) is connected to a symmetrically arranged servo motor (2), and the output end of the servo motor (2) is connected to two sets of symmetrically arranged screw extrusion assemblies. The screw extrusion assemblies are used to perform three-stage conveying, compression, melting and plasticizing of plastic pellet raw materials. The screw extrusion assembly includes a variable pitch screw (3) connected to the output end of the servo motor (2), a variable diameter screw (4) connected to one end of the variable pitch screw (3), and a constant pitch, constant diameter screw (5) connected to one end of the variable diameter screw (4).

2. The extruder for preparing high-hardness plastic pellets according to claim 1, characterized in that: The screw diameter of the variable pitch screw (3) is 50 mm, the initial pitch is 40 mm, and the pitch increases linearly to 70 mm along the axial direction of the variable pitch screw (3). The pitch of the variable diameter screw (4) is 30 mm, the initial screw diameter is 50 mm, and the screw diameter increases linearly to 100 mm along the axial direction of the variable diameter screw (4). The pitch of the equal pitch and equal diameter screw (5) is 30mm, and the screw diameter is 100mm.

3. The extruder for preparing high-hardness plastic pellets according to claim 1, characterized in that: The surfaces of the variable pitch screw (3) and the variable diameter screw (4) are provided with staggered raised ribs, the height of which is 2mm and the width of which is 3mm, and are arranged along the helical direction of the variable pitch screw (3) and the variable diameter screw (4).

4. The extruder for preparing high-hardness plastic pellets according to claim 1, characterized in that: The outer surface of the extruder housing (1) is connected to a melt cooling assembly, which is used to control the temperature of the plastic raw material during compression, melting and plasticizing processes; The melt cooling assembly includes a heating plasticizing layer (6) disposed on the outer surface of the extruder housing (1), and uniformly arranged resistance wires are disposed inside the heating plasticizing layer (6); A cooling circulation layer (7) is provided on the outer surface of the heating plasticized layer (6), and a spiral cooling channel (8) is provided inside the cooling circulation layer (7).

5. The extruder for preparing high-hardness plastic pellets according to claim 4, characterized in that: The cooling channel (8) is provided with uniformly arranged baffles inside. The baffles are right-angled triangles with a height of 5 mm and a base length of 10 mm.

6. The extruder for preparing high-hardness plastic pellets according to claim 4, characterized in that: One end of the cooling channel (8) is connected to a coolant inlet (9), and the coolant inlet (9) penetrates the top of the cooling circulation layer (7). The other end of the cooling channel (8) is connected to a coolant outlet (10), and the coolant outlet (10) penetrates the bottom of the cooling circulation layer (7).

7. The extruder for preparing high-hardness plastic pellets according to claim 1, characterized in that: The top of the extruder housing (1) is provided with a feed inlet (11), and the feed inlet (11) is located above the variable pitch screw (3); The other side of the extruder housing (1) is connected to the discharge port (12), and the discharge port (12) is located on one side of the equal pitch and equal diameter screw (5).

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