A hybrid screw for conductive engineering plastics

Abstract

The utility model relates to screw rod technical field, specifically disclose a kind of mixed screw rod for conductive engineering plastics, including feeding section, compression section, mixing section and homogenization metering section connected coaxially in order along material conveying direction, the mixing section is alternately arranged and is constituted by at least two distribution mixing blocks and at least one weak shear pin block;The distribution mixing block is constituted by a group of small gap barrier thread and large gap barrier thread;Weak shear pin block is the cylindrical body with multiple rows of protrusions on the surface, through mixing section structure combination, the full dispersion and physical protection to conductive filler are effectively taken into account, improve the uniformity and stability of product conductivity, its excellent wear resistance ensures the long-term stability of mixing effect and the long life of screw rod, reduce maintenance cost. Overall structure design is reasonable, solve the problem of single mixing function and insufficient wear resistance in prior art.

Description

Technical Field

[0001] This utility model relates to the field of screw technology, and specifically discloses a hybrid screw for conductive engineering plastics. Background Technology

[0002] In the field of plastics processing, the screw is a core component of extruders or injection molding machines, responsible for conveying, compacting, melting, mixing, and homogenizing solid materials. For the processing of filled conductive engineering plastics (such as composites with added carbon fibers, carbon nanotubes, and metal powders), general-purpose screws typically achieve material melting and initial mixing through the shearing action generated by their threaded structure. In existing technologies, to improve the mixing effect, some mixing elements are often set in the melting or homogenizing section of the screw. However, general-purpose mixing structures often focus on a single strong shearing or weak distribution function, making it difficult to simultaneously achieve effective dispersion and physical structure protection of conductive fillers (especially fibrous fillers with large aspect ratios). While strong shearing helps break up agglomerates, it can easily lead to the fracture of brittle fillers, destroying the conductive network they form. On the other hand, weak shearing or pure distribution mixing makes it difficult to ensure sufficient deagglomeration and uniform distribution of fillers, affecting the uniformity of the conductivity of the product. In addition, insufficient wear resistance affects the stability of the process. Conductive fillers are usually hard and highly abrasive, and general-purpose screw materials or their surface treatments are difficult to resist such wear in the long term. Excessive wear of key parts of the screw can lead to changes in the mixing gap, which in turn causes fluctuations in the mixing effect, unstable extrusion, and ultimately affects product quality. Utility Model Content

[0003] This invention proposes a hybrid screw for conductive engineering plastics. Through the combination of hybrid sections, it effectively balances the full dispersion and physical protection of conductive fillers, thereby improving the uniformity and stability of the conductive properties of the product.

[0004] This invention is implemented as follows: a hybrid screw for conductive engineering plastics, which includes, in sequence along the material conveying direction, a feeding section, a compression section, a mixing section and a homogenizing metering section connected coaxially. The mixing section is composed of at least two distributed mixing blocks and at least one weak shear pin block arranged alternately. The distributed mixing block is composed of a set of small-gap barrier threads and large-gap barrier threads; The weak shear pin block is a cylinder with multiple rows of protrusions on its surface.

[0005] As a preferred embodiment of the present invention for a hybrid screw used in conductive engineering plastics, the gap between the small-gap barrier thread and the inner wall of the barrel is 0.1-0.15 times the screw diameter, and the gap between the large-gap barrier thread and the inner wall of the barrel is 0.2-0.3 times the screw diameter.

[0006] As a preferred embodiment of the hybrid screw for conductive engineering plastics according to this utility model, the protrusion on the surface of the weak shear pin block is a hemispherical pin.

[0007] As a preferred embodiment of the present invention for a hybrid screw used in conductive engineering plastics, the base of the screw is made of nitrided steel with nitrided surface, and a metal-ceramic wear-resistant coating is applied to the threaded top of the distributed hybrid block and the raised surface of the weak shear pin block.

[0008] As a preferred embodiment of the present invention for a hybrid screw used in conductive engineering plastics, the screw groove depth of the feeding section is 1.5-2.5 times the screw groove depth of the homogenizing and metering section.

[0009] As a preferred embodiment of the hybrid screw for conductive engineering plastics according to this utility model, the metal-ceramic wear-resistant coating is a tungsten carbide-cobalt coating with a thickness of 0.1-0.2 mm.

[0010] The beneficial effects of this utility model are: By combining different mixing sections, the system effectively balances the full dispersion and physical protection of the conductive filler, improving the uniformity and stability of the product's conductivity. Its excellent wear resistance ensures long-term stability of the mixing effect and a long screw life, reducing maintenance costs. The overall structural design is reasonable, solving the problems of limited mixing function and insufficient wear resistance in existing technologies. Attached Figure Description

[0011] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0012] Figure 1 This is a structural diagram of the present invention; Figure 2 This is a cross-sectional structural diagram of the weak shear pin block of this utility model.

[0013] The markings in the diagram are: 1. Feeding section; 2. Compression section; 3. Mixing section; 4. Homogenization and metering section; 5. Distribution mixing block; 6. Weak shear pin block; 7. Small gap barrier thread; 8. Large gap barrier thread. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments to aid in understanding its content. Unless otherwise specified, the methods used in this invention are conventional methods; the raw materials and apparatus used, unless otherwise specified, are conventional commercially available products.

[0015] Please see Figure 1-2 A hybrid screw for conductive engineering plastics, comprising, in sequence along the material conveying direction, a feeding section 1, a compression section 2, a mixing section 3, and a homogenizing and metering section 4, all coaxially connected. The mixing section 3 is composed of at least two distributed mixing blocks 5 and at least one weak shear pin block 6 arranged alternately; The distribution mixing block 5 is composed of a set of small-gap barrier threads 7 and large-gap barrier threads 8; The weak shear pin block 6 is a cylinder with multiple rows of protrusions on its surface.

[0016] In this embodiment: In the mixing section 3 in the middle of the screw, the distribution mixing block 5 and the weak shear pin block 6 are arranged alternately. Each distribution mixing block 5 is composed of a set of small gap barrier threads 7 and large gap barrier threads 8. By combining the material blocking effect of the small gap barrier threads 7 with the return channel provided by the large gap barrier threads 8, the material is forced to undergo multiple diversions and convergences, achieving efficient distribution mixing and making the packing uniformly distributed in space. The following weak shear pin block 6 has multiple rows of protrusions on its surface. These pins are used to gently cut and reorganize the material flow, generating a moderate shear and stretching flow field. This can effectively break the agglomeration of the packing without excessively damaging the fiber structure, thus solving the contradiction between strong shear and fiber protection.

[0017] As a technical optimization of this utility model, the gap between the small gap barrier thread 7 and the inner wall of the barrel is 0.1-0.15 times the screw diameter, and the gap between the large gap barrier thread 8 and the inner wall of the barrel is 0.2-0.3 times the screw diameter.

[0018] In this embodiment, the required pressure difference and reflux intensity can be stably generated, ensuring the controllability and efficiency of the distribution mixing effect, while avoiding excessive shearing and overheating due to too small a gap or weakening of the mixing effect due to too large a gap.

[0019] As a technical optimization of this utility model, the protrusion on the surface of the weak shear pin block 6 is a hemispherical pin.

[0020] In this embodiment, the streamlined hemispherical design further reduces the impact on materials and local shear stress, maximizing the protection of brittle fillers such as carbon fibers while achieving the cutting and diversion function, preventing them from being cut by sharp edges.

[0021] As a technical optimization of this utility model, the base of the screw is made of nitrided steel with nitriding surface, and the thread top of the distribution mixing block 5 and the raised surface of the weak shear pin block 6 are coated with a metal ceramic wear-resistant coating.

[0022] In this embodiment, the screw is provided with dual wear resistance protection. The high strength of the substrate and the ultra-high hardness of the coating work together to significantly improve the screw's ability to resist the abrasion of conductive filler, thereby ensuring the stability of the mixing gap during long-term operation and extending its service life.

[0023] As a technical optimization of this utility model, the screw groove depth of the feeding section 1 is 1.5-2.5 times the screw groove depth of the homogenization metering section 4.

[0024] In this embodiment: the screw is made to adapt to the reduced material flowability after the addition of conductive filler, and a larger space is provided in the feeding section 1 to ensure smooth conveying of solid materials and prevent bridging.

[0025] As a technical optimization of this utility model, the metal-ceramic wear-resistant coating is a tungsten carbide-cobalt coating with a thickness of 0.1-0.2 mm.

[0026] In this embodiment: the coating has extremely high hardness and good bonding strength. With an optimized thickness of 0.1-0.2mm, it can provide excellent wear resistance while avoiding the risk of brittle peeling that may be caused by excessive coating thickness, thus ensuring the reliability of the protective effect.

[0027] The working principle and usage process of this utility model are as follows: The material first enters the feeding section 1 and is stably conveyed to the compression section 2 by its deep groove thread. In the compression section 2, the depth of the screw groove gradually becomes shallower, the material is compacted and begins to melt under the action of shear heat and external heating. Subsequently, the material enters the core mixing section 3. When it flows through the distribution mixing block 5, the material is blocked by the small gap barrier thread 7, the pressure increases, and some of the melt is forced to flow back from the large gap barrier thread 8 and the wide gap between the barrel, repeatedly diverting and converging with the subsequent material to achieve distribution mixing. Next, the material enters the weak shear pin block 6, where it is cut, stretched and recombined by the hemispherical pins on its surface. The filler clusters are further dispersed in the mild shear field. After the distribution and dispersion processes are repeated several times, the material enters the homogenization metering section 4, where it is further homogenized by its shallow groove thread, and finally extruded in a stable and uniform state.

[0028] In the description of this utility model, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] However, the above description is only a specific embodiment of this utility model and should not be construed as limiting the scope of implementation of this utility model. Therefore, any substitution of equivalent components or equivalent changes and modifications made in accordance with the scope of protection of this utility model should still fall within the scope of the claims of this utility model.

Claims

1. A hybrid screw for conductive engineering plastics, comprising, in sequence along the material conveying direction, a feeding section (1), a compression section (2), a mixing section (3), and a homogenizing and metering section (4) connected coaxially, characterized in that: The mixing section (3) is composed of at least two distributed mixing blocks (5) and at least one weak shear pin block (6) arranged alternately; The distributed mixing block (5) is composed of a set of small-gap barrier threads (7) and large-gap barrier threads (8); The weak shear pin block (6) is a cylinder with multiple rows of protrusions on its surface.

2. A hybrid screw for conductive engineering plastics according to claim 1, characterized in that: The gap between the small-gap barrier thread (7) and the inner wall of the barrel is 0.1-0.15 times the screw diameter, and the gap between the large-gap barrier thread (8) and the inner wall of the barrel is 0.2-0.3 times the screw diameter.

3. A hybrid screw for conductive engineering plastics according to claim 1, characterized in that: The protrusions on the surface of the weak shear pin block (6) are hemispherical pins.

4. A hybrid screw for conductive engineering plastics according to claim 1, characterized in that: The base of the screw is made of nitrided steel with nitriding surface, and the thread top of the distribution mixing block (5) and the raised surface of the weak shear pin block (6) are coated with a metal ceramic wear-resistant coating.

5. A hybrid screw for conductive engineering plastics according to claim 1, characterized in that: The screw groove depth of the feeding section (1) is 1.5-2.5 times the screw groove depth of the homogenization metering section (4).

6. A hybrid screw for conductive engineering plastics according to claim 4, characterized in that: The metal-ceramic wear-resistant coating is a tungsten carbide-cobalt coating with a thickness of 0.1-0.2 mm.

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