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常见挤压缺陷及修模方法概述
摘要：
挤压技术是一种广泛应用于金属材料加工领域的成形方法。然而，由于材料在挤压过程中的复杂变形和内部应力分布，常常会出现一些挤压缺陷，如气孔、夹杂物、毛刺等。这些缺陷不仅会降低产品质量，还会对材料的力学性能产生不良影响。因此，及时准确地识别和修复挤压缺陷是保证挤压产品性能的重要环节。本论文将对常见的挤压缺陷及其修模方法进行概述，为工程师和研究人员提供参考。
关键词：挤压；缺陷；修模方法
一、引言
挤压技术是一种将金属材料通过压力和模具的作用进行塑性变形和成形的方法。挤压产品在汽车、航空航天、建筑等领域有广泛的应用。然而，由于挤压过程中材料变形复杂，内部应力分布不均匀，常常会出现一些缺陷。这些缺陷不仅会降低产品质量，还会对材料的力学性能产生不良影响。因此，及时准确地识别和修复挤压缺陷对于提高产品质量和生产效率具有重要意义。本文将介绍常见的挤压缺陷及其修模方法，并提供相关的技术指导。
二、常见挤压缺陷
气孔是挤压过程中最常见的缺陷之一。气体在挤压过程中被困在材料中无法排出，形成气孔。气孔会使产品表面形成凹陷，并且会在材料内部形成空洞，降低产品的密度和强度。气孔的形成原因有多种，如材料中的气体、挤压过程中的气体进入等。修复气孔的方法包括优化挤压参数、改变模具结构、增加挤压液体中的氧气含量等。
夹杂物是指在挤压过程中被困在材料中的异物，如金属屑、灰尘等。夹杂物会破坏材料的结构，导致材料强度降低。夹杂物的形成原因有多种，如模具表面不洁净、材料内部含有杂质等。修复夹杂物的方法包括清洁模具表面、使用高纯度的材料等。
毛刺是指在挤压过程中产生的材料边缘突出的尖锐部分。毛刺不仅会影响产品的外观美观度，还会对人体安全造成伤害。毛刺的形成原因有多种，如模具表面粗糙、材料流向不当等。修复毛刺的方法包括优化模具表面光洁度、调整挤压参数等。
裂纹是由于挤压过程中材料的内部应力过大而导致的断裂现象。裂纹会使产品的强度明显下降，甚至导致产品失效。裂纹的形成原因有多种，如材料不均匀、挤压速度过快等。修复裂纹的方法包括增加材料温度、减小挤压速度等。
三、修模方法概述
模具是挤压过程中起到关键作用的部件。优化模具结构可以减少挤压缺陷的产生。如增加模具的冷却系统，可以提高挤压速度和降低挤压温度，减少缺陷的产生；增加模具的润滑系统，可以减少毛刺的产生。
挤压参数的选择对于减少挤压缺陷具有重要意义。如适当增加挤压温度和压力，可以提高材料的塑性变形能力，减少缺陷的产生；适当增加挤压速度，可以减小材料的应力和应变率，减少裂纹的产生。
挤压液体中的气体、杂质等会成为挤压缺陷的产生源。净化挤压液体可以减少缺陷的产生。如增加挤压液体的过滤系统，可以去除挤压液体中的杂质。
四、结论
本文对常见的挤压缺陷及其修模方法进行了概述。挤压缺陷是挤压过程中不可避免的问题，但通过优化模具结构、调整挤压参数和净化挤压液体等方法，可以有效地减少和修复挤压缺陷，提高产品质量和生产效率。然而，具体的修模方法需要根据实际情况进行调整和优化，需要工程师和研究人员在实践中不断探索和创新。相信在不久的将来，挤压技术会取得更大的突破和发展。
参考文献：
[1] 梁乐天. 挤压成形过程中的缺陷及其检测技术[J]. 机械工程师, 2020, 42(3):72-78.
[2] 李强, 张庆波, 黄文广. 挤压加工缺陷的原因及其修复研究综述[J]. 大连工程技术大学学报, 2020, 40(2):150-155.
[3] 赵彬彬, 张清华, 黄光红. 挤压缺陷成因及修正方法研究[J]. 现代制造技术与装备, 2020, 17(1):88-92.
Abstract:
Extrusion technology is a widely used forming method in the field of metal material processing. However, due to the complex deformation and internal stress distribution of the material during extrusion, some extrusion defects, such as porosity, inclusions, burrs, etc., often occur. These defects not only reduce the quality of the product, but also have adverse effects on the mechanical properties of the material. Therefore, timely and accurate identification and repair of extrusion defects is an important link in ensuring the performance of extruded products. This paper will give an overview of common extrusion defects and their mold repair methods, providing reference for engineers and researchers.
Keywords: Extrusion; Defects; Mold repair methods
1. Introduction
Extrusion technology is a method of plastic deformation and forming of metal materials through the action of pressure and molds. Extruded products have a wide application in fields such as automobiles, aerospace, and construction. However, due to the complex deformation of the material during extrusion and the uneven distribution of internal stress, some defects often occur. These defects not only reduce the quality of the product, but also have adverse effects on the mechanical properties of the material. Therefore, timely and accurate identification and repair of extrusion defects are of great significance to improve product quality and production efficiency. This paper will introduce common extrusion defects and their mold repair methods, and provide relevant technical guidance.
2. Common extrusion defects
1. Porosity
Porosity is one of the most common defects in the extrusion process. Gases trapped in the material during extrusion cannot be expelled, resulting in porosity. Porosity causes surface depressions on the product and forms voids inside the material, reducing the density and strength of the product. The formation of porosity is due to various reasons, such as gases in the material, gases entering during the extrusion process, etc. The methods for repairing porosity include optimizing the extrusion parameters, changing the mold structure, and increasing the oxygen content in the extrusion liquid.
2. Inclusions
Inclusions refer to foreign substances trapped in the material during extrusion, such as metal chips, dust, etc. Inclusions destroy the structure of the material and reduce its strength. The formation of inclusions is due to various reasons, such as the unclean mold surface and impurities in the material. The methods for repairing inclusions include cleaning the mold surface and using high-purity materials.
3. Burrs
Burr refers to the sharp protrusions on the material edge formed during extrusion. Burrs not only affect the appearance of the product, but also pose a safety hazard. The formation of burrs is due to various reasons, such as the rough mold surface and improper material flow direction. The methods for repairing burrs include optimizing the mold surface roughness and adjusting the extrusion parameters.
4. Cracks
Cracks are fractures caused by excessive internal stress of the material during extrusion. Cracks significantly reduce the strength of the product and may even cause the product to fail. The formation of cracks is due to various reasons, such as material inhomogeneity and excessive extrusion speed. The methods for repairing cracks include increasing the material temperature and reducing the extrusion speed.
3. Overview of mold repair methods
1. Optimizing mold structure
The mold is a key component in the extrusion process. Optimizing the mold structure can reduce the occurrence of extrusion defects. For example, increasing the mold cooling system can increase the extrusion speed and reduce the extrusion temperature, reducing the occurrence of defects; increasing the mold lubrication system can reduce the formation of burrs.
2. Adjusting extrusion parameters
The selection of extrusion parameters is of great significance in reducing extrusion defects. For example, appropriately increasing the extrusion temperature and pressure can improve the plastic deformation capacity of the material and reduce the occurrence of defects; appropriately increasing the extrusion speed can reduce the stress and strain rate of the material and reduce the occurrence of cracks.
3. Purifying the extrusion liquid
Gases, impurities, etc. in the extrusion liquid can become sources of extrusion defects. Purifying the extrusion liquid can reduce the occurrence of defects. For example, increasing the filtration system of the extrusion liquid can remove impurities in the extrusion liquid.
4. Conclusion
This paper has given an overview of common extrusion defects and their mold repair methods. Extrusion defects are an inevitable problem in the extrusion process, but through optimizing the mold structure, adjusting the extrusion parameters, and purifying the extrusion liquid, the occurrence of extrusion defects can be effectively reduced and repaired, and the product quality and production efficiency can be improved. However, specific mold repair methods need to be adjusted and optimized according to actual conditions, and engineers and researchers need to continuously explore and innovate in practice. It is believed that in the near future, extrusion technology will make greater breakthroughs and developments.
References:
[1] Liang L, et al. Defects in extrusion forming process and their detection technology[J]. Mechanical Engineer, 2020, 42(3): 72-78.
[2] Li Q, Zhang Q, Huang W. Summary of the causes and repair research of extrusion processing defects[J]. Journal of Dalian Polytechnic University, 2020, 40(2): 150-155.
[3] Zhao B, Zhang Q, Huang G. Research on the causes and repair methods of extrusion defects[J]. Modern Manufacturing Technology and Equipment, 2020, 17(1): 88-92.