Views: 3 Author: Site Editor Publish Time: 2022-04-04 Origin: Site
The task of mechanical structure design is to determine the principle scheme and draw the specific structure diagram on the basis of the overall design concept according to the design task, in order to achieve the function required by the design. The process of design is to concrete the abstract working principle into a certain type of component or parts, including the determination of the material, shape, size, tolerance, heat treatment and surface treatment of the structural parts, but also to consider its processing technology, strength, stiffness, accuracy and the relationship between other parts and other issues. Therefore, although the direct product of structural design is technical drawings, but the work is not a simple mechanical drawing, drawing is only the expression of the design of the engineering language; the use of various techniques of institutional design to design ideas is the basic content of structural design.
1 Geometric elements of structural parts
The function of mechanical structure is mainly realized by the geometric shape of mechanical parts and the relative position of each part. The geometry of parts is composed of its surface. A part usually has multiple surfaces, and some of these surfaces are in direct contact with other parts. This part of the surface is called the functional surface. The connecting parts between functional surfaces are called connecting surfaces. The functional surface of parts is an important factor to determine the mechanical function, and the design of functional surface is the core of the structural design of parts. The main geometric parameters describing the functional surface include the surface geometry, size, surface number, location, sequence, etc. Through the different design of functional surface, various structural schemes can be obtained to realize the same technical function.
2 Association between structural parts
In a machine or machine, no part exists in isolation. Therefore, in the structural design, in addition to studying the function and related characteristics of the parts themselves, we must also study the relationship between the parts. The relationship between parts can be divided into direct correlation and indirect correlation. Two parts that have a direct assembly relationship becomes directly related. No direct assembly relationship becomes indirect correlation. Indirect correlation can be divided into position correlation and motion correlation. Position correlation refers to two parts in the mutual position of the requirements. Such as reducer in two adjacent drive shafts, the center distance must ensure certain accuracy, and the two axes must be parallel to ensure the normal meshing of gear. Motion correlation means that the motion track of one part is related to another part. For example, the motion track of the lathe tool rest must be parallel to the center line of the spindle, which is guaranteed by the parallel of the bed guide rail and the spindle axis, so the spindle is related to the position of the guide rail, while the tool rest is related to the spindle. Most parts have two or more directly related parts, so most parts have two or more parts that are structurally related to other parts. In structural design, the structures of the directly related parts of the two parts must be considered at the same time, so as to reasonably choose the heat treatment mode, shape, size, accuracy and surface of the material. At the same time, indirect correlation conditions such as dimension chain and precision calculation must be considered. Generally speaking, the more directly related parts a part has, the more complex its structure is.
3 Materials of structural parts in structural design
So many parts can choose in design of material, different material has different properties of different materials for different processing technology, should according to the functional requirements in the design of reasonably selecting the appropriate materials, and to determine the appropriate according to the types of materials processing technology, and according to the requirement of processing technology of the appropriate structure, Only through appropriate structural design can the selected materials give full play to their advantages. Designers must fully understand the mechanical properties, machining properties, cost and other information of relevant materials in order to correctly choose the materials of parts. Different design principles should be followed in structural design according to the characteristics of selected materials and their corresponding processing technology.
Mechanical products are used in all walks of life, the specific content and requirements of structural design are also varied, but the basic requirements of structural design are common. The following three different levels of mechanical structure design to illustrate the requirements of structural design.
1 Function Design
Function to meet the main mechanical function requirements, in the technical specification, such as the realization of working principle, work reliability, process, materials and assembly, etc.
2 Quality Design
It is a feature of modern engineering design to take into account all kinds of requirements and restrictions and improve the quality and cost performance of products. Specific for operational, aesthetic, safety, cost, environmental protection and other factors. In modern design, quality design is very important and often decides the competitiveness of products. That only focus on meeting the main technical functional requirements of the design thought has become the past, overall consideration of various requirements, to meet the main function of the premise of other requirements to make a proper balance and trade-off, improve the quality of products, is the core of modern mechanical design.
3 Optimized design and innovative design
Using structural design variables and other methods to systematically construct optimal design space, using creative design thinking method and other scientific methods to optimize and innovate.