How to read the engineering drawings of CNC

1. It is necessary to clarify what type of drawing is obtained, whether it is an assembly drawing, schematic diagram, schematic diagram, or a part drawing, BOM table. Different types of drawing groups need to express different information and focus;
-For mechanical processing, the selection and configuration of the following processing elements are involved
A. Selection of processing equipment
B. Selection of machining tools;
C. Selection of processing fixtures;
D. Processing program and parameter settings:
E. Selection of quality inspection tools;

2. Look at the object described in the drawing, that is, the title of the drawing; Although everyone and every company have their own drawings, everyone basically follows the relevant national drafting standards. A group of drawings is created for engineers to see. If there are too many special areas that others cannot understand, it loses its significance. So, first look at the object name, number, quantity, material (if any), proportion, unit, and other information in the title bar (bottom right corner);

3. Determine the direction of the view; Standard drawings have at least one view. The concept of view is derived from the projection of descriptive geometry, so the concept of three views of Gita must be clear, which is the basis of our drawings. Understanding the relationship between the views on the drawings, we can express the general shape of the product based on the non line drawings of Gita; According to the principle of projection, the shape of an object can be represented by placing the object within any quadrant. The method of obtaining a projected view by exposing the object to the first quadrant is generally called the first angle projection method. Therefore, in the same way, the second, third, and fourth angle projection methods can be obtained.
-The first corner method is widely used in European countries (such as the UK, Germany, Switzerland, etc.);
-The third angle method is the same as the direction in which we view the position of the object, so countries such as the United States and Japan use this projection method
-According to the Chinese national standard CNSB1001, both the first angle method and the third angle method are applicable, but they cannot be used simultaneously in the same diagram.

4. The key structure of the corresponding product; This is the key point of the view, which requires accumulation and spatial imagination ability;

5. Determine product dimensions;

6. Structure, materials, accuracy, tolerances, processes, surface roughness, heat treatment, surface treatment, etc
It is quite difficult to quickly learn how to read pictures, but it is not impossible. It is necessary to lay a solid and gradual foundation, avoid mistakes in work, and communicate details with customers in a timely manner;
Based on the above processing elements, we need to know which information in the drawing will affect our selection of these processing elements, which is where the technology lies
1. Drawing elements that affect the selection of processing equipment:
A. The structure and appearance of the parts, as well as the processing equipment including turning, milling, creating, grinding, sharpening, drilling, etc. For shaft type parts, we choose to use a lathe to add box type parts. Usually, we choose to use an iron bed and a lathe to process these skills, which belong to common sense skills and are easy to learn.
2. B. The material of the parts, in fact, the important consideration for the material of the parts is the balance between machining rigidity and machining accuracy. Of course, there are also some considerations in terms of physical and chemical properties, while also taking into account stress release and so on. This is a university science.
3. C. The machining accuracy of parts is often guaranteed by the accuracy of the equipment itself, but it is also closely related to the machining method. For example, compared to grinding machines, the surface roughness of milling machines is relatively poor. If it is a workpiece with high surface roughness requirements, it is usually necessary to consider grinding machines. In fact, there are many types of grinding machines, such as surface grinding machines, cylindrical grinding machines, centerless grinding machines, guide grinding machines, etc, This also needs to match the structure and shape of the parts
D. The processing cost of parts and the control of processing costs can be considered as a combination of technology and on-site management for mechanical processing work, which is not something that ordinary people can achieve. This is complex and needs to be accumulated in actual work. For example, the rough processing requirement of the drawings is 1.6, which can be fine iron or grinding, but the processing efficiency and cost of these two are completely the same, So there will be trade-offs and choices.
2. Drawing elements that affect the selection of machining tools
A: The material of the parts and the type of material naturally require the selection of processing tools, especially in milling machine processing. Common examples include steel processing, aluminum processing, cast iron Q processing, etc. The selection of tools for various materials is completely different, and many materials have specific processing tools.
B. The machining accuracy of parts is usually divided into rough machining, semi precision machining, and precision machining during the machining process. This process division is not simply to improve the machining quality of the parts, but also to improve machining efficiency and reduce the production of machining stress. The improvement of machining efficiency involves the selection of cutting tools, rough machining tools, and semi precision machining tools, There are different types of small tools for precise L addition. Leasing and adding L is a high dual rate method for controlling the weight of mercury and stress deformation. Adding L slightly to sheep is more effective in controlling the weight of mercury and ensuring processing accuracy.
C. The matching of processing equipment and the selection of processing tools are also related to the processing equipment, such as using iron knives for iron machine processing, turning tools for lathe processing, and grinding wheels for grinding machine processing. Each type of tool selection has its own specific knowledge and approach, and many of the technical thresholds cannot be directly guided by theory, which is the biggest challenge for process engineers. D. The processing cost of parts, Good cutting tools mean high efficiency, good quality, but also high cost consumption, and a higher reliance on processing equipment; Although poor cutting tools have low efficiency and difficult to control quality, their costs are relatively controllable and more suitable for processing equipment. Of course, in high-precision machining processes, the increase in processing costs cannot be controlled.
3. Drawing elements that affect the selection of machining fixtures
A. The structure and appearance of parts are usually completely based on the design of fixtures, and even the vast majority of fixtures are specialized. This is also an important factor restricting machining automation. In fact, in the process of building intelligent factories, the biggest trouble in the processing automation process is the automation and universality design of fixtures, which is one of the biggest challenges for design engineers
B. Generally speaking, the higher the machining accuracy of a part, the more precise the fixture is required to be made. This precision is reflected in various aspects such as rigidity, accuracy, and structural treatment, and must be a specialized fixture. General purpose fixtures must have compromises in machining accuracy and structure, so there is a big trade-off in this regard
C. The processing process design of parts, although the drawings do not reflect the process flow, can be judged based on the drawings. This is a reflection of the skills of non EWBV workers L1200 and 00, which is a part design engineer,
4. Drawing elements that affect processing programs and parameter settings
A. The structure and shape of the parts determine the selection of machine tools and equipment, as well as the selection of machining methods and cutting tools, which can affect the programming of machining programs and the setting of machining parameters
B. The machining accuracy, program, and parameters of the parts ultimately need to serve the machining accuracy of the parts, so the machining accuracy of the parts ultimately needs to be guaranteed by the machining parameters of the program
C. The technical requirements for parts are actually reflected in many drawings, which not only reflect the structural characteristics, geometric accuracy, and geometric tolerances of the parts, but also involve specific technical requirements, such as quenching treatment, paint treatment, stress relief treatment, etc. This also involves changes in processing parameters
5. Drawing elements that affect the selection of quality inspection tools
A. The structure and appearance of the parts, as well as the processing quality of the parts, are subject to evaluation. Quality inspectors, as authoritative individuals, can certainly do this work, but they rely on corresponding testing tools and instruments. Many parts' quality inspection cannot be determined solely by the naked eye
B. The machining accuracy and high-precision quality inspection of parts must be completed through professional and high-precision quality inspection equipment, such as coordinate measuring machines, laser measuring instruments, etc. The machining accuracy requirements of drawings directly determine the configuration standards of inspection tools.
C. The technical requirements of the parts correspond to different technical and quality requirements, and different inspection equipment needs to be configured for corresponding quality testing. For example, for measuring the length, we can use calipers, rulers, three coordinates, and so on. For testing the hardness, we can use a hardness tester. For testing the surface smoothness, we can use a roughness tester or a roughness comparison block, and so on. The above are the several entry points for us to understand a drawing, which are actually the professional technical capabilities of mechanical process engineers. Through these entry points, we can better understand and interpret a drawing, and concretize the requirements of the drawing.

Post time: Apr-13-2023