Machining process refers to the use of traditional machining methods, in accordance with the drawings of the drawings and dimensions, so that the shape of the blank, dimensions, relative position and nature of the qualified parts of the whole process, the machining process is the work that needs to be done by the workers before the processing, to avoid the occurrence of machining errors in the processing process, resulting in economic losses.
Machining process is the workpiece or part manufacturing and processing steps, the use of machining methods, directly change the shape, size and surface quality of the blank, etc., so that it becomes a part of the process is called machining process. For example, an ordinary part of the machining process is roughing-finishing-assembly-inspection-packaging, is a generalized process of machining.
Machining process is based on the process, change the shape, size, relative position and nature of the production object, so that it becomes a finished or semi-finished product, is a detailed description of each step, each process, for example, the above, roughing may include blank manufacturing, grinding, etc., finishing may be divided into the car, clamping, milling, and so on, each step will have detailed data, such as how much roughness to achieve, tolerances, and so on. For example, the roughness to achieve how much, tolerance to achieve how much.
Technical staff according to the number of products, equipment conditions and quality of workers and other circumstances, to determine the process used, and will be written into the relevant content of the process document, this document is called process regulations. This is more targeted. Each factory may not be the same, because the actual situation is different.
In a nutshell, the process is the program, the process is the detailed parameters of each step, the process is a specific factory according to the actual situation of the process.
Machining process:
Machining process regulations is one of the parts of the machining process and operating methods, etc. process documents, it is in the specific production conditions, the more reasonable process and operating methods, in accordance with the prescribed form written as a process document, after approval to guide production. Machining process regulations generally include the following: workpiece processing process route, the specific content of each process and the equipment used and process equipment, workpiece inspection items and inspection methods, cutting, time quota.
Machining production process:
The production process of the machine refers to the raw materials (or semi-finished products) made from the product of the whole process. For machine production, including the transportation and preservation of raw materials, production preparation, manufacturing of blanks, parts processing and heat treatment, product assembly, and debugging, painting and packaging. The content of the production process is very broad, modern enterprises with the principles and methods of systems engineering to organize and guide production, the production process as a production system with input and output.
In the production process, any process that changes the shape, size, location and nature of the production object, etc., so that it becomes a finished or semi-finished product is called a process. It is the main part of the production process. Process can be divided into casting, forging, stamping, welding, machining, assembly and other processes, mechanical manufacturing process generally refers to the sum of the parts of the machining process and the assembly process of the machine, other processes are called auxiliary processes, such as transportation, storage, power supply, equipment maintenance. The process is composed of one or several sequential processes, a process consists of a number of steps.
Process is the basic unit of machining process. The so-called process is a (or a group of) workers, on a machine tool (or a workplace), on the same workpiece (or several workpieces at the same time) that part of the process completed in succession. The main feature that constitutes a process is not to change the object of processing, equipment and operators, and the content of the process is completed continuously step is unchanged in the machining surface, the machining tool is unchanged, the amount of cutting under the conditions of unchanged tool walking is also known as the work stroke, is the machining tool in the machining of the surface of the work step completed once.
Development of machining process, it must be determined that the workpiece to go through several processes and the sequence of processes, only the name of the main processes and their processing order of the abbreviated process, known as the process route.
The formulation of the process route is to develop the overall layout of the process, the main task is to select the surface of each processing method, to determine the processing order of each surface, as well as the number of processes throughout the process, such as the number of processes. Process route development must follow certain principles.
Types of machining production:
Types of production are usually divided into three categories:
1, single-piece production: individual production of different structures and different sizes of products, and rarely repeated.
2. Mass production: the same products are manufactured in batches throughout the year, with some repetition of the manufacturing process.
3, mass production: products are manufactured in large quantities, and most workplaces often repeat the processing of a particular process for a particular part.
Process design, machining design principles:
(1) the design of the process should be able to ensure that the processing quality of machine parts (or machine assembly quality), to achieve the design drawings on the provisions of the technical requirements.
(2) should make the process has a high productivity, so that the product as soon as possible on the market.
(3) try to reduce manufacturing costs.
(4) Pay attention to reduce the labor intensity of workers, to ensure production safety.
Machining raw materials:
(1) product assembly drawings, parts drawings.
(2) product acceptance quality standards.
(3) the annual production program of the product.
(4) the production conditions of the manufacturing plant, including machine tools and equipment and process equipment specifications, performance and existing state, the technical level of the workers, the factory's ability to self-produced technology and equipment, as well as the factory's power supply, gas supply capacity and other relevant information.
(5) design manuals and relevant standards required for the design of process procedures and process equipment.
(6) domestic and foreign advanced manufacturing technology information.
Machining step content:
(1) analyze and study the product's assembly and parts drawings.
(2) determine the blank.
(3) Drawing up the process route and selecting the positioning base surface.
(4) Determine the equipment to be used for each process.
(5) Determine the tools, jigs, gauges and auxiliary tools used in each process.
(6) to determine the technical requirements of the main processes and inspection methods.
(7) Determine the machining allowance of each process, calculate process dimensions and tolerances.
(8) Determine the amount of cutting.
(9) Determine the working hour quota.
Machining machining allowance:
From the blank into a finished product in the process, the total thickness of the metal layer removed from a machined surface is called the total machining allowance of the surface. The thickness of the metal layer removed in each process is called inter-process machining allowance. For the outer circle and holes and other rotating surfaces, the machining allowance is considered from the diameter, so it is called symmetrical allowance (i.e., bilateral allowance), that is, the actual thickness of the metal layer removed is the diameter of the machining allowance of half. The machining allowance for flat surfaces is unilateral, which is equal to the actual thickness of the removed metal layer. In the workpiece to leave the machining allowance is designed to remove the last process left behind by the processing errors and surface defects, such as casting surface cold hard layer, porosity, sand layer, the surface of the forging surface oxide, decarburization layer, surface cracks, cutting and processing of internal stress layer and surface roughness, etc.. Thus improve the precision and surface roughness of the workpiece. The size of the machining allowance on the processing quality and productivity have a greater impact. Machining allowance is too large, not only increase the amount of machining labor, reduce productivity, and increase the material, tools and power consumption, improve the processing cost. If the machining allowance is too small, it can neither eliminate the various defects and errors in the previous process, but also can not compensate for the process of machining the clamping error, resulting in scrap. The principle of selection is to ensure quality under the premise of making the allowance as small as possible. Generally speaking, the more finishing, the smaller the process margin.
Machining development status:
With the rapid development of modern machining, the rapid development of machining technology, slowly emerged many advanced machining technology methods, such as micro-machining technology, rapid prototyping technology, precision ultra-precision machining technology.
1, micro-machining technology
With the development of micro / nano science and technology (Micro / NanoScienceandTechnology), the shape of its own size is small or very small operating scale as the characteristics of the micro-mechanical has become a high-tech people to understand and transform the microscopic world. Micromechanics has a broad application potential in aerospace, precision instruments, biomedical and other fields due to its ability to operate in a small space without disturbing the working environment and the characteristics of the object, and has become an important means of nanotechnology research, and thus has been highly valued and is listed as the first key technology of the 21st century.
2, rapid prototyping machining technology
Rapid prototyping technology is developed in the 20th century, according to the CAD model can be quickly manufactured sample or parts. It is a material accumulation processing manufacturing method, that is, through the orderly accumulation of materials to complete the three-dimensional molding. Rapid prototyping technology integrates CNC technology, material technology, laser technology and CAD technology and other modern scientific and technological achievements, is an important part of modern advanced machining technology.
3, precision and ultra-precision machining technology
Precision and ultra-precision machining when the modern machining manufacturing technology is an important part of the measure of a country's high-tech manufacturing level of one of the important indicators. 1960s, with the development of computers and information technology, the manufacturing technology has put forward higher requirements, not only for extremely high dimensional, shape and positional accuracy, but also the requirement to obtain a high degree of precision. Size, shape and positional accuracy, but also requires a very high surface quality. It is in this market demand, ultra-precision machining technology has been rapid development, a variety of processes, new methods continue to emerge.