How Many Basic Requirements Do You Know About the Design of Machine Parts?

Machine parts refer to the inseparable basic units that make up the machine, such as bolts, screws, keys, belts, gears, shafts, springs, pins, etc. The design of machine parts is to study the design problems of general machine parts from the aspects of the working principle, bearing capacity, structure, and maintenance of the machine, including how to reasonably determine the shape and size of the parts, how to reasonably select the materials of the parts, and how to make the parts have good quality. craftsmanship, etc.

Machine parts are the basic units that make up the machine. In order to make the designed machine meet the basic use requirements, the constituent machine parts must meet the following requirements.

The requirements for not failing within a predetermined life span include three aspects: strength, stiffness, and life.

Machine parts breakage, wear, or unacceptable deformation during work are all due to insufficient strength. The above failure modes should be avoided for any part except those intended for timely failure in the safety device. Therefore, ensuring that the parts have sufficient strength is a basic requirement for the normal operation of the machine.

In order to improve the strength of machine parts, in principle, the following measures can be adopted in the design: use high-strength materials; make the parts have sufficient cross-sectional dimensions; reasonably design the cross-sectional shape of the parts to increase the moment of inertia of the cross-section; adopt heat treatment and chemical heat treatment methods to improve the mechanical properties of the material; improve the manufacturing accuracy of moving parts to reduce the dynamic load during work; reasonably configure the mutual positions of the parts in the machine to reduce the load acting on the parts, etc.

When the elastic deformation of machine parts does not exceed the allowable limit, it is called to meet the stiffness requirements. For the parts whose elastic deformation is too large to affect the working performance of the machine, in addition to the strength calculation, the stiffness calculation must be carried out in the design.

In order to improve the overall stiffness of the part, the following measures can be taken: increase the section size of the part or increase the moment of inertia of the section; shorten the support span or use a multi-pivot structure to reduce deflection and deformation.

Although some machine parts can meet various requirements in the early stage of work, they may fail for some reason after a certain period of work. The time that this part works normally is called the life of the part.

The service life of the parts is the basis for determining the life of the machine, and the destruction of the parts will cause the machine to not work properly. The main reasons that affect the life of parts are fatigue of materials, corrosion of materials, and wear of contact surfaces of relatively moving parts.

machine parts have good structural manufacturability, which means that they can be produced conveniently and economically under the given production conditions, and are easy to assemble. Therefore, the structural manufacturability of parts should be comprehensively considered from several production links such as blank manufacturing, machining process, and assembly.

The manufacturability is also related to the batch size and specific production conditions. In order to improve the manufacturability of parts, one should be familiar with current production levels and conditions. The structural design of the part, which has a decisive influence on the structural manufacturability of the part, occupies a large proportion in the whole design work, so it must be paid enough attention.

The economy of machine parts is first manifested in the production cost of the parts themselves. The economy of parts determines the economy of the machine. When designing parts, we should strive to design the parts with the least cost (including money, manufacturing time, and labor).

To reduce the cost of machine parts, we must first adopt a lightweight part structure to reduce material consumption, and use cheap and abundant materials to replace precious materials, which can reduce material costs; use a small or no margin blank or simplify parts structure to reduce the processing time; the structure with good manufacturability means that the processing and assembly costs are low, so the craftsmanship has a direct impact on the economy.

For large parts, the combined structure is used instead of the overall structure, which can reduce the cost of the parts. significant effect. In addition, the use of standardized parts and components as much as possible can achieve great economic benefits.

The reliability of the machine is guaranteed by the reliability of the parts. The reliability of the parts refers to the probability that the machine parts can normally complete their functions within the specified use time and predetermined environmental conditions.

For most machines, failure occurs randomly. Therefore, in order to improve the reliability of machine parts, the random variation in both working conditions and parts performance should be as small as possible. In addition, enhanced maintenance and monitoring of working conditions during use can also improve the reliability of machine parts.

If you want to know more about machine parts after reading the above, please continue to pay attention to our news.

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