How to deal with the problem of precision Castings deformation
Precision Castings in the production process because of some hardware facilities, management, Castings cooling and correction of the problem, will produce Castings deformation of the problem, then we encountered in the Castings deformation of the time how to deal with it?
Castings deformation is divided into: trace from the deformation, Castings the flaring deformation and warping deformation.
Micro-self-deformation: alloy material, gray cast iron is the most prone to trace from the deformation. After the gray cast iron is cleaned, the residual stress is mainly residual thermal stress. Residual stress in addition to the Castings will produce cold cracking, Castings deformation and other defects, but also produce a small number of self-deformation of the main reasons. Residual stress, even if no more than the yield strength of the material, but in its role, gray cast iron with the passage of time, will slowly occur micro-plastic deformation, this deformation is called trace self-deformation.
Flaring deformation: The reason for the formation is that the sand core or sand at the opening size hinders the shrinkage of the Castings and causes the plastic deformation of the free structure of the Castings opening, resulting in flaring deformation defects.
Warping deformation: sand after the Castings at both ends or even the end of the outer edge of the warping deformation, so that the middle of the Castings concave, resulting in Castings is not smooth, this form of deformation known as warping deformation. The reason for the formation is: due to Castings cooling, Castings thickness or uneven thickness, there is temperature difference, resulting in different parts of the cooling rate of different parts, resulting in uneven plastic deformation, resulting in the formation of warping deformation.
For the deformation of precision Castingss, this paper mainly put forward the relevant four suggestions:
1. Wax the wax before the first to find out the mold in the wax chamber preset, until the mold temperature and wax chamber room temperature when the same start waxing; as the rear shell when the temperature of the wax parts do not have to mention, because there is no control Well, perhaps directly on the list, up the shell of the.
2. After the wax out of the first self-test, the main view from the mold in the project whether there is deformation, or other defects; wax should be placed in a unified way neatly placed, and try to avoid overlap, vacant; Fixture inspection to improve the detection speed and accuracy, and according to a certain period of calibration fixture.
3. After opening the furnace, the module temperature is still high when the overlap should be avoided, so that a regular placement, so that the direction of deformation to facilitate the correct shape of the plastic clip.
4. Correction of Castings fixture should be used hard material, the surface to wear, for some of the larger parts of the parts to a reasonable calculation of the press or punch tonnage, in order to avoid equipment waste or strength is not enough.
Precision Castingss on the performance of mechanical products have a great impact on the quality of poor precision Castingss will seriously affect the life of mechanical products, so once the precision Castings deformation and other issues, to be timely correction, so as not to affect the precision Castings of mechanical products The performance.
In the field of modern manufacturing, the precision and quality requirements of Castingss are increasing, and the near netting of Castingss changes the traditional concept of Castings only to provide blanks, with the aim of reducing material consumption, energy consumption, labor consumption, and improving the product The quality of internal and external, for the market and high efficiency. However, Castings dimensional accuracy and surface roughness due to many factors and constraints, control is very difficult. The Castings is liquid shaped and has a unique superiority in achieving near netting. The inner cavity and shape of the Castings are formed by Castings method in a way that is close to the final shape of the part to minimize the processing and assembly process. Dimensional accuracy and surface quality, so that the Castings can be close to the final requirements of the product, so that yuan margin or small margin; the other hand, the original Castings surface is conducive to maintaining the Castings corrosion and fatigue resistance and other superior performance, Thereby improving product life.
The structure and growth of liquid metal, the formation and growth of crystal nuclei, the size, direction and shape of crystal grains are closely related to the solidification structure of Castingss, which have a significant influence on the physical and mechanical properties of Castingss. The purpose of controlling the solidification structure of Castingss is to obtain the desired structure and to control the solidification structure, and it is necessary to have a comprehensive understanding and in-depth study on its formation mechanism, formation process and influencing factors. Currently established methods of effective control of the organization are metamorphism, birth, dynamic knot, sequential solidification, rapid solidification and so on.