General requirements for the selection of stamping die materials
The materials for the stamping die are steel, hard alloy, steel-bonded hard alloy, zinc-based alloy, low-melting alloy, aluminum bronze, polymer material, and the like. At present, most of the materials used in the manufacture of stamping dies are mainly steel. The types of commonly used mold working parts are: carbon tool steel, low alloy tool steel, high carbon high chromium or medium chrome tool steel, medium carbon alloy steel, high speed. Steel, base steel and hard alloy, steel bonded carbide and so on.
Carbon tool steel
The carbon tool steel used in the mold is T8A, T10A, etc. The advantages are good processing performance and low price. However, the hardenability and the red hardness are poor, the heat treatment deformation is large, and the bearing capacity is low.
2. Low alloy tool steel
Low-alloy tool steel is based on carbon tool steel with the right amount of alloying elements. Compared with the carbon tool steel, the quenching deformation and cracking tendency are reduced, the hardenability of the steel is improved, and the wear resistance is also good. The low alloy steel used for the production of the mold includes CrWMn, 9Mn2V, 7CrSiMnMoV (code CH-1), 6CrNiSiMnMoV (code GD) and the like.
3. High carbon high chromium tool steel
Commonly used high-carbon high-chromium tool steels are Cr12 and Cr12MoV, Cr12Mo1V1 (code D2), which have good hardenability, hardenability and wear resistance, and have small heat treatment deformation, which is a high wear-resistant micro-deformed die steel. The ability is second only to high speed steel. However, the segregation of carbides is serious, and it is necessary to carry out repeated plucking (axial enthalpy, radial drawing) to forge to reduce the non-uniformity of carbides and improve the performance.
4. High carbon medium chromium tool steel
High-carbon medium-chromium tool steels for molds include Cr4W2MoV, Cr6WV, Cr5MoV, etc., which have low chromium content, less eutectic carbides, uniform carbide distribution, small heat treatment deformation, good hardenability and dimensional stability. Sex. Performance is improved compared to high carbon high chromium steels where carbide segregation is relatively severe.
FAG bearing rating life and load carrying capacity
The life of FAG bearings, the number of revolutions or hours that FAG bearing bearings experience before pitting, under a certain load, is called FAG bearing life.
The life of a rolling FAG bearing is defined by the number of revolutions (or the number of hours of operation at a certain speed): FAG bearings within this life are subject to initial fatigue damage (flaking or missing) on any of their bearing rings or rolling elements.
However, whether in the laboratory test or in actual use, it can be clearly seen that the FAG bearing has the same appearance under the same working conditions, and the actual life is very different.
In addition, there are several different definitions of FAG bearing "life", one of which is the so-called "working life", which means that the actual life that a FAG bearing can reach before it is damaged is caused by wear and damage, usually not caused by fatigue. It is caused by wear, corrosion, seal damage and other reasons.
FAG bearing bearings, due to manufacturing precision and material uniformity, even the same material, the same batch of FAG bearing bearings of the same size, under the same working conditions, the length of life is not the same.
If the statistical life is 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, and the ratio of the longest to the shortest life is 20-40 times.
To determine FAG bearing life standards, FAG bearing bearing life and reliability are linked.
First, the rated life of FAG bearings:
A batch of FAG bearings of the same specifications (model, material, process) are used under the same working conditions. 90% of TIMKEN bearings do not produce pitting, and the number of revolutions or hours experienced is called FAG bearing rated life.
Second, the basic dynamic load rating of FAG bearings:
In order to compare the bearing capacity of FAG bearings against pitting, when the rated life of FAG bearings is one million revolutions (106), the maximum load that can be withstood is the basic dynamic load rating, expressed in C.
That is to say, under the action of the rated dynamic load C of the FAG bearing, the reliability of the FAG bearing operating one million revolutions (106) without pitting failure is 90%, and the larger the C, the higher the bearing capacity.
Therefore, for the basic dynamic load rating of FAG bearings, we should pay attention to the following items:
1. The radial bearing refers to a pure radial load;
2. Thrust ball bearings refer to pure axial loads;
3. Centripetal thrust bearing refers to the radial component that produces pure radial displacement;
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