PSI - Issue 59

Viktor Kovalov et al. / Procedia Structural Integrity 59 (2024) 779–785 V. Kovalov et al. / Structural Integrity Procedia 00 (2019) 000 – 000

783

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rate of blocks, a  2 - the failure rate of inserts, and  2 >  1 . Let further  1 be the intensity of cutting part recovery, i.e. plate replacement or rotation, and  2 be the intensity of block recovery. Let's define four states in which the systems will be: state 0 - the system is serviceable after the block replacement; state 1 - the turning cutter does not work due to the failure of the insert, its rotation or replacement is carried out; state 2 - the turning cutter is in working condition after the insert replacement; state 3 - the turning cutter does not work due to the failure of the attachment elements or the block as a whole, the block replacement is carried out. States 0 and 2 represent the permissible states for reliable operation of the tool. The matrix of transitions from one state to another in this case has the following form

0

1

2 3

1

0  

0 0



3 2 1 0

1

0 1

 P



 

1

1

0

0 0 1



 

2

2

0 1

2 



2 

A system of algebraic equations is represented by: 0= - λ 1 Р 0 + μ 2 Р 3 , 0= λ 1 Р 0 - μ 1 Р 1 ,

0= μ 1 Р 1 - λ 2 Р 2 , 0= λ 2 Р 2 -, μ 2 Р 3, 1= Р 0 + Р 1 + Р 2 + Р 3. Omitting the intermediate mathematical calculations, we determine the availability factor, which represents the proportion of time the cutter is in a serviceable condition:



2 1 2      

(6)

1 2 1 1 1 2 1 2 2 2 1 2 1 1 2  

 As F

   

In this way, using expressions (3), it is possible to determine the readiness factor of the tool according to the given indicators of its reliability: failure rates  1 and  2 and maintainability rates  1 and  2 obtained on the basis of the results of operational tests. Dependence (6) can be used at the design stage to distribute a given level of reliability of the entire tool of a given design between its elements, having a priori information on the intensity of their recovery. If it is necessary to design a turning cutter for the given machining conditions (i.e. the intensities  1 and  2 are set), then in order to obtain a given level of reliability, it is necessary to select such design solutions that will make it possible to ensure the maintainability indicators defined by this dependence. 3. Experimental results In order to improve the reliability of cutting tools, carbide inserts of prefabricated tools were subjected to pulsed magnetic field treatment. Pulsed magnetic field treatment is a method of changing the physical and mechanical properties of materials, which has been used to improve the wear resistance and strength of materials. During pulsed magnetic field treatment, a complex effect on the tool material is carried out in the form of magnetostrictive effect of mechanical deformation, thermal and electromagnetic eddy currents. The study of structural changes in the cobalt phase of hard alloy samples subjected to pulsed magnetic field treatment was carried out by X-ray diffractometer analysis. The position of the diffraction maximum of the cobalt phase lines before and after treatment with a pulsed magnetic field was recorded.