Stainless steel is usually divided into martensitic steel, ferritic steel, austenitic steel, austenitic-ferritic (duplex) stainless steel and precipitation hardening stainless steel. In addition, it can be divided into chromium stainless steel, chromium-nickel stainless steel and chromium-manganese-nitrogen stainless steel. There is also a special stainless steel for pressure vessel "GB24511_2009 stainless steel plate and strip for pressure equipment".
Stainless steel small deep hole processing difficulties - deep hole processing manufacturers to tell you:
(1) Cutting heat
In the process of cutting, the expression of cutting work is cutting heat; under the same other cutting parameters, the higher the cutting speed, the more cutting work consumed per unit time, and the greater the calorific value per unit time. Calorific value per unit time
Key Technical Problems and Solutions in High Speed Drilling of Stainless Steel Small Deep Holes
Because of the high strength of the material and the fast cutting speed, the heat of high-speed drilling of stainless steel small deep holes is very high. Because the bit works in a semi-enclosed environment, the cutting heat is difficult to dissipate. If the cutting heat can't be discharged out of the hole by effective means, the high temperature will be generated in the hole due to the accumulation of cutting heat; the strength and wear resistance of the drill will decrease rapidly and the cutting ability will decrease sharply when annealed at high temperature; with the increase of temperature, bond wear and diffusion wear become the main wear mode of the tool, and the service life of the drill will be greatly reduced.
Cutting fluid is usually used to solve the cutting heat problem in engineering practice. For small diameter deep hole drilling, it is difficult to inject cutting fluid into the cutting area from the outside. Only the bit with internal cooling structure can be used to solve the problem (which is good for deep hole drilling).
Assuming that the cutting heat is transferred to the cutting fluid completely and evenly during drilling, and that the temperature of the cutting zone is the same as that of the cutting fluid, the total amount of cutting heat is obtained.
It can be seen that in order to maintain the temperature rise in the cutting zone unchanged, the flow rate of cutting fluid La needs to be proportional to the cutting speed vz. If T is a specific value, the cutting fluid flow can be calculated. Because of the complex cross-section shape of the drill, the drill and the hole are considered as a whole. According to the knowledge of hydrodynamics, the required flow of La and the hydraulic pressure of the cutting fluid should be achieved.
(2) chip removal
Chip removal is a common problem in small diameter deep hole drilling. Because of the shallow spiral groove of small drill bit and the difficulty of chip removal, chip blockage often occurs in the process of drilling small deep hole. In high-speed drilling, the cutting speed is high, and the chip generation speed is also increased. The chip removal problem is more prominent. Because of the good strength and toughness of stainless steel material, the chip produced is not easy to break, which further increases the difficulty of chip removal. A large amount of chips accumulated in the hole can easily jam the bit and cause the bit to break.
To solve the problem of chip removal in high-speed drilling of small deep holes, one way is to use step-by-step drilling method, which brings chips out of the hole through repeated retreat of the drill bit; the other way is to use large flow of cutting fluid to forcibly discharge the chips accumulated in the hole out of the hole. Stepping drilling (also known as pecking drilling) is a drilling method to remove chips and cool deep hole drills by periodically retreating the bit during drilling. A lot of experiments have proved that stepping drilling is a very effective method for processing small deep holes. However, due to the repeated return of drill bit takes a lot of time, the processing efficiency is low. The method of forcing chip removal by cutting fluid is consistent with the method of solving the cutting heat problem, which can realize the unification of solving methods. Chip Formation Velocity (Chip Flow Velocity) at Cutting Velocity of VZ
In order to force the cutting fluid to take away the chips, the flow rate of the cutting fluid needs to be much faster than that of the chips. Assuming that the cutting fluid velocity VA needs to be cut
