Due to the particularity of the valve seat material, the tool wears quickly, consumes a lot, and the production cost is high. If can reduce the processing cost of this part to control the engine processing cost has certain significance. To reduce the production cost of the tool:
First, design new tools:
1. Design points: The basic idea of ​​designing this tool is that the structure should be simple to reduce the production cost of the tool; the re-grinding times of the tool can be increased, and the total tool life can be increased, so as to reduce the consumption cost of the tool. This tool achieves this goal in two ways.
2. The processing of valve seat adopts forming processing, which simplifies the structure of the cutter body, reduces the difficulty of tool making and improves the processing efficiency. 1. Blade 2. Blade 3. Blade 4. Knife body 5. Adjustment screw 6. Pressure block Figure 1 Tool structure Blade Design The long strip shape allows the tool to re-grind many times.
3, tool structure: the structure of the tool shown in Figure. The three long blades 1, 2 and 3 are respectively fixed on the blade body by pressing blocks, and the axial dimension of the blade is adjusted by adjusting screws. The radial dimension of the blade does not need to be adjusted. Therefore, the presetting of this tool is very simple. The inner hole fD can be used to install a valve guide reamer for simultaneous machining of the valve seat and the valve guide.
Blade: The shape and size of the blade, and the width dimension L of the three blades must be greater than the three taper sizes ab, bc, and cd, respectively, of the valve seat in order to achieve the forming process. The three blades are the same except for the angle q. Blade material: CBN blade Because the tool is formed, the insert must have sufficient wear resistance to ensure the accuracy of the valve seat and prevent the valve seat from leaking. The blade material is preferably CBN.
Second, processing technology:
1, the processing process: When using CBN inserts, the intake valve and exhaust valve each with a tool in a process can be achieved on a process forming, and to meet the accuracy requirements. It does not require roughing and finishing in multiple processes.
2. Because the cutting parameters are formed once, the cutting parameters have certain requirements. The cutting speed is too low to meet the accuracy requirements, especially valve seat leakage;
3, cutting speed is too high, tool wear too fast. Practice has proved that when the valve seat material hardness is about 280HB, the cutting speed of 200m/min is appropriate.
Third, the re-grinding of the blade:
The economy of regrind blades is generally that one blade can be reground more than 30 times, which can save more than 70% of the cost by including the regrind cost compared to the use of triangular indexable blades.
When re-grinding the blade:
1. The straightness of the cutting edge must be controlled within 0.01/100. Failure to meet the straightness requirement will cause valve seat leakage.
2, using a 600 # diamond grinding wheel. The size of the grinding wheel is easy to meet the blade straightness and roughness requirements.
3. Use grinding fluid to prevent the tool from reducing its durability.
4, the tool grinder has enough rigidity. Domestic tool grinders can meet the requirements.