Tool life setting of the hottest automatic machini

2022-08-25
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Setting the tool life of the automatic machining line

for the automatic engine machining line with short beat, long production line and complex products, it is a very noteworthy work focus to reasonably set the tool life of the tool originally equipped by the machine tool supplier (most of the tools used in the automatic machining line are non-standard tools and realize industrialization) before the tool is optimized. Reasonable setting can ensure product quality and reduce tool cost; On the contrary, the cost of cutting tools rises, workpiece scrap continues to appear, the starting rate of machine tools decreases, and the damage of machine tools intensifies, so the purpose of lean production cannot be achieved

the reasonable setting of tool life is to process the most qualified products with the lowest tool cost on the premise of ensuring product quality. But for automatic machining line, it is different from single machine. The production capacity of the machine tool, the beat, determines the cutting parameters of the tool, so the cutting parameters cannot be reduced in order to improve the tool life. Under the premise that the beat is fixed, and the conditional factors affecting the tool life are also fixed facts, it can be said that it requires the collective wisdom and efforts of a team to set a more reasonable life for each tool. A reasonable value can be given only through the cooperation of tool suppliers, tool grinders, tool adjusters, production operators and technical support departments. Through groping and testing, we can finally achieve a more reasonable value of the service life of various cutting tools. The details are as follows

1 reference

setting tool life can first reasonably reference the recommended value. The recommended value is the value recommended by the tool supplier. However, some recommended values are not suitable for actual use due to different factors such as machine tools, coolant, workpiece materials, cutting parameters, workpiece processing technical requirements, etc., so there must be a certain certification process. Blind implementation may suffer

for example, in the V6 engine cylinder head line of our power assembly plant, there is a tool (No. ch9003) at the op90 station, which is the pilot tool for machining the cylinder head seat guide tube, and the cutting edge of the tool is made of PCD. The recommended service life of the pilot cutter given by the cutter supplier is 24h. It takes 4.4S for the machine tool to process one conduit hole and 414 for one station to process three conduit holes × 3=13.2s。 That is, the service life of the pilot knife is 24 × 3600 ÷ 13.2=6545 pieces R nthe machine tool supplier can meet the product processing requirements at the equipment acceptance stage. However, after the acceptance of the equipment, shortly after the pre trial production stage, there were waste workpieces that could not meet the processing technical requirements (that is, the runout of the seat ring to the guide tube was out of tolerance). At first, we thought it was the reason for the 6-blade CBN reamer in the subsequent process, but there were still scrap products after replacing the new reamer. Finally, after searching in many ways, it was found that it was caused by ch9003 pilot knife. Ch9003 arrives at the automatic uniform cooling and constant temperature of the sample. After several times of use, it is found that when the tool is processed to more than 700 cylinder heads each time, the cylinder cover processed after tool wear cannot meet the product requirements, and the runout is out of tolerance. Finally, we set the service life of the tool to 700 pieces, and finally make the runout of the seat ring of the cylinder head to the guide tube 100% meet the technical requirements

2 test

according to different tools, different processing workpieces and different processing methods, we can observe the tool life when the tool reaches the normal wear VB amount; It also adopts the reliability life of completing the rated workload according to the quality under the specified processing conditions; It can also maintain the dimensional life of the dimensional accuracy of the workpiece and the fatigue life of the tool when it reaches the specified impact times

for general tools, we can finally determine the number of pieces processed through the actual use of comprehensive set values, that is, through the workpiece processing in several stages. For example, the service life of milling cutter head is determined according to the different conditions of rough machining and finish machining, the wear of blade, the roughness of workpiece processing, the chipping of workpiece edge, the machining size of workpiece and the change of blank allowance. Generally speaking, it is easy to determine the service life of milling cutter, reamer and boring cutter, and it is difficult to determine the secondary purification caused by determining the drill bit, especially for the easily broken deep hole drill bit. But the data acquisition of tool life is almost the same. Specific operation take an example of deep hole drill

there is no recommended value when a new drill is first used. The method of bit life data acquisition is as follows: the first new bit breaks when processing 3000 pieces; When processing 3980 pieces for the second time, the aperture is too small (not desirable)

the cutting edge broke when machining 2500 pieces for the third time

according to the above three processing data, the first service life of the drill bit can be set to 2500 × 80% =2000 pieces, and the drill bits will be replaced normally every 2000 pieces processed in the future. If the drill bit is not broken, does not collapse, the hole diameter is normal, and the tool is not seriously worn, then now more and more plastic processing enterprises are buying the so-called universal experimental machine "universal" experimental machine? After three consecutive times, the service life can be adjusted to 2500 × 90% = 2250 pieces. After continuous use for three times, it is normal, and then the service life is adjusted to 2500 × 95% = 2375 pieces. After that, the service life will be increased by 5% every three times until the VB wear of the last tool exceeds the standard or other phenomena such as edge collapse. The tool life is 10% less than that in case of abnormality, which is the life at this stage

on the contrary, after the first initial service life, if the drill bit breaks when processing 1980 pieces or 1800 pieces, the service life will be reduced. If the fourth drill bit breaks when it is processed to 1800 pieces, then the fifth drill bit is processed to 1800 pieces × When 80%=1440 pieces, remove it to check the wear of the drill bit. Visually inspect the horizontal edge, main cutting edge, auxiliary cutting edge, main rear face, rear corner, etc. if everything is normal, it can be increased to 1800 at the sixth root × 90% = 1620 pieces. When 1620 pieces are processed, check the tool again. If everything is normal, remove the seventh piece when 1800 pieces are processed for visual inspection. If it is normal, continue processing 1800 pieces of the eighth and ninth bit, and then check the tool. If it is still normal, it can be considered that the fourth bit broke at 1800 is an accidental factor. The same method can confirm the reason for the fracture of 1980 pieces

confirm the service life of the tool after using it for a period of time

it is more reasonable to use this method to set the service life. For example, in the V6 cylinder block line of Pt engine workshop, the deep hole drill with 7 and 8 stations in op30 process was originally recommended by the supplier as 3000 pieces. The deep hole drill for processing the main oil passage of op30 is famous for being easy to break

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