Li Tianfeng walked to the side of the imported CNC cylindrical grinder and saw that the workers were making preparations before processing, and the parts to be processed were neatly placed in the wooden box next to the machine tool.

The parts to be processed are of good quality, the surface condition is also very good, and they look very beautiful, Li Tianfeng estimated in his heart that no matter how picky the people of Harry Burton Company are, they are afraid that it will be difficult to find any fault.

There is no problem with the processing size! The technical conditions are all up to the requirements! The appearance quality is also excellent, and Li Tianfeng is confident in this batch of parts.

Of course, this cylindrical grinding process is very critical and there must be no problems, otherwise all the work done will be wasted!

"How are you preparing?" Li Tianfeng personally asked the workers who were making preparations.

Seeing that it was his top boss, the worker master was a little excited, and immediately said: "Mr. Li, the preparation work before processing will be done immediately, and the first part can be processed in a while, but I have rarely encountered such high-demand parts in my whole life as a grinder." ”

Li Tianfeng nodded, the grinding journal outer circle requirements are extremely high, the outer circle tolerance is only a trace of two, the outer contour of the journal is required to reach five thousandths, and the outer cycle runout of the journal to the benchmark A is required to be within five thousandths.

It is a few thousandths of a requirement, and the difficulty of processing can be imagined!

Li Tianfeng didn't dare to be careless in his heart, such a requirement is just the requirements of some key shaft parts on the aero engine, which is only a part of the oil drilling equipment, and the requirements of foreigners are really harsh.

Although he thought so in his heart, Li Tianfeng was still cautious, and he must be qualified for processing as required, and Li Tianfeng personally looked at the inspection work of the worker master before processing.

"I don't think this grinding wheel is enough, give me another repair." Li Tianfeng said.

Grinding process, generally before machining, the grinding wheel must be carefully resharpened. As the grinding wheel wears out during the machining process, it may be necessary to regrind the wheel from time to time.

It is found that the new tool can be replaced if the turning tool is worn, but the grinding process is different, after the grinding wheel is worn, it cannot be replaced, but resharpened. A large grinding wheel has to be resharpened until it can no longer be resharpened, and then replaced.

Li Tianfeng found that the grinding wheel was not in place, so he asked for another grinding.

The worker also looked at it carefully, and glanced at Li Tianfeng with admiration, the grinding wheel can really be repaired and sharpened better.

The CNC cylindrical grinding machine is equipped with a special diamond for grinding wheels. The hardness of the grinding wheel is very high, otherwise. It is also impossible to grind all kinds of metal materials, and the grinding wheel must use something higher than the grinding wheel, and diamond is the best choice.

A diamond is a diamond, and of course, the diamond used for the grinding wheel is not a gem-quality diamond, otherwise, such a large one is worth a lot of money. This is an industrial-grade diamond, black and not slippery. Although it is not pretty, it is a veritable diamond, and the hardness is out there.

The worker's master took out the grinding diamond, installed it on the CNC cylindrical grinder, and then operated the grinder to start grinding the grinding wheel.

The grinding wheel is a very wide one. Rotating at high speed, as soon as the grinding wheel touches the diamond, it immediately raises bursts of dusty powder, which fly and work all at once. The grinding wheel is reground very flat.

"That's it!" Li Tianfeng said.

Hearing this, the master worker immediately stopped grinding. Li Tianfeng said, "Now you can start processing, and install the parts to be processed." ”

The installation of parts is also a meticulous work, the worker master will be the shaft to be processed two ends of the tip hole smeared with a little oil, and then use the two ends of the CNC cylindrical grinder to jack up the two ends of the part, and then carefully align the parts.

"No, we need to further align it, and the beating of the A benchmark to be processed is best within three thousandths."

The requirements on the process regulations are five thousandths, for the sake of insurance, and for the sake of better processing quality of parts, Li Tianfeng put forward higher requirements, looking for within three thousandths.

The worker master complied, but the search is within three thousandths, don't look at the five thousandths only improved by two thousandths, but the difficulty has increased a lot, the workers and masters have spent a lot of effort to find the right, and the beating of the surface to be processed is finally within three thousandths.

Looking at the dial gauge used to correct the beating is always within three thousandths, Li Tianfeng nodded, "It's okay, it's up to the requirements." ”

There is a dial gauge, there is naturally a dial gauge, the dial gauge is to divide a millimeter into 100 equal parts, a circle on the dial is a millimeter, a dial indicator is to divide a millimeter into 1,000 equal parts, a small grid on the dial is a thousandth of a millimeter, a circle is generally 0.1 millimeter, and a small grid is a micron.

In some demanding machining operations with very tight tolerances, dial gauges are often used, such as the grinding process of this journal.

After the parts were aligned, they were checked again, and the worker said, "Mr. Li, can you start processing?" ”

Li Tianfeng nodded, "You can start processing!" ”

Hearing this, the worker master pressed the start button of the machine tool, because it is a CNC cylindrical grinder, the processing process is naturally CNC program control, the grinding wheel rotates at high speed, and gently touches the slowly rotating parts.

Grinding processing, its processing is very distinctive, that is, the grinding line speed is very fast, much faster than any number of turns, number of milling and other processing.

The soft sound of processing sounds very beautiful, and under the milky white cooling and full cooling, the processing is very stable.

Grinding processing, machining allowance is generally not large, this part is the same, only a few dozen filament allowance, that is, a few tenths of a millimeter machining allowance, it does not take long, it is only ten minutes, the CNC program shows that it has been processed to the required size.

If it is a number of turns, the machining can be retracted to the required size, and then the machining is stopped, which means that the machining is completed, but the grinding is not.

After the machining has been reached the required size, the CNC cylindrical grinder does not retract the tool under the control of the CNC machining program, but continues to grind without margin.

The so-called "no margin grinding" is that there is no machining allowance, which is equivalent to a hollow knife, only to see that the parts are still slowly rotating, and the grinding wheel is still continuing to rotate at high speed, but it is not entering the tool, but reciprocating left and right, moving horizontally.

It seems that there is no margin grinding, but this is not absolute, but the amount of grinding is too small, almost nothing, as called "no margin grinding", the purpose of this is to further correct the outer circle of the part, that is, the outer circle of the journal of this shaft.

"No margin grinding" has been carried out for at least one minute, and Li Tianfeng can clearly see that the shaft journal part that is ground is bright, almost like a mirror, which shows that the surface roughness of the machined surface is very good and fully meets the required standards.

After more than a minute of grinding without allowance, the machine begins to retract, the grinding wheel leaves the part, and slowly rotates freely, and then gradually stops.

The parts are finished!

After the grinding wheel completely stops rotating and there is no residual rotation at all, the master worker blows the coolant on the parts with an air gun, and then picks up the measuring tool and begins to carefully check the table, ready to measure the outer diameter of the parts first.

For parts with such a very small tolerance size and such strict requirements, it is very particular to measure the outer circle of the part, rather than just finding a caliper or micrometer to measure, because the tolerance of the outer circle of the part is only one or two, that is, 0.012 mm, which requires the use of a special micrometer.

This kind of special micrometer should be strictly calibrated before measuring, just like our common high-precision electronic scale, the electronic scale has a weight, this weight is only used to calibrate the electronic scale, this special micrometer is the same, there is also a calibration piece.

This calibration piece, marked with the outer circle size, is generally accurate to 4 decimal places, before measuring the formal part, first use a special micrometer to measure this calibration piece, to see whether the measured value and the value marked above accurate to the 4 decimal places are basically the same, it is impossible to be completely consistent, because there is a measurement error, within a permissible range can be.

Li Tianfeng noticed that the skills of this worker master are good, and the operation of using this special micrometer is very standardized, and there is nothing to be faulted with.

After carefully calibrating the micrometer, Li Tianfeng felt that he was also a little nervous, and he was about to measure the outer circle of the part, that is, the outer circle of the journal that he had just grinded.

The master worker took the micrometer and carefully began to measure the outer circle, Li Tianfeng paid attention, the master worker looked serious, but soon Li Tianfeng found that the face of the master worker had changed slightly, and there seemed to be something wrong.

Something could be wrong!

I saw that after the worker's face changed slightly, he continuously measured several places on the shaft journal that had just ground the outer circle, and after measuring these several places in a row, the worker's face changed again.

Zhang Can was also very abnormal, and immediately said nervously: "What's wrong?" Questions? ”

The worker master sighed and said, "Director Zhang, the parts are out of tolerance!" ”

Parts are out of tolerance!

That is to say, the size is not qualified!

Hearing this, Zhang Can's face also changed, and he hurriedly asked, "How much is the difference?" ”

The master worker said truthfully: "The grinding is five thousandths smaller." ”

It's five thousandths smaller!

As far as machining the outer circle is concerned, if it is large, it is easy to do, because it means that there is still a machining allowance, you can continue to grind, and then carefully and carefully process may be able to process to qualify, but the grinding is not the same, you can't grind the small one bigger, because the grinding will only grind smaller and smaller.

All the work has been wasted!

Zhang Can's face turned pale for a while, he didn't expect such a problem to occur, and it was scrapped at this critical moment, which was really a waste of his previous efforts.

Li Tianfeng's face also changed, and Li Tianfeng was far from expecting that there would be such a quality problem, and it was actually five thousandths smaller.

……

Finally finished a chapter, so tired, that's all for today! (To be continued......) R1292