Dong Huai said: "The production of drill bits is quite troublesome, we have made a few twist drill bits according to the pattern, there is no problem at low cutting, but if it is turned too high, the cutting surface of the drill bit will be dulled quickly, which may be because the drill bit is cast." Pen Fun Pavilion www.biquge.info" Li Xiang nodded, and was silent for a while.

In fact, Li Xiang also knows that with the current processing technology, if the casting method is used for the production of lathe parts, it is obviously impossible to meet the requirements. For example, the gap between the gears will affect the smoothness of the spindle rotation, and will also affect the control of the pass and feed quantity, and the gap between the lead screw threads will affect the accuracy of the automatic follow-up, and all these defects will be transferred to the workpiece, so that the machined workpiece can not meet the accuracy requirements.

In fact, there should have been some clearance between the shaft and the bearing, otherwise the oil wedge could not be formed between the two, and the lubrication effect would not have been achieved, but Li Xiang had no time to talk about this theory at this time, so he had to avoid talking about it at the moment, just thinking that if the first lathe was manufactured, the second lathe with higher precision should be manufactured as soon as possible anyway.

Next, Dong Huai told Li Xiang about the recent situation. It turned out that in order to complete the task assigned to him by Li Xiang, Dong Huai spent most of his time in the steel factory in the past few months, and only returned home twice in the past month.

Li Xiang was moved when he heard this, patted Dong Huai's shoulder and said: "Lord Dong, you have worked hard these days, when you know how much change this month's efforts will bring to the Great Song Dynasty, you will feel that this kind of effort is absolutely worth it, and Li is deeply grateful here." ”

Dong Huai hurriedly said: "Lord Li is polite, this is the official's business." "In fact, since Dong Huai was dismissed, if Li Xiang hadn't spoken, how could he have come out of the mountain again, at least now he is still a waiter in the Ministry of Works, and it feels very meaningful for him to do what he is doing now.

In fact, the design and manufacture of a lathe is extremely complex, and the matching tolerances of each component are extremely serious, and the shape tolerance, position tolerance, parallelism, flatness, and tolerance due to movement must be considered.

Li Xiang naturally understands these truths, but judging from the current situation, it can only be like this for the time being, and there is no requirement to make other precision workpieces at the moment. Watching Dong Huai leave with great ambition, Li Xiang fell into contemplation for a while, although Dong Huai is proficient in the casting of copper and iron, but it is estimated that most of it depends on his experience, if you want to further improve the level of technology, you must master some theoretical knowledge. In this way, with the future exhibition, each factory must have a certain number of technical personnel, but in the current situation, some relevant knowledge has not yet begun to be taught, and it is still not easy to find talents to meet the requirements.

Thinking of this, Li Xiang made another plan, he had been a little relaxed these days, but this plan will keep him busy again, this plan is that he is ready to start talking about materials, machinery, and advanced mathematics.

Li Xiang chose some table data, including the stress limit, thermal expansion coefficient, density, melting point, hardness of various materials, as well as the bending moment calculation method of various profiles, torsional stress calculation method, etc., but at present, scholars have no concept of some of these data, such as temperature and hardness. At this time, the temperature unit had not yet been determined, so Li Xiang decided to use two units, one was Celsius, which was used for daily temperature representation, and the other was absolute temperature, so as to facilitate the teaching of engineering thermodynamics, and as for the hardness unit, it was still expressed on the Mohs scale.

Li Xiang decided to start teaching machinery and materials knowledge, because these two kinds of talents are most needed in various factories. Li Xiang divides the course into three categories, one is the mechanics of materials, mainly about the force analysis of various workpieces in different situations, as well as the various stress diagrams, especially the compressive stress, tensile stress, shear stress is described in detail, and then the bending stress is divided into shear stress and normal stress to explain, and at the same time, the bending strength calculation method of various profiles is explained in detail, and finally the static indefinite problem will be talked about, but Li Xiang suddenly appears that the static indefinite problem will involve differential equations, Therefore, it was decided to postpone this part of the content and continue after the lecture on advanced mathematics.

In the mechanical and mechanism part, Li Xiang is going to talk about the crank connecting rod mechanism, gears, complex gear sets such as star gear mechanism, and then talk about the cam mechanism, and the cam shape that the circular motion is converted into linear motion, such as what shape of cam is needed for equal linear motion, and what kind of cam shape is uniform linear motion, etc.

Of course, the most important of them is the design of gears, gears are the focus of Li Xiang's story, including spur teeth, helical teeth, and vertebral gears, and worm gear mechanism should of course also be the focus. Li Xiang is the key point of the involute gear in the gear classification, especially for the part of the gear strength calculation. Because there is no sliding friction between the involute gears, that is to say, from the moment the two tooth surfaces are occluded, until they are separated again, there is no relative sliding between the tooth surfaces, and the force of the tooth surface must always be perpendicular to the tooth surface, so Li Xiang has made a very detailed analysis and explanation of the force of the tooth root and tooth top.

The material part is the subject that Li Xiang values the most, and it can even be said that the material determines everything. Without the right materials, the barrels of the new guns could not be made at all, and the strength of the bearings could not be guaranteed, let alone some machine tools. But because it is quite difficult to talk about this knowledge, mainly because some research equipment or materials were not available at that time, such as metallographic microscopes, various other rare earth metals, etc., so for this course, Li Xiang took a lot of thought when choosing the chapters, and finally decided to tell all the scholars regardless of whether there were conditions or not, as for how much they can understand, it depends on their understanding.

At the same time, Li Xiang also began to teach advanced mathematics. After a few days of lectures, Li Xiang was extremely surprised by the high comprehension ability and the speed of learning of these scholars, so much so that he later became out of control and explained all kinds of knowledge in more depth. At this time, Li Xiang had reached the limit, and the concepts of derivatives and calculus had been finished, and everyone was still unsatisfied, so he talked about the curve of the coordinates, the surface of the curvature, and the integral of the curve of the arc length.

As for some formulas such as Green's formula, Taylor's formula, Newton's Leibniz theorem, etc., Li Xiang has all changed their names, either after ancient Chinese celebrities, such as Zhang Heng's formula, Zu Chong's No. 1 theorem, or after concepts, such as the curve integral formula, and even some after himself, such as Lee's No. 12 formula, etc., completely attributed Western scholarship to Greater China. (To be continued.) )