As we all know, the function of the guide rail pair of the machine tool is guiding and carrying, wherein the moving rail is either linear motion or rotary motion, and the linear sliding sliding guide material is usually cast iron, cast iron, cast iron-hardened casting, cast iron-hardened steel, quenching. Steel-hardened steel. The sliding guide material in our products is cast iron-hardened cast iron. Since the physical properties of the metal are determined by the static friction coefficient between the metals being greater than the dynamic friction coefficient of the metal, it is easy to cause the rail crawling phenomenon, thereby affecting the precision of the micro-feeding and the repeated walking. By eliminating the analysis of the crawling phenomenon of the guide rail, we believe that the method of reducing the grinding material is more economical than the method of using the unloading guide rail, the static pressure guide rail and the rolling friction. To this end, our factory has used the plastic coating technology of American Xiaban on several CNC lathes and MD1550 lathe guide rails, and achieved good results.
This measurement method has the characteristics of simple operation, high efficiency, high precision, and low investment by utilizing relative coordinates and its clearing function on the machine tool.
2. 'Memory tool position in CNC machining, due to workpiece size measurement, tool wear monitoring, etc., or accidents need to suspend machining in the middle, remove the tool, wait for the processing after the completion of processing, if you re-cut from the beginning Processing is obviously a waste of time. In order to reduce machining time and increase efficiency, it is often desirable to move the tool to an advanced position to continue machining. The actual fluoroplastic guide rail is a kind of soft belt. It is formed by sticking on the guide rail. It has small friction coefficient, good wear resistance, strong tear resistance, low speed creeping, good processability and chemical stability. The process is simple, low cost and the like.
2. The friction mechanism of fluoroplastic materials on metallic materials The frictional velocity characteristics of fluoroplastic materials for metallic materials are fundamentally different from those of metallic materials. As the sliding speed increases, the coefficient of friction of the fluoroplastic material also increases; while the coefficient of friction of the metal decreases with increasing speed (see, 2). For fluoroplastic materials, when the speed exceeds a certain value, the friction is close to the value. At low speeds, adhesion dominates the friction. As the speed increases, the shear rate also increases, causing the total friction to increase. In high-speed, dynamic and static friction machining, we combine this with the relative coordinates and its zeroing function. The operation steps are as follows: When the machining needs to be paused and the tool is removed, press the feed hold button on the machine operation panel and clear the relative coordinates (, ), *.
Move the tool away in the handwheel feed mode, stop the spindle rotation, and perform related processing.
After the process is completed, turn the spindle and move the tool back to the original machining position. When moving the tool, observe the change of relative coordinate value. If the tool is not replaced, when the relative coordinates are all zero, it indicates that the tool returns to the original machining position; if the tool with different length has been changed, just move the tool to when The relative coordinate* value is equal to the difference between the current tool and the previous tool length.
Go back to the automatic machining mode and press the cycle start button to continue machining.
3 Conclusion Relative coordinates can be arbitrarily cleared, making the operation convenient and flexible, so it is widely used in CNC machining. (Editing Mao Liqing) Research.
The mechanical engineers exert almost the same effect on the total friction, so that the total friction tends to stabilize. Therefore, the fluoroplastic material has a positive gradient on the friction-speed map of the metal material.
The fluoroplastic rail is composed of PTFE and bronze powder and other filling materials such as asbestos, fiberglass, graphite and lead. Since the friction coefficient between metals becomes smaller as the sliding speed increases, creeping occurs, and PTFE has excellent friction characteristics. When combined with cast iron guide rails, the friction coefficient increases with the sliding speed. It is tilted in the positive direction or remains unchanged. Therefore, the fluoroplastic guide rail does not creep when moving at low speed and micro feed.
2. Accuracy retention In general, the metal rails of the machine tool have large mutual friction and wear. Between the fluoroplastic guide rail and the hardened cast iron, since the surfaces of different hardness rub each other, the soft surface wears quickly, so the fluoroplastic guide rail is often worn first. According to material analysis and statistics, the fluoroplastic guide rail under the pressure of 0.6% Ra, when running 105m, the average wear is less than 0.01. Therefore, the life of the fluoroplastic guide rail is 3-5 times higher than that of the metal guide rail. 2. Micro-feeding position When the micro-feeding is required in the machine tool, it is difficult for the metal guide rail to reach a very precise position. Whether it is a rolling guide or a hydraulic guide rail, the floating phenomenon often occurs, and additional loads and the like are required. Means can achieve micro-feeding. The fluoroplastic guide rail has sufficient friction to prevent overtravel, and the dry and wet friction coefficients of the fluoroplastic guide rail are similar, which can prevent excessive looseness or over-slip between the guide rail pairs and achieve precise positioning.
2.% Fluoroplastic guide rail Lubricating fluoroplastic guide rail has excellent friction characteristics. When dry friction, friction coefficient /, 0.05% oil lubrication, friction coefficient /, 0.03. Therefore, regardless of lubrication, this guide rail can work normally, and can run stably. Our factory adopts the form of oil lubrication, and it has been proved that it can meet the requirements of use.
2. 'The power loss of the machine tool The wear of the fluoroplastic guide rail after loading is lower than that at no load (), thus reducing the power loss during load and absorbing some vibration caused by internal or external factors.
In the use of the machine tool, the wear of the long rail is uneven, the wear of the machine has a great influence on the precision of the machine tool, and the wear of the short rail is relatively uniform, which has little effect on the precision. Therefore, the factory adopts the plastic molding on the short rail (on the bed saddle). The way. Before the plastic molding, the roughness of the surface of the saddle is reached (a6.3~(a3.2, and should have considerable precision, pay attention to deburring. The specific steps are as follows: cleaning: use gasoline, acetone, etc. to remove the adhesive surface Dirt and oil collapse, and at the same time clean the adhesive surface of the fluoroplastic soft belt and make the adhesive surface dry.
Brushing: The binder is a bad oxygen resin solution. In order to ensure uniform adhesion when painting, the direction of the two sides of the brush should be perpendicular to each other. The thickness of the coating is solidified: after pasting the crucible, press it with a slightly heavy object on the soft belt. The back, or clamped with a special tool, to make it stick together. At room temperature, it needs to be scraped: After the paste is firm, the fluoroplastic guide rails are scraped and repaired according to the requirements of normal assembly. The thickness of the product of our factory is 1.5mm. Under normal circumstances, the scraping is 0.2-0.3mm, and the plug of 0.02mm is required. Into the rule. Every 25mmx25mm surface should be no less than 10 points, and the fluoroplastic guide surface can be at (a1.6 or above).
Oil tank processing: In the case of conditions, the oil tank can be machined by mechanical means or manually. The depth requirement of the oil tank of our factory is no more than 1mm. 4 Conclusion The fluoroplastic guide rail is an ideal material for the sliding guide of the machine tool. It is not only simple in process but also low in cost, which shortens the manufacturing cycle of the machine tool. In foreign countries, this kind of material has been widely used. I believe that with the promotion of this technology, it will be widely used in China. (Editing Li Ming) work on creation.
(Finish)
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