It is well known that the cutting fluid in metal cutting has the functions of cooling lubrication and chip evacuation, and can obtain good processing quality and improve tool durability and productivity. However, with the total lifting rate of cutting speed and cutting power in recent years, the amount of cutting fluid is increasing and the amount of cutting fluid is increasing. + Only increase the production cost of the factory. It also pollutes the ecological environment and damages the health of workers. Therefore, dry cutting without using cutting fluid or using a small amount of plant-based lubricating rafts is an ecological environment. Effective measures to reduce production costs.
1 Dry cutting requirements for machine structure In dry cutting, there is no cooling and lubrication of the cutting fluid and chip removal. Cutting force and cutting heat increase sharply, and the use of super-hard tool materials for the appropriate coating treatment of the tool surface optimizes the geometry of the tool and reduces the cutting force with the appropriate amount of cutting. Reduce the cutting temperature. However, it is impossible to avoid the accumulation of hot chips in the cutting area and the machine. This not only destroys the cutting process, but also causes the re-cutting of the cutting to deteriorate the processed surface, and also causes the temperature rise and thermal deformation of the machine tool to be intensified, which seriously affects the processing quality and the yield. therefore. Dry cutting requires the machine; the overall layout and structure of the meter should be able to quickly remove the cut away from the work area and machine tool; and have better thermal stability and higher rigidity.
2 Overall layout characteristics of dry cutting machine tools Although the components of dry cutting machine tools are similar to wet cutting machines. It seems that in order to meet the requirements of fast chip removal, the overall layout of the machine tool still has a great change.
The workpiece is vertically inverted. The new vertical layout of the knife cutting from the bottom up or the horizontal layout of the workpiece spindle, and leaving enough space between the vertical plane of the machine column and the workpiece clamping position, so that the chips can be quickly removed by gravity away from the cutting area. At the same time, the high-speed large-capacity chip conveyor is installed in the low position of the boring, ensuring that all the chips are fast and discharged from the machine. For example, in Germany, the company 1 is a 125-high-counter boring boring machine that adopts this new vertical layout.
If the conventional vertical layout of the workpiece on the lower tool is used, the chip removal device is installed under the workpiece to assist the chip removal device commonly used in chip removal. The vacuum chip removal device uses air to blow the chip out of the cutting zone by using compressed air. , a siphon chip evacuation device that uses dry air to suck the cut shoulders.
For semi-dry cutting machines with minimal lubrication cutting cold air cutting or nitrogen cutting, a spray device cold air supply or nitrogen supply is also installed near the cutting zone to ensure that the oil mist or nitrogen can be sprayed reliably and quickly into the cutting zone.
In addition, in order to reduce and eliminate the harmful effects of dust and mist and smoke on the environment and the operator, a dust suction device should be provided to remove the shoulder dust and seal the cutting area with a fully enclosed safety shield.
3 Characteristics of mechanical structure design of dry cutting machine tools Although dry cutting machine tools are developed from wet cutting machine tools, they have higher requirements in terms of thermal stability and rigidity of quick shoulders, so their key components are also better in structural design. Big change.
3.1 Support structure characteristics The support member is the basic large part of the machine tool, and its structure should have high strength and stiffness and good vibration resistance and thermal stability. The main measures adopted by the currently produced wet cutting machine tools include the use of fully enclosed sections for castings, rational placement of internal partitions and ribs, sand-filled or filled concrete, widened guide rails, inclined bed for lathes and bed columns. Steel welded structure and thermal symmetrical structure. The support structure of the dry cutting machine tool must pay sufficient attention to the shoulder and thermal stability. The structure has the following features to ensure smooth chip removal. Lower the column height as the structure allows. For example, the hobbing machine adopts the structure of the horizontal arrangement of the workpiece spindle, and the height of the column is reduced by half, which not only facilitates smooth chip removal, but also reduces thermal deformation of the machine tool support. A shoulder groove is designed on the bed under the knife holder to ensure that the chips fall smoothly under the action of gravity into the chip conveying device under the chip flute.
Magically improves thermal insulation and reduces the amount of heat transferred by the chips to the machine components during chip removal. For the cast iron bed, a protective cover is used to protect the steep inclined wall to prevent direct contact between the chip and the machine tool casting; the chip flute is made of heat insulating material.
4 The specially designed bending-torque tubular casting bed is used, and the bed is filled with loose polymer material. In this way, not only the rigidity of the bed is good, but also the vibration absorption capacity is several times higher than that of the ordinary casting bed; or the material with small thermal expansion rate is integrally manufactured, for example, the column and the base are integrally casted with artificial granite resin concrete, and the artificial granite has low heat conduction pole. Good vibration damping characteristics The damping ratio is increased by an average of 40, 90 and no hygroscopicity, and the processing and manufacturing of castings are in full compliance with ecological requirements.
3.2 Spindle assembly structure characteristics When the machine tool is working, the spindle assembly holds the workpiece or the tool directly participates in the forming motion, and its working performance has an important influence on the processing quality and productivity. Therefore, the spindle assembly is required to have a rotation precision, a static stiffness, a high vibration resistance, a good thermal stability, and a good wear resistance. The current structure is a high-precision spindle bearing hybrid ceramic bearing static pressure or dynamic pressure bearing; the angular contact bearing adopts a paired back-to-back combined square lubrication device and a spindle constant temperature water cooling device to maintain the thermal stability of the spindle assembly; To increase rigidity and so on. In addition, the structure of the dry-cutting machine tool spindle assembly has the following characteristics: The spindle is made of a new material. For example, Japan 3, ç»», Division uses ceramic materials to manufacture the spindle, low thermal expansion rate, lighter weight than steel 60, high rigidity and precision. .
0 Using a special heat-dissipating coupling The thermal conductivity is a 1200-separated spindle motor of iron, which blocks the heat transfer from the rotor to the main shaft of the motor with large heat.
3.3 Feeding transmission mechanism and guide rail structure characteristics The feed transmission mechanism of the wet cutting machine tool is to ensure the transmission precision and working stability. In design, the principle of no gap, low friction, low inertia and high stiffness should be followed. The current structure is low. Turning to page 0, the specific structure of the corpse CNC equipment and the number of the original is not necessary to teach in this course.
5 Application In the construction of the basic course of mechanical manufacturing technology, after the preparation of the series, we first started the pilot in the 3rd class of the 97-level mechanism, and the design of the lecture experiment course was successfully opened; this year, it was carried out in class 4 of the 98-level mechanism. The pilot. The progress of the construction of this course has been improved and supplemented. Improved weaknesses. Summarized the experience. From the results of the design of the basic course of mechanical manufacturing technology in the two pilot classes. The knowledge and depth of the students' mastery achieved the expected results, and the students also reflected good. The wood course has been piloted twice. Guarantee the burden of the new program. A total of more than 10 classes for our 99-level major mechanical majors have laid a solid foundation for the smooth implementation of the teaching plan for comprehensive reform in the next year.
Xi Ning. Wang Zhongfeng and so on. Cultivate talents with new and dumb talents. 1 Chinese university teaching 200.14.
The combination guide rail 3 of the mining hall passes the first guide rail at the center position of the two side rails to eliminate the moving parts on the bed body, adopts the rolling and sliding mixed rail structure, and the guide rail adopts the rolling guide rail to ensure the movement precision is stable and reliable; The layered rectangular sliding guides reduce creep and ensure smooth motion during intermittent cutting, and improve damping and vibration suppression.
3 Linear guide rails use a guide rail slider to improve the bearing capacity of the guide rail and the rigidity of the conclusion. The dry cutting machine should be based on the existing wet cutting machine, suitable for changing the overall layout of the machine and the key component structure. .
To meet the requirements of dry cutting. before. The dry-cutting machine tool produced by many foreign countries is matched with the tool suitable for dry cutting and selects the appropriate cutting parameters. The processing quality and productivity can reach the level of wet cutting. From the perspective of sustainable development, dry-cutting machine tools will be the main trend of machine tools.
Li Liangfu. The development of the Japanese machine tool manufacturing industry and the 19th Japan Machine Tool Expo, the manufacturing technology and the machine tool Li Liangfu compiled. Cooling fluids and methods for protecting ecological safety in machining 1. World Manufacturing Technology and Equipment Market 1999.4.
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