What are the vibration and prevention of Disc Type Special Machine? The vibration generated by the working of the machine tool will not only affect the dynamic accuracy of the machine tool and the quality of the machined parts, but also reduce the production efficiency and the durability of the tool, and even reduce the performance of the machine tool when the vibration is severe, and the noise emitted by the vibration will affect the health of the machine worker.

Generally speaking, the vibration generated by the machine tool is basically two categories:

1, forced vibration;

2, self-excited vibration.

For example, on lathes, milling machines and grinders, the forced vibration of the rotary spindle system is often seen, and its frequency depends on the speed of the rotary spindle system (in milling also depends on the number of teeth of the milling cutter). There are many types of self-excited vibration that occur on the machine tool, such as the torsional or bending self-excited vibration of the rotating spindle (or the workpiece, or the tool) system; Self-excited vibration of bending or torsional pendulum of machine tool bed, column, beam and other supporting parts; There are also the relaxation friction self-excited vibration (commonly known as crawling) that occurs when moving parts such as worktables are running at low speeds.

This self-excited vibration, which is usually represented as a strong relative vibration between the tool and the workpiece in the metal cutting process, is called "flutter".

It is common for machine tools to vibrate during operation. The vibration of the machine tool not only distorts the geometry and size of the workpiece, but also leaves vibration marks on the machined surface, reducing the accuracy and surface finish, intensifying the hardening of the metal surface layer, the durability of the tool will also decline sharply during vibration, and even lead to the collapse of the blade, this problem is particularly serious for the more brittle carbide tools and ceramic tools.

After the vibration of the machine tool, it often forces the operator to reduce the cutting amount, thus limiting the productivity of the machine tool. In addition, in the machine tool automatic line, as long as a machine tool vibrates and is forced to suspend operation, it will destroy the rhythm of production and cause chaos in the production process. It can be seen that machine tool vibration is an important problem that must be paid attention to.

With the rapid development of science and technology, higher requirements are put forward for the manufacturing accuracy and surface quality of machine tool parts, so that the study of machine tool vibration has become a major issue that departments such as the development, production and use of machine tools must face. The purpose of studying machine tool vibration is to explore the causes of machine tool vibration and seek ways to prevent and eliminate machine tool vibration. To develop machine tools with better vibration resistance.

In general, enhancing the rigidity of the "machine-tool-workpiece" process elastic system is the most common way to improve the vibration resistance of the process system to prevent vibration, which can be used in any case to prevent forced vibration and self-excited vibration, and can eliminate the impact of individual impact factors that disrupt the smooth progress of the work process. Therefore, in order to improve the rigidity of the entire process system, it is obviously very important to enhance the rigidity of each link of the process system, especially the weakest link on the cutting force transmission route.

When reducing the weight of the parts will neither reduce the rigidity of the system nor cause other adverse changes in the characteristics of the system, reducing the mass of the main vibration system can improve the natural vibration frequency of the system as well as the effect of improving the stiffness of the system, thus reducing the amplitude of the vibration, that is, improving the vibration resistance of the system. It must be pointed out that increasing the damping of the vibration system, such as the appropriate adjustment of the clearance of some parts, and the use of damping vibration suppression devices, will increase the dissipation of the system on the excitation energy, so as to prevent and eliminate vibration and ensure the smooth operation of the system.

When the vibration occurs, reduce the exciting force of the excited vibration, that is, reduce the external exciting force of the forced vibration, or the internal exciting force of the self-excited vibration, often must be taken to eliminate vibration measures, for the former, such as reducing the centrifugal force caused by the imbalance of the rotating parts, the impact force generated by intermittent cutting, etc., this must be done:

1, for the speed of the parts above 600 RPM /min must be balanced, the grinding wheel on the grinder should be carefully balanced, and often corrected to maintain its correct shape, can also take automatic balancing device. The chuck and cutter head used on the machine tool should be balanced;

2, improve the stability of belt drive, chain drive, gear drive and other transmission devices. At higher speed, the main shaft is directly connected with the motor by belt or shaft joint; Adopt the most perfect belt joint, so that the stiffness and thickness changes after the connection are minimal; The triangular belt is used instead of the flat belt to make the stiffness and thickness of the triangular belt as uniform as possible. Transmission belt made of fiber; Helical or herringbone gear instead of spur gear; Install flywheel on milling machine spindle.

For high-precision low-power machine tools, try not to use gears, belts and other components that may become external vibration sources. The power source is fully isolated from the machine body, and the belt is used to drive. Appropriate adjustment of triangle belt tension, reasonable choice of belt length, so that its disturbance frequency is not close to the spindle speed. Try to make the main direction of the belt tension different parts or the main direction of the tool movement coincide to avoid the influence of the belt disturbance;

3. Improve the different coaxiality between the axis lines of each shaft connected by the coupling, remove the CAM driving the oil pump from the high-speed shaft and the spindle; For the latter, the method of changing the cutting conditions is used, such as:

(1) Select shock-proof cutting parameters. In all cases, the removal of wide and thin chips (i.e. chips cut at a large depth of cutting and a small amount of cutting) should be avoided; The cutting speed should be outside the range that is prone to vibration, that is, lower speed and higher speed are used to work;

(2) Reasonable selection of geometric parameters of the tool. The main and secondary declination angles should be as large as possible. The front Angle has a great influence on vibration, the larger the front Angle, the more stable the cutting process, so the positive front Angle should be used. The back Angle should be as small as possible, but not too small, so that there is strong friction between the back of the tool and the machining surface, especially for the small amount of cutting;

(3) The use of anti-vibration tools.

The general direction of preventing and eliminating machine tool vibration listed above does not fully summarize all possible vibration suppression measures, such as choosing a reasonable process, can greatly reduce the risk of vibration: such as avoiding machining limit diameter or limit length of the workpiece on the universal machine tool, clamping the workpiece as close to the processing as possible, so that the cutting force is close to the workpiece clamping; Turning thin-walled tubes to fill them with water, oil, or sand to improve the damping performance of the workpiece system; Improve the quality of shaft parts' center holes; Use the center frame when processing the slender shaft; A device must be provided to eliminate the gap of the drive system when milling on the milling machine; Make the cutting force and gravity in the same direction; And make the force act on the side of the guide rail without stopper iron and so on.

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