Tool dynamic balance technology introduction (2)
In fact, the quality of a rotor balance is a dynamic concept, which is related to the speed of use. As shown in the ISO 1940 standard, a set of discrete 45° slashes marked with G values ​​on the balanced quality level diagram indicate different equilibrium quality levels, which are eper (gmm/kg) and angular velocity ω (rad/s). The product (in mm/s) is used to indicate the quality of a rotor's balance. For example, the equilibrium quality level of a rotor is G = 6.3, indicating that the product of the e value of the rotor and the value of ω when used should be less than or equal to 6.3. In use, according to the required balance quality level G and the maximum speed that the rotor can use, the allowable eper value of the rotor can be found from the figure, and then multiplied by the rotor mass to determine the allowable imbalance of the rotor. Previous page next page Needle Flame Test Apparatus,Flammability Needle Apparatus,Needle Flame Tester Machine,Needle Flame Retardant Test Equipment Dongguan Best Instrument Technology Co., Ltd , https://www.best-tester.com
The next question is how to determine the reasonable balance quality level G of the high speed rotary tool, resulting in the required Uper value at the highest use speed.
3. Reasonable balance of quality level determination
In order to determine the uniform and reasonable quality level G of the high-speed rotary tool, the working group was led by the Precision Tools Professional Committee of the German Government and Machine Manufacturers Association (VDMA), and the tool balancing technology was carried out as a “required open†project. system Research. The research team is based on relevant industry and technology areas such as tooling, machine tool and balancing machine manufacturing, user industry, universities and research institutions. Based on their research results, the guiding specification for the "High Speed ​​Rotary Tool System Balance Requirements" (FMK-Richtlinie) was proposed.
The specification has three main points:
(1) It is considered that the requirement for the tool balance quality level is a range defined by the upper limit value and the lower limit value. When the upper limit value is greater than the upper limit value, the unbalanced amount of the tool will have a negative impact on the processing, and less than the lower limit value indicates the unevenness. Too strict a measurement is technically and economically unreasonable and unnecessary.
(2) The size of the dynamic load of the spindle bearing is used as the evaluation scale of the tool balance quality, and G16 is specified as the uniform upper limit value. Due to the cutting processing conditions and the diversity of factors affecting the processing effect, the evaluation of the tool balance is not universally applicable, and the dynamic load of the spindle bearing caused by the tool imbalance is directly related to the imbalance. The parameters, therefore, the size of the dynamic load of the spindle bearing is proposed as the basis for the development of uniform balance requirements.
According to the VDI plus 56 (DIN/ISO10816) "Mechanical Vibration Evaluation Standard", the unbalance amount that causes the spindle bearing to generate the maximum vibration speed (1 to 2.8 mm/s) can be used as the upper limit of the allowable unbalance amount of the tool system. When the vibration speed of lmm/s or 2.8mm/s is used as the evaluation scale, the upper limit value (three curves b) of the equilibrium mass level G allowed for the HSK-63 shank of different weights in a certain speed range indicates that G The upper limit is related to the quality of the tool, the speed and the selected machine spindle vibration speed, and is spread over a wide range. The working group selects HSK holders with different vibration speeds of 1.2mm/S, 2mm/s, speed range 10000~40000r/min and weight 0.5～10kg, and calculates the upper limit of 27 G, of which the maximum G value is 201. The minimum G value is only 9.
Considering the safety requirements and ease of use of high-speed rotary tools, the working group proposed a compromised tool system balance level requirement, that is, G16 was selected as the uniform upper limit value, so that all the calculations could be satisfied except that one G9 value could not be satisfied. The range of processing conditions covered by the G value (ie, the rotational speed is l0000 to 40000r/min, the weight of the tool system is 0.5 to 12 kg, and the vibration speed is 2 mm/s).