[Electric spindle talk] The principle of selection of electric spindle

Now we will introduce the principle of selection of high-speed electric spindles in general, so as to avoid unnecessary troubles for users who do not understand the electric spindle.

High-speed electric spindles can be roughly divided into 8 categories according to the application: grinding, milling, turning, drawing, drilling, machining center, mechanical spindle (without built-in motor), belt drive spindle , special rotary test spindles, etc. Commonly used by the general users are grinding, milling, turning, machining centers, mechanical spindles (without built-in motors), belt drive spindles.

When selecting an electric spindle, be sure to pay attention to your application. The interface of different applications is different. In addition, it is necessary to understand the power requirements of the working conditions and the corresponding speed at this power. This is critical because The same is 1kW. The size of the electric spindle is quite different under the requirements of 1000 rpm and 10000 rpm. The difficulty of designing the electric spindle is also different, so the working condition must be accurate. Another reminder is that the interface of the tool must be clear. This is also a principle. Under normal circumstances, the interface speed of BT50 can only be used in the electric spindle of 8000RPM. The interface of BT40 can be used in the electric spindle of 18000RPM. For higher speeds, the tool interface needs to select the corresponding HSK high-speed tool interface. The ER spring chuck or SD spring chuck on the CNC milling motor spindle also has a certain maximum speed.

The third point: the grinding electric spindle is generally a motor designed with transverse torque. The relationship between the maximum speed of the motor and the power and voltage is proportional. The voltage and power increase linearly with the increase of the rotational speed of the electric spindle. The current is kept substantially constant. Since the relationship between torque and current is linear, the electric spindle of this type is called a constant torque motor. The design of the electric spindle is generally small, usually 80%~100% of the maximum speed. At the same time, it must also take into account the maximum allowable line speed of the grinding wheel. Therefore, it is generally not possible to use both high-speed small grinding wheels and Low-speed large grinding wheel, otherwise the effect and efficiency of large grinding wheel grinding will be relatively low due to insufficient low-speed power. In addition, due to the self-weight of the large grinding wheel itself, the high-speed electric spindle bearing is usually designed to meet the high-speed rotation, and the bearing is designed to meet the maximum speed. The requirements are mainly based on a certain degree of bearing capacity. When the large grinding wheel is used at low speed, the bearing capacity of the bearing itself cannot meet the requirements, which will lead to a sharp decrease in the life of the spindle bearing, and the precision life is greatly shortened. In addition, since the electric spindle is close to the speed, the user can completely select different products to meet different grinding requirements, so as to exert greater and better performance and efficiency potential of the electric spindle. The electric spindles for milling and machining centers are usually designed with a horizontal torque section and a constant power section to meet the cutting needs in a wide speed range. Low speed requires heavy torque and heavy cutting, and high speed requires a certain amount of precision cutting, so the electric mechanism and Grinding electric spindles and the like are quite different.

In addition, the motor parameter system of the grinding electric spindle is usually marked with S6 working system, and there are several types such as S6-40%, S6-60%, etc., which are inseparable from the working characteristics of grinding, and one workpiece during grinding. Grinding beats usually include several steps such as rapid feed, grinding, retracting, grinding wheel, etc. The power consumption of the motor is not a constant load, and we usually need to increase the overload of the electric spindle motor design. Ability, therefore, when looking at the parameters of the grinding electric spindle, you will see two sets of parameters S1 and S6. S6 is usually much higher than S1. First, it is related to the motor working system. First, it is related to the overload capability of the motor. The S6 system power indicates that the motor can be overloaded to the power system within 30s~120s for a short period of time. The long-term use can only be used according to the S1 system. This is a place that is not similar to other electric spindles. Other types of electric spindles, such as turning, milling, etc., are different from grinding electric spindles, and often require constant power speed regulation in one speed range. Users of such electric spindles often feel that its power is small, which is wrong because Its power corresponds to a relatively low rotational speed. According to the torque formula of M=9550P/n1, the torque it can output is relatively high. The purpose of designing the electric spindle is to satisfy the user within a certain range of common speeds. The electric spindle can be operated better. Another more complicated type is the electric spindle used in the machining center, usually the horizontal torque and constant power hybrid design, which is inseparable from the working mode of the machining center type electric spindle. In the low speed section, it usually refers to 1500 rpm or less. The machining center needs a large amount of cutting, the torque output is very large, and has a strong short-term overload capability, usually required to achieve 2.2 times or more. In the high speed section, it is necessary to have sufficient power to achieve constant power finishing, and it is necessary to keep the power constant with the increase of the rotational speed. With the servo controller capable of realizing several times of rated torque output in the low speed section, the ability of the machining center electric spindle to output at low speed and high torque can be better improved. In summary, the key is to look at the needs of end users. If the indicators are too high, the design difficulty and cost of the electric spindle will increase very high, resulting in unnecessary waste.

Writing this article only tells the users and potential customers of the electric spindles some basic principles, so that they can correctly request and find the products that suit them. It is not that all the electric spindles must be selected according to the above regulations. The electric spindle can also be designed with a constant power section, and the milling shaft is also designed with a transverse torque. The most important thing is: as long as it is suitable for your own needs, it is the best.

Now we will introduce the principle of selection of high-speed electric spindles in general, so as to avoid unnecessary troubles for users who do not understand the electric spindle.

High-speed electric spindles can be roughly divided into 8 categories according to the application: grinding, milling, turning, drawing, drilling, machining center, mechanical spindle (without built-in motor), belt drive spindle , special rotary test spindles, etc. Commonly used by the general users are grinding, milling, turning, machining centers, mechanical spindles (without built-in motors), belt drive spindles.

When selecting an electric spindle, be sure to pay attention to your application. The interface of different applications is different. In addition, it is necessary to understand the power requirements of the working conditions and the corresponding speed at this power. This is critical because The same is 1kW. The size of the electric spindle is quite different under the requirements of 1000 rpm and 10000 rpm. The difficulty of designing the electric spindle is also different, so the working condition must be accurate. Another reminder is that the interface of the tool must be clear. This is also a principle. Under normal circumstances, the interface speed of BT50 can only be used in the electric spindle of 8000RPM. The interface of BT40 can be used in the electric spindle of 18000RPM. For higher speeds, the tool interface needs to select the corresponding HSK high-speed tool interface. The ER spring chuck or SD spring chuck on the CNC milling motor spindle also has a certain maximum speed.

The third point: the grinding electric spindle is generally a motor designed with transverse torque. The relationship between the maximum speed of the motor and the power and voltage is proportional. The voltage and power increase linearly with the increase of the rotational speed of the electric spindle. The current is kept substantially constant. Since the relationship between torque and current is linear, the electric spindle of this type is called a constant torque motor. The design of the electric spindle is generally small, usually 80%~100% of the maximum speed. At the same time, it must also take into account the maximum allowable line speed of the grinding wheel. Therefore, it is generally not possible to use both high-speed small grinding wheels and Low-speed large grinding wheel, otherwise the effect and efficiency of large grinding wheel grinding will be relatively low due to insufficient low-speed power. In addition, due to the self-weight of the large grinding wheel itself, the high-speed electric spindle bearing is usually designed to meet the high-speed rotation, and the bearing is designed to meet the maximum speed. The requirements are mainly based on a certain degree of bearing capacity. When the large grinding wheel is used at low speed, the bearing capacity of the bearing itself cannot meet the requirements, which will lead to a sharp decrease in the life of the spindle bearing, and the precision life is greatly shortened. In addition, since the electric spindle is close to the speed, the user can completely select different products to meet different grinding requirements, so as to exert greater and better performance and efficiency potential of the electric spindle. The electric spindles for milling and machining centers are usually designed with a horizontal torque section and a constant power section to meet the cutting needs in a wide speed range. Low speed requires heavy torque and heavy cutting, and high speed requires a certain amount of precision cutting, so the electric mechanism and Grinding electric spindles and the like are quite different.

In addition, the motor parameter system of the grinding electric spindle is usually marked with S6 working system, and there are several types such as S6-40%, S6-60%, etc., which are inseparable from the working characteristics of grinding, and one workpiece during grinding. Grinding beats usually include several steps such as rapid feed, grinding, retracting, grinding wheel, etc. The power consumption of the motor is not a constant load, and we usually need to increase the overload of the electric spindle motor design. Ability, therefore, when looking at the parameters of the grinding electric spindle, you will see two sets of parameters S1 and S6. S6 is usually much higher than S1. First, it is related to the motor working system. First, it is related to the overload capability of the motor. The S6 system power indicates that the motor can be overloaded to the power system within 30s~120s for a short period of time. The long-term use can only be used according to the S1 system. This is a place that is not similar to other electric spindles. Other types of electric spindles, such as turning, milling, etc., are different from grinding electric spindles, and often require constant power speed regulation in one speed range. Users of such electric spindles often feel that its power is small, which is wrong because Its power corresponds to a relatively low rotational speed. According to the torque formula of M=9550P/n1, the torque it can output is relatively high. The purpose of designing the electric spindle is to satisfy the user within a certain range of common speeds. The electric spindle can be operated better. Another more complicated type is the electric spindle used in the machining center, usually the horizontal torque and constant power hybrid design, which is inseparable from the working mode of the machining center type electric spindle. In the low speed section, it usually refers to 1500 rpm or less. The machining center needs a large amount of cutting, the torque output is very large, and has a strong short-term overload capability, usually required to achieve 2.2 times or more. In the high speed section, it is necessary to have sufficient power to achieve constant power finishing, and it is necessary to keep the power constant with the increase of the rotational speed. With the servo controller capable of realizing several times of rated torque output in the low speed section, the ability of the machining center electric spindle to output at low speed and high torque can be better improved. In summary, the key is to look at the needs of end users. If the indicators are too high, the design difficulty and cost of the electric spindle will increase very high, resulting in unnecessary waste.

Writing this article only tells the users and potential customers of the electric spindles some basic principles, so that they can correctly request and find the products that suit them. It is not that all the electric spindles must be selected according to the above regulations. The electric spindle can also be designed with a constant power section, and the milling shaft is also designed with a transverse torque. The most important thing is: as long as it is suitable for your own needs, it is the best.