RU2587371C1 - High-speed motor spindle for metal cutting machines - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building. Motor spindle includes housing, spindle running in housing with possibility to run in bearings and with mandrel to tool clamping mechanism installed inside it on side of front bearing support, motor, which rotor is located on spindle shaft, and stator is in housing, stator cooling system and bearing supports to be connected to coolant supply station, vibration sensor installed in housing, and temperature sensors mounted on bearing supports. At that, it is equipped with additional temperature sensor arranged on stator, and digital control device, and cooling system is made separate for stator and bearing supports and is equipped with cooling intensity regulators for each of them. Vibration sensor is made with possibility of measuring vibration acceleration. Digital control device is connected with temperature sensors and vibration transducer, as well as with coolant feed and stator and bearing supports cooling intensity regulators.

EFFECT: higher efficiency and service life of motor spindle.

2 cl, 3 dwg, 1 tbl

Description

The invention relates to mechanical engineering, in particular to high-speed motor spindles for metal cutting machines.

Known high-speed motor spindle for machine tools, comprising a housing with a mandrel clamping tool and tool installed inside it, a spindle mounted in the housing by means of a flange for rotation in the front and rear bearing bearings, and an electric motor, the rotor of which is located on the spindle shaft, the clamping mechanism of the mandrel with the tool is installed in the spindle (patent application US 2008/080943 A1, publ. 03.04.2008).

While the structurally known motor spindle is efficient, compact and rational, it has a significant drawback - the lack of a motor cooling system and bearing assemblies, which is an important condition for its speed for a high-speed system.

The closest technical solution to the claimed object - the prototype - is a high-speed motor spindle for metal cutting machines, comprising a housing, a spindle mounted in the housing for rotation in bearing bearings and with a mandrel clamping tool with tool installed inside the front bearing support, an electric motor the rotor of which is located on the spindle shaft, and the stator is in the housing, the cooling system of the stator and bearing bearings, made with the possibility of connecting to the station for refrigerant supply mounted on the spindle motor vibration sensor and temperature sensors mounted on bearing supports (patent RF OUT №2509627, publ. 20.03.2014).

The disadvantages of the prototype include the imbalance of control and the uneven cooling of the stator and bearing bearings, limiting speed and causing a tendency to occur in the motor spindle of vibrations, which leads to a low resource and efficiency of the node as a whole.

The objective of the invention is to equip the motor spindle with a controlled cooling system of its stator and bearing bearings in order to minimize vibration.

The technical result is an increase in speed, stability, efficiency and service life of a high-speed motor spindle for metal cutting machines.

The problem is solved, and the claimed technical result is achieved by the fact that in a high-speed motor spindle for metal-cutting machines, comprising a housing, a spindle mounted in the housing for rotation in bearing bearings and with a mandrel clamping tool and tool mounted inside it from the front of the bearing support , an electric motor, the rotor of which is located on the spindle shaft, and the stator in the housing, a cooling system for the stator and bearing bearings, made with the possibility of connecting to the station and for supplying refrigerant, a vibration sensor mounted on the motor spindle and temperature sensors mounted on the bearings, the cooling system is separate for the stator and bearing bearings and includes regulators of the cooling intensity of each of them, the vibration sensor is configured to measure vibration acceleration, and the motor spindle equipped with an additional temperature sensor mounted on the stator, and a digital control device with inputs functionally connected to temperature and vibration sensors by a probe, and outputs, one of which is made with the possibility of functional connection with a station for supplying refrigerant, and the rest are functionally connected with regulators of the intensity of cooling of the stator and bearing bearings, while it is optimal for the vibration sensor to be configured to measure the amplitude of vibration.

The invention is illustrated by drawings, where

in FIG. 1 shows a structural diagram of a high-speed motor spindle for machine tools;

- in FIG. 2 is a block diagram of a stator cooling system and bearing bearings of a high-speed motor spindle for machine tools;

- in FIG. 3 is a graph of vibration (f) versus temperature (T °).

A high-speed motor-spindle for metal-cutting machine tools (VMSh) includes two blocks of subsystems: the main ones built into the VMSh, subsystems and additional subsystems serving the VMSh.

In FIG. 1 presents a structural diagram of the NMS. The main subsystems built into the VMS include an engine, spindle bearings, a position feedback sensor, a tool clamping mechanism, a spindle with basic surfaces for installing a tool, a coolant (coolant) supply subsystem with both internal and external its supplies to the cutting zone, and the diagnostic subsystem (not shown in the drawing). Additional subsystems servicing NMS include the following subsystems: engine cooling, cooling of supports, lubrication of supports, creating interference in supports, protection of supports from dust, control system (not shown in Fig. 1).

The high-speed motor spindle for machine tools (Fig. 1) contains an electric motor rotor 1, which is installed with an interference fit to transmit torque to the spindle 2. The spindle 2, together with the electric motor rotor 1 and other rotating parts, is balanced to ensure residual imbalance at which the center of gravity of the spindle shifted by no more than 1 ... 2 microns. The influence of electromagnetic fields of the engine is reduced by rings 3 of non-magnetic material, which can also be used for balancing. The stator 4 is installed in the VMSh housing 5 and is cooled when the refrigerant is supplied to the cavity of the cooling jacket 6. The cooling intensity is set by the regulator 7. Using the same system, the front and rear bearings are cooled. The double spherical angular contact ball bearings 8 and 9 serve as the front bearing support of the spindle, the interference in which is provided by the springs 10 (at high rotational speeds) and the pneumatic cylinder 11 (at lower frequencies and high loads). The tool is mounted in a mandrel 12, which is secured by a clamping mechanism 13 to the spindle, based on the connection type 14 HSK-A. The mandrel 12 is unclenched when oil under pressure is supplied to the right cavity 15 of the hydraulic cylinder 16, the movable housing of which is connected to the spindle 2 through the gripper 17. Thus, when the mandrel 12 is unstretched, the axial spring expansion force is only partially perceived by the spindle bearings. The angular position of the spindle is monitored by a Heidenhain sensor, which consists of a magnetized disk 18 mounted on the spindle and a read head 19 mounted on the housing flange. Sensors: oscillations - vibration sensor 20 and the movement of the front end 21 - sensor 22, are located in the housing VMSh. The temperature sensors of FIG. 1 are not shown. Coolant is supplied through nozzles 23 or through an opening in the rod 24 of the clamping mechanism 13.

In FIG. 2 is a block diagram of a stator cooling system and a VMSh bearing support. The system includes a stator cooling jacket 6 with a regulator 7 for its cooling intensity, a cooling jacket 25 for the front bearing support with a regulator 26 for its cooling and a jacket 27 for cooling the rear bearing bracket with a regulator 28 for its cooling intensity. To the regulators 7, 26 and 28, the refrigerant is supplied from the station 29 for supplying refrigerant. The operating parameters of the regulators 7, 26 and 28 and the station 29 are set by the digital control device 30 depending on the readings of the temperature sensors 31, 32 and 33 installed respectively on the stator, front and rear bearing bearings, and the vibration sensor 20, configured to measure vibration acceleration and mounted on the motor spindle.

High-speed motor spindle for machine tools operates as follows.

Motor spindles can be installed in horizontal, vertical and inclined positions. The VMS is integrated into the structure of the machine, so the static and dynamic characteristics must be consistent between the VMS and the headstock. When designing the headstock, the following features should be considered. The main parameters, such as engine power and torque, rotational speeds, allowable cutting forces, were assigned based on an analysis of the processing modes for steel and aluminum billets with face, long edge, end, disk mills, as well as boring, drilling and threading tools (drills, reamers, cutters and etc.). Carbide and ceramics were used as the tool material. When choosing the processing modes, the circumstance was taken into account that during acceleration above certain rotation frequencies in the conical connection of the mandrel and spindle, a gap may arise, which must be excluded. The main parameters developed in the framework of the state contract of the military school are presented in table 1.

flange; L _cor - the length of the landing diameter of the housing; L is the total length of the NMS.

The rotor 1 of the electric motor is installed with an interference fit to transmit torque to the spindle 2. The influence of electromagnetic fields of the motor is reduced by rings 3 of non-magnetic material, which can also be used for balancing. The stator 4 with the cooling jacket 6 is installed in the VMSh housing 5 and is cooled when refrigerant is supplied to the jacket. Using the same system, bearings are cooled. The front spindle bearings are double angular contact ball bearings 8 and 9, the interference of which is provided by springs 10 (at high speeds) and a pneumatic cylinder 11 (at lower frequencies and high loads). The tool is mounted in a mandrel 12, which is secured by a clamping mechanism 13 to the spindle, based on the connection type 14 HSK-A. For monitoring the condition and functioning of the tool clamping mechanism, appropriate sensors are provided. When installing and securing a new mandrel, the conical surface of the spindle is cleaned with air under pressure. The supply of cutting fluid (coolant) can be carried out in two ways: external coolant supply through nozzles mounted on the front end of the motor spindle and internal coolant supply through a rotating spindle directly into the cutting zone. In this case, coolant is supplied through the central hole in the traction of the clamping mechanism. To prevent leaks, appropriate seals are provided. The control carried out by the CNC machine tool provides the required parameters for spindle rotation, front end movement, operation of the VMSh subsystems (pneumatics, tool clamp-opener, etc.), automatic tool change, evaluation of diagnostic results, etc.

Of particular interest is the operation of the stator cooling system and the VMSh bearing bearings. VMSh operates in various modes, due to the provision of the required processing modes. It has been established that for a number of reasons, for each such regime and / or their combination (a certain rotation speed and / or a certain load, etc.), there is an optimal operating temperature at which vibration is minimal. In general, the dependence is shown in FIG. 3, which shows that the minimum vibration corresponds to a zero value of vibrational acceleration (a _f = 0, the tangent to the graph at this point is horizontal). In this case, the amplitude of vibration is less, the less factors that cause it. In our case, these factors include the uneven distribution of the thermal field in the GSM. The main sources of heat in the GSM are the stator (its heat generation is 5-20 times higher than the heat generation of the rotor) and bearing bearings. Based on this algorithm, depending on the readings of temperature sensors 31, 32, and 33 installed on the stator, front and rear bearings, respectively, the digital control device 30 sets the operating parameters (for example, the volume of refrigerant pumped, the temperature of the refrigerant) to regulators 7, 26, and 28 and station 29 so that the temperature measured by temperature sensors 31, 32 and 33 tends to equilibrium, which can be additionally recorded by reaching the minimum amplitude measured by vibration sensor 20 when supplied with the latter the ability to perform such a control function. In this case, the actual temperature value (rms temperature on the stator, front and rear bearing bearings) is set by its approximation by means of the same regulators 7, 26 and 28 and station 29 to the corresponding zero value of vibration acceleration measured by vibration sensor 20. Communication of the digital control device 30 with the station 29 is needed to provide the necessary and sufficient amount of refrigerant supplied to regulators 7, 26 and 28.

Based on the foregoing, we can conclude that the claimed design of a high-speed motor spindle for metal cutting machines allows you to control the cooling system of its stator and bearing bearings to minimize vibration, and therefore, the claimed technical result is an increase in speed, stability, efficiency and service life of high-speed spindle motor for machine tools - achieved.

The analysis of the claimed technical solution for compliance with the conditions of patentability showed that the characteristics indicated in the independent claim are interrelated with each other with the formation of a stable set of necessary attributes unknown at the priority date from the prior art sufficient to obtain the required synergistic (over-total) technical result.

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed technical solution:

- an object embodying the claimed technical solution, when implemented, relates to mechanical engineering, in particular, to high-speed motor spindles for metal cutting machines;

- for the claimed object in the form described in the independent clause of the formula below, the possibility of its implementation using the means and methods described above or known from the prior art on the priority date is confirmed;

- the object embodying the claimed technical solution, when implemented, is able to ensure the achievement of the technical result perceived by the applicant.

Therefore, the claimed subject matter meets the requirements of the patentability conditions of “novelty”, “inventive step” and “industrial applicability” under applicable law.

Claims (2)

1. High-speed motor spindle for machine tools, comprising a housing, a spindle mounted in the housing rotatably in bearing bearings and having a mandrel clamping tool with a tool mounted inside it from the front bearing support, an electric motor whose rotor is located on the spindle shaft, and stator - in the housing, a cooling system for the stator and bearing bearings, made with the possibility of connecting to the station for supplying refrigerant, a vibration sensor installed in the housing, and temperature sensors ry mounted on bearing bearings, characterized in that it is equipped with an additional temperature sensor mounted on the stator and a digital control device, while the cooling system is separate for the stator and bearing bearings and is equipped with cooling intensity controls for each of them, and the vibration sensor is made with the ability to measure vibrational acceleration, and the inputs of the digital control device are connected to the said temperature sensors and vibration sensors, and the outputs, respectively, with ntsiey for supplying the refrigerant and controls the cooling rate of the stator and bearing supports. 2. The motor spindle according to claim 1, characterized in that the vibration sensor is configured to measure the amplitude of vibrational acceleration.

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