TWI649545B - Smart sensing device and smart sensing method for hydrostatic bearing - Google Patents

Abstract

The invention provides a smart sensing device for a hydrostatic bearing. The hydrostatic bearing comprises at least one fluid chamber, and the sensing device comprises at least one pressure sensor, at least one flow sensor and a control unit. The pressure sensor is disposed in the fluid chamber and senses a pressure value in the corresponding fluid chamber. The flow sensor senses the flow rate through the hydrostatic bearing. The control unit is coupled to the pressure sensor, and the control unit derives a pressure distribution in the hydrostatic bearing according to the pressure, and the control unit obtains the static and dynamic working performance of the hydrostatic bearing according to the pressure distribution. In order to respond to the industrial 4.0 and intelligent mechanical technology, the hydrostatic bearing and the smart sensing device are composed of a liquid/air static pressure spindle, a rotating platform, a thrust stop and a guide rail, etc., and can be immediately monitored and corrected in time without affecting normal operation.

Description

Smart sensing device and smart sensing method for hydrostatic bearing

The invention relates to a hydrostatic bearing, in particular to a smart sensing device and a smart sensing method for a hydrostatic bearing.

The operation of the hydrostatic bearing is mainly to feed the pressurized gas/liquid into the bearing and the bearing surface (for example, the main shaft, the guide surface, etc.) to form a gas/oil film, and to resist the pressure or the change of the gas/oil film gap. The change in force allows the mandrel to move in a state where the friction is extremely small. Due to the low frictional resistance, high rigidity and high positioning accuracy of hydrostatic bearings, hydrostatic bearings are widely used in precision machine tools.

On the other hand, in order to know the operational performance of the machine tool, the machine tool usually has a sensing device such as a cutting dynamometer. However, in the process of processing the object by the machine tool, since the sensing device such as the cutting dynamometer is directly disposed on the main shaft of the machine tool, the sensing devices may affect the processing operation, so the monitoring and correction cannot be simultaneously performed. It is even more difficult to correct the motion behavior of bearings such as the spindle. The hydrostatic bearing can provide a kind of smart sensing method, but it can make the normal operation of the processing operation one of the goals that the related fields want to achieve.

In view of the above, the object of the present invention is to provide a smart sensing device and a smart sensing method for a hydrostatic bearing, which can monitor the operation performance of the hydrostatic bearing in real time without affecting the operation of the device for loading the hydrostatic bearing. .

To achieve the above object, the present invention provides a smart sensing device for a hydrostatic bearing, the hydrostatic bearing comprising at least one fluid chamber, and the sensing device comprises at least one pressure sensor and a control unit. The pressure sensor is configured to be disposed in the fluid chamber and sense a pressure value in a corresponding fluid chamber. The control unit is coupled to the pressure sensor, and the control unit derives a pressure distribution in the hydrostatic bearing according to the pressure, and the control unit obtains an operational performance of the hydrostatic bearing according to the pressure distribution.

In another aspect, the present invention further provides a smart sensing method suitable for a hydrostatic bearing, the hydrostatic bearing comprising at least one fluid chamber, and the sensing method comprises the following steps. The pressure value within the fluid chamber is sensed. Based on this pressure, a pressure distribution within the hydrostatic bearing is derived. According to the pressure distribution, an operational performance of the hydrostatic bearing is obtained.

The sensing device is located in the fluid chamber and is not disposed on a mandrel/rail surface. The sensing device does not affect the operation of the mandrel/rail surface, so that the function of real-time monitoring processing/operation can be realized, thereby Achieved the goal of wisdom sensing, analysis and self-correction proposed by Industry 4.0.

1‧‧‧Smart sensor

10‧‧‧ Pressure Sensor

20‧‧‧Flow sensor

30‧‧‧temperature sensor

40‧‧‧Control unit

50‧‧‧Hydraulic pressure spindle system

51‧‧‧ bearing

52‧‧‧Internal space

53‧‧‧ oil inlet

55‧‧‧ fluid chamber

57‧‧‧ throttle

59‧‧‧ mandrel

S31~S37‧‧‧Steps

e ‧‧‧displacement

1 is a block diagram of components of a smart sensing device in accordance with a first preferred embodiment of the present invention.

2 and 3 are schematic views showing the application of the smart sensing device according to the second preferred embodiment of the present invention to a radial bearing of a hydrostatic spindle system.

Figure 4 is a flow chart of a smart sensing method in accordance with a second preferred embodiment of the present invention.

Figure 5 is an example of a pressure distribution scenario.

1 is a block diagram of a smart sensing device 1 according to a first preferred embodiment of the present invention, the smart sensing device 1 includes at least one pressure sensor 10, at least one flow sensor 20, A temperature sensor 30 and a control unit 40.

The pressure sensor 10 can be a piezoelectric, capacitive, electromagnetic, optical, etc. type of sensor for sensing pressure. The flow sensor 20 can be a type of sensor that senses flow, such as electromagnetic, eddy current, impeller, pressure, ultrasonic, and the like. The temperature sensor 30 can be a type of sensor for sensing temperature, such as a thermistor, a thermocouple, a resistor, or the like. The control unit 40 can be a microcontroller, a chip or other programmable general purpose or special purpose controller or the like or a combination of the above. The control unit 40 is coupled to the pressure sensor 10, the flow sensor 20, and the temperature sensor 30. The control unit 40 can perform data capture (for example, obtaining the sensors 10, 20, The sensed values of 30 (ie, pressure values, flow values, temperature values) and data analysis (eg, analysis of the sensed values).

The smart sensing device 1 is used for sensing the operational performance of a hydrostatic bearing, which may be a hydrostatic, hydrostatic or other hydrostatic spindle, radial, thrust, guide, rotation Types of bearings such as platforms, rails or flat pads. The pressure sensor 10, the flow sensor 20, the number and position of the temperature sensor 30 are adjusted depending on the type of the hydrostatic bearing. For convenience of explanation, a hydrostatic radial bearing will be exemplified below, and the remaining types of hydrostatic bearings can be deduced by analogy.

Please refer to FIGS. 2 and 3 for a schematic diagram of a smart sensing device 1 according to a second preferred embodiment of the present invention applied to a hydrostatic spindle system 50. The hydrostatic spindle system 50 includes a bearing 51 having an inner space 52, and four oil inlet holes 53 radially disposed opposite to each other and communicating with the inner space. 52 and the outside (representing the bearing 51), a four-fluid chamber 55 is disposed on the inner wall of the bearing 51 and its position corresponds to the four-inlet oil hole 53, and the four-throttle 57 is disposed in the four-inlet oil hole 53 and communicates with The four-fluid chamber 55 and a mandrel 59 are rotatably passed through the bearing 51. The smart sensing device 1 includes four pressure sensors 10 disposed in the four-fluid chamber 55 and adjacent to the outlet of the restrictor 57. The flow sensor 20 is disposed in the four-fluid chamber 55. Next to the exit of the throttle 57, the temperature sensor 30 is disposed in the inner space 52, and the control unit 40 is disposed in the bearing 51. It should be noted that, according to different design requirements, in other embodiments, the number, position and shape of the oil inlet holes 53, the fluid chambers 55, and the throttle devices 57 can be adjusted correspondingly.

The foregoing description is related to the component design of the smart sensing device 1 and the hydrostatic spindle system 50. The smart sensing method of the smart sensing device 1 will be further described below with reference to FIGS.

The pressurized hydraulic oil is supplied into the four-fluid chamber 55 through an oil supply device (not shown) that communicates with the four-inlet oil hole 53 to form an oil film. Referring to FIG. 4, in step S31, the four-pressure sensor 10 senses the pressure value in the four-fluid chamber 55 during the rotation of the bearing 51 and the mandrel 59, and the control unit 40 obtain these pressure values. At this time, the control unit 40 can also sense the flow value in the four-fluid chamber 55 through the four-flow sensor 20 .

In step S33, the control unit 40 analyzes the type of the bearing and the pressure value, and derives a pressure distribution in the bearing 51 through a Reynolds equation. The Renault equation is as follows: x is defined as the circumferential direction of the bearing 51 (as shown in Fig. 3, the circumference of the bearing 51, and defines the uppermost portion is 0°), z is defined as the axial direction of the bearing 51 (i.e., the axial direction of the bearing 51, and is defined The end of the bearing 51 is the starting point), the density of the ρ- based hydraulic oil, the pressure value of the p- based oil film, the kinematic viscosity of the η- based hydraulic oil, the h-type oil film thickness, and the U _a-type oil film on the inner wall of the bearing 51. speed direction, U _b speed based film distance h in the x direction in the inner wall of the bearing 51, V _a film-based method in the x direction of the inner wall of the bearing 51 to the velocity, V _b based on the oil film bearing 51 The inner wall is at a normal velocity in the x direction from h .

Referring to FIG. 5, the pressure distribution of the spindle shaft 59 and the displacement amount e of the bearing 51 (as shown in FIG. 3) is zero and the spindle 59 has no rotation speed, corresponding to each of the fluid chambers 55. The pressure values are roughly equal.

It is worth noting that the flow equation of small orifice throttling, capillary throttling, membrane restrictor, etc. can be derived from the Reynolds equation, and the control unit 40 can determine the flow value and the pressure value according to the sensed flow rate. Pressure distribution. It should be noted that the flow value is used to verify the pressure distribution. However, in other embodiments, if the result of the Reynolds equation has been confirmed to be correct, the flow sensor 20 may be omitted. In addition, since only four pressure sensors 10 are provided in this embodiment, the Renault equation is used to estimate the pressure distribution, and there are many calculation methods for the pressure distribution, for example, more or less pressure can be set. The sensor 10 uses a correlation formula such as an empirical formula, an interpolation method, etc. to estimate the pressure distribution.

In step S35, the control unit 40 performs on-line retrieval (via the internet, cloud, server, etc.) according to the pressure distribution and analyzes relevant data to obtain an operational performance of the hydrostatic spindle system 50. The operational performance is, for example, the bearing capacity W of the bearing 51, and the control unit 40 can integrate the pressure distribution in the corresponding axial pressure values (ie, calculate the area corresponding to each axial direction on the pressure distribution). The bearing capacity W is obtained. When the bearing force W corresponding to the specific angular interval is increased, the bearing force W of the relative angular interval is reduced, and the control unit 40 can monitor the change of the bearing force W to determine the stability of the rotation of the spindle 59. In addition, the operational performance may be the stiffness C _{L of the} hydrostatic spindle system 50, and the control unit 40 may calculate the equation of motion of the hydrostatic spindle system 50 to derive the displacement e , and according to the displacement e And the bearing capacity W gives the stiffness C _L (ie ) (spindle frequency domain characteristics). The control unit 40 can further derive an axial bearing capacity (based on the axial pressure distribution) and a radial bearing capacity (this is the bearing capacity W) according to the bearing force W. In addition to the static (steady state) characteristics described above, the control unit 40 can also perform time domain analysis to further derive dynamic characteristics such as the trajectory of the mandrel 59, flutter, and the like.

It is assumed that the hydrostatic spindle system 50 is applied to a machine tool (not shown). Since the sensors 10, 20, 30 do not affect the operation of the spindle 59, the control unit 40 can be used in the tool. The operating performance of the machine tool is monitored immediately in the normal operation of the machine. In addition, during the operation of the machine tool, the control unit 40 can also derive the radial, axial cutting force and cutting accuracy of the mandrel 59 based on the pressure distribution. On the other hand, if one end of the mandrel 59 is provided with a grinding wheel (not shown), the control unit 40 can monitor the grinding state, the degree of wear and the grinding torque of the different thickness of the grinding wheel according to the cutting force, after signal analysis and cloud The database is documented to provide recommendations for grinding parameters. Depending on the type of machining of the different machine tools, the control unit 40 can derive the characteristics of the different forces.

In addition, if the control unit 40 is coupled to the oil supply device that supplies hydraulic oil to the hydrostatic spindle system 50 and can control the operation of the oil supply device, the control unit 40 can be based on the operational performance ( For example, the pressure distribution situation, the displacement amount e, the chattering condition, the bearing force W, and the like) adjust the oil supply condition (for example, pressurizing the hydraulic oil of the specific oil inlet hole 53) to adjust the pressure distribution to adjust the bearing 51. The bearing force W, thereby correcting the operation of the hydrostatic spindle system 50 (step S37), enables the spindle 59 to rotate stably, thereby improving the cutting quality and suppressing chatter vibration. It should be noted that the hydraulic hydrostatic spindle is controlled. There are many ways in which the system 50 can operate, such as adjusting the rotational speed of the mandrel 59 by a brake device, and the like.

On the other hand, the operation of the hydrostatic spindle system 50 generally causes the temperature rise in the bearing 51, and the control unit 40 can obtain the temperature value in the bearing 51 through the temperature sensor 30, and the control unit 40 The operation of the hydrostatic spindle system 50 can be adjusted based on the temperature value to avoid temperature rise affecting overall operation. It should be noted that, in addition to the above-mentioned corrections such as cutting chattering and temperature rise, the operating states corresponding to other static and dynamic motion characteristics can be corrected according to the specifications, components and settings of the hydrostatic spindle system 50.

Based on the spirit of the foregoing invention, the hydrostatic spindle system 50 can be replaced with other hydrostatic bearings, and in principle the pressure sensors 10 are placed in the fluid chamber of the hydrostatic bearing to further evaluate the fluid chambers. The pressure distribution in the 55 and the operational performance of the hydrostatic bearing are even the dynamic characteristics of the mandrel (for example, the guide rail, the rotating platform, etc.) (for example, the relevant performance, accuracy, etc. of the bearing force dynamic characteristics). For different types of hydrostatic bearings, the inventors of the present invention are required to adjust the Reynolds equation, the fluid equation and other equations for calculating operational performance and settings for operational correction. In this way, it is possible to monitor various types of hydrostatic bearings in real time and give appropriate corrections to maintain optimal cutting and running conditions, prolong service life and reduce vibration or temperature rise, thus achieving the wisdom sensing and analysis proposed by Industry 4.0. And the goal of self-correction.

The above is only the description of the embodiments of the present invention, and is not intended to limit the scope of the present invention. Any simple structural retouching or variation that does not depart from the spirit of the present invention is still within the scope of the patent application scope of the present invention.

Claims (8)

A smart sensing device for a hydrostatic bearing, the hydrostatic bearing comprising at least one fluid chamber, and the smart sensing device comprises: at least one pressure sensor for being disposed in the fluid chamber and sensing a corresponding fluid chamber a pressure value in the chamber; and a control unit coupled to the pressure sensor, the control unit deriving a pressure distribution in the hydrostatic bearing according to the pressure, and the control unit obtains the hydrostatic bearing according to the pressure distribution An operational performance of the hydrostatic bearing further includes at least one flow sensor coupled to the control unit and disposed in the fluid chamber, the flow sensor sensing the interior of the fluid chamber The flow rate value, and the control unit obtains the pressure distribution according to the type of the bearing and the pressure value and through a Reynolds equation, and the control unit determines the pressure distribution according to the flow value and the pressure value. The smart sensing device of the hydrostatic bearing according to claim 1, wherein the hydrostatic bearing is provided with at least a throttle connected to the fluid chamber, and the pressure sensor is disposed beside the restrictor outlet. The smart sensing device of the hydrostatic bearing according to claim 1, wherein the operational performance comprises a bearing capacity, and at least one of a rigid, an axial bearing capacity and a radial bearing capacity, and the control unit is configured according to the The pressure distribution results in the bearing capacity, and the control unit derives the rigidity, the axial bearing capacity or the radial bearing capacity according to the bearing capacity, thereby obtaining the static or dynamic performance of the hydrostatic bearing. The smart sensing device of the hydrostatic bearing of claim 1, wherein the control unit is further coupled to the hydrostatic bearing, and the control unit controls the operation of the hydrostatic bearing according to the operational performance. A smart sensing method is applicable to a hydrostatic bearing, the static pressure bearing includes at least one fluid chamber, and the smart sensing method comprises: sensing a pressure value in the fluid chamber; Determining a pressure distribution in the hydrostatic bearing according to the pressure; and obtaining an operational performance of the hydrostatic bearing according to the pressure distribution; wherein the step of obtaining the operational performance of the hydrostatic bearing according to the pressure distribution comprises Having: obtaining the pressure distribution according to the type of the bearing and the pressure value and passing through a Reynolds equation; sensing the flow value in the fluid chamber; and the step of deriving the pressure distribution in the hydrostatic bearing according to the pressure includes The pressure distribution is determined based on the flow rate value and the pressure value. The smart sensing method of claim 5, wherein the operational performance comprises a bearing capacity, and the step of obtaining the operational performance of the hydrostatic bearing according to the pressure distribution comprises: obtaining the bearing capacity according to the pressure distribution . The smart sensing method of claim 6, wherein the operational performance comprises at least one of a rigid, an axial bearing capacity and a radial bearing capacity, and the operation of the hydrostatic bearing is obtained according to the pressure distribution. The step of performance comprises: determining the stiffness, the axial bearing capacity or the radial bearing capacity according to the bearing capacity; and obtaining the static or dynamic performance of the hydrostatic bearing. The smart sensing method according to claim 5, wherein after the operating performance of the hydrostatic bearing is obtained according to the pressure distribution, the method further comprises: controlling the operation of the hydrostatic bearing according to the operating performance.