A damping coefficient testing device and method for an air-floating cylinder with eddy current damping

Abstract

The invention discloses a damping coefficient testing device for an air-floating cylinder with eddy current damping, comprising the air-floating cylinder with eddy current damping, a laser displacement sensor, a vertical mounting platform for detachably mounting the air-floating cylinder with eddy current damping and the laser displacement sensor, and an air path control system; the air-floating cylinder comprises a cylinder barrel, an air-floating piston arranged in the cylinder barrel and having a gap with the cylinder barrel, a piston rod penetrating into the air-floating piston and threadedly connected with the air-floating piston, a front end cover and a rear end cover arranged at both ends of the cylinder barrel, the piston rod is supported in the front end cover by an air bearing and having a gap between the piston rod and the air bearing, and a permanent magnet module is fixed on the air-floating piston. The damping coefficient testing method of the invention is simple and easy to implement, and the test result is accurate. An average value is taken by multiple tests to further improve the accuracy of the test result, and buffering is achieved during the falling process of the moving parts combination, thereby protecting the air-floating cylinder.

Description

Technical Field

[0001] The invention relates to the technical field of cylinders, and in particular to a damping coefficient testing device and method for an air-floating cylinder with eddy current damping. Background Art

[0002] Pneumatic technology is an engineering technology that uses compressed air as a working medium to transmit energy and signals. It is widely used in robotics, medical machinery and other fields due to its clean, pollution-free and high power-to-weight ratio. However, due to the strong nonlinear friction force of the traditional structure of the actuator cylinder, it is easy to produce a "creeping" phenomenon of stopping and starting at low speeds, which seriously affects the performance of the cylinder.

[0003] In recent years, some scholars have designed air-floating pistons of various structures based on the principle of hydrostatic gas lubrication in air bearings, and finally developed frictionless cylinders. For example, the Chinese utility model patent with application number 201721624619.5 discloses a universal double-acting air-floating frictionless cylinder, which uses an existing air bearing and a designed air-floating piston to achieve contact-free movement between the piston rod and the front end cover and between the piston and the inner wall of the cylinder barrel, thus truly achieving frictionless motion. However, although this can achieve high-precision output force servo control of the cylinder, its motion servo control accuracy is not high. This is precisely because the system has no damping, and oscillations will occur during movement.

[0004] When adding damping to the air-floating cylinder, it is necessary to consider the stability of the added damping. The use of stable eddy current damping to replace the unstable friction in the traditional cylinder can not only avoid the uncertainty of the friction between the piston and the cylinder barrel in the traditional cylinder, but also reduce the oscillation of the cylinder during movement after the frictionless state is achieved in the existing air-floating cylinder. The greater the added eddy current damping, the greater the energy loss of the cylinder, and the smaller the eddy current damping, the easier it is to oscillate in the cylinder. Therefore, when increasing the eddy current damping, it is necessary to consider the size of the eddy current damping. The size of the eddy current damping is affected by the eddy current damping coefficient and the relative motion speed between the piston and the cylinder barrel, wherein the relative motion speed between the piston and the cylinder barrel is adjusted according to work needs. Therefore, testing the size of the eddy current damping coefficient can facilitate the analysis of the working state of the cylinder. Therefore, it is very necessary to design a cylinder damping coefficient size test device. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a damping coefficient test device for an air-floating cylinder with eddy current damping. In the present invention, the air pressure above and below the moving parts assembly are equal during the falling process, and when the eddy current damping force is equal to the gravity, the uniform falling begins, and the size of the eddy current damping coefficient can be calculated by testing the speed during the uniform falling.

[0006] The technical solution adopted by the present invention is:

[0007] A damping coefficient testing device for an air-floating cylinder with eddy current damping, comprising an air-floating cylinder with eddy current damping, a laser displacement sensor, a vertical mounting platform for detachably mounting the air-floating cylinder with eddy current damping and the laser displacement sensor, and an air path control system;

[0008] The air-floating cylinder with eddy current damping comprises a cylinder barrel, an air-floating piston arranged in the cylinder barrel with a gap between the cylinder barrel, a piston rod inserted into the air-floating piston and threadedly connected to the air-floating piston, a front end cover and a rear end cover arranged at both ends of the cylinder barrel, the piston rod is supported in the front end cover by an air bearing and a gap is left between the piston rod and the air bearing, a permanent magnet module is fixed on the air-floating piston, the cylinder barrel is divided into a rod cavity and a rodless cavity containing the piston rod by the air-floating piston, the rear end cover is provided with a rodless cavity air hole connected to the rodless cavity in the cylinder barrel, the front end cover is provided with an air bearing vent connected to the air bearing, and the front end cover is also provided with a rod cavity air hole connected to the rod cavity in the cylinder barrel;

[0009] The air path control system includes an air supply device, a computer, a data acquisition card, a signal generator, a high-speed switch valve 1 and a high-speed switch valve 2 for controlling the air supply of the air bearing. The A / D end of the data acquisition card is electrically connected to the laser displacement sensor above the piston rod and is used to collect data detected by the laser displacement sensor. The data acquisition card is electrically connected to the computer, and the D / A end of the data acquisition card is electrically connected to the high-speed switch valve 1 and the high-speed switch valve 2 via the signal generator. The high-speed switch valve 2 is connected to the rodless cavity air hole on the rear end cover, and the high-speed switch valve 1 is connected to the air supply device and the air bearing vent on the front end cover.

[0010] Furthermore, a groove is provided on the inner side of the rear end of the air-floating piston, so that the piston rod and the groove form a small cavity, and throttle holes connecting the inner cavity and the gap between the air-floating piston and the cylinder are evenly provided on the circumferential wall of the air-floating piston, an axially extending internal channel 1 is provided on the circumferential wall of the air-floating piston, and a radially distributed internal channel 2 is provided on the end wall of the air-floating piston, and the internal channel 2 connects the internal channel 1 and the small cavity;

[0011] An air intake channel and an air exhaust channel which are not connected to each other are axially arranged in the piston rod. The air intake channel terminates inside the piston rod, and a radial lateral connecting hole which connects the air intake channel and the inner cavity of the air-floating piston is arranged on the piston rod. The exhaust channel axially penetrates the piston rod and is connected with the small cavity. The air-floating piston is supported by an air film which is provided from the outside and enters the gap between the air-floating piston and the cylinder barrel through the air intake channel, the inner cavity of the air-floating piston and the throttle hole.

[0012] Furthermore, the gas supply device includes an air source and an air tank, a separator and a pressure reducing valve are connected between the air source and the air tank in sequence, a pressure sensor is provided on the air tank and the pressure sensor is connected to the A / D end of the data acquisition card, the air tank is connected to a high-speed switching valve, and a filter is connected between the high-speed switching valve and the air bearing.

[0013] Furthermore, an electromagnet is arranged below the air-floating cylinder with eddy current damping, and the magnetic pole of the electromagnet is opposite to the magnetic pole of the permanent magnet module; the electromagnet is connected to an external power supply, and the on and off state of the external power supply is controlled by a computer through the D / A terminal of a data acquisition card.

[0014] Furthermore, the air circuit control system also includes a three-position four-way solenoid valve, which is connected to the high-speed switch valve 2 and the rodless cavity air hole on the rear end cover. The three-position four-way solenoid valve is electrically connected to the D / A end of the data acquisition card, and the high-speed switch valve 2 is also connected to the gas tank.

[0015] Furthermore, the end of the air-floating piston away from the piston rod can be connected to the conical cone head in a detachable connection manner.

[0016] Furthermore, the air-floating piston and the piston rod are both made of non-ferromagnetic materials; the air-floating cylinder with eddy current damping is detachably connected to the fixing plate via threaded fasteners, and the fixing plate is detachably connected to the vertical mounting platform via threaded fasteners.

[0017] A method for testing the damping coefficient of an air-floating cylinder with eddy current damping comprises the following steps:

[0018] S1. Select the air-floating cylinder with eddy current damping to be tested, remove the front cover, take out the air-floating piston, and connect the cone head to the end of the air-floating piston away from the piston rod. At the same time, measure the total mass of the piston rod, air-floating piston, permanent magnet module and cone head. m , remember that the piston rod, air-floating piston, permanent magnet module and cone head are a combination of moving parts. After the moving parts are installed in the cylinder, the front end cover is installed on the cylinder;

[0019] S2. Install the air-floating cylinder with eddy current damping on the vertical mounting table, install the laser displacement sensor just above the piston rod, so that the laser emitted by the laser displacement sensor irradiates the end face of the piston rod to monitor the position information of the piston rod, connect the air bearing vent hole to the high-speed switch valve 1, connect the rod cavity vent hole to the atmosphere, connect the rodless cavity vent hole to the high-speed switch valve 2, and set the lower threshold of the moving parts combination from the bottom end of the cylinder on the computer;

[0020] S3. Open the high-speed switch valve 1 through the computer, and ventilate the air tank into the air bearing to center the piston rod. Open the high-speed switch valve 2 to connect the rodless chamber gas to the atmosphere, that is, the rodless chamber gas pressure is equal to the atmospheric pressure. Manually pull the moving parts assembly upward until the air-floating piston is pulled to the front end cover.

[0021] S4. Manually release the moving component assembly, and the moving component assembly falls. During the falling process, the speed of the moving component assembly gradually increases, and the eddy current damping generated by the cylinder on the moving component assembly gradually increases until the eddy current damping is equal to the gravity of the moving component assembly, and then the moving component assembly begins to fall at a uniform speed. The laser displacement sensor monitors the position information of the piston rod in real time, and transmits the information to the computer in real time through the data acquisition card, so that the computer obtains the time-position information of the piston rod;

[0022] S5. When the computer calculates that the distance between the moving component assembly and the bottom end of the cylinder reaches the set threshold lower limit, the computer controls the high-speed switch valve 2 to close, the gas below the air-floating piston is compressed, and a pressure difference is generated between the gas below the air-floating piston and the gas above the air-floating piston. The moving component assembly is subjected to resistance formed by the pressure difference during its falling process, which has a buffering effect on the falling of the moving component assembly;

[0023] S6. The computer calculates the uniform motion speed when the eddy current damping and the combined gravity of the moving parts are equal based on the time-position information of the piston rod. v , according to the eddy current damping and the combined gravity of the moving parts are equal, that is mg = cv ,in c is the eddy current damping coefficient, the eddy current damping coefficient can be calculated c ;

[0024] S7. Repeat steps S1-S6 and calculate the eddy current damping coefficient c average value.

[0025] Step S5 can also be set as follows: when the computer calculates that the distance between the moving parts assembly and the bottom end of the cylinder has reached the set threshold lower limit, the computer controls the external power supply connected to the electromagnet through the D / A terminal of the data acquisition card to turn on. Since the magnetic poles of the electromagnet are opposite to the magnetic poles of the permanent magnet module, the magnetic field generated by the electromagnet will generate resistance to the falling process of the moving parts assembly, thereby buffering the falling of the moving parts assembly.

[0026] The damping coefficient test method of the air-floating cylinder with eddy current damping can also be the following steps:

[0027] S1. Select the air-floating cylinder with eddy current damping to be tested, remove its front cover, take out the air-floating piston, and connect the cone head to the end of the air-floating piston away from the piston rod. At the same time, measure the total mass of the piston rod, air-floating piston, permanent magnet module and cone head. m , remember that the piston rod, air-floating piston, permanent magnet module and cone head are a combination of moving parts. After the moving parts are installed in the cylinder, the front end cover is installed on the cylinder;

[0028] S2. Install the air-floating cylinder with eddy current damping on a vertical mounting table, install the laser displacement sensor just above the piston rod, so that the laser emitted by the laser displacement sensor irradiates the end face of the piston rod to monitor the position information of the piston rod, connect the air bearing vent to the high-speed switch valve, connect the rod cavity vent to the atmosphere, connect the rodless cavity vent to the three-position four-way solenoid valve, and set the lower threshold of the moving parts combination from the bottom end of the cylinder on the computer;

[0029] S3. Open the high-speed switch valve 1 through the computer, and the gas tank ventilates the air bearing to center the piston rod. The high-speed switch valve 2 is closed by the computer, and the B port to the T port of the three-position four-way solenoid valve are controlled to communicate, so that the gas in the rodless chamber is connected to the atmosphere, that is, the gas pressure in the rodless chamber is equal to the atmospheric pressure. The moving parts assembly is manually pulled up until the air-floating piston is pulled to the front end cover.

[0030] S4. Manually release the moving component assembly, and the moving component assembly falls. During the falling process, the speed of the moving component assembly gradually increases, and the eddy current damping generated by the cylinder on the moving component assembly gradually increases until the eddy current damping is equal to the gravity of the moving component assembly, and then the moving component assembly begins to fall at a uniform speed. The laser displacement sensor monitors the position information of the piston rod in real time, and transmits the information to the computer in real time through the data acquisition card, so that the computer obtains the time-position information of the piston rod;

[0031] S5. When the computer calculates that the distance between the moving component assembly and the bottom end of the cylinder reaches the set threshold lower limit, the computer controls the high-speed switch valve 2 to open and controls the three-position four-way solenoid valve to be adjusted to connect the B port and the P port, and fills the rodless cavity with air, so that a pressure difference is generated between the gas below the air-floating piston and the gas above the air-floating piston. The moving component assembly is subjected to resistance formed by the pressure difference during its falling process, which has a buffering effect on the falling of the moving component assembly;

[0032] S6. The computer calculates the uniform motion speed when the eddy current damping and the combined gravity of the moving parts are equal based on the time-position information of the piston rod. v , according to the eddy current damping and the combined gravity of the moving parts are equal, that is mg = cv ,in c is the eddy current damping coefficient, the eddy current damping coefficient can be calculated c ;

[0033] S7. Repeat steps S1-S6 and calculate the eddy current damping coefficient c average value.

[0034] The beneficial effects of the present invention are:

[0035] 1. The present invention provides a damping coefficient testing device for an air-floating cylinder with eddy current damping, the damping coefficient testing method thereof is simple and easy to implement, and the test result is accurate.

[0036] 2. The present invention also takes an average value through multiple tests to eliminate accidental factors and further improve the accuracy of the test results.

[0037] 3. In the test of the present invention, the high-speed switch valve 2 is closed by computer control, the gas below the air-floating piston is compressed, and a pressure difference is generated between the gas below the air-floating piston and the gas above the air-floating piston. The moving parts assembly is subjected to resistance formed by the pressure difference during the falling process, which has a buffering effect on the falling of the moving parts assembly; or the external power supply connected to the electromagnet is turned on by computer control. Since the magnetic poles of the electromagnet are opposite to the magnetic poles of the permanent magnet module, the magnetic field generated by the electromagnet will generate resistance during the falling process of the moving parts assembly, which has a buffering effect on the falling of the moving parts assembly; or the high-speed switch valve 2 is opened by computer control and the three-position four-way solenoid valve is adjusted to communicate with the B port and the P port, and the rodless cavity is inflated. A pressure difference is generated between the gas below the air-floating piston and the gas above the air-floating piston. The moving parts assembly is subjected to resistance formed by the pressure difference during the falling process, which has a buffering effect on the falling of the moving parts assembly; it plays a protective role on the air-floating cylinder with eddy current damping.

[0038] 4. In the test of the present invention, a cone head is installed at one end of the air-floating piston. During the falling process of the air-floating piston, a small amount of gas flows evenly from the gap between the air-floating piston and the cylinder under the guidance of the cone head, thereby realizing automatic centering of the air-floating piston 8 and ensuring that the air-floating piston and the cylinder are not in contact. In addition, by supplying air to the air bearing, contactless centering of the air bearing to the piston rod is realized.

[0039] 5. In the present invention, the air-floating cylinder is provided with a permanent magnet module. When the air-floating piston and the cylinder barrel move relative to each other, eddy currents will be generated in the cylinder barrel. The magnetic field generated by the eddy currents will hinder the relative movement between the air-floating piston and the cylinder barrel, that is, eddy current damping is generated. The unstable friction force in the traditional cylinder is replaced by stable eddy current damping, which can avoid the uncertainty of the friction force between the piston and the cylinder barrel in the traditional cylinder and reduce the oscillation of the cylinder during movement after the frictionless state is achieved in the existing air-floating cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the structure of the air flotation cylinder of the present invention.

[0041] Figure 2 It is a schematic diagram of the internal structure of the piston rod and the air-floating piston of the present invention.

[0042] Figure 3 It is a schematic diagram of the connection between the air-floating piston and the cone head of the present invention.

[0043] Figure 4This is a structural diagram of Embodiment 1 of the present invention.

[0044] Figure 5 This is a working principle diagram of Embodiment 1 of the present invention.

[0045] Figure 6 This is a structural diagram of Embodiment 2 of the present invention.

[0046] Figure 7 This is a working principle diagram of embodiment 3 of the present invention.

[0047] In the figure, 1, piston rod; 2, air bearing; 3, front end cover; 4, cylinder; 5, intake channel; 6, exhaust channel; 7, permanent magnet module; 8, air floating piston; 9, throttle hole; 10, rear end cover; 11, internal channel one; 12, small cavity; 13, internal channel two; 14, vertical mounting table; 15, laser displacement sensor; 16, air floating cylinder with eddy current damping; 17, fixing plate; 18, computer; 19, data acquisition card; 20, signal generator; 21, pressure sensor; 22, gas tank; 23, pressure reducing valve; 24, separator; 25, gas source; 26, high-speed switching valve one; 27, high-speed switching valve two; 28, filter; 29, cone head; 30, electromagnet; 31, three-position four-way solenoid valve; 32, rod cavity air hole; 33, rodless cavity air hole; 34, air bearing vent. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below with reference to the specific implementation modes of the accompanying drawings, but the protection scope of the present invention is not limited thereto. Embodiment 1

[0049] Combination Figure 1-3The air-floating cylinder 16 with eddy current damping comprises a cylinder barrel 4, an air-floating piston 8 arranged in the cylinder barrel 4 and having a gap with the cylinder barrel 4, a piston rod 1 inserted into the air-floating piston 8 and threadedly connected with the air-floating piston 8, a front end cover 3 and a rear end cover 10 arranged at both ends of the cylinder barrel 4, the piston rod 1 is supported in the front end cover 3 by an air bearing 2 and a gap is left between the piston rod 1 and the air bearing 2, a permanent magnet module 7 is fixed on the air-floating piston 8, and the cylinder barrel 4 is divided into a rod cavity containing the piston rod 1 and a cavity by the air-floating piston 8. The rodless cavity, the rear end cover 10 is provided with a rodless cavity air hole 33 connected with the rodless cavity in the cylinder 4, the front end cover 3 is provided with an air bearing vent 34 connected with the air bearing 2, and the front end cover 3 is also provided with a rod cavity air hole 32 connected with the rod cavity in the cylinder 4, which is used to connect the rod cavity and the atmosphere, so that the gas pressure of the rod cavity is equal to the atmospheric pressure. In order to prevent the magnetic field generated by the permanent magnet module 7 from being affected, the air floating piston 8 and the piston rod 1 are made of non-ferromagnetic materials; the permanent magnet module is fixed by the air floating piston 8 Block 7, when the air-floating piston 8 and the cylinder barrel 4 move relative to each other, eddy currents will be generated in the cylinder barrel 4, and the magnetic field generated by the eddy currents will hinder the relative movement between the air-floating piston 8 and the cylinder barrel 4, that is, eddy current damping will be generated. The magnitude of the eddy current damping is affected by the damping coefficient and the magnitude of the relative movement speed between the air-floating piston 8 and the cylinder barrel 4, and the damping coefficient is affected by the magnetic field strength of the permanent magnet module 7, and the magnetic field strength of the permanent magnet module 7 is affected by itself. The relative movement speed between the air-floating piston 8 and the cylinder barrel 4 is adjusted according to work needs. Therefore, when the damping coefficient of the eddy current damping generated between the permanent magnet module 7 and the cylinder barrel 4 is tested, the magnitude of the eddy current damping can also be calculated according to the required relative movement speed between the air-floating piston 8 and the cylinder barrel 4, which can facilitate the analysis of the working state of the air-floating cylinder 16 with eddy current damping, and replace the unstable friction in the traditional cylinder with stable eddy current damping, which can avoid the uncertainty of the friction between the piston and the cylinder barrel in the traditional cylinder, and reduce the oscillation of the cylinder during movement after the frictionless cylinder is realized in the existing air-floating cylinder.

[0050] A groove is provided on the inner side of the rear end of the air-floating piston 8, so that the piston rod 1 and the groove form a small cavity 12, and a sealing ring is provided at the connection between the piston rod 1 and the small cavity 12. A throttle hole 9 connecting the inner cavity and the gap between the air-floating piston 8 and the cylinder 4 is evenly provided on the circumferential wall of the air-floating piston 8, which is used for ventilation into the gap between the air-floating piston 8 and the cylinder 4 to form an air film. An axially extending internal channel 11 is provided on the circumferential wall of the air-floating piston 8, and a radially distributed internal channel 2 13 is provided on the end wall of the air-floating piston 8, and the internal channel 2 13 connects the internal channel 11 and the small cavity 12;

[0051] An air inlet channel 5 and an air exhaust channel 6 which are not communicated with each other are axially arranged in the piston rod 1. The air inlet channel 5 terminates inside the piston rod 1, and a radial lateral connecting hole which connects the air inlet channel 5 and the inner cavity of the air-floating piston 8 is arranged on the piston rod 1, so as to allow gas to enter the inner cavity of the air-floating piston 8. The air exhaust channel 6 axially penetrates the piston rod 1 and is communicated with the small cavity 12, and exhausts the gap between the air-floating piston 8 and the cylinder barrel 4 through the internal channel 1 11, the internal channel 2 13, the small cavity 12, and the air exhaust channel 6 in sequence. The air-floating piston 8 is provided by the outside and passes through the air inlet channel 5. The air film bearing of the air channel 5, the inner cavity of the air-floating piston 8, and the throttle hole 9 enters the gap between the air-floating piston 8 and the cylinder 4; the end of the air-floating piston 8 away from the piston rod 1 can also be connected to the conical cone head 29 by a detachable connection. During the test, the cone head 29 is first installed at one end of the air-floating piston 8. During the falling process of the air-floating piston 8, a small part of the gas flows evenly from the gap between the air-floating piston 8 and the cylinder 4 under the guidance of the cone head 29, thereby realizing automatic centering of the air-floating piston 8 and ensuring that the air-floating piston 8 and the cylinder 4 do not contact.

[0052] Figure 3 and Figure 4 The damping coefficient test device of the air-floating cylinder with eddy current damping in the first embodiment of the present invention comprises an air-floating cylinder with eddy current damping 16, a laser displacement sensor 15, a vertical mounting platform 14 for mounting the air-floating cylinder with eddy current damping 16 and the laser displacement sensor 15, and an air path control system. The air-floating cylinder with eddy current damping 16 is detachably connected to a fixing plate 17 through a threaded fastener, and the fixing plate 17 is detachably connected to the vertical mounting platform 14 through a threaded fastener, so that the air-floating cylinder with eddy current damping 16 can be detachably mounted on the vertical mounting platform 14. The vertical mounting platform 14 is provided with a mounting groove for connecting with the fixing plate 17 through a threaded fastener, and the air-floating cylinder with eddy current damping 16 can be mounted at a suitable position as required.

[0053] The air circuit control system includes an air supply device, a computer 18, a data acquisition card 19, a signal generator 20, a high-speed switch valve 1 26 and a high-speed switch valve 2 27 for controlling the air supply to the air bearing 2. The A / D end of the data acquisition card 19 is electrically connected to the laser displacement sensor 15 above the piston rod 1, and is used to collect data detected by the laser displacement sensor 15. The data acquisition card 19 is electrically connected to the computer 18. The D / A end of the data acquisition card 19 is electrically connected to the high-speed switch valve 1 26 and the high-speed switch valve 2 27 via the signal generator 20, and is used to control the high-speed switch valve 1 26 and the high-speed switch valve 2 27. The high-speed switch valve 2 27 is connected to the rodless cavity air hole 33 on the rear end cover 10, and can be used to control the entry and discharge of the rodless cavity gas in the cylinder barrel 4, so as to realize the control of the rodless cavity. Control of air pressure, a high-speed switch valve 26 connects the air supply device and the air bearing vent 34 on the front end cover 3, and is used to control the air supply state of the air bearing 2. When supplying air, the air bearing 2 can be non-contactly aligned with the piston rod 1. A filter 28 is connected between the high-speed switch valve 26 and the air bearing 2, and is used to filter the gas entering the air bearing 2 to ensure the cleanliness of the gas entering the air bearing 2. The air supply device includes an air source 25 and an air tank 22, and a separator 24 and a pressure reducing valve 23 are connected between the air source 25 and the air tank 22 in sequence. A pressure sensor 21 is provided on the air tank 22, and the pressure sensor 21 is connected to the A / D end of the data acquisition card 19, and is used for real-time detection of the air pressure in the air tank 22. The air tank 22 is connected to a high-speed switch valve 26, and is used to supply air to the air bearing 2.

[0054] The damping coefficient testing method of the air-floating cylinder with eddy current damping in the first embodiment of the present invention comprises the following steps:

[0055] S1. Select the air-floating cylinder 16 with eddy current damping to be tested, remove the front cover 3, take out the air-floating piston 8, and connect the cone head 29 to the end of the air-floating piston 8 away from the piston rod 1. At the same time, measure the total mass of the piston rod 1, the air-floating piston 8, the permanent magnet module 7 and the cone head 29. m , the piston rod 1, the air-floating piston 8, the permanent magnet module 7 and the cone head 29 are a combination of moving parts. After the moving parts are installed in the cylinder 4, the front end cover 3 is installed on the cylinder 4;

[0056] S2. Install the air-floating cylinder 16 with eddy current damping on the vertical mounting platform 14, install the laser displacement sensor 15 just above the piston rod 1, so that the laser emitted by the laser displacement sensor 15 irradiates the end face of the piston rod 1 to monitor the position information of the piston rod 1, connect the air bearing vent 34 to the high-speed switch valve 1 26, connect the rod cavity vent 32 to the atmosphere, connect the rodless cavity vent 33 to the high-speed switch valve 2 27, and set the lower threshold of the moving parts combination from the bottom end of the cylinder barrel 4 on the computer 18;

[0057] S3. The high-speed switch valve 26 is opened through the computer 18, and the gas tank 22 is ventilated to the air bearing 2, so that the piston rod 1 is centered, and the high-speed switch valve 27 is opened to connect the rodless chamber gas to the atmosphere, that is, the rodless chamber gas pressure is equal to the atmospheric pressure, and the moving parts assembly is manually pulled up until the air-floating piston 8 is pulled to the front end cover 3;

[0058] S4. Manually release the moving component assembly, and the moving component assembly falls. During the falling process, the speed of the moving component assembly gradually increases, and the eddy current damping generated by the cylinder 4 on the moving component assembly gradually increases until the eddy current damping is equal to the gravity of the moving component assembly, and then the moving component assembly begins to fall at a uniform speed. The laser displacement sensor 15 monitors the position information of the piston rod 1 in real time, and transmits the information to the computer 18 in real time through the data acquisition card 19, so that the computer 18 obtains the time-position information of the piston rod 1;

[0059] S5. In combination with the total movable stroke of the air-floating piston 8 in the cylinder 4 and the time-position information of the piston rod 1, the computer 18 can calculate the distance between the moving component assembly and the bottom end of the cylinder 4. When the computer 18 calculates that the distance between the moving component assembly and the bottom end of the cylinder 4 reaches the set threshold lower limit, the computer 18 controls the high-speed switch valve 27 to close, and the gas below the air-floating piston 8 is compressed, and a pressure difference is generated between the gas below the air-floating piston 8 and the gas above. The moving component assembly is subjected to resistance formed by the pressure difference during the falling process, which has a buffering effect on the falling of the moving component assembly;

[0060] S6. The computer 18 calculates the uniform motion speed when the eddy current damping and the combined gravity of the moving parts are equal according to the time-position information of the piston rod 1. v , according to the eddy current damping and the combined gravity of the moving parts are equal, that is mg = cv ,in c is the eddy current damping coefficient, the eddy current damping coefficient can be calculated c ;

[0061] S7. Repeat steps S1-S6 and calculate the eddy current damping coefficient c average value.

[0062] Test principle: The eddy current damping force is affected by the damping coefficient and the relative movement speed between the air-floating piston 8 and the cylinder 4. During the test, the gas pressure at the upper and lower ends of the air-floating piston 8 is equal to the atmospheric pressure, that is, the gas pressure at the upper and lower ends of the air-floating piston 8 is equal, and there is no friction between the moving component assembly and the cylinder 4 and the front end cover 3. Therefore, the moving component assembly is affected by its own gravity and damping force during the falling process. The damping force of the moving component assembly increases with the increase of the relative movement speed between the moving component assembly and the cylinder, until the moving component assembly's own gravity and the damping force are equal. At this time, the moving component assembly falls at a uniform speed, that is, mg = cv , the eddy current damping coefficient can be calculated c ; Then take the average value through multiple tests to improve the accuracy of the test results.

[0063] The total movable stroke of the air-floating piston 8 in the cylinder 4 is the length of the inner cavity of the cylinder 4 minus the total length of the air-floating piston 8, the permanent magnet module 7 and the cone head 29. By measuring the inner cavity length of the cylinder 4 and the total length of the air-floating piston 8, the permanent magnet module 7 and the cone head 29, the total movable stroke of the air-floating piston 8 in the cylinder 4 can be calculated.

[0064] During the test, the lower threshold of the moving component assembly from the bottom of the cylinder barrel 4 is set as the maximum safe distance of the moving component assembly buffer to prevent the moving component assembly from colliding with the rear end cover 10 and protect the air floating cylinder 16 with eddy current damping.

[0065] The test method is simple to operate and easy to implement, and the test results are accurate. In addition, an average value is taken through multiple tests to eliminate accidental factors and improve the accuracy of the test results. Embodiment 2

[0066] Figure 6 This is a structural schematic diagram of embodiment 2 of the present invention. On the basis of embodiment 1, an electromagnet 30 is arranged below the air-floating cylinder 16 with eddy current damping, and the magnetic poles of the electromagnet 30 are opposite to those of the permanent magnet module 7; the electromagnet 30 is connected to an external power supply, and the on and off state of the external power supply is controlled by the computer 18 through the D / A end of the data acquisition card 19; the computer 18 can control the external power supply connected to the electromagnet 30 to turn on through the D / A end of the data acquisition card 19. Since the magnetic poles of the electromagnet 30 are opposite to those of the permanent magnet module 7, the magnetic field generated by the electromagnet 30 will generate resistance to the falling process of the moving component combination, thereby achieving a buffering effect on the falling process of the moving component combination. The computer 18 can also adjust the current of the external power supply according to the time-position information of the piston rod 1, thereby adjusting the resistance generated by the electromagnet 30 to achieve a better buffering effect.

[0067] The damping coefficient testing method of the air-floating cylinder with eddy current damping in the second embodiment of the present invention is to adjust step S5 in the first embodiment to: when the computer 18 calculates that the distance between the moving component assembly and the bottom end of the cylinder 4 reaches the set threshold lower limit, the computer 18 controls the external power supply connected to the electromagnet 30 to turn on through the D / A terminal of the acquisition card 19. Since the magnetic poles of the electromagnet 30 are opposite to the magnetic poles of the permanent magnet module 7, the magnetic field generated by the electromagnet 30 will generate resistance to the falling process of the moving component assembly, thereby buffering the falling of the moving component assembly. Embodiment 3

[0068] Figure 7This is a working principle diagram of embodiment 3 of the present invention. On the basis of embodiment 1, a three-position four-way solenoid valve 31 is added to the air circuit control system. The three-position four-way solenoid valve 31 is connected to the high-speed switch valve 27 and the rodless cavity air hole 33 on the rear end cover 10. The three-position four-way solenoid valve 31 is electrically connected to the D / A terminal of the data acquisition card 19, and the high-speed switch valve 27 is also connected to the gas tank 22. When the B port and the T port of the three-position four-way solenoid valve 31 are connected, the rodless chamber of the cylinder barrel 4 is connected to the external atmosphere, so that the air pressure of the rodless chamber is equal to the atmospheric pressure; when the B port and the P port of the three-position four-way solenoid valve 31 are connected, the rodless chamber of the cylinder barrel 4 is connected to the gas tank 22 through the high-speed switch valve 27. At this time, the high-speed switch valve 27 is opened, and the rodless chamber of the cylinder barrel 4 can be inflated to increase the air pressure in the rodless chamber of the cylinder barrel 4, and then in the process of the moving parts assembly falling, the speed of the pressure difference between the upper and lower ends of the air-floating piston 8 is accelerated, so that the moving parts assembly falls faster and tends to be stable. The computer 18 can also adjust the control voltage of the high-speed switch valve 27 according to the time-position information of the piston rod 1, so as to control the flow through the high-speed switch valve 27 and achieve a better buffering effect.

[0069] The damping coefficient testing method of the air-floating cylinder with eddy current damping according to the third embodiment of the present invention comprises the following steps:

[0070] S1. Select the air-floating cylinder 16 with eddy current damping to be tested, remove its front cover 3, take out the air-floating piston 8, and connect the cone head 29 to the end of the air-floating piston 8 away from the piston rod 1. At the same time, measure the total mass of the piston rod 1, the air-floating piston 8, the permanent magnet module 7 and the cone head 29. m , the piston rod 1, the air-floating piston 8, the permanent magnet module 7 and the cone head 29 are a combination of moving parts. After the moving parts are installed in the cylinder 4, the front end cover 3 is installed on the cylinder 4;

[0071] S2. Install the air-floating cylinder 16 with eddy current damping on the vertical mounting platform 14, install the laser displacement sensor 15 just above the piston rod 1, so that the laser emitted by the laser displacement sensor 15 irradiates the end face of the piston rod 1 to monitor the position information of the piston rod 1, connect the air bearing vent 34 to the high-speed switch valve 26, connect the rod cavity vent 32 to the atmosphere, connect the rodless cavity vent 33 to the three-position four-way solenoid valve 31, and set the lower threshold of the moving parts combination from the bottom end of the cylinder barrel 4 on the computer 18;

[0072] S3. The high-speed switch valve 1 26 is opened through the computer 18, and the gas tank 22 ventilates the air bearing 2 to center the piston rod 1. The high-speed switch valve 2 27 is closed through the computer 18, and the B port to the T port of the three-position four-way solenoid valve 31 are controlled to communicate, so that the rodless chamber gas is communicated with the atmosphere, that is, the rodless chamber gas pressure is equal to the atmospheric pressure, and the moving parts assembly is manually pulled up until the air-floating piston 8 is pulled to the front end cover 3;

[0073] S4. The moving component assembly is manually released, and the moving component assembly falls. During the falling process, the speed of the moving component assembly gradually increases, and the eddy current damping generated by the cylinder 4 on the moving component assembly gradually increases until the eddy current damping is equal to the gravity of the moving component assembly, and then the moving component assembly begins to fall at a uniform speed. The laser displacement sensor 15 monitors the position information of the piston rod 1 in real time, and transmits the information to the computer 18 in real time through the data acquisition card 19, so that the computer 18 obtains the time-position information of the piston rod 1;

[0074] S5. In combination with the total movable stroke of the air-floating piston 8 in the cylinder 4 and the time-position information of the piston rod 1, the computer 18 can calculate the distance between the moving component assembly and the bottom end of the cylinder 4. When the computer 18 calculates that the distance between the moving component assembly and the bottom end of the cylinder 4 reaches the set lower threshold, the computer 18 controls the high-speed switch valve 27 to open and controls the three-position four-way solenoid valve 31 to be adjusted to communicate with the B port and the P port, and inflates the rodless cavity, so that a pressure difference is generated between the gas below the air-floating piston 8 and the gas above it. The moving component assembly is subjected to resistance formed by the pressure difference during its falling process, which has a buffering effect on the falling of the moving component assembly;

[0075] S6. The computer 18 calculates the uniform motion speed when the eddy current damping and the combined gravity of the moving parts are equal according to the time-position information of the piston rod 1. v , according to the eddy current damping and the combined gravity of the moving parts are equal, that is mg = cv ,in c is the eddy current damping coefficient, the eddy current damping coefficient can be calculated c ;

[0076] S7. Repeat steps S1-S6 and calculate the eddy current damping coefficient c average value.

[0077] The examples are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A damping coefficient test device for an air-floating cylinder with eddy current damping, characterized in that: It comprises an air-floating cylinder (16) with eddy current damping, a laser displacement sensor (15), a vertical mounting platform (14) for detachably mounting the air-floating cylinder (16) with eddy current damping and the laser displacement sensor (15), and an air path control system; The air-floating cylinder (16) with eddy current damping comprises a cylinder barrel (4), an air-floating piston (8) arranged in the cylinder barrel (4) and having a gap between the cylinder barrel (4), a piston rod (1) inserted into the air-floating piston (8) and threadedly connected to the air-floating piston (8), a front end cover (3) and a rear end cover (10) arranged at both ends of the cylinder barrel (4), the piston rod (1) being supported in the front end cover (3) through an air bearing (2) and having a gap between the piston rod (1) and the air bearing (2). A permanent magnet module (7) is fixed on the air-floating piston (8); the cylinder barrel (4) is divided into a rod chamber containing a piston rod (1) and a rodless chamber by the air-floating piston (8); a rodless chamber air hole (33) communicating with the rodless chamber in the cylinder barrel (4) is provided on the rear end cover (10); an air bearing vent (34) communicating with the air bearing (2) is provided on the front end cover (3); and a rod chamber air hole (32) communicating with the rod chamber in the cylinder barrel (4) is also provided on the front end cover (3); The air path control system comprises an air supply device, a computer (18), a data acquisition card (19), a signal generator (20), a high-speed switch valve 1 (26) and a high-speed switch valve 2 (27) for controlling the air supply of the air bearing (2); the A / D end of the data acquisition card (19) is electrically connected to a laser displacement sensor (15) above the piston rod (1) and is used to collect data detected by the laser displacement sensor (15); the data acquisition card (19) is electrically connected to the computer (18); the D / A end of the data acquisition card (19) is electrically connected to the high-speed switch valve 1 (26) and the high-speed switch valve 2 (27) via the signal generator (20); the high-speed switch valve 2 (27) is connected to the rodless cavity air hole (33) on the rear end cover (10); and the high-speed switch valve 1 (26) is connected to the air supply device and the air bearing vent (34) on the front end cover (3).

2. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 1, characterized in that: A groove is provided on the inner side of the rear end of the air-floating piston (8), so that the piston rod (1) and the groove form a small cavity (12); throttle holes (9) are evenly provided on the circumferential wall of the air-floating piston (8) to connect the inner cavity and the gap between the air-floating piston (8) and the cylinder (4); an axially extending internal channel 1 (11) is provided on the circumferential wall of the air-floating piston (8); a radially distributed internal channel 2 (13) is provided on the end wall of the air-floating piston (8); the internal channel 2 (13) connects the internal channel 1 (11) and the small cavity (12); An air intake channel (5) and an air exhaust channel (6) which are not connected to each other are axially arranged in the piston rod (1); the air intake channel (5) terminates in the interior of the piston rod (1); and a radial lateral connecting hole which connects the air intake channel (5) and the inner cavity of the air-floating piston (8) is arranged on the piston rod (1); the air exhaust channel (6) axially penetrates the piston rod (1) and is connected to the small cavity (12); the air-floating piston (8) is provided with air film support from the outside and enters the gap between the air-floating piston (8) and the cylinder barrel (4) through the air intake channel (5), the inner cavity of the air-floating piston (8) and the throttle hole (9).

3. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 1, characterized in that: The gas supply device comprises a gas source (25) and a gas tank (22), a separator (24) and a pressure reducing valve (23) are connected in sequence between the gas source (25) and the gas tank (22), a pressure sensor (21) is provided on the gas tank (22), and the pressure sensor (21) is connected to the A / D terminal of a data acquisition card (19), the gas tank (22) is connected to a high-speed switch valve (26), and a filter (28) is connected between the high-speed switch valve (26) and the air bearing (2).

4. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 1, characterized in that: An electromagnet (30) is arranged below the air-floating cylinder (16) with eddy current damping, and the magnetic pole of the electromagnet (30) is opposite to the magnetic pole of the permanent magnet module (7); the electromagnet (30) is connected to an external power supply, and the on / off state of the external power supply is controlled by a computer (18) via a D / A terminal of a data acquisition card (19).

5. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 3, characterized in that: The gas circuit control system also includes a three-position four-way solenoid valve (31), which is connected to the second high-speed switch valve (27) and the rodless cavity air hole (33) on the rear end cover (10), and the three-position four-way solenoid valve (31) is electrically connected to the D / A terminal of the data acquisition card (19), and the second high-speed switch valve (27) is also connected to the gas tank (22).

6. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 1, characterized in that: The end of the air-floating piston (8) away from the piston rod (1) can also be connected to the conical cone head (29) in a detachable connection manner.

7. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 1, characterized in that: The air-floating piston (8) and the piston rod (1) are both made of non-ferromagnetic materials; the air-floating cylinder (16) with eddy current damping is detachably connected to a fixing plate (17) via a threaded fastener, and the fixing plate (17) is detachably connected to a vertical mounting platform (14) via a threaded fastener.

8. The damping coefficient testing method of the air-floating cylinder with eddy current damping according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Select the air-floating cylinder (16) with eddy current damping to be tested, remove the front cover (3), take out the air-floating piston (8), and connect the cone head (29) to the end of the air-floating piston (8) away from the piston rod (1). At the same time, measure the total mass m of the piston rod (1), the air-floating piston (8), the permanent magnet module (7) and the cone head (29). The piston rod (1), the air-floating piston (8), the permanent magnet module (7) and the cone head (29) are recorded as a combination of moving parts. After the combination of moving parts is installed in the cylinder barrel (4), the front cover (3) is installed on the cylinder barrel (4); S2. Install the air-floating cylinder (16) with eddy current damping on the vertical mounting platform (14), install the laser displacement sensor (15) directly above the piston rod (1), so that the laser emitted by the laser displacement sensor (15) irradiates the end face of the piston rod (1) to monitor the position information of the piston rod (1), connect the air bearing vent (34) to the high-speed switch valve 1 (26), connect the rod cavity vent (32) to the atmosphere, connect the rodless cavity vent 33 to the high-speed switch valve 2 (27), and set the lower threshold of the moving parts combination from the bottom end of the cylinder barrel (4) on the computer (18); S3. Open the high-speed switch valve 1 (26) through the computer (18), ventilate the air tank (22) into the air bearing (2), center the piston rod (1), open the high-speed switch valve 2 (27), connect the rodless chamber gas to the atmosphere, that is, the rodless chamber gas pressure is equal to the atmospheric pressure, and manually pull the moving parts assembly upward until the air-floating piston (8) is pulled to the front end cover (3); S4. The moving component assembly is manually released, and the moving component assembly falls. During the falling process, the speed of the moving component assembly gradually increases, and the eddy current damping generated by the cylinder (4) on the moving component assembly gradually increases until the eddy current damping is equal to the gravity of the moving component assembly, and then the moving component assembly begins to fall at a uniform speed. The laser displacement sensor (15) monitors the position information of the piston rod (1) in real time, and transmits the information to the computer (18) in real time through the data acquisition card (19), so that the computer (18) obtains the time-position information of the piston rod (1); S5. When the computer (18) calculates that the distance between the moving component assembly and the bottom end of the cylinder (4) reaches the set threshold lower limit, the computer (18) controls the high-speed switch valve 2 (27) to close, the gas below the air-floating piston (8) is compressed, and a pressure difference is generated between the gas below the air-floating piston (8) and the gas above the air-floating piston (8). The moving component assembly is subjected to resistance formed by the pressure difference during its falling process, which has a buffering effect on the falling of the moving component assembly; S6. The computer (18) calculates the uniform motion velocity v when the eddy current damping and the combined gravity of the moving parts are equal based on the time-position information of the piston rod (1). The eddy current damping coefficient c can be calculated based on the fact that the eddy current damping and the combined gravity of the moving parts are equal, that is, mg=cv, where c is the eddy current damping coefficient; S7. Repeat steps S1-S6 and calculate the average value of the eddy current damping coefficient c.

9. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to claim 8, characterized in that: The step S5 may also be configured as follows: when the computer (18) calculates that the distance between the moving component assembly and the bottom end of the cylinder barrel (4) reaches a set threshold lower limit, the computer (18) controls the external power supply connected to the electromagnet (30) to be turned on through the D / A terminal of the data acquisition card (19); since the magnetic poles of the electromagnet (30) are opposite to the magnetic poles of the permanent magnet module (7), the magnetic field generated by the electromagnet (30) will generate resistance during the falling process of the moving component assembly, thereby playing a buffering role in the falling of the moving component assembly.

10. The damping coefficient testing device of the air-floating cylinder with eddy current damping according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Select the air-floating cylinder (16) with eddy current damping to be tested, remove its front end cover (3), take out the air-floating piston (8), and connect the cone head (29) to the end of the air-floating piston (8) away from the piston rod (1). At the same time, measure the total mass m of the piston rod (1), the air-floating piston (8), the permanent magnet module (7) and the cone head (29). The piston rod (1), the air-floating piston (8), the permanent magnet module (7) and the cone head (29) are recorded as a combination of moving parts. After the combination of moving parts is installed in the cylinder barrel (4), the front end cover (3) is installed on the cylinder barrel (4); S2. Install the air-floating cylinder (16) with eddy current damping on the vertical mounting platform (14), install the laser displacement sensor (15) directly above the piston rod (1), so that the laser emitted by the laser displacement sensor (15) irradiates the end face of the piston rod (1) to monitor the position information of the piston rod (1), connect the air bearing vent (34) to the high-speed switch valve (26), connect the rod cavity vent (32) to the atmosphere, connect the rodless cavity vent (33) to the three-position four-way solenoid valve (31), and set the lower threshold of the moving parts combination from the bottom end of the cylinder barrel (4) on the computer (18); S3. The high-speed switch valve 1 (26) is opened by the computer (18), and the gas tank (22) is ventilated into the air bearing (2) to center the piston rod (1). The high-speed switch valve 2 (27) is closed by the computer (18) and the B-T ports of the three-position four-way solenoid valve (31) are controlled to communicate with each other, so that the gas in the rodless chamber is communicated with the atmosphere, that is, the gas pressure in the rodless chamber is equal to the atmospheric pressure, and the moving parts assembly is manually pulled up until the air-floating piston (8) is pulled to the front end cover (3); S4. The moving component assembly is manually released, and the moving component assembly falls. During the falling process, the speed of the moving component assembly gradually increases, and the eddy current damping generated by the cylinder (4) on the moving component assembly gradually increases until the eddy current damping is equal to the gravity of the moving component assembly, and then the moving component assembly begins to fall at a uniform speed. The laser displacement sensor (15) monitors the position information of the piston rod (1) in real time, and transmits the information to the computer (18) in real time through the data acquisition card (19), so that the computer (18) obtains the time-position information of the piston rod (1); S5. When the computer (18) calculates that the distance between the moving component assembly and the bottom end of the cylinder (4) reaches the set threshold value, the computer (18) controls the high-speed switch valve 2 (27) to open and controls the three-position four-way solenoid valve (31) to be adjusted to connect the B port and the P port, and fills the rodless cavity with air, so that a pressure difference is generated between the gas below the air-floating piston (8) and the gas above the air-floating piston (8). The moving component assembly is subjected to resistance formed by the pressure difference during its falling process, which has a buffering effect on the falling of the moving component assembly; S6. The computer (18) calculates the uniform motion velocity v when the eddy current damping and the combined gravity of the moving parts are equal based on the time-position information of the piston rod (1). The eddy current damping coefficient c can be calculated based on the fact that the eddy current damping and the combined gravity of the moving parts are equal, that is, mg=cv, where c is the eddy current damping coefficient; S7. Repeat steps S1-S6 and calculate the average value of the eddy current damping coefficient c.

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