Closed inner feedback type static pressure rotary table axial single oil pad experimental device

Abstract

The application discloses a closed inner feedback type hydrostatic rotary table axial single oil pad experimental device, which comprises a support, a bearing support column, a tension and pressure sensor, an oil inlet pipe, an instrument panel, an oil outlet pipe, an oil return tank, an oil circuit block, an overflow valve, an oil pump motor, an oil inlet tank, a lead screw motor, a fixing rod, a lead screw, a bearing, a nut, an upper supporting plate, an upper oil pad, a lower supporting plate, a lower oil pad, an oil sealing edge, a flow restrictor, an oil inlet cavity, an inner feedback oil return port, a working oil cavity, an inner feedback oil inlet port, an oil return cavity, a total oil inlet port, a rotary table guide rail and an oil source. Compared with other hydrostatic rotary table experimental devices, the closed inner feedback type hydrostatic rotary table axial single oil pad experimental device can provide a basis for closed inner feedback hydrostatic rotary table bearing performance research, reduces cost and is more stable.

Description

Technical Field

[0001] This invention is a closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device, belonging to the field of mechanical design and manufacturing. Background Technology

[0002] High-end CNC machine tools have become key equipment in my country's major manufacturing sectors in recent years. The requirements for various CNC machine tools are increasingly stringent in the production of parts for aerospace, shipbuilding, and energy industries. There are continuous improvements in the load-bearing capacity, machining accuracy, and long-term operational reliability of CNC machine tools. Currently, my country's CNC machine tool industry still has significant room for improvement.

[0003] Hydrostatic rotary tables are crucial components in various high-end CNC machine tools, boasting advantages such as high-precision rotation, low friction, and high load-bearing capacity, significantly outperforming traditional mechanical rotary tables. The hydrostatic oil pad, which bears the load, is one of the most critical parts of the hydrostatic rotary table. Its working principle involves using an oil pump to supply oil and various throttling methods to create a hydrostatic effect, greatly enhancing the rotary table's performance. Therefore, studying the dynamic and static characteristics of the oil pad during operation and designing a test bench is essential. Many experimental devices for hydrostatic rotary tables exist in China. Typical structures of existing hydrostatic rotary table experimental devices are described in patents published under CN102980755A and CN105458744A. While these structures allow for experimental research on the overall characteristics of the hydrostatic rotary table, the compact structure makes overall design and manufacturing difficult and costly. Therefore, from an experimental verification perspective, it is entirely possible to design an experimental device that studies only a single set of oil pads. The existing hydrostatic turntable experimental device with a throttle is described in publication number CN105424361B. This device can replace different throttles, which is convenient for studying the influence of different throttles on the load-bearing performance of the hydrostatic turntable. Unlike the above-mentioned patent, the throttle of the present invention adopts a gap throttling method located inside the oil pad and can form an internal feedback oil circuit.

[0004] This invention proposes a closed-loop, internal feedback hydrostatic turntable axial single oil pad experimental device. The study of only a single oil pad not only reduces processing and usage costs but also provides a basis for developing high-load-bearing, high-precision, and ultra-precision hydrostatic turntables. The use of a slot-throttling internal feedback oil pad structure can also significantly improve its load-bearing capacity. Furthermore, this device employs a servo motor and dual lead screws to control the oil film thickness, which not only improves experimental accuracy but also enhances the stability of the hydrostatic support system. Summary of the Invention

[0005] This invention mainly designs an experimental device for studying the load-bearing characteristics of a single set of oil pads in an axial bearing for a closed-type internal feedback hydrostatic turntable, providing a basis for theoretical research on various dynamic and static characteristics of the hydrostatic turntable during operation.

[0006] The technical problem to be solved by the present invention is achieved by the following technical solution.

[0007] A closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device. It mainly includes: a support frame 1, a bearing support column 2, a tension / compression sensor 3, an oil inlet pipe 4, an instrument panel 5, an oil outlet pipe 6, a return oil tank 7, an oil passage block 8, an overflow valve 9, an oil pump motor 10, an oil inlet tank 11, a lead screw motor 12, a fixing rod 13, a lead screw 14, a bearing 15, a nut 16, an upper support plate 17, an upper oil pad 18, a lower support plate 19, a lower oil pad 20, an oil sealing edge 21, a throttle 22, an oil inlet chamber 23, an internal feedback return oil port 24, a working oil chamber 25, an internal feedback oil inlet 26, a return oil chamber 27, a main oil inlet 28, a turntable guide rail 29, and an oil source 30. This device mainly consists of a hydrostatic support system and an oil supply system.

[0008] Connections between the various parts that make up the device:

[0009] The hydrostatic support system is as follows Figure 1 As shown, it mainly includes: bracket 1, bearing support 2, tension / compression sensor 3, lead screw motor 12, fixing rod 13, lead screw 14, bearing 15, nut 16, upper support plate 17, upper oil pad 18, lower support plate 19, and lower oil pad 20. Bracket 1 serves as the overall connector and must have high strength to ensure the stable operation of the entire support system. The bracket 1 is mounted on top of the oil supply system via bearing support 2. A tension / compression sensor 3 is installed between the top of the oil supply system and the bottom of the bracket 1. The lead screw motor 12 is fixed on the bracket 1 and connected to the lead screw 14 to control its rotation. The upper support plate 17 and lower support plate 19 are mounted on the lead screw 14, which drives them to move up and down. There are two sets of lead screws 14 and lead screw motors 12, symmetrically arranged on both sides of the upper support plate 17 and lower support plate 19, respectively controlling their up and down movement. The upper support plate 17 and lower support plate 19 are fixed together by a fixing rod 13 and a nut 16. The upper oil pad 18 and lower oil pad 20 are sandwiched between the bearing 15 and the upper and lower support plates 17 and 19, providing static pressure support. The tension / compression sensor 3 is used to measure the load-bearing capacity of the static pressure support system.

[0010] The oil supply system includes an oil inlet pipe 4, an oil outlet pipe 6, a return oil tank 7, an oil circuit block 8, an overflow valve 9, an oil pump motor 10, and an oil inlet tank 11. The oil supply system mainly supplies oil through an oil pump; the oil pump supply pipe is equipped with an overflow valve 9, which controls the oil supply pressure or flow rate; then, through the oil circuit block 8 integrating various controllers, sensors, etc.; the oil is transported to the hydrostatic support system through the oil inlet pipe 4; from the return oil port of the hydrostatic support system, it flows back to the return oil tank 7 through the oil outlet pipe 6; the oil pump is driven by the oil pump motor 10, and the oil pump is connected to the oil inlet tank 11.

[0011] Furthermore, the oil supply system is divided into quantitative oil supply and constant pressure oil supply. The first type uses a separate oil pump for each oil pad to maintain a quantitative oil supply, or uses a single oil pump but a flow control valve for each oil pad to maintain a quantitative oil supply. Each oil pad works independently and does not affect the others. The second type, constant pressure oil supply, uses a single oil pump to directly supply oil to multiple oil pads. When the oil pad with the smallest load is working, the working pressure of the oil pump will not increase further. To allow the oil pump pressure to continue to rise, a liquid resistor, also called a throttle, is installed in the oil line with the smallest load. When the oil flows through the liquid resistor, a pressure drop occurs, thus forcing the oil pump's supply pressure to exceed the pressure required by the oil chamber. This device uses a constant pressure oil supply method, and the throttle is located inside the oil pad, employing a slit throttle 22.

[0012] The hydrostatic support system operates as follows: In the initial state, the upper support plate 17 and the lower support plate 19 are tightly attached to the upper oil pad 18 and the lower oil pad 20, respectively. In this state, excluding the weight of the mechanism itself, the reading of the tension / compression sensor should be 0. Then, the height of the upper support plate 17 and the lower support plate 19 is adjusted by rotating the lead screw 14 via the servo motor 12 to simulate the load-bearing performance of the turntable under different conditions. Generally, the oil film thickness between the support plate and the oil pad is about 0.03mm, so the precision requirements for the servo motor 12 and the lead screw 14 are very high. After adjusting the upper and lower support plates to a certain position, the support plates are fixed by the fixing rod 13 and its nut 16 to ensure that the support plates do not experience axial displacement and can withstand a certain load without bending or deformation. After fixing, oil can be supplied to the oil inlet by the oil pump for testing. When the thickness of the upper and lower oil films is different, a pressure difference will be generated, which can be reflected by the reading of the tension / compression sensor.

[0013] The main working principle of the slit throttle is as follows: Figure 2As shown, firstly, hydraulic oil from a certain oil source, supplied at a constant pressure, enters the oil inlet chamber 23 of one of the oil pads through the oil inlet 28 of the bearing; after passing through two gaps, a certain pressure drop occurs, and the oil enters the return oil chamber 27, then flows from the internal feedback return oil port 24 to the working oil chamber 25 of the opposite oil pad. In other words, the pressure in the upper working oil chamber is obtained by throttling the oil supplied by the oil pump through the throttle of the lower oil chamber, and the pressure in the lower working oil chamber is obtained by throttling the oil supplied by the oil pump through the throttle of the upper oil chamber.

[0014] The internal feedback hydrostatic support shown works on the following principle: Hydraulic oil at constant pressure flows through two channels: one channel is throttled by a throttle located in the upper oil chamber and then flows into the lower oil chamber; the other channel is throttled by a throttle located in the lower oil chamber and then flows into the upper oil chamber. When the turntable surface is subjected to a downward force w, a clearance change Δh will occur. At this time, on the one hand, due to the increased gap in the lower oil chamber, the sealing edge fluid resistance decreases, i.e., the outlet fluid resistance decreases, causing the oil chamber pressure to decrease. On the other hand, the throttle device arranged in the upper oil chamber to control the lower oil chamber has an increased throttling edge fluid resistance due to the smaller gap. At this time, for the lower oil chamber, the upper oil chamber controls the inlet fluid resistance of the lower oil chamber. Due to the increased pressure loss from fluid resistance during throttling, the pressure entering the lower oil chamber becomes even smaller, thus playing a feedback role. Similarly, on the other hand, due to the smaller gap in the upper oil chamber, the sealing edge fluid resistance increases, i.e., the outlet fluid resistance increases, causing the oil chamber pressure to increase. At the same time, the throttle device arranged in the lower oil chamber to control the upper oil chamber has an increased gap, causing the throttling edge fluid resistance. At this time, for the upper oil chamber, the lower oil chamber controls the inlet fluid resistance of the upper oil chamber. Due to the decreased pressure loss from fluid resistance during throttling (which can also be understood as a decrease in pressure drop), the pressure entering the upper oil chamber becomes even larger, thus playing a feedback role.

[0015] Compared to other hydrostatic turntable experimental setups, the advantages of this invention are:

[0016] 1. This device is a closed-loop internal feedback hydrostatic turntable axial single oil pad test device, which can provide a basis for the study of the load-bearing performance of closed-loop internal feedback hydrostatic turntables.

[0017] 2. The turntable model has been simplified, focusing only on one set of oil pads, eliminating the need to build the entire hydrostatic turntable and significantly reducing costs.

[0018] 3. The oil film thickness of this device is more flexible to adjust, and the oil pad is also detachable, making it more experimental; moreover, this device does not need to bear heavy objects, but simulates the bearing state by changing the thickness of the upper and lower oil films, which reduces the requirements for materials.

[0019] 4. This device adjusts the oil film thickness through a servo motor, reducer, and lead screw, resulting in higher precision; moreover, the upper and lower support plates are reinforced for enhanced stability. Attached Figure Description

[0020] Figure 1 This is a structural diagram of an axial single oil pad experimental device for a closed-type internal feedback hydrostatic turntable.

[0021] Figure 2 This is a diagram of the oil pad structure;

[0022] Figure 3 This is a schematic diagram of the internal feedback principle.

[0023] Figure 4 This is a diagram of the internal oil circuit of the bearing. (a) is section AA, (b) is section BB, and (c) is section CC. Detailed Implementation

[0024] The following is a combination of structural appendix Figure 1 , Figure 2 , Figure 3 , Figure 4 This device will be described in further detail.

[0025] A closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device. It mainly includes: a support frame 1, a bearing support column 2, a tension / compression sensor 3, an oil inlet pipe 4, an instrument panel 5, an oil outlet pipe 6, a return oil tank 7, an oil passage block 8, an overflow valve 9, an oil pump motor 10, an oil inlet tank 11, a lead screw motor 12, a fixing rod 13, a lead screw 14, a bearing 15, a nut 16, an upper support plate 17, an upper oil pad 18, a lower support plate 19, a lower oil pad 20, an oil sealing edge 21, a throttle 22, an oil inlet chamber 23, an internal feedback return oil port 24, a working oil chamber 25, an internal feedback oil inlet 26, a return oil chamber 27, a main oil inlet 28, a turntable guide rail 29, and an oil source 30. This device mainly consists of a hydrostatic support system and an oil supply system.

[0026] Connections between the various parts that make up the device:

[0027] The hydrostatic support system is as follows Figure 1 As shown, the system mainly includes: a bracket 1, a bearing support column 2, a tension / compression sensor 3, a lead screw motor 12, a fixing rod 13, a lead screw 14, a bearing 15, a nut 16, an upper support plate 17, an upper oil pad 18, a lower support plate 19, and a lower oil pad 20. The bracket 1 serves as the overall connector and must have high strength to ensure the stable operation of the entire support system. The lead screw motor 12 is fixed to the bracket 1 and controls the rotation of the lead screw 14, thereby driving the support plate to move up and down. There are two lead screws and motors on the left and right sides, respectively controlling the up and down movement of the upper support plate 17 and the lower support plate 19. The fixing rod 13 and the nut 16 are mainly used to fix the upper and lower support plates. The upper oil pad 18 and the lower oil pad 20 are sandwiched between the bearing 15 and the upper and lower support plates, providing the main static pressure support. The tension / compression sensor 3 is used to measure the load-bearing capacity.

[0028] The oil supply system mainly includes an inlet pipe 4, an instrument panel 5, an outlet pipe 6, a return oil tank 7, an oil circuit block 8, an overflow valve 9, an oil pump motor 10, and an inlet tank 11. The oil supply system primarily supplies oil through an oil pump; then, the overflow valve 9 controls the oil supply pressure or flow rate; next, the oil passes through the oil circuit block 8, which integrates various controllers and sensors; the oil is then transported to the hydrostatic support system through the inlet pipe; finally, the oil flows back to the return oil tank 7 from the return port in the support device via the outlet pipe 6. The oil supply system is divided into quantitative oil supply and constant pressure oil supply. The first type uses a separate oil pump for each oil pad to maintain a quantitative oil supply, or uses a single oil pump but a flow control valve for each oil pad to maintain a quantitative oil supply. In this way, each oil pad works independently without affecting the others. The second type, constant pressure oil supply, uses a single oil pump to directly supply oil to multiple oil pads. When the oil pad with the smallest load is working, the working pressure of the oil pump no longer increases. To allow the oil pump pressure to continue rising, a liquid resistor, also called a throttle, is installed in the oil circuit with low load. When the oil flows through the liquid resistor, a pressure drop occurs, thus forcing the oil pump to supply oil pressure greater than the pressure required by the oil chamber. This device uses a constant pressure oil supply method, and the throttle is located inside the oil gasket, employing a slit throttle 22.

[0029] The hydrostatic support system operates as follows: In the initial state, the upper support plate 17 and the lower support plate 19 are tightly attached to the upper oil pad 18 and the lower oil pad 20, respectively. In this state, excluding the weight of the mechanism itself, the reading of the tension / compression sensor should be 0. Then, the height of the upper and lower support plates is adjusted by rotating the lead screw 14 via the servo motor 12 to simulate the load-bearing capacity of the turntable under different conditions. Generally, the oil film thickness between the support plate and the oil pad is approximately 0.03 mm, so the precision requirements for the servo motor 12 and the lead screw 14 are very high. After adjusting the upper and lower support plates to a certain position, the support plates are fixed by the fixing rod 13 and its nut 16 to ensure that the support plates do not experience axial displacement and can withstand a certain load without bending or deformation. After fixing, oil can be supplied to the oil inlet by the oil pump for testing. When the thickness of the upper and lower oil films is different, a pressure difference will be generated, which can be reflected by the reading of the tension / compression sensor.

[0030] The main working principle of the slit throttle is as follows: Figure 2 As shown, firstly, hydraulic oil from a certain oil source, supplied at a constant pressure, enters the oil inlet chamber 23 of one of the oil pads through the oil inlet 28 of the bearing; after passing through two gaps, a certain pressure drop occurs, and the oil enters the return oil chamber 27, then flows from the internal feedback return oil port 24 to the working oil chamber 25 of the opposite oil pad. In other words, the pressure in the upper working oil chamber is obtained by throttling the oil supplied by the oil pump through the throttle of the lower oil chamber, and the pressure in the lower working oil chamber is obtained by throttling the oil supplied by the oil pump through the throttle of the upper oil chamber.

[0031] The internal feedback hydrostatic support shown works on the following principle: Hydraulic oil at constant pressure flows through two channels: one channel is throttled by a throttle located in the upper oil chamber and then flows into the lower oil chamber; the other channel is throttled by a throttle located in the lower oil chamber and then flows into the upper oil chamber. When the turntable surface is subjected to a downward force w, a clearance change Δh will occur. At this time, on the one hand, due to the increased gap in the lower oil chamber, the sealing edge fluid resistance decreases, i.e., the outlet fluid resistance decreases, causing the oil chamber pressure to decrease. On the other hand, the throttle device arranged in the upper oil chamber to control the lower oil chamber has an increased throttling edge fluid resistance due to the smaller gap. At this time, for the lower oil chamber, the upper oil chamber controls the inlet fluid resistance of the lower oil chamber. Due to the increased pressure loss from fluid resistance during throttling, the pressure entering the lower oil chamber becomes even smaller, thus playing a feedback role. Similarly, on the other hand, due to the smaller gap in the upper oil chamber, the sealing edge fluid resistance increases, i.e., the outlet fluid resistance increases, causing the oil chamber pressure to increase. At the same time, the throttle device arranged in the lower oil chamber to control the upper oil chamber has an increased gap, causing the throttling edge fluid resistance. At this time, for the upper oil chamber, the lower oil chamber controls the inlet fluid resistance of the upper oil chamber. Due to the decreased pressure loss from fluid resistance during throttling (which can also be understood as a decrease in pressure drop), the pressure entering the upper oil chamber becomes even larger, thus playing a feedback role.

[0032] Compared to other hydrostatic turntable experimental setups, the advantages of this invention are:

[0033] 1. This device is a closed-loop internal feedback hydrostatic turntable axial single oil pad test device, which can provide a basis for the study of the load-bearing performance of closed-loop internal feedback hydrostatic turntables.

[0034] 2. The turntable model has been simplified, focusing only on one set of oil pads, eliminating the need to build the entire hydrostatic turntable and significantly reducing costs.

[0035] 3. The oil film thickness of this device is more flexible to adjust, and the oil pad is also detachable, making it more experimental; moreover, this device does not need to bear heavy objects, but simulates the bearing state by changing the thickness of the upper and lower oil films, which reduces the requirements for materials.

[0036] 4. This device adjusts the oil film thickness through a servo motor, reducer, and lead screw, resulting in higher precision; moreover, the upper and lower support plates are reinforced for enhanced stability.

Claims

1. A closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device, characterized in that, Including hydrostatic support system and oil supply system; The hydrostatic support system includes: a bracket, a bearing support column, a tension / compression sensor, a lead screw motor, a fixing rod, a lead screw, a bearing, a nut, an upper support plate, an upper oil pad, a lower support plate, and a lower oil pad. The bracket is installed on top of the oil supply system via the bearing support column, and a tension / compression sensor is installed between the top of the oil supply system and the bottom of the bracket. The lead screw motor is fixed to the bracket and connected to the lead screw to control its rotation. The upper and lower support plates are installed on the lead screw, which drives the upper and lower support plates to move up and down. There are two sets of lead screws and lead screw motors, symmetrically arranged on both sides of the upper and lower support plates, respectively controlling their up and down movement. The upper and lower support plates are fixed together by the fixing rod and the nut. The upper and lower oil pads are sandwiched between the bearing and the upper and lower support plates, respectively, providing hydrostatic support. The tension / compression sensor is used to measure the load-bearing capacity of the hydrostatic support system. The oil supply system includes an oil inlet pipe, an oil outlet pipe, a return oil tank, an oil circuit block, an overflow valve, an oil pump motor, and an oil inlet tank. The oil supply system supplies oil through an oil pump. An overflow valve is installed on the oil pump supply pipe to control the oil supply pressure or flow rate. The oil then passes through an oil circuit block integrating various controllers and sensors. The oil is delivered to the hydrostatic support system through the oil inlet pipe. The oil flows back to the return oil tank from the return port of the hydrostatic support system through the oil outlet pipe. The oil pump is driven by an oil pump motor and is connected to the oil inlet tank. The hydrostatic support system operates as follows: In the initial state, the upper support plate and the lower support plate are tightly attached to the upper oil pad and the lower oil pad, respectively; the height of the upper support plate and the lower support plate is adjusted by rotating the lead screw of the servo motor to simulate the load-bearing performance of the turntable under different conditions; after the upper and lower support plates are adjusted to a certain position, the support plates are fixed by the fixing rod and the nut on it, and oil is supplied to the oil inlet by the oil pump for the experiment; when the thickness of the upper and lower oil films is different, a pressure difference will be generated, and the pressure difference is reflected by the reading of the tension and compression sensor.

2. The closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device according to claim 1, characterized in that, The oil supply system uses a constant pressure oil supply method, and a gap throttle is used in the oil pad.

3. The closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device according to claim 2, characterized in that, The working process of the gap throttle is as follows: First, a certain oil source, with hydraulic oil at a constant pressure, enters the oil inlet chamber of one of the oil pads through the oil inlet of the bearing; after passing through two gaps, a certain pressure drop is generated, and the oil enters the return oil chamber, and goes to the working oil chamber of the opposite oil pad from the internal feedback return oil port; that is to say, the pressure of the upper working oil chamber is obtained by the oil pump supplying oil through the throttle of the lower oil chamber, and the pressure of the lower working oil chamber is obtained by the oil pump supplying oil through the throttle of the upper oil chamber.

4. The closed-loop internal feedback hydrostatic turntable axial single oil pad experimental device according to claim 3, characterized in that, Hydraulic oil at constant pressure flows through two channels: one channel, throttled by a throttle located in the upper oil chamber, flows into the lower oil chamber; the other channel, throttled by a throttle located in the lower oil chamber, flows into the upper oil chamber. When the turntable surface is subjected to a downward force w, a force Δh will be generated. The gap changes; as the gap in the lower oil chamber increases, the hydraulic resistance at the sealing edge decreases, meaning the hydraulic resistance at the outlet decreases, causing the oil chamber pressure to decrease. Simultaneously, the throttle valve in the upper oil chamber, used to control the lower oil chamber, experiences a decrease in gap, increasing the hydraulic resistance at the throttling edge. For the lower oil chamber, the upper oil chamber controls the inlet hydraulic resistance; the pressure loss due to the throttling increases, resulting in a decrease in the pressure entering the lower oil chamber, thus providing a feedback effect. Conversely, as the gap in the upper oil chamber decreases, the hydraulic resistance at the sealing edge increases, meaning the hydraulic resistance at the outlet increases, causing the oil chamber pressure to increase. Simultaneously, the throttle valve in the lower oil chamber, used to control the upper oil chamber, experiences a decrease in gap, decreasing the hydraulic resistance at the throttling edge. At this point, for the upper oil chamber, the lower oil chamber controls the inlet hydraulic resistance; the pressure loss due to the throttling decreases, resulting in a increase in the pressure entering the upper oil chamber, thus providing a feedback effect.

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