Two-degree-of-freedom shaking table for super-high test specimens

Abstract

The application provides a super-high test piece two-degree-of-freedom swing table, and belongs to the technical field of offshore super-high test piece testing. The swing table comprises a base structure, a fixed hinge and a platform for mounting a test piece mounted on the upper surface of the base structure, four concrete columns arranged on the base and connected into a whole through a steel railing, embedded parts arranged on the columns, a roll-pitch driving device comprising a roll actuator and a pitch actuator, a tail of the roll-pitch driving device fixed on the embedded parts of the columns through a rear hinge, and a head of the roll-pitch driving device fixed on a connecting tool, and a connecting tool fixedly connected with the test piece and a hydraulic system. The swing table can accurately simulate ocean sloshing conditions, and provides an effective testing method for verifying the performance of LNG / FLNG pipe-around heat exchangers under static and sloshing conditions.

Description

Technical Field

[0001] This invention relates to the field of marine ultra-high-altitude specimen testing technology, specifically to a two-degree-of-freedom swing table for ultra-high-altitude specimens. Background Technology

[0002] To realize the application of wound-tube heat exchangers on offshore LNG-FPSOs, a large two-degree-of-freedom swing platform capable of simulating ocean swaying conditions needs to be constructed. This platform will be used to conduct performance tests on the entire LNG / FLNG wound-tube heat exchanger under both static and swaying conditions, verifying CNOOC's key technologies for the design and manufacture of large-scale LNG / FLNG wound-tube heat exchangers. The swing platform, while ensuring safety and reliability, enables the wound-tube heat exchanger and its supporting frame to achieve single-degree-of-freedom motion (pitch and roll) and combined motion (both degrees of freedom).

[0003] (1) Overall parameters of the wound tube heat exchanger:

[0004] The coiled tube heat exchanger is assembled as a skid with a steel frame. The main frame dimensions are approximately 4m (length) × 4m (width) × 38m (height).

[0005] (2) The operating weight of the coiled tube heat exchanger (containing liquid) and its supporting frame shall not exceed 160t.

[0006] A two-degree-of-freedom swing table typically consists of a platform (for mounting the test specimen) and two or four actuators (for driving the platform to swing), such as... Figure 1 As shown. This type of swaying table is not suitable for ultra-high specimens such as coiled tube heat exchangers because the specimen's center of mass is too high, the moment of inertia is too large, the driving torque required for swaying is too large, and the actuator is difficult to manufacture. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the shortcomings of the prior art by proposing a two-degree-of-freedom swing table for ultra-high-altitude specimens, comprising:

[0008] The basic structure has a fixed hinge and a platform for mounting the test specimen mounted on its upper surface;

[0009] Four concrete columns are set on the foundation and connected as a whole by steel railings. The columns are equipped with embedded parts.

[0010] The roll and pitch drive device includes a roll actuator and a pitch actuator. Its tail is fixed to the embedded part of the column by a rear hinge, and its head is fixed to the connecting fixture by a front hinge.

[0011] The connecting fixture is fixedly connected to the test specimen.

[0012] Hydraulic system, including:

[0013] A single-rod asymmetric hydraulic cylinder, the rod chamber of which is controlled by an explosion-proof servo valve;

[0014] A cover-type cartridge valve is installed between the explosion-proof servo valve and the hydraulic cylinder;

[0015] Solenoid directional valve controls the opening and closing of cartridge valves;

[0016] The electromagnetic directional valve and the hydraulic check valve are used to restore the swing table to its working zero position during maintenance.

[0017] A pressure sensor monitors the pressure in the rod chamber of a hydraulic cylinder.

[0018] Preferably, the hydraulic system is connected as follows: the rod chamber of the hydraulic cylinder is connected to the load port B of the explosion-proof servo valve, and the rodless chamber is connected to the return oil line; a cover-type cartridge valve is installed in parallel on the oil line between the explosion-proof servo valve and the hydraulic cylinder; an electromagnetic directional valve is connected to the control chamber of the cartridge valve through a control oil line; a hydraulically controlled check valve is installed between the rod chamber of the hydraulic cylinder and the supply / return oil line; and a pressure sensor is connected to the oil line of the rod chamber of the hydraulic cylinder.

[0019] Preferably, the hydraulic system further includes: a solenoid directional valve three and a throttle valve disposed on the explosion-proof servo valve mounting block; the solenoid directional valve three is used to connect the oil supply line and the oil return line; the throttle valve is used to regulate the circulation flow, together playing the roles of pipeline flushing and hydraulic oil preheating.

[0020] Preferably, the structural parameters of the swing table include:

[0021] The radius Ra of the front connecting hinge point is 2750mm;

[0022] The radius Rb of the rear connecting hinge point circle is 7600 mm;

[0023] When the machine is in the working position, the distance L2 between the front and rear connecting hinge points is 4850mm;

[0024] When in the middle position, the height H1 of the front connecting hinge point is 12700mm;

[0025] When in the middle position, the height H2 of the rear connecting hinge point is 12700mm.

[0026] Preferably, the parameters of the hydraulic cylinder include:

[0027] The piston / piston rod diameter is 200 / 125mm;

[0028] The effective stroke is 2247mm;

[0029] The maximum extension / retraction speed is 0.697 m / s.

[0030] More preferably, the rated flow rate of the explosion-proof servo valve is 630 L / min, and the valve pressure drop is 7 MPa.

[0031] More preferably, the actuator generates only tension and not thrust.

[0032] Preferably, the swaying table is used to test the coiled tube heat exchanger, and the main frame dimensions of the test specimen are 4m (length) × 4m (width) × 38m (height).

[0033] Preferably, the swing table realizes single-degree-of-freedom motion and two-degree-of-freedom compound motion of the test specimen by controlling the displacement of four actuators.

[0034] In a further preferred embodiment, when the hydraulic system malfunctions, the cartridge valve can be closed by de-energizing the first solenoid directional valve to stop the movement of the swaying table; after the swaying table stops due to a malfunction, the platform can be returned to the working zero position by the second solenoid directional valve to repair the malfunction.

[0035] Compared with the prior art, the present invention achieves the following technical effects:

[0036] Firstly, this swing platform innovatively adopts a four-column support structure. By fixing the actuator tail to the embedded parts of the columns and connecting the head to the test specimen, it effectively solves the technical challenge of traditional swing platforms being unable to drive ultra-high and large-mass test specimens. Its unique hydraulic system design, including a single-rod asymmetric hydraulic cylinder, explosion-proof servo valve control, and cartridge valve safety protection devices, not only avoids actuator rod instability but also achieves precise motion control and fault-tolerant protection. This structural design enables the swing platform to stably drive a 38-meter-high, 160-ton wound-tube heat exchanger in two-degree-of-freedom compound motion, providing a reliable testing platform for simulating the offshore operating conditions of large LNG equipment.

[0037] Secondly, the swaying platform, through its optimized hydraulic oil circulation heating system, solves the problems of high hydraulic oil viscosity and poor fluidity in low-temperature winter environments, ensuring reliable system operation in harsh conditions. Its innovative hydraulic circuit design, including the combined use of electromagnetic directional valves and throttle valves, enables rapid preheating of the hydraulic oil, significantly improving the system's start-up performance and operational stability in low-temperature environments. These technical measures collectively ensure that the swaying platform can accurately simulate ocean swaying conditions, providing an effective testing method for verifying the performance of LNG / FLNG coiled-tube heat exchangers under static and swaying conditions. Attached Figure Description

[0038] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0039] Figure 1 A diagram showing the typical structural form of a two-degree-of-freedom swing table;

[0040] Figure 2This is a structural diagram of the two-degree-of-freedom swing table for the ultra-high-altitude specimen of the present invention;

[0041] Figure 3 This is a diagram showing the structural parameters of the two-degree-of-freedom swing table for the ultra-high-altitude specimen of this invention.

[0042] Figure 4 This is a hydraulic schematic diagram of the actuator of the present invention.

[0043] In the diagram: 1. Single-acting asymmetric hydraulic cylinder; 2. Explosion-proof servo valve; 3. Solenoid directional valve one; 4.1. Check valve one; 4.2. Check valve two; 5. Hydraulic control check valve; 6. Solenoid directional valve two; 7. Cover-type cartridge valve; 8. Basic structure; 9. Solenoid directional valve three; 10. Throttle valve; 11. Pressure sensor; 12. Platform; 13. Column; 14. Railing; 15. Roll and pitch drive device; 16. Test specimen; 17. Connecting fixture. Detailed Implementation

[0044] The following are specific embodiments of the present invention, in conjunction with the appendix. Figure 1-4 The technical solutions of the present invention will be further described below, but the present invention is not limited to these embodiments; in the following description, specific details such as specific configurations are provided only to help to fully understand the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0046] like Figure 2 As shown, a two-degree-of-freedom swing table for ultra-high-altitude specimens includes:

[0047] The basic structure 8 has a fixed hinge and a platform 12 for mounting the test specimen installed on its upper surface;

[0048] Four concrete columns 13 are set on the foundation structure 8 and connected into a whole by steel railings 14. Embedded parts are provided on the columns 13.

[0049] The roll and pitch drive device 15 includes a roll actuator and a pitch actuator. Its tail is fixed to the embedded part of the column by a rear hinge, and its head is fixed to the connecting fixture 17 by a front hinge.

[0050] The connecting fixture 17 is fixedly connected to the test piece 16;

[0051] Hydraulic system, including:

[0052] A single-rod asymmetric hydraulic cylinder, the rod chamber of which is controlled by an explosion-proof servo valve;

[0053] A cover-type cartridge valve is installed between the explosion-proof servo valve and the hydraulic cylinder;

[0054] Solenoid directional valve controls the opening and closing of cartridge valves;

[0055] The electromagnetic directional valve and the hydraulic check valve are used to restore the swing table to its working zero position during maintenance.

[0056] The electromagnetic directional valve and the throttle valve are used to connect the oil supply line and the oil return line. The throttle valve is used to regulate the circulation flow and is used for pipeline flushing and hydraulic oil preheating.

[0057] A pressure sensor monitors the pressure in the rod chamber of a hydraulic cylinder.

[0058] The structural parameters of the swing table include:

[0059] The radius Ra of the front connecting hinge point is 2750mm;

[0060] The radius Rb of the rear connecting hinge point circle is 7600 mm;

[0061] When the machine is in the working position, the distance L2 between the front and rear connecting hinge points is 4850mm;

[0062] When in the middle position, the height H1 of the front connecting hinge point is 12700mm;

[0063] When in the middle position, the height H2 of the rear connecting hinge point is 12700mm.

[0064] Preferably, the parameters of the hydraulic cylinder include:

[0065] The piston / piston rod diameter is 200 / 125mm;

[0066] The effective stroke is 2247mm;

[0067] The maximum extension / retraction speed is 0.697 m / s.

[0068] The rated flow rate of the explosion-proof servo valve is 630 L / min, and the valve pressure drop is 7 MPa.

[0069] The actuator generates only tension and not thrust.

[0070] The swing table is used to test a coiled tube heat exchanger. The main frame dimensions of the test specimen are 4m (length) × 4m (width) × 38m (height). The swing table achieves single-degree-of-freedom motion and two-degree-of-freedom combined motion of the test specimen by controlling the displacement of four actuators. In the event of a control system failure, the hydraulic system can stop the swing table by de-energizing the first solenoid directional valve to close the cartridge valve. After the swing table stops due to a failure, the second solenoid directional valve can be used to return the platform to the zero working position for troubleshooting.

[0071] right Figure 2 The structural parameters of the two-degree-of-freedom swing table shown are optimized. A schematic diagram of the structural parameters is shown below. Figure 3 As shown, the following four parameters determine the connection: the radius of the front hinge circle Ra, the radius of the rear hinge circle Rb, the height of the front hinge point H1, and the height of the rear hinge point H2.

[0072] The above four structural parameters determine the kinematic and dynamic characteristics of the rocker platform. When designing the rocker platform, these four structural parameters must first be determined according to the principles of optimal design. The distance L2 between the front and rear connecting hinge points when the rocker platform is in its zero-position working state is also considered.

[0073] The optimization of the swing table structure mainly involves determining the optimal structural parameters based on kinematic and dynamic analysis and calculations. The following principles are considered in the structural optimization design of the swing table:

[0074] 1) No unusual structural design

[0075] When a singular configuration occurs, the mechanism becomes uncontrollable, and forces exceeding limits are generated at the connecting hinges, causing the swaying platform to lose stability or even overturn. Therefore, the overall structural design should aim to eliminate singular configurations to fundamentally ensure the platform's safety.

[0076] 2) Interference-free structural design

[0077] Interference refers to the collisions that occur between components of a platform during certain movements. In the overall structural design, it is essential to ensure that no interference occurs between components under various extreme configurations of the platform.

[0078] 3) The structure's natural frequency is high enough.

[0079] The frequency of the first mode of vibration of the structure is the main factor limiting the frequency characteristics of the system. Since the dynamic characteristics of each degree of freedom of the platform are quite different, it is necessary to analyze the frequency of structural vibration to ensure that the designed system structure meets the requirements of the system frequency characteristics.

[0080] 4) Low power consumption and low operating costs

[0081] In the design of the swing table structure, in addition to ensuring safety and performance, it is also necessary to minimize the power consumption of the system and reduce operating costs.

[0082] Due to the large stroke of the actuator and the excessively long distance between the front and rear hinges, the actuator suffers from lever instability. To address this issue, the actuator was designed to generate only tension, not thrust. The tension from the four actuators drives the test specimen's lateral and longitudinal rolls. The hydraulic principle of the actuator is as follows: Figure 4 As shown, the principle is explained below:

[0083] The single-rod asymmetric hydraulic cylinder 1 has its rod chamber connected to the load port B of the explosion-proof servo valve 2 (the other load port A is blocked), and its rodless chamber is connected to the return oil. The hydraulic cylinder does not generate thrust, thus avoiding rod instability.

[0084] A cover-type cartridge valve 7 is installed between the explosion-proof servo valve 2 and the hydraulic cylinder. When the solenoid directional valve 3 is energized, the control chamber of the cover-type cartridge valve 7 is depressurized, the cartridge valve opens, and the explosion-proof servo valve controls the movement of the hydraulic cylinder. When the control system malfunctions and the solenoid directional valve 3 is de-energized, the highest pressure of the rodless chamber of the hydraulic cylinder or the hydraulic source pressure is introduced into the control chamber of the cover-type cartridge valve 7 through the check valve 4.1 and the check valve 4.2, causing the cartridge valve to close. The explosion-proof servo valve loses control of the hydraulic cylinder, the hydraulic cylinder stops at its current position, and the swing table stops moving, thus providing safety protection for the swing table.

[0085] When the control system malfunctions and the swing table stops moving, it needs to be repaired. This requires restoring the swing table to its working zero position (platform horizontal, test piece vertical). This can be achieved using solenoid directional valve 26 and hydraulic check valve 5. Taking the horizontal rocking motion as an example, when the left solenoid of solenoid directional valve 26 for actuator 1 is energized, hydraulic oil is supplied through hydraulic check valve 5 into the rod chamber of the hydraulic cylinder, causing actuator 1 to retract. Simultaneously, the right solenoid of solenoid directional valve 26 for actuator 2 is energized, and hydraulic check valve 5 opens in the reverse direction, allowing return oil to flow into the rod chamber of the hydraulic cylinder. Actuator 2 is pulled out, and the swing table begins its horizontal rocking motion. The energization of the left or right solenoid of solenoid directional valve 26 for the horizontal rocking actuator is determined by the tilt direction of the swing table when it stops. When the swing table is operating normally, both solenoids of solenoid directional valve 26 are de-energized. Hydraulic check valve 5 disconnects the supply and return oil flow to the rod chamber of the hydraulic cylinder, and the explosion-proof servo valve controls the normal movement of the hydraulic cylinder. A damping orifice is provided between the electromagnetic directional valve 6 and the hydraulic check valve 5 to limit the movement speed of the swing table during the recovery process.

[0086] The swing platform is installed outdoors. Before testing in winter, the hydraulic oil in the pipeline becomes viscous and has poor flowability due to the low temperature, affecting the performance of the explosion-proof servo valve. To solve this problem, an electromagnetic directional valve (3.9) and a throttle valve (10) are designed on the explosion-proof servo valve mounting block. Before the test begins, the hydraulic power source is started (indoors), and the electromagnetic directional valve (3.9) is energized, connecting the supply and return oil lines, allowing the hydraulic oil to circulate. The opening of the throttle valve (10) is adjusted so that the oil source output pressure is slightly lower than the rated pressure of the oil source. At this point, the hydraulic power source outputs at full flow (a constant pressure variable pump outputs at full displacement when the load pressure is lower than the constant pressure point). The product of the circulating flow rate and pressure is the output power of the hydraulic power source, which is entirely used to heat the hydraulic oil. After the hydraulic oil temperature rises to normal, the test begins.

[0087] Pressure sensor 11 monitors the pressure in the rod chamber of the hydraulic cylinder and can be used to set overpressure protection.

[0088] Those skilled in the art to which this application pertains may make various modifications or additions to the specific embodiments described, or adopt similar methods to replace them, without departing from the inventive concept of this application or exceeding the scope defined by the appended claims.

Claims

1. A two-degree-of-freedom swing table for ultra-high-altitude specimens, characterized in that, include: The basic structure has a fixed hinge and a platform for mounting the test specimen mounted on its upper surface; Four concrete columns are set on the foundation and connected as a whole by steel railings. The columns are equipped with embedded parts. The roll and pitch drive device includes two roll actuators and two pitch actuators. The tails of all four actuators are fixed to the embedded parts of the column by rear hinges, and the heads are fixed to the connecting fixture by front hinges. The connecting fixture is fixedly connected to the test specimen. Hydraulic system, including: The hydraulic cylinder has a single-rod asymmetric structure, including a rod chamber and a rodless chamber, with the rod chamber controlled by an explosion-proof servo valve. A cover-type cartridge valve is installed between the explosion-proof servo valve and the hydraulic cylinder; Electromagnetic directional valve controls the opening and closing of cover-type cartridge valves. The electromagnetic directional valve and the hydraulic check valve are used to restore the swing table to its working zero position during maintenance. The electromagnetic reversing valve is used to connect the oil supply line and the oil return line; Throttling valves are used to regulate circulating flow; Pressure sensors monitor the pressure in the rod chamber of the hydraulic cylinder; The four actuators only generate tension and not thrust. The swing table achieves single-degree-of-freedom motion and two-degree-of-freedom composite motion of the test specimen by controlling the displacement of the horizontal and vertical rocking drive device. The hydraulic system is connected as follows: the rod chamber of the hydraulic cylinder is connected to the load port B of the explosion-proof servo valve, and the rodless chamber is connected to the return oil line; a cover-type cartridge valve is connected in parallel on the oil line between the explosion-proof servo valve and the hydraulic cylinder; an electromagnetic directional valve and a throttle valve are installed on the explosion-proof servo valve mounting block to jointly flush the pipeline and preheat the hydraulic oil; the electromagnetic directional valve is connected to the control chamber of the cover-type cartridge valve through the control oil line; a hydraulically controlled check valve is installed between the rod chamber of the hydraulic cylinder and the supply / return oil line; a pressure sensor is connected to the oil line of the rod chamber of the hydraulic cylinder. When the control system malfunctions, the hydraulic system can close the cover-type cartridge valve by de-energizing the solenoid directional valve, thereby stopping the movement of the swaying table. After the swing platform malfunctions and stops, the platform can be restored to its working zero position using the solenoid directional valve and the hydraulic check valve, and the malfunction can be repaired.

2. The two-degree-of-freedom swing table for ultra-high-altitude specimens according to claim 1, characterized in that, The structural parameters of the swing table include: The radius Ra of the front connecting hinge point is 2750mm; The radius Rb of the rear connecting hinge point circle is 7600 mm; When the machine is in the working position, the distance L2 between the front and rear connecting hinge points is 4850mm; When in the middle position, the height H1 of the front connecting hinge point is 12700mm; When in the middle position, the height H2 of the rear connecting hinge point is 12700mm.

3. The two-degree-of-freedom swing table for ultra-high-altitude specimens according to claim 1, characterized in that, The parameters of the hydraulic cylinder include: The piston / piston rod diameter is 200 / 125mm; The effective stroke is 2247mm; The maximum extension / retraction speed is 0.697 m / s.

4. The two-degree-of-freedom swing table for ultra-high-altitude specimens according to claim 1, characterized in that, The rated flow rate of the explosion-proof servo valve is 630 L / min, and the valve pressure drop is 7 MPa.

5. The two-degree-of-freedom swing table for ultra-high-altitude specimens according to claim 1, characterized in that, The swing table is used to test the coiled tube heat exchanger, and the main frame of the test piece has dimensions of 4m×4m×38m.

Images