Multi-stage movable counterweight system for large geotechnical centrifuge

Abstract

The invention discloses a multi-stage movable counterweight system for a large geotechnical centrifuge. The multi-stage movable counterweight system comprises at least two counterweight units and at least one limiting device, the adjusting capacity of the movable counterweight system is effectively improved; the multi-stage movable counterweight system is adopted, the number of turns of force-bearing threads in the system can be effectively increased, the overall bearing capacity of the thread structure is improved, and therefore the total weight of the movable counterweight system can be allowed to be further increased so as to improve the balance adjusting capacity of the movable counterweight system. The method has good design expansibility; through the modular design form of multi-stage series connection, when the balance mass required for balancing the rotating arm is increased, the number of the counterweight units can be increased, and vice versa; therefore, the structural design has good expansibility; in practical application, the weight of the movable counterweight system at the counterweight end and the number of the counterweight units are adjusted according to the load scales of different geotechnical centrifuge experiment ends, so that requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical centrifuges, and in particular to a multi-stage mobile counterweight system for a large geotechnical centrifuge. Background Art

[0002] Large geotechnical centrifuge is an important experimental equipment in the field of geotechnical engineering. It can generate centrifugal acceleration ng of the earth's gravity acceleration g through the high-speed rotation of the centrifuge arm, so that the geotechnical model is in a centrifugal field that is n times the earth's gravity field, thereby reproducing the stress state of the prototype soil structure and achieving the purpose of scaled simulation experiment. (For related information, see: Jia Puzhao. Steady-state acceleration simulation experimental equipment-Centrifuge Overview and Design [M]. Beijing: National Defense Industry Press, 2013). Asymmetric arm is a typical structural form of large geotechnical centrifuge arm. One side of the arm is the experimental end, with a large-sized hanging basket installed at the end and an airborne experimental device installed; the other side is the counterweight end, with a balancing mass block installed. Before conducting the experiment, it is necessary to adjust the mass distribution of the balancing mass block according to the mass of the experimental end so that the center of gravity of the entire arm is located at the rotation center of the arm. At this time, the arm of the geotechnical centrifuge can maintain balance during high-speed rotation. According to the principle of rotating structure balancing, in the balanced state, the product of the structural mass on the left and right sides of the swing arm and the radius of the center of mass should be consistent. Therefore, the balancing adjustment method of the geotechnical centrifuge can be adopted by manually increasing or decreasing the balancing mass block or changing the position of the balancing mass block. The latter is easy to operate and can realize automatic balancing, reducing dependence on manual labor.

[0003] The position of the balancing mass block is generally changed by thread transmission, in which a thread is processed on one side of the counterweight end of the rotating arm, and a nut is assembled on it. The driving mechanism drives the nut to rotate, and drives the balancing mass block to achieve reciprocating motion. In this structure, the nut and the thread on the rotating arm need to withstand the huge centrifugal force generated by the balancing mass block during the high-speed rotation of the rotating arm. The thread matching part is the part with the most complex stress condition in the entire structure. The failure of the thread matching part will cause the counterweight structure to fly out, causing huge damage. Therefore, it is also the most critical part and must be guaranteed to be safe and reliable. Due to the deformation of the thread structure under stress, the main load-bearing part of a thread matching structure is usually limited to a limited number of thread turns, which leads to an upper limit on the weight of the mobile counterweight that can be carried by a thread matching structure. When the scale of the centrifuge increases, the weight of the mobile counterweight required will also increase. When a primary counterweight is used, the force acting on the thread under the centrifugal field will also exceed the permitted range.

[0004] Therefore, it is necessary to develop a multi-stage mobile counterweight system for a large geotechnical centrifuge to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to design a multi-stage mobile counterweight system for a large geotechnical centrifuge in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: A multi-stage mobile counterweight system for a large geotechnical centrifuge, comprising: At least two counterweight units; the counterweight unit includes a driving assembly, a nut, a counterweight block, and a guide block. A guide rail is provided along the axial inward concave of the outer wall of the rotating arm tension shaft of the centrifuge. A through hole is provided on the counterweight block, and the rotating arm tension shaft is provided through the through hole. A guide block is provided on the counterweight block, and the guide block can be guided and slidably placed in the guide rail. An installation cavity is provided in the through hole of the counterweight block, and the nut is placed in the installation cavity. The width of the installation cavity is greater than the width of the through hole, and the width of the nut is greater than the width of the through hole. An external thread is provided on the outer wall of the rotating arm tension shaft, and the nut is threadedly matched with the rotating arm tension shaft. The driving assembly is used to drive the nut to rotate, and the nut is used to push the counterweight block to move axially along the rotating arm tension shaft; At least one limit device; the limit device includes a front limit switch, a rear limit switch, and a sensing block. The front limit switch and the rear limit switch are installed at intervals on the first counterweight block. The front limit switch and the rear limit switch are installed in sequence along the axial direction of the swing arm tension axis. The rear limit switch is arranged close to the second counterweight block. The fixed end of the sensing block is installed on the second counterweight block. The first counterweight block and the second counterweight block are arranged adjacent to each other. A gap is arranged between the first counterweight block and the second counterweight block. The sensing part of the sensing block cooperates with the front limit switch and the rear limit switch induction. The signal output end of the front limit switch is connected to the signal input end of the drive component.

[0007] The beneficial effects of the present invention are: 1. Effectively improve the adjustment ability of the mobile counterweight system. The use of a multi-stage mobile counterweight system can effectively increase the number of load-bearing threads in the system and improve the overall load-bearing capacity of the threaded structure, thereby allowing the overall weight of the mobile counterweight system to be further increased to improve its balance adjustment ability.

[0008] 2. Good design scalability. Through the modular design of multi-stage series connection, when the balancing mass required for balancing the swing arm increases, the number of counterweight units can be increased, and vice versa; therefore, the structural design has good scalability; in practical applications, according to the load scale of the experimental end of different geotechnical centrifuges, the weight of the mobile counterweight system and the number of counterweight units at the counterweight end can be adjusted to meet the needs.

[0009] 3. Good operating stability. Multiple counterweight units use the same drive control system, and there is a safety gap between the counterweight blocks. A limit device is set to ensure that multiple counterweight units move synchronously, so that they can operate stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of this application; Figure 2 It is a structural schematic diagram of the counterweight unit in this application (partial cross-section); Figure 3 It is a structural schematic diagram of the limiting device in this application; Figure 4 This is a schematic diagram of the matching structure of the guide rail and the guide block in this application; Figure 5 for Figure 4 A schematic diagram of the enlarged structure of part A.

[0011] Legend: 1-Counterweight unit one; 2-Counterweight unit two; 3-Counterweight unit three; 4-Limiting device; 5-Tension axis of swing arm; 6-Guide rail; 7-Counterweight block; 8-Motor; 9-Reducer; 10-Small pulley; 11-Large pulley; 12-Timing belt; 13-Nut; 14-Bracket; 15-Front limit switch; 16-Rear limit switch; 17-Sensing part; 18-Sensing block; 19-Guide block. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0013] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0015] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0016] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0017] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0018] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0019] like Figure 1-5 As shown, a multi-stage mobile counterweight system for a large geotechnical centrifuge comprises: Counterweight unit 1, counterweight unit 2, counterweight unit 3; each counterweight unit includes a drive assembly, two nuts 13, a counterweight block 7, and two guide blocks 19. A guide rail 6 is provided along the upper axial inward concave of the outer wall of the rotating arm tension shaft 5 of the centrifuge. The counterweight block 7 is provided with two through holes parallel to each other. The two rotating arm tension shafts 5 are respectively provided through the two through holes. The counterweight block 7 is provided with two guide blocks 19 (such as Figure 4 and 5 As shown, in some embodiments, the guide block 19 is placed on the inner upper wall of the through hole), the guide block 19 can be placed in the guide rail 6 in a guided sliding manner, a mounting cavity is provided in the through hole of the counterweight block 7 (in some embodiments, the cavity is cylindrical), the nut 13 is placed in the mounting cavity, the mounting cavity width is greater than the through hole width, the nut 13 width is greater than the through hole width (the width here can also be understood as the diameter), an external thread is provided on the outer wall of the swing arm tension shaft 5 (not a full circumferential arrangement), the nut 13 is threadedly matched with the swing arm tension shaft 5, the driving assembly is used to drive the nut 13 to rotate, and the nut 13 is used to push the counterweight block 7 to move axially along the swing arm tension shaft 5; Two limit devices 4; the limit device 4 includes a front limit switch 15, a rear limit switch 16, and a sensing block 18. The front limit switch 15 and the rear limit switch 16 are installed at intervals on the first counterweight block 7. The front limit switch 15 and the rear limit switch 16 are installed in sequence along the axial direction of the swing arm tension axis 5. The rear limit switch 16 is arranged close to the second counterweight block 7. The fixed end of the sensing block 18 is installed on the second counterweight block 7. The first counterweight block 7 and the second counterweight block 7 are arranged adjacent to each other. A gap is arranged between the first counterweight block 7 and the second counterweight block 7. The sensing part 17 of the sensing block 18 cooperates with the front limit switch 15 and the rear limit switch 16 for sensing. The signal output end of the front limit switch 15 is connected to the signal input end of the drive component.

[0020] During operation, the driving assembly driving nut 13 rotates on the rotating arm tension shaft 5 to achieve axial movement. The two ends of the driving nut 13 are respectively used to push the two ends of the installation cavity in the counterweight block 7 to achieve forward and backward pushing adjustment of the counterweight block 7.

[0021] In this embodiment, the cooperation between the guide block 19 and the guide rail 6 can not only support the counterweight block 7 but also guide the moving direction of the counterweight block 7 .

[0022] like Figure 3 As shown, in some embodiments, the limit device 4 further includes a bracket 14 , the bracket 14 is mounted on the first counterweight 7 , and the front limit switch 15 and the rear limit switch 16 are mounted on the bracket 14 in parallel with each other.

[0023] like Figure 3 As shown, in some embodiments, the bracket 14 and the sensor block 18 are respectively installed on the adjacent ends of the two counterweight blocks 7.

[0024] like Figure 2 As shown, in some embodiments, the driving assembly includes a motor 8, a reducer 9, a small pulley 10, two large pulleys 11, and a synchronous belt 12. One end faces of the two large pulleys 11 are respectively connected to one end faces of two nuts 13, and the two large pulleys 11 are respectively coaxially arranged with the two nuts 13. The large pulley 11 is mounted on the rotating arm tension shaft 5 (not fixedly connected). The motor 8 and the reducer 9 are fixedly mounted on the counterweight 7, and the small pulley 10 is rotatably mounted on the counterweight 7. The motor 8 is connected to the small pulley 10 through the reducer 9, and the small pulley 10 is connected to the two large pulleys 11 through the synchronous belt 12.

[0025] like Figure 2 As shown, in some embodiments, the driving assembly also includes two rotating wheels, which are respectively placed on both sides below the small pulley 10. The synchronous belt 12 passes around the rotating wheels and then passes around the large pulley 11. The purpose of setting the small pulley 10 is to increase the contact area between the synchronous belt 12 and the large pulley 11.

[0026] When the balancing mass required for balancing the centrifuge is too large, the force on the threaded part under the centrifugal field will exceed the safe range. The present application believes that it is necessary to increase the number of balancing masses at this time and equip each with a set of independent thread transmission units to distribute the load in multiple stages so that each threaded mating part can meet the load-bearing requirements, thereby improving the balance adjustment capability.

[0027] like Figure 1 As shown, the multi-stage mobile counterweight system is composed of multiple groups of counterweight units. In actual situations, the number can be increased or decreased according to demand. Each counterweight unit is installed in series on the arm tension shaft 5 of the centrifuge (the arm structure is irrelevant to this patent and is not shown as a whole in the figure). The arm tension shaft 5 is processed with threads for spiral transmission.

[0028] like Figure 2 As shown, each set of counterweight units is provided with a set of drive components, and the drive components can be of different types. The example in the figure is driven by a motor 8, which can make the nuts 13 on both sides move synchronously along the threads on the two swing arm tension shafts 5. The inner ring of the nut 13 is processed with threads, which cooperate with the threads on the tension shaft. The end of the outer ring is installed with a large pulley 11, which is meshed with the synchronous belt 12. The other end of the synchronous belt 12 is meshed with the small synchronous belt 12 connected to the output shaft of the reducer 9. There is a reduction gear ratio between the small pulley 10 and the large pulley 11, which can reduce the demand for motion input torque; at the same time, the reducer 9 itself also has a reduction ratio, which further effectively reduces the demand for the driving torque of the motor 8.

[0029] like Figure 3 As shown, multiple counterweight units use the same set of drive control system, a safety gap is set between the counterweight blocks 7, and a limit device 4 is set to ensure the synchronous movement of multiple counterweight units, thereby realizing the balance adjustment function. The limit device 4 is composed of a front limit switch 15, a rear limit switch 16, and a sensor block 18. The working sensing part 17 of the sensor block 18 is between the front limit switch 15 and the rear limit switch 16. When the gap between the counterweight blocks 7 becomes larger, the front limit switch 15 will feedback a signal to the drive control system, and the drive control system can give different speeds to the motors 8 of the two counterweight units to realize gap callback; vice versa.

[0030] This patent application proposes a multi-stage mobile counterweight system for balancing large arm-type geotechnical centrifuges, which improves the force characteristics of the most critical threaded transmission parts of the structure, enhances the balance adjustment ability of the system, and has good functional scalability, which can meet the balance adjustment requirements of geotechnical centrifuges with different load capacities. At the same time, in addition to being applied to geotechnical centrifuge structures, the multi-stage mobile counterweight system can also be applied in other scenarios that require the synchronous operation of multi-stage mobile masses.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-stage mobile counterweight system for a large geotechnical centrifuge, characterized in that: include: At least two counterweight units; The counterweight unit includes a driving assembly, a nut, a counterweight block, and a guide block. A guide rail is provided along the axial inward concave of the outer wall of the rotating arm tension shaft of the centrifuge. A through hole is provided on the counterweight block, and the rotating arm tension shaft is provided through the through hole. A guide block is provided on the counterweight block, and the guide block can be guided and slidably placed in the guide rail. An installation cavity is provided in the through hole of the counterweight block, and the nut is placed in the installation cavity. The width of the installation cavity is greater than the width of the through hole, and the width of the nut is greater than the width of the through hole. An external thread is provided on the outer wall of the rotating arm tension shaft, and the nut is matched with the thread of the rotating arm tension shaft. The driving assembly is used to drive the nut to rotate, and the nut is used to push the counterweight block to move axially along the rotating arm tension shaft. At least one limit device; the limit device includes a front limit switch, a rear limit switch, and a sensing block. The front limit switch and the rear limit switch are installed at intervals on the first counterweight block. The front limit switch and the rear limit switch are installed in sequence along the axial direction of the swing arm tension axis. The rear limit switch is arranged close to the second counterweight block. The fixed end of the sensing block is installed on the second counterweight block. The first counterweight block and the second counterweight block are arranged adjacent to each other. A gap is arranged between the first counterweight block and the second counterweight block. The sensing part of the sensing block cooperates with the front limit switch and the rear limit switch induction. The signal output end of the front limit switch is connected to the signal input end of the drive component.

2. A multi-stage mobile counterweight system for a large geotechnical centrifuge according to claim 1, characterized in that: The limit device also includes a bracket, which is installed on the first counterweight block, and the front limit switch and the rear limit switch are installed on the bracket in parallel with each other.

3. A multi-stage mobile counterweight system for a large geotechnical centrifuge according to claim 2, characterized in that: The bracket and the induction block are respectively installed on the adjacent ends of the two counterweight blocks.

4. The multi-stage mobile counterweight system for a large geotechnical centrifuge according to claim 1, characterized in that: The driving assembly includes a motor, a reducer, a small pulley, a large pulley, and a synchronous belt. One end face of the large pulley is connected to one end face of a nut, the large pulley and the nut are coaxially arranged, the large pulley is mounted on the tension shaft of the rotating arm, the motor and the reducer are fixedly mounted on the counterweight block, the small pulley is rotatably mounted on the counterweight block, the motor is connected to the small pulley through the reducer, and the small pulley is connected to the large pulley through the synchronous belt.

5. A multi-stage mobile counterweight system for a large geotechnical centrifuge according to claim 4, characterized in that: The rotating arm pulling shafts are two parallel to each other, and correspondingly there are two large pulleys, and the small pulley is connected to the two large pulleys through a synchronous belt.

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