Pneumatic high-g impact excitation device based on two-stage velocity amplifier

Abstract

The present invention discloses a pneumatic high-g impact excitation device based on a two-stage velocity amplifier, comprising an air cannon, a cylinder assembly and a two-stage velocity amplifier, wherein the two-stage velocity amplifier comprises an outer rod assembly, an inner rod assembly and a test head assembly, wherein a primary collision portion is arranged in the inner cavity of the outer rod assembly, the inner rod assembly vertically slides and sleeves in the outer rod assembly and is suspended above the primary collision portion, a secondary collision portion is arranged in the inner cavity of the inner rod assembly, the test head assembly can vertically slide and sleeve in the inner rod assembly and be suspended above the secondary collision portion, the mass of the outer rod assembly is greater than the mass of the inner rod assembly, the mass of the inner rod assembly is greater than the mass of the test head assembly, and the outer rod assembly can be vertically slidably installed in the cylinder assembly. The excitation device of the present invention can generate impact acceleration with a higher g value level; moreover, the device has a simple structure, a small space size, and a very low processing and manufacturing cost.

Description

Technical Field

[0001] The invention relates to the technical field of high acceleration impact excitation test in a mechanical environment, and in particular to a pneumatic high g-value impact excitation device based on a two-stage velocity amplifier. Background Art

[0002] High acceleration impact test has a high demand for the peak value of impact acceleration. The existing Hopkinson pressure bar technology, air cannon technology, vertical drop technology, live ammunition target shooting and other methods can achieve high acceleration, but the above technologies have obvious limitations on the occasions of use and are expensive. They cannot meet the demand for high acceleration impact mechanical environmental excitation technology that can be conducted multiple times indoors, conveniently, cheaply, safely and reliably, especially for high acceleration impact mechanical environmental excitation technology with a g-value level exceeding 100,000 g.

[0003] In view of the above problems, a pneumatic high-g impact excitation device based on a two-stage velocity amplifier is proposed. The device has a simple structure, small space size, and very low processing and manufacturing cost, and can generate impact acceleration at a higher g value level. Summary of the invention

[0004] In view of this, the present invention provides a pneumatic high-g impact excitation device based on a two-stage velocity amplifier, which has a simple structure, a small space size, and a very low processing and manufacturing cost, and can generate an impact acceleration with a higher g value level;

[0005] The pneumatic high-g impact excitation device based on a two-stage velocity amplifier of the present invention comprises an air cannon, a cylinder assembly and a two-stage velocity amplifier, wherein the two-stage velocity amplifier comprises an outer rod assembly, an inner rod assembly and a test head assembly, wherein a primary collision portion is arranged in the inner cavity of the outer rod assembly corresponding to the bottom end of the inner rod assembly, the inner rod assembly is vertically slidably sleeved in the outer rod assembly and suspended above the primary collision portion, a secondary collision portion is arranged in the inner cavity of the inner rod assembly corresponding to the bottom end of the test head, the test head assembly can be vertically slidably sleeved in the inner rod assembly and suspended above the secondary collision portion, the mass of the outer rod assembly is greater than the mass of the inner rod assembly, the mass of the inner rod assembly is greater than the mass of the test head assembly, the outer rod assembly can be vertically slidably installed in the cylinder assembly, the air outlet of the air cannon is connected to the air inlet of the cylinder assembly to drive the outer rod assembly to accelerate vertically downward.

[0006] Furthermore, the two-stage speed amplifier also includes a piston and a magnet installed on the upper surface of the piston. The piston is fixed on the outer rod assembly. The piston is axially sealed and slidably matched with the inner wall of the cylinder body of the cylinder assembly. The cylinder body of the cylinder assembly has a necking section, and the necking section is located above the piston. The air inlet of the cylinder assembly is located above the necking section. There is a set gap between the inner circle of the necking section and the outer circle of the outer rod assembly. The piston can be adsorbed to the bottom of the necking section by magnetism so that the two-stage speed amplifier is suspended in the cylinder assembly.

[0007] Furthermore, the cylinder assembly includes a base, a cylinder and an air inlet seat, the base sealing cover is on the bottom of the cylinder, the air inlet seat sealing cover is on the top of the cylinder, the tapered section is arranged in the cylinder, a through hole is arranged in the middle of the air inlet seat, the outer rod assembly is sealingly slidably matched with the through hole, an air inlet flow channel is arranged on the air inlet seat, the air outlet end of the air inlet flow channel is located below the air inlet seat and is connected with the inner cavity of the cylinder, and the air inlet end of the air inlet flow channel serves as the air inlet of the cylinder assembly and is connected with the air outlet of the air cannon.

[0008] Furthermore, an air vent is provided at a lower middle portion of the cylinder, and the air vent enables the inner cavity of the cylinder to communicate with the outside. When the two-stage speed amplifier is suspended in the cylinder assembly, the air vent is located below the piston.

[0009] Furthermore, a guide bearing is provided in the through hole, and the outer rod assembly is sealingly and slidingly matched with the guide bearing.

[0010] Furthermore, the inner rod assembly includes an inner rod that is vertically slidably sleeved in the outer rod assembly and an inner rod suspension ejector pin connected to the bottom of the inner rod. A primary mounting hole is opened at the bottom of the inner cavity of the outer rod assembly. The inner rod suspension ejector pin is vertically slidably sleeved in the primary mounting hole and a primary elastic member installed in the primary mounting hole allows the bottom end of the inner rod to be suspended above the bottom of the inner cavity of the outer rod assembly.

[0011] Furthermore, the test head assembly includes a test head and a test head suspension pin connected to the bottom end of the test head. A secondary mounting hole is opened at the bottom of the inner cavity of the inner rod assembly. The test head suspension pin vertically slides inside the secondary mounting hole and the bottom end of the test head is suspended above the bottom of the inner cavity of the inner rod assembly through a secondary elastic member installed in the secondary mounting hole.

[0012] Furthermore, the outer rod assembly includes an outer rod and an inner rod fixing cap connected to the outer rod, the piston is fixedly mounted on the outer rod, the outer rod is vertically sealed and slidably matched with the through hole, and the inner rod fixing cap and the outer circle of the inner rod are provided with mutually matching limiting parts, and the inner rod fixing cap forms an axial limit to the inner rod through the cooperation of the limiting parts and has a pre-tightening force on the inner rod so that the inner rod floating ejector pin is pressed onto the primary elastic member.

[0013] Furthermore, the inner rod assembly also includes an inner rod upper seat and a test head fixing cap, the upper end of the inner rod extends to the outside of the outer rod assembly and is fixedly connected to the inner rod upper seat, the test head fixing cap is an annular structure, the test head fixing cap portion is sleeved on the upper end of the inner rod and forms an inner cavity of the inner rod assembly at the upper end of the inner rod; the test head fixing cap and the outer circle of the test head are provided with mutually matching limiting portions, the test head fixing cap forms an axial limit for the test head through the cooperation of the limiting portion and has a pre-tightening force on the test head to press the suspended ejector pin of the test head onto the secondary elastic member.

[0014] Furthermore, a waveform generator is provided at the bottom of the inner cavity of the inner rod assembly to form a secondary collision portion, and the waveform generator is used to adjust the acceleration waveform of the test head.

[0015] Beneficial effects of the present invention:

[0016] The excitation device of the present invention can obtain a half-sine impact acceleration pulse waveform with a peak value of more than 100,000 g through two-stage amplification, and can generate an impact acceleration with a higher g value level; a constricted section is arranged in the cylinder assembly, which is helpful to increase the flow rate of the jet airflow. When the air cannon passes the jet airflow into the cylinder body, the constricted section is conducive to the expansion of the jet airflow of the air cannon and external work, so that the two-stage velocity amplifier obtains the largest possible initial collision velocity, and the step position at the bottom of the constricted section is also used to cooperate with the magnetic attraction, so that the two-stage velocity amplifier can be manually operated to a hovering state, and it is easy to be impacted and fall off by the impact force of the airflow;

[0017] Moreover, the device has a simple structure, small space dimensions, and very low processing and manufacturing costs; it can be operated purely manually, with almost no maintenance costs, and is simple and convenient to operate. The structure occupies a small space, is easy to carry, and is not restricted by the occasion of use, which greatly improves the flexibility of use. In addition, the assembly requirements of each component are relatively low. For example, the inner rod and the outer rod, the test head and the test head fixing cap can all be clearance-fitted, which can reduce manufacturing costs and simplify the assembly process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 for Figure 1 A schematic diagram of a local enlarged structure;

[0021] Figure 3 It is a schematic diagram of the air intake seat structure;

[0022] Figure 4 It is a schematic diagram of the cylinder structure;

[0023] Figure 5It is a schematic diagram of the structure of a two-stage speed amplifier;

[0024] Figure 6 for Figure 5 A local enlarged structural diagram Figure 1 ;

[0025] Figure 7 for Figure 5 A local enlarged structural diagram Figure 2 ; DETAILED DESCRIPTION

[0026] The present embodiment provides a pneumatic high-g impact excitation device based on a two-stage velocity amplifier, including an air cannon I, a cylinder assembly and a two-stage velocity amplifier V. The two-stage velocity amplifier includes an outer rod assembly, an inner rod assembly and a test head assembly. A primary collision portion is arranged in the inner cavity of the outer rod assembly corresponding to the bottom end of the inner rod assembly. The inner rod assembly vertically slides inside the outer rod assembly and is suspended above the primary collision portion. A secondary collision portion is arranged in the inner cavity of the inner rod assembly corresponding to the bottom end of the test head. The test head assembly can vertically slide inside the inner rod assembly and is suspended above the secondary collision portion. The mass of the outer rod assembly is greater than that of the inner rod assembly. The mass of the inner rod assembly is greater than that of the test head assembly. The outer rod assembly can be vertically slidably installed in the cylinder assembly. The air outlet of the air cannon I is connected to the air inlet of the cylinder assembly to drive the outer rod assembly to accelerate vertically downward. Figure 1 As shown, the air cannon I is an existing structure and can be purchased directly. The air outlet of the air cannon is directly connected to the inner cavity of the cylinder assembly, which can quickly drive the two-stage speed amplifier V to accelerate downward vertically. The outer rod assembly and the inner rod assembly are both long rod-shaped structures. The structure of the corresponding excitation device is a long strip structure, which is vertically consistent with the length direction of the excitation device. The upper and lower ends are based on the length direction of the excitation device. The sliding direction of the inner rod assembly and the sliding direction of the test head assembly are the same. During the operation of the excitation device, the sliding directions of the two are vertical sliding. Figure 1 As shown, the upper end is close to the test head along the length direction of the excitation device, and the lower end is close to the tail end of the outer rod assembly along the length direction of the excitation device. The outer rod assembly has an inner cavity with an upper end opening, and the inner rod assembly also has an inner cavity with an upper end opening. The suspension setting means that the bottom end of the test head or the bottom end of the inner rod assembly is not in contact with the corresponding collision part in the initial state. The suspension setting can be achieved by various existing means, such as by an elastic member supported between the bottom end of the test head or the bottom end of the inner rod assembly and the corresponding collision part, or by a like-sex magnetic pole set between the bottom end of the test head or the bottom end of the inner rod assembly and the corresponding collision part. The details are not repeated here.

[0027] When in use, the test piece is installed on the test head, the mass of the outer rod assembly is m1, the mass of the inner rod assembly is m2, and the mass of the test head assembly and the test piece is m3, and it is ensured that m1>m2>m3; when working, the test head faces upward and keeps the excitation device vertical as a whole. Driven by the air cannon I, the two-stage velocity amplifier V obtains a faster initial velocity and moves vertically downward to hit the cylinder assembly. First, the outer rod assembly collides with the cylinder assembly. After the collision, the outer rod assembly rebounds first. Since the inner rod assembly and the test head assembly are suspended, the inner rod assembly and the test head assembly continue to move downward at this time; the inner rod assembly first collides with the first-level collision part of the rebounded outer rod assembly. Since m1>m2, after the collision, the inner rod assembly rebounds upward. By controlling the masses m1 and m2, the rebound speed of the inner rod assembly is greater than the initial speed of the downward movement, and the first-level speed amplification is obtained; finally, the test head assembly moves downward to collide with the rebounding second-level collision part of the inner rod assembly, and the same reason is due to m2 >m3, after the collision, the test head assembly rebounds upward, and by controlling the masses m2 and m3, the rebound speed of the test head assembly is further amplified to obtain a second speed amplification, namely a two-stage speed amplification; finally, the test piece installed on the test head will be subjected to a huge impact acceleration; the device can obtain a semi-sine impact acceleration pulse waveform with a peak value of more than 100,000 g, and can produce an impact acceleration with a higher g value level; and the invented test device has a simple structure, a small space size, and a very low processing and manufacturing cost; it can be operated purely manually, with almost no maintenance cost, and is simple and convenient to operate. The structure occupies a small space, is easy to carry, is not limited by the use occasion, and greatly improves the flexibility of use. An external air cannon is used as an excitation energy source, which is safe and convenient. The volume and pressure can be flexibly selected according to the peak acceleration to meet different test requirements. The air cannon combined with the two-stage speed amplifier can produce an impact overload test environment with a higher g value level.

[0028] In this embodiment, the cylinder assembly includes a base II, a cylinder III and an air intake seat IV. The base II is sealed on the bottom of the cylinder III, the air intake seat IV is sealed on the top of the cylinder III, the necking section 24 is arranged in the cylinder III, a through hole 18 is arranged in the middle of the air intake seat IV, the outer rod assembly is sealed and slidably matched with the through hole, an intake flow channel 17 is arranged on the air intake seat IV, the air outlet of the intake flow channel 17 is located below the air intake seat IV and is connected to the inner cavity of the cylinder, and the air inlet of the intake flow channel 17 serves as the air inlet of the cylinder assembly and is connected to the air outlet of the air cannon I. The two-stage speed amplifier also includes a piston 12 and a magnet 13 installed on the upper surface of the piston. The piston is fixed on the outer rod assembly. The piston and the inner wall of the cylinder assembly are axially sealed and slidably matched. The cylinder assembly has a necking section 24 in the cylinder body. The necking section is located above the piston. The air inlet of the cylinder assembly is located above the necking section. There is a set gap between the inner circle of the necking section and the outer circle of the outer rod assembly. The piston can be adsorbed to the bottom of the necking section by magnetism so that the two-stage speed amplifier is suspended in the cylinder assembly.

[0029] Combination Figures 1 to 4 As shown, the cylinder III includes a cylindrical cylinder body 21 and connecting flanges connected to the upper and lower ends of the cylinder body 21, wherein the connecting flange at the lower end of the cylinder body is sealed and connected to the base II through bolts I22, and the base II also serves as an anvil for collision with the outer rod assembly, and the connecting flange at the upper end of the cylinder body is sealed and connected to the intake seat IV through bolts II23; the piston is a cylindrical structure, the piston, the outer rod assembly and the cylinder are coaxially arranged, the upper end surface of the piston has an annular groove, and the magnetic attraction is embedded in the groove; the necking section 24 is located at the inner circle of the cylinder body 21, and the inner wall of the cylinder body 21 radially protrudes to form an inner step ring, and the upper end of the inner step ring is The end is in the shape of a trumpet that expands upward; when the air cannon introduces a jet of air into the cylinder body 21, the narrowing section is conducive to the expansion of the jet of air from the air cannon and the external work, so that the two-stage velocity amplifier obtains the largest possible initial collision velocity, and the step position at the bottom of the narrowing section 24 is also used to cooperate with the magnetic attraction 13, so that the two-stage velocity amplifier forms a hovering shape; the setting of the air intake seat makes the cylinder and the air cannon separately set, so that the structure of the excitation device is simple, the inner wall structure of the cylinder body uses the jet of air from the air cannon to expand and do work externally, and the processing accuracy requirement is low, and it has the functions of connection, support, and hovering.

[0030] In this embodiment, a vent hole 25 is provided at the lower middle position of the cylinder III, and the vent hole connects the inner cavity of the cylinder with the outside. When the two-stage speed amplifier is suspended in the cylinder assembly, the vent hole 25 is located below the piston. The lower middle position of the cylinder III refers to the lower middle position in the vertical direction. Figure 4As shown, there are a number of vent holes 25 distributed circumferentially at the lower middle part of the cylinder III. When the piston is driven downward, the gas below the piston in the cylinder III can be discharged through the vent holes. When the piston moves below the vent holes, the gas in the chamber above the piston can be discharged through the vent holes. At this time, the downward air pressure on the outer rod assembly is released, thereby ensuring that the outer rod assembly rebounds upward after colliding with the base II.

[0031] In this embodiment, a guide bushing 15 is disposed in the through hole 18, and the outer rod assembly is in sealing and sliding cooperation with the guide bushing. Figure 3 As shown, the upper end of the guide bearing 15 has an annular mounting edge formed along a radial edge, which abuts against the upper surface of the intake seat IV and is fixed by screws 16. A sealing ring can be arranged between the mounting edge and the upper surface of the intake seat IV for sealing. The arrangement of the guide bearing 15 is conducive to reducing the wear of the intake seat IV, facilitating the replacement of components, and reducing the subsequent maintenance costs.

[0032] In this embodiment, the inner rod assembly includes an inner rod 2 that is vertically slidably sleeved in the outer rod assembly and an inner rod suspension ejector pin 5 connected to the bottom of the inner rod. The bottom of the inner cavity of the outer rod assembly is provided with a primary mounting hole. The inner rod suspension ejector pin 5 is vertically slidably sleeved in the primary mounting hole and the bottom end of the inner rod is suspended above the bottom of the inner cavity of the outer rod assembly through a primary elastic member 4 installed in the primary mounting hole. The inner rod suspension ejector pin is a thin shaft structure. The bottom of the inner cavity of the outer rod assembly forms an inner shoulder structure due to the opening of the primary mounting hole. The inner shoulder is the primary collision part of the outer rod assembly. The corresponding bottom end of the inner rod and the primary collision part form a primary collision acceleration. The primary elastic member adopts a cylindrical coil spring. The two ends of the primary elastic member are respectively connected to the bottom end of the inner rod suspension ejector pin and the bottom of the primary mounting hole. The setting of the primary elastic member ensures that the bottom end of the inner rod is suspended and set on the primary collision part, leaving a certain running space for the outer rod to collide with the inner rod when rebounding, so as to achieve a higher primary collision acceleration.

[0033] In this embodiment, the test head assembly includes a test head 3 and a test head suspension pin 9 connected to the bottom of the test head. A secondary mounting hole is provided at the bottom of the inner cavity of the inner rod assembly. The test head suspension pin 9 is vertically slid into the secondary mounting hole and the bottom of the test head is suspended above the bottom of the inner cavity of the inner rod assembly through a secondary elastic member 8 installed in the secondary mounting hole. The test head suspension pin is a thin shaft structure. The bottom of the inner cavity of the inner rod assembly also forms an internal shoulder structure due to the opening of the secondary mounting hole. The internal shoulder structure can be used as a secondary collision part, and of course it can also be used as a Figure 1A waveform generator is arranged at the shoulder as a secondary collision part, and the corresponding bottom end of the test head forms a secondary collision with the secondary collision part. The secondary elastic member also adopts a cylindrical coil spring, and the two ends of the secondary elastic member are respectively connected to the bottom end of the suspended ejector pin of the test head and the bottom of the secondary mounting hole. The primary elastic member and the secondary elastic member can also adopt a wave spring or other known elastic structure, which will not be described in detail. The setting of the secondary elastic member also makes the test head suspended above the secondary collision part, leaving a certain running space for the inner rod assembly to collide with the test head when rebounding, so as to achieve a higher secondary collision acceleration.

[0034] In this embodiment, the inner rod assembly further comprises an inner rod upper seat 7 and a test head fixing cap 11. The upper end of the inner rod extends to the outside of the outer rod assembly and is fixedly connected to the inner rod upper seat. The test head fixing cap 11 is an annular structure. The test head fixing cap is partially sheathed on the upper end of the inner rod and forms an inner cavity of the inner rod assembly at the upper end of the inner rod. The test head fixing cap is not limited to a circular ring structure, but may also be an elliptical ring or other polygonal ring structure. The specific structure is adapted to the inner rod and combined with the inner rod. Figures 5 to 7 As shown, the test head fixing cap and the inner rod upper seat together form an inner cavity of the inner rod assembly, and the test head can be axially slidably installed in the inner cavity. The inner rod upper seat is located outside the outer rod, so that the specific structure of the inner rod upper seat is not limited by the inner cavity of the outer rod, which is conducive to the conformal setting of the structure of the test head and also facilitates the installation of the test head and the test piece;

[0035] In this embodiment, the outer rod assembly includes an outer rod 1 and an inner rod fixing cap 6 connected to the outer rod. The inner rod fixing cap 6 and the outer circle of the inner rod have mutually matching limiting parts. The piston 12 is fixedly installed on the outer rod. The outer rod and the through hole 18 are vertically sealed and slidably matched. The inner rod fixing cap 6 forms an axial limit to the inner rod through the matching of the limiting part and has a pre-tightening force on the inner rod to make the inner rod suspension ejector pin press on the primary elastic member. The axial direction is consistent with the vertical direction; combined Figure 5 As shown, the inner diameter of the outer rod is matched with the outer diameter of the inner rod, and the clearance between the inner rod and the outer rod is matched to realize the axial sliding of the inner rod relative to the outer rod. The inner cavity of the inner rod fixing cap is an inner stepped shaft structure with a small upper part and a large lower part. The corresponding inner rod is divided into a stepped shaft structure with a small upper part and a large lower part near the upper end. The small diameter section of the inner rod is provided with an external thread and is threadedly connected with the inner rod upper seat 7, and the large diameter section of the inner rod fixing cap is provided with an external thread and is threadedly connected with the outer rod. The inner rod fixing cap is outer-mounted on the inner rod, and the shoulder of the inner rod fixing cap is axially abutted against the shoulder of the inner rod to form a limiting portion. Through this structure, an axial limit is formed on the inner rod, so that the inner rod slides within a predetermined sliding stroke to prevent the inner rod from detaching from the outer rod assembly during rebound, and the pre-tightening force of the inner rod fixing cap can ensure the stability of the inner rod in the initial state, thereby improving the compactness of assembly between the components.

[0036] In this embodiment, the test head fixing cap 11 has a stopper that cooperates with the outer circumference of the test head. The test head fixing cap 11 forms an axial stopper for the test head through the cooperation of the stopper and exerts a preload force on the test head to press the test head suspension pin onto the secondary elastic member. Figure 6 As shown, the outer rod, the inner rod, the inner rod suspension ejector, the inner rod fixing cap, the inner rod upper seat, the test head suspension ejector, the test head fixing cap and the test head are all coaxially arranged, the inner circle of the test head fixing cap is a two-stage inner stepped shaft structure with the inner diameter decreasing from bottom to top, and the corresponding outer circle of the test head is a stepped shaft structure with a small top and a large bottom, wherein the large diameter section of the test head fixing cap is an internal thread section connected with the outer circle thread of the inner rod upper seat, the middle diameter section of the test head fixing cap is adapted to the large diameter section of the test head to ensure the stable axial sliding of the test head, and the small diameter section of the test head is threaded through the test head fixing cap The small diameter section extends out of the test head fixing cap, wherein the axial shoulder between the middle diameter section and the small diameter section of the test head fixing cap and the axial shoulder of the test head abut against each other axially to form a limiting portion. The test head fixing cap presses down the axial shoulder of the test head so that the suspended ejector pin of the test head is pressed on the secondary elastic member. This structure not only forms an axial limit for the test head, allowing the test head to slide within a predetermined sliding stroke, thereby preventing the test head from detaching from the inner rod assembly during rebound, but also the pre-tightening force of the test head fixing cap can ensure the stability of the test head in the initial state, thereby improving the compactness of assembly between the components.

[0037] In this embodiment, a waveform generator 10 is provided at the bottom of the inner cavity of the inner rod assembly to form a secondary collision portion. The waveform generator is used to adjust the acceleration waveform of the test head. Figure 5 As shown, the waveform generator 10 is installed on the top of the inner rod upper seat 7 and is located in the fixing cap 11. The waveform generator here can be made of nylon sheet, plastic sheet or other thin sheet materials with certain plastic deformation or elasticity. When the wave generator collides with the test head, the wave generator is deformed to adjust the contact time with the test head through the deformation, thereby adjusting the acceleration change trend of the test head, so that the acceleration of the test head changes according to the required acceleration waveform curve trend.

[0038] In this embodiment, the inner rod fixing cap 6 is detachably connected to the outer rod 1. The inner rod upper seat 7 is detachably connected to the inner rod 2. The inner rod upper seat 7 is detachably connected to the fixing cap 11. Figure 5 As shown, the outer circle of the upper end of the outer rod is an external thread structure, the inner rod fixing cap is threadedly connected and sleeved on the outer circle of the upper end of the outer rod, the outer circle of the upper end of the inner rod 2 is an internal thread structure, the lower end of the inner rod upper seat 7 has a threaded hole, the inner rod thread is screwed into the threaded hole, the outer circle of the upper end of the inner rod upper seat 7 is an external thread structure, and the fixing cap 11 is threadedly connected and sleeved on the upper end of the outer circle of the inner rod upper seat; the detachable connection structure is convenient for the assembly and subsequent maintenance and overhaul of the pneumatic high-g value impact excitation device based on the two-stage velocity amplifier.

[0039] Working principle of the present invention:

[0040] The masses of the primary elastic part, the inner rod suspension ejector pin, the secondary elastic part, the test head suspension ejector pin and the waveform generator are all very small and can be ignored. At this time, the outer rod and the inner rod fixing cap constitute an outer rod assembly with a mass block of m1, the inner rod, the inner rod upper seat and the test head fixing cap constitute an inner rod assembly with a mass block of m2, and the test head and the test piece constitute a test head assembly with a mass block of m3. The design ensures that m1>m2>m3.

[0041] The air cannon test pressure is set, and the air cannon is inflated to reach the set pressure; the two-stage speed amplifier is manually pulled to make the outer rod assembly move upward relative to the cylinder assembly, and the magnetic force of the magnet on the piston attracts the bottom of the constricted section 24 in the cylinder body, so that the two-stage speed amplifier remains suspended. The air cannon is operated to cause an explosion, and the ejected high-speed air flow enters the cylinder body through the intake flow channel of the intake seat, driving the piston to drive the two-stage speed amplifier to accelerate downward movement. When the piston position exceeds the air vent of the cylinder body, the gas is quickly discharged from the air vent, and then the outer rod assembly with a mass of m1 collides with the base and rebounds. Since the inner rod and the test head are suspended and supported, the inner rod assembly with a mass of m2 and the test head assembly with a mass of m3 will compress the corresponding elastic parts and continue to move downward, wherein the inner rod assembly with a mass of m2 will first collide with the outer rod inner step in the rebounded outer rod assembly with a mass of m1. Since m1>m2, after m2 collides with m1, the inner rod assembly with a mass of m2 will rebound upward, and the rebound speed is greater than the initial speed of the downward movement, and a first-level speed amplification is obtained. Finally, the inner rod assembly with mass m2 collides with the test head assembly with mass m3 which is still moving downward. For the same reason, because m2>m3, after the collision between m3 and m2, m3 will rebound upward. At this time, the rebound speed of m3 is further amplified, and a second speed amplification is obtained. Finally, the test piece installed on the test head will be subjected to huge impact acceleration.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A pneumatic high-g impact excitation device based on a two-stage velocity amplifier, characterized in that: It comprises an air cannon, a cylinder assembly and a two-stage speed amplifier, wherein the two-stage speed amplifier comprises an outer rod assembly, an inner rod assembly and a test head assembly, wherein a primary collision part is arranged in the inner cavity of the outer rod assembly corresponding to the bottom end of the inner rod assembly, the inner rod assembly is vertically slidably sleeved in the outer rod assembly and suspended above the primary collision part, a secondary collision part is arranged in the inner cavity of the inner rod assembly corresponding to the bottom end of the test head, the test head assembly can be vertically slidably sleeved in the inner rod assembly and suspended above the secondary collision part, the mass of the outer rod assembly is greater than the mass of the inner rod assembly, the mass of the inner rod assembly is greater than the mass of the test head assembly, the outer rod assembly can be vertically slidably installed in the cylinder assembly, the air outlet of the air cannon is connected with the air inlet of the cylinder assembly to drive the outer rod assembly to accelerate vertically downward; The two-stage speed amplifier also includes a piston and a magnet installed on the upper surface of the piston. The piston is fixed on the outer rod assembly. The piston and the inner wall of the cylinder body of the cylinder assembly are axially sealed and slidably matched. The cylinder body of the cylinder assembly has a constricted section, and the constricted section is located above the piston. The air inlet of the cylinder assembly is located above the constricted section. A set gap is provided between the inner circle of the constricted section and the outer circle of the outer rod assembly. The piston can be adsorbed to the bottom of the constricted section by magnet so that the two-stage speed amplifier is suspended in the cylinder assembly. The inner wall of the cylinder body (21) radially protrudes to form an inner step ring. The upper end of the inner step ring is in the shape of a trumpet that expands upward. The step position at the bottom of the constricted section (24) is also used to cooperate with the magnet (13), so that the two-stage speed amplifier forms a suspended state.

2. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 1 is characterized in that: The cylinder assembly includes a base, a cylinder and an air inlet seat, the base sealing cover is on the bottom of the cylinder, the air inlet seat sealing cover is on the top of the cylinder, the necking section is arranged in the cylinder, a through hole is arranged in the middle of the air inlet seat, the outer rod assembly is in sealing and sliding cooperation with the through hole, an air inlet flow channel is arranged on the air inlet seat, the air outlet end of the air inlet flow channel is located below the air inlet seat and is connected with the inner cavity of the cylinder, and the air inlet end of the air inlet flow channel serves as the air inlet of the cylinder assembly and is connected with the air outlet of the air cannon.

3. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 2 is characterized in that: A vent hole is provided at the lower middle part of the cylinder, and the vent hole enables the inner cavity of the cylinder to communicate with the outside. When the two-stage speed amplifier is suspended in the cylinder assembly, the vent hole is located below the piston.

4. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 2 is characterized in that: A guide bush is arranged in the through hole, and the outer rod assembly is sealingly and slidingly matched with the guide bush.

5. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 2 is characterized in that: The inner rod assembly includes an inner rod that is vertically slidably sleeved in the outer rod assembly and an inner rod suspension ejector pin connected to the bottom of the inner rod. A primary mounting hole is opened at the bottom of the inner cavity of the outer rod assembly. The inner rod suspension ejector pin is vertically slidably sleeved in the primary mounting hole and a primary elastic member installed in the primary mounting hole allows the bottom end of the inner rod to be suspended above the bottom of the inner cavity of the outer rod assembly.

6. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 5 is characterized in that: The test head assembly includes a test head and a test head suspension pin connected to the bottom end of the test head. A secondary mounting hole is opened at the bottom of the inner cavity of the inner rod assembly. The test head suspension pin is vertically slidably sleeved in the secondary mounting hole and the bottom end of the test head is suspended above the bottom of the inner cavity of the inner rod assembly through a secondary elastic member installed in the secondary mounting hole.

7. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 5 is characterized in that: The outer rod assembly includes an outer rod and an inner rod fixing cap connected to the outer rod, the piston is fixedly mounted on the outer rod, the outer rod is vertically sealed and slidably matched with the through hole, the inner rod fixing cap and the outer circle of the inner rod are provided with mutually matching limiting parts, the inner rod fixing cap forms an axial limit to the inner rod through the matching of the limiting parts and has a pre-tightening force on the inner rod to press the inner rod floating ejector pin onto the primary elastic member.

8. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 6 is characterized in that: The inner rod assembly also includes an inner rod upper seat and a test head fixing cap. The upper end of the inner rod extends to the outside of the outer rod assembly and is fixedly connected to the inner rod upper seat. The test head fixing cap is an annular structure. The test head fixing cap is partially sleeved on the upper end of the inner rod and forms an inner cavity of the inner rod assembly at the upper end of the inner rod. The test head fixing cap and the outer circle of the test head are provided with mutually matching limiting parts. The test head fixing cap forms an axial limit for the test head through the cooperation of the limiting part and has a pre-tightening force on the test head to press the suspended ejector pin of the test head onto the secondary elastic member.

9. The pneumatic high-g impact excitation device based on a two-stage velocity amplifier according to claim 5 is characterized in that: A waveform generator is provided at the bottom of the inner cavity of the inner rod assembly to form a secondary collision portion, and the waveform generator is used to adjust the acceleration waveform of the test head.

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