A device and method for measuring collision restitution coefficient

Abstract

This application discloses a collision restitution coefficient measuring device and method, relating to the field of mechanical engineering. The device includes a catapult, an electromagnet, a moving block, a stationary block, and a base. The stationary block is connected to the base by screws. The electromagnet includes a fixed structure and an armature. One end of the fixed structure is connected to the base, and the other end is connected to the catapult. The armature slides relative to the fixed structure along a direction close to or away from the stationary block. The end of the armature close to the stationary block is connected to the moving block, and the other end faces the output end of the catapult. The fixed structure generates a magnetic force on the armature in the direction of the catapult or the stationary block, depending on the position of the armature. The output end of the catapult applies a launching force to the armature. The device has a simple and compact overall structure, low development cost, and is easy to use for testing the collision restitution coefficient under actual collision conditions. The testing operation and calculation are simple.

Description

Technical Field

[0001] This invention relates to a collision recovery coefficient measuring device and method, belonging to the field of mechanical engineering. Background Technology

[0002] Collisions are ubiquitous in mechanical systems, representing a form of interaction between parts. They are characterized by high intensity but short duration, and complex mechanisms. In engineering, the change in the motion state of an object before and after a collision is a primary concern, and the coefficient of restitution (CR) is a crucial parameter characterizing this change. Researchers both domestically and internationally have conducted extensive studies on the CR, proposing various collision model assumptions and calculation formulas. However, these studies are largely theoretical, and the proposed models and formulas are often complex and not widely applicable to general engineering problems.

[0003] In existing technologies, there are relatively few experimental studies on the coefficient of restitution (CR) of collision. A common method involves using an acceleration system to launch a collider into a target object, recording the collision process with a high-speed camera, and then converting the recorded data into velocities before and after the collision to calculate the CR. This testing method typically requires a complex experimental system, generally including: a gas tank, a high-pressure gas chamber, a gas flow trigger, a collider guide rail, and a high-speed camera. Due to the limitations of the high-speed camera's frame rate, the testing accuracy is usually not very high, and this method is mainly suitable for collisions between large colliders, not for collisions between smaller colliders. Summary of the Invention

[0004] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide a collision recovery coefficient measuring device and method. The device has a simple and compact overall structure, low development cost, is easy to test the collision recovery coefficient according to actual collision conditions, and is simple to test and calculate.

[0005] The technical solution provided in this application is as follows:

[0006] A collision recovery coefficient measuring device includes a catapult, an electromagnet, a moving block, a stationary block, and a base. The stationary block is connected to the base by screws. The electromagnet includes a fixed structure and an armature. One end of the fixed structure is connected to the base, and the other end is connected to the catapult. The armature slides relative to the fixed structure along a direction close to or away from the stationary block. The end of the armature close to the stationary block is connected to the moving block, and the other end faces the output end of the catapult. The fixed structure is used to generate a magnetic force on the armature in the direction of the catapult or in the direction of the stationary block, depending on the position of the armature. The output end of the catapult is used to apply a catapult force to the armature.

[0007] The ejector includes a fixed sleeve, a rotating sleeve, a lower end cover, an upper end cover, a spring, an ejection rod, a hook, a wing nut, and a pull rope. The lower end cover is connected to one end of the fixed sleeve, and the other end of the fixed sleeve is connected to the rotating sleeve via a fine-pitch thread. The rotating sleeve is connected to the upper end cover, and an electromagnet is connected to the lower end cover. The ejection rod passes through the fixed sleeve and the rotating sleeve, and is slidably connected to both along the axis of the rotating sleeve. One end of the armature is directly opposite the end of the ejection rod. The spring connects the ejection rod and the electromagnet to apply an ejection force to the armature. The wing nut is rotatably connected to the upper end cover, and the hook is threadedly connected to the wing nut. The ejection rod moves along the axis of the fixed sleeve, and the pull rope connects the hook and the ejection rod. By rotating the wing nut, the hook moves, causing the ejection rod to contact the fixed sleeve. The upper end of the ejection rod is connected to the hook via the pull rope, and the hook is threadedly connected to the wing nut. When the wing nut is tightened, the hook moves upward, pulling the ejector rod through the rope and squeezing the spring. When the rope is cut, the spring applies an ejection force to the ejector rod, causing the ejector rod to push the armature towards the stationary block.

[0008] The upper cover has a rectangular limiting groove, and the hook end has a flat structure, which matches the rectangular limiting groove of the upper cover.

[0009] The rotating sleeve has a rectangular limiting groove, and the ejector rod has a flat structural part that mates with the rectangular limiting groove.

[0010] The inner wall of the fixed sleeve is provided with an annular surface E, and the outer wall is provided with an annular surface F. Annular surface E and annular surface F are on the same plane. The inner wall of the rotating sleeve is provided with an annular surface M, and the outer wall is provided with an annular surface N. Annular surface M and annular surface N are on the same plane. The ejector rod is provided with a convex ring. Annular surface E is located on the side of the convex ring away from the moving block and is used to limit the movement stroke of the convex ring. The spring contacts the side of the convex ring away from the moving block, and the spring contacts annular surface M.

[0011] The fixing structure includes an upper stop, a lower stop, an outer sleeve, a magnet, an upper coil, a lower coil, and a frame. The upper and lower stops are respectively connected to both ends of the outer sleeve. The upper stop is used to connect to the catapult, and the lower stop is used to connect to the base. The outer sleeve is a cylindrical shape with openings at both ends. The frame is located inside the outer sleeve, and the magnet is bonded to the middle part of the outer frame. The upper and lower coils are wound on the frame and located on both sides of the magnet. The armature is located inside the frame, and its two ends pass through the upper and lower stops respectively. The magnet is a toroidal permanent magnet material, with its two poles located on the cylindrical surface in contact with the frame and the cylindrical surface in contact with the outer sleeve, respectively. The upper stop, lower stop, outer sleeve, and armature are made of soft magnetic material.

[0012] When the ejector rod is pulled up to contact the fixed sleeve, there is a gap Δ between the ejector rod and the lower end cover. This position is taken as the zero point of displacement. If the armature is gradually moved towards the downward stop until the magnetic force is zero, the displacement is recorded as δ0, where Δ < δ0.

[0013] A method for measuring the coefficient of restitution, comprising measuring using any of the aforementioned devices for measuring the coefficient of restitution, including:

[0014] S1: Calculate the work W done by the magnet force during the process from the position where the armature's force is zero until the moving block and the stationary block just come into contact. c ;

[0015] S2: Obtain the relationship between the compressive force F on the spring and the length x of the spring;

[0016] S3: Measure the masses of the armature, moving block, and ejector rod as m1, m2, and m3, respectively;

[0017] S4: Rotate the rotating sleeve to compress the spring and generate spring force; rotate the wing nut to pull the ejector rod up to contact the fixed sleeve through the pull rope; supply power to the upper coil so that the armature contacts the lower end face of the ejector rod; cut the pull rope and check whether the upper end face of the armature is separated from the lower end face of the ejector rod.

[0018] S5: If the upper end face of the armature is still in contact with the lower end face of the ejector rod, repeat step S4 and gradually tighten the rotating sleeve to increase the spring force until the upper end face of the armature separates from the lower end face of the ejector rod.

[0019] Repeat step S4 and rotate the sleeve in the opposite direction to reduce the spring force until the state where the upper end face of the armature is just separated from the lower end face of the ejection rod is found.

[0020] Measure the distance between the fixed collar surface F and the rotating collar surface N, and record it as x1; calculate the work W done by the spring force during this process based on x1 and the relationship between the compressive force F on the spring and the spring length x. s1 ;

[0021] S6: Repeat step S4 and continue to compress the spring further by twisting the rotating sleeve to generate a greater spring force; observe whether the upper end face of the armature contacts the lower end face of the ejector rod after the static block bounces back after the pull rope is cut.

[0022] S7: If the upper end face of the armature is still separated from the lower end face of the ejector rod, repeat step S4 to continue increasing the spring force until the upper end face of the armature contacts the lower end face of the ejector rod.

[0023] Repeat step S5, twisting the rotating sleeve in the opposite direction until you find the state where the armature just bounces back to the side of the upper stop.

[0024] Measure the distance between the fixed collar surface F and the rotating collar surface N, and record it as x2; calculate the work W done by the spring force during this process based on x2 and the relationship between the compressive force F on the spring and the spring length x. s2 ;

[0025] S8: The work W done by the spring force during the process when the upper end face of the armature just separates from the lower end face of the ejection rod. s1 The work done by the spring force W during the process of the armature just rebounding to the side of the upper stop. s2 W c The mass of the armature, moving block, and ejector rod are used to calculate the velocity v of the moving block just before it collides with the stationary block, as well as the collision recovery coefficient e between the moving block and the stationary block.

[0026] In step S5, the work W done by the spring force is calculated based on x1 and the relationship between the compressive force F on the spring and the spring length x. s1 This includes: calculating the spring force f1 when the ejector rod contacts the fixed sleeve and the spring force f2 when the ejector rod contacts the lower end cover, based on the relationship between x1 and the compressive force F on the spring and the spring length x.

[0027]

[0028] The velocity v of the moving block and the stationary block just before the collision is:

[0029] The collision recovery coefficient e between the moving block and the stationary block is:

[0030]

[0031] In summary, this application includes at least the following beneficial technical effects:

[0032] 1. The collision recovery coefficient measuring device disclosed in this invention is mainly a mechanical structure and does not involve sensors or electronic equipment. It has a simple structure, low development cost, and is easy to implement.

[0033] 2. The collision recovery coefficient measuring device disclosed in this invention is particularly suitable for measuring the collision recovery coefficient during low-speed collisions between small parts.

[0034] 3. The collision recovery coefficient measuring device disclosed in this invention has an independent structure for the moving block and the stationary block, and the collision contact surface of the two can be designed according to the actual collision contact surface, so that the collision recovery coefficient test results are closer to the actual situation. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a collision recovery coefficient measuring device according to the present invention;

[0036] Figure 2This is a schematic diagram of the catapult's structure;

[0037] Figure 3 A cross-sectional schematic diagram of the structure in which the hook and the upper end cap fit together;

[0038] Figure 4 This is a cross-sectional schematic diagram of the assembly structure of the ejection rod and the rotating sleeve.

[0039] Figure 5 This is a schematic diagram of the structure of an electromagnet. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0041] This application discloses a collision recovery coefficient measuring device, such as... Figure 1 As shown, it specifically includes: catapult 1, electromagnet 2, moving block 3, stationary block 4, and base 5; catapult 1 and electromagnet 2 are connected by screws, electromagnet 2 and moving block 3 are connected by threads, and stationary block 4 and base 5 are connected by screws.

[0042] Figure 2 This is a structural diagram of the catapult 1. The catapult 1 is one of the power sources affecting the movement of the moving block 3, and specifically includes: a fixed sleeve 1-1, a rotating sleeve 1-2, a lower end cover 1-3, an upper end cover 1-4, a spring 1-5, a catapult rod 1-6, a hook 1-7, a wing nut 1-8, and a pull rope 1-9. The fixed sleeve 1-1 and the rotating sleeve 1-2 are connected by fine-pitch threads, and their coaxiality is limited by the mating surface. The fixed sleeve 1-1 and the lower end cover 1-3 are connected by screws. The rotating sleeve 1-2 is connected to the upper end cover 1-4 by screws; the ejector rod 1-6 is installed between the rotating sleeve 1-2 and the lower end cover 1-3, and is connected to the rotating sleeve 1-2 and the lower end cover 1-3 by thin shafts at both ends respectively; the spring 1-5 is installed between the ejector rod 1-6 and the rotating sleeve 1-2; the hook 1-7 passes through the upper end cover 1-4 and is connected to the wing nut 1-8 by threads; the ejector rod 1-6 and the hook 1-7 are connected by a pull rope 1-9.

[0043] Figure 3 This is a cross-sectional view of the mating part between the upper end cover 1-4 and the hook 1-7. The upper end cover 1-4 has a rectangular limiting groove. The hook end of the hook 1-7 has a flat structure. The flat structure of the hook 1-7 mates with the rectangular limiting groove of the upper end cover 1-4, so that when the wing nut 1-8 is rotated, the hook 1-7 can only move up and down, and cannot rotate relative to the upper end cover 1-4.

[0044] Figure 4This is a cross-sectional view of the mating part between the rotating sleeve 1-2 and the ejector rod 1-6. The rotating sleeve 1-2 has a rectangular limiting groove. The hook end of the ejector rod 1-6 has a flat structure. The flat structure of the ejector rod 1-6 mates with the rectangular limiting groove of the rotating sleeve 1-2, ensuring that when the rotating sleeve 1-2 rotates, the ejector rod 1-6 can only move up and down relative to the rotating sleeve 1-2, and cannot rotate relative to the rotating sleeve 1-2. The annular surface E and annular surface F of the fixed sleeve 1-1 are on the same plane, and the annular surface M and annular surface N of the rotating sleeve 1-2 are on the same plane. The distance between annular surface N and annular surface F is equal to the length of the spring when the ejector rod 1-6 is pulled up and contacts the fixed sleeve 1-1.

[0045] Figure 5 The diagram shows the structure of electromagnet 2, which is one of the power sources affecting the movement of moving block 3. Specifically, it includes: upper stop 2-1, lower stop 2-2, outer sleeve 2-3, magnet 2-4, upper coil 2-5, lower coil 2-6, armature 2-7, and frame 2-8. The outer sleeve 2-3 is connected to the upper stop 2-1 and lower stop 2-2 by screws. The magnet 2-4 is bonded to the middle part of the frame 2-8. The upper coil 2-5 and lower coil 2-6 are wound around the frame 2-8 and located on both sides of the magnet 2-4. The whole assembly is fitted between the upper stop 2-1 and lower stop 2-2. The cavity between the outer sleeve 2-3, upper stop 2-1, lower stop 2-2, upper coil 2-5, and lower coil 2-6 is filled with thermally conductive adhesive. The armature 2-7 is located inside the frame 2-8 and passes through the upper stop 2-1 and lower stop 2-2. Magnet 2-4 is a toroidal permanent magnet, with its two poles located on the cylindrical surfaces in contact with the frame 2-8 and the outer sleeve 2-3, respectively. The upper stop 2-1, lower stop 2-2, outer sleeve 2-3, and armature 2-7 are made of soft magnetic material. Armature 2-7 has thin shafts at both ends, with one end of the shaft having a threaded structure for connection to the stationary block 4. When armature 2-7 is close to the upper stop 2-1, it experiences an upward magnetic force from magnet 2-4; when it is close to the lower stop 2-2, it experiences a downward magnetic force; and when it is in a neutral position, the force on armature 2-7 is zero.

[0046] like Figure 1 As shown, when the electromagnet 2 is installed on the catapult 1 and the catapult rod 1-6 is pulled up to contact the fixed sleeve 1-1, there is a gap Δ between the catapult rod 1-6 and the lower end cover 1-3. Taking this position as the zero point of displacement, if the armature 2-7 is gradually moved towards the lower stop 2-2 until the magnetic force is zero, the displacement is recorded as δ0. In order to ensure that the collision recovery coefficient measuring device of the present invention can be tested normally, it is required that Δ < δ0.

[0047] When armature 2-7 is on the side of upper stop 2-1, armature 2-7 can be moved to the side of lower stop 2-2 by energizing lower coil 2-6; when armature 2-7 is on the side of lower stop 2-2, armature 2-7 can be moved to the side of upper stop 2-1 by energizing upper coil 2-5, and the position of armature 2-7 can be reset to the top.

[0048] The steps for measuring the collision recovery coefficient in this invention are as follows:

[0049] S1. Calculation of the work done by the magnet force on armature 2-7 from the position where the magnetic force is zero until the moving block 3 and the stationary block 4 just come into contact: Taking the position where the magnetic force on armature 2-7 is zero as the zero displacement point, move armature 2-7 a small displacement towards the downward stop 2-2, and record the position as δ1, and measure the magnetic force as F1; continue to move armature 2-7 a small displacement towards the downward stop 2-2, and record the position as δ2, and measure the magnetic force as F2; ​​... until the moving block 3 is installed on armature 2-7 and the moving block 3 comes into contact with the stationary block 4, the displacement of the armature at this time is recorded as δn, and the magnetic force on armature 2-7 is recorded as Fn. The work done by the magnetic force is then calculated according to the following formula:

[0050]

[0051] S2. Spring Original Length and Stiffness Test: Measure the length of the spring in its natural, unforced state, denoted as x0; measure the length of the spring under a certain compressive force f. a Length x under action a The spring stiffness k is calculated using the following formula:

[0052]

[0053] The relationship between the compressive force F on the spring and the spring length x is as follows:

[0054] f = k(x0 - x)(1-3)

[0055] S3. Measure the mass of armature 2-7, moving block 3, and ejector rod 1-6. Record the masses of the three parts as m1, m2, and m3 respectively.

[0056] S4. Assemble the catapult 1, electromagnet 2, moving block 3, stationary block 4, and base 5.

[0057] S5. By rotating the sleeve 1-2, the spring 1-5 is compressed, generating spring force. Rotating the wing nut 1-8 pulls the ejector rod 1-6 up to contact the fixed sleeve 1-1 via the pull rope 1-9, supplying power to the upper coil 2-5, so that the armature 2-7 is on the side of the upper stop 2-1, and the upper end face of the armature 2-7 is in contact with the lower end face of the ejector rod 1-6. Cut the pull rope, and check through the observation window on the lower end cover 1-3 whether the upper end face of the armature 2-7 is separated from the lower end face of the ejector rod 1-6.

[0058] S6. If the upper end face of armature 2-7 is still in contact with the lower end face of ejector rod 1-6, it means that armature 2-7 is still on the side of upper stop 2-1. Then, follow step S5 and further tighten the rotating sleeve 1-2 to increase the spring force until the upper end face of armature 2-7 separates from the lower end face of ejector rod 1-6, indicating that armature 2-7 has moved to the side of lower stop 2-2. At this time, repeat step S5 and tighten the rotating sleeve 1-2 in the opposite direction to fine-tune the spring force and reduce it. Find the state when the upper end face of armature 2-7 is just separated from the lower end face of ejector rod 1-6. Measure the distance between the annular surface F of fixed sleeve 1-1 and the annular surface N of rotating sleeve 1-2, and record it as x1. Calculate the spring force when ejector rod 1-6 is in contact with fixed sleeve 1-1 and the spring force when ejector rod 1-6 is in contact with lower end cover 1-3 according to formula (1-3), and record them as f1 and f2 respectively. The work W done by the spring force in this process is... s1 Calculate using the following formula:

[0059]

[0060] S7. Repeat step S5, continuing to compress the spring 1-5 further by turning the rotating sleeve 1-2 to generate a greater spring force. Rotate the wing nut 1-8 to pull the ejector rod 1-6 up to contact the fixed sleeve 1-1 via the pull rope 1-9, supplying power to the upper coil 2-5, so that the armature 2-7 is on the side of the upper stop 2-1, and the upper end face of the armature 2-7 is in contact with the lower end face of the ejector rod 1-6. Cut the pull rope, and check through the observation window on the lower end cover 1-3 whether the upper end face of the armature 2-7 is in contact with the lower end face of the ejector rod 1-6 (it is bounced back by the stationary block 4 and then contacts the lower end face of the ejector rod 1-6).

[0061] S8. If the upper end face of armature 2-7 is still separated from the lower end face of ejector rod 1-6, it means that armature 2-7 has moved to the side of lower stop 2-2, and moving block 3 collides with stationary block 4, eventually contacting the stationary block. In this case, repeat step S5 to continue increasing the spring force, referring to S8, until the upper end face of armature 2-7 contacts the lower end face of ejector rod 1-6. This means that armature 2-7 first moves to the side of lower stop 2-2, moving block 3 collides with stationary block 4, and then moving block 3 drives armature 2-7 to rebound to the side of upper stop 2-1. Repeat step S5, reverse the rotation sleeve 1-2, fine-tune the spring force, and refer to S7 to find the state where armature 2-7 just rebounds to the side of upper stop 2-1. Measure the distance between the annular surface F of fixed sleeve 1-1 and the annular surface N of rotating sleeve 1-2, and record it as x2. Calculate the spring force when ejector rod 1-6 contacts fixed sleeve 1-1 and the spring force when ejector rod 1-6 contacts lower end cover 1-3 according to formula (1-3), and record them as f3 and f4 respectively. The work W done by the spring force in this process is... s2 Calculate using the following formula:

[0062]

[0063] S9, the velocities v of moving block 3 and stationary block 4 just before the collision, and the collision recovery coefficient e are calculated using the following formulas:

[0064]

[0065] Factors affecting the collision speed include the magnitude of the magnetic potential energy of electromagnet 2 and the total mass of armature 2-7 and moving block 3. Once electromagnet 2 is determined, the collision speed can be adjusted by adjusting the mass of moving block 3. If the required collision speed cannot be achieved by adjusting the mass of moving block and armature 2-7, the collision speed can be adjusted by first replacing electromagnet 2 with one that has a different magnetic potential energy and then adjusting the mass of moving block.

[0066] The beneficial effects of the present invention are as follows: The collision recovery coefficient measuring device disclosed in this invention is mainly a mechanical structure and does not involve sensors or electronic devices. It has a simple structure, low development cost, and is easy to implement. It is especially suitable for measuring the collision recovery coefficient when small parts collide at low speeds. The moving block and the stationary block are independent structures, and their collision contact surfaces can be designed according to the actual collision contact surfaces, so that the collision recovery coefficient test results are closer to the actual situation.

[0067] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

[0068] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

Claims

1. A collision recovery coefficient measuring device, characterized in that: It includes a catapult (1), an electromagnet (2), a moving block (3), a stationary block (4), and a base (5), with the stationary block (4) and the base (5) connected by screws; The electromagnet (2) includes a fixed structure and a moving armature (2-7). One end of the fixed structure is connected to the base (5) and the other end is connected to the catapult (1). The armature (2-7) slides relative to the fixed structure along the direction close to or away from the stationary block (4). The end of the armature (2-7) close to the stationary block (4) is connected to the moving block (3) and the other end faces the output end of the catapult (1). The fixed structure is used to generate a magnetic force on the armature (2-7) in the direction of the catapult (1) or the direction of the stationary block (4) according to the position of the armature (2-7). The output end of the catapult (1) is used to apply a catapult force to the armature (2-7); The ejector (1) includes a fixed sleeve (1-1), a rotating sleeve (1-2), a lower end cover (1-3), an upper end cover (1-4), a spring (1-5), an ejection rod (1-6), a hook (1-7), a wing nut (1-8), and a pull rope (1-9); The lower end cap (1-3) is connected to one end of the fixed sleeve (1-1), and the other end of the fixed sleeve (1-1) is connected to the rotating sleeve (1-2) via a fine thread. The rotating sleeve (1-2) is connected to the upper end cap (1-4), and the electromagnet (2) is connected to the lower end cap (1-3). The ejector rod (1-6) passes through the fixed sleeve (1-1) and the rotating sleeve (1-2), and is slidably connected to the fixed sleeve (1-1) and the rotating sleeve (1-2) along the axial direction of the rotating sleeve (1-2). One end of the armature (2-7) is directly opposite the end of the ejector rod (1-6). The spring (1-5) is installed on the ejector rod (1-6). Between the rotating sleeve (1-2) and the ejector rod (1-6), the ejector rod (1-6) applies ejection force to the armature (2-7); the wing nut (1-8) is rotatably connected to the upper end cap (1-4), and the hook (1-7) is threadedly connected to the wing nut (1-8); the ejector rod (1-6) moves along the axis of the fixed sleeve (1-1), and the pull rope (1-9) is connected between the hook (1-7) and the ejector rod (1-6); by rotating the wing nut (1-8), the hook (1-7) is moved, and the hook (1-7) moves the ejector rod (1-6) to contact the fixed sleeve (1-1); The inner wall of the fixed sleeve (1-1) is provided with an annular surface E and the outer wall is provided with an annular surface F. The annular surface E and the annular surface F are on the same plane. The rotating sleeve (1-2) has an annular surface M inside and an annular surface N on the outer wall. The annular surface M and the annular surface N are on the same plane. The fixing structure includes an upper stop (2-1), a lower stop (2-2), an outer sleeve (2-3), a magnet (2-4), an upper coil (2-5), a lower coil (2-6), and a frame (2-8); the upper stop (2-1) and the lower stop (2-2) are respectively connected to the two ends of the outer sleeve (2-3), the upper stop (2-1) is used to connect the catapult (1), and the lower stop (2-2) is used to connect the base (5); When the ejector rod (1-6) is pulled up to contact the fixed sleeve (1-1), there is a gap Δ between the ejector rod (1-6) and the lower end cover (1-3). Taking this position as the zero point of displacement, if the armature (2-7) is gradually moved towards the lower stop (2-2) until the magnetic force is zero, the displacement is recorded as δ0, where Δ < δ0.

2. The collision recovery coefficient measuring device according to claim 1, characterized in that: The upper end cover (1-4) has a rectangular limiting groove, and the hook end of the hook (1-7) has a flat structure. The flat structure of the hook (1-7) cooperates with the rectangular limiting groove of the upper end cover (1-4).

3. The collision recovery coefficient measuring device according to claim 1, characterized in that: The rotating sleeve (1-2) has a rectangular limiting groove, and the ejector rod (1-6) has a flat structure part, which cooperates with the rectangular limiting groove.

4. The collision recovery coefficient measuring device according to claim 1, characterized in that: The ejector rod (1-6) is provided with a convex ring. The ring surface E is located on the side of the convex ring away from the moving block (3) and is used to limit the movement stroke of the convex ring. The spring (1-5) is in contact with the side of the convex ring away from the moving block (3) and the spring (1-5) is in contact with the ring surface M.

5. The collision recovery coefficient measuring device according to claim 1, characterized in that: The outer sleeve (2-3) is a cylindrical shape with openings at both ends. The frame (2-8) is located inside the outer sleeve (2-3). The magnet (2-4) is bonded to the middle part of the outside of the frame (2-8). The upper coil (2-5) and the lower coil (2-6) are wound on the frame (2-8) and located on both sides of the magnet (2-4). The armature (2-7) is located inside the frame (2-8), and the two ends of the armature (2-7) pass through the upper stop (2-1) and the lower stop (2-2) respectively. The magnet (2-4) is a toroidal permanent magnet material, with its two poles located on the cylindrical surface in contact with the frame (2-8) and the cylindrical surface in contact with the outer sleeve (2-3), respectively; the upper stop (2-1), lower stop (2-2), outer sleeve (2-3) and armature (2-7) are made of soft magnetic material.

6. A method for measuring the coefficient of restitution in a collision, characterized in that, The measurement is performed using a collision recovery coefficient measuring device according to any one of claims 1-5, comprising: S1: Calculate the work done by the magnet force of the armature (2-7) from the position where the magnet force is zero until the moving block (3) and the stationary block (4) just come into contact. ; S2: Obtain the relationship between the compressive force F on the spring and the length x of the spring; S3: Measure the masses of the armature (2-7), the moving block (3), and the ejection rod (1-6) as m1, m2, and m3, respectively; S4: Rotate the rotating sleeve (1-2) to compress the spring (1-5) and generate spring force; rotate the wing nut (1-8) to pull the ejector rod (1-6) up to contact the fixed sleeve (1-1) through the pull rope (1-9); supply power to the upper coil (2-5) so that the armature (2-7) contacts the lower end face of the ejector rod (1-6); cut the pull rope and check whether the upper end face of the armature (2-7) is separated from the lower end face of the ejector rod (1-6); S5: If the upper end face of the armature (2-7) is still in contact with the lower end face of the ejector rod (1-6), repeat step S4 and gradually increase the spring force by further twisting the rotating sleeve (1-2); until the upper end face of the armature (2-7) separates from the lower end face of the ejector rod (1-6); Repeat step S4 and twist the rotating sleeve (1-2) in the opposite direction to reduce the spring force until the state at which the upper end face of the armature (2-7) is just separated from the lower end face of the ejection rod (1-6) is found. Measure the distance between the ring surface F of the fixed sleeve (1-1) and the ring surface N of the rotating sleeve (1-2), and record it as x1; calculate the work W done by the spring force in this process based on x1 and the relationship between the compressive force F on the spring and the spring length x. s1 ; S6: Repeat step S4 and continue to compress the spring (1-5) further by twisting the rotating sleeve (1-2) to generate a greater spring force; observe whether the upper end face of the armature (2-7) contacts the lower end face of the ejector rod (1-6) after the pull rope is cut and the static block (4) bounces back. S7: If the upper end face of the armature (2-7) is still separated from the lower end face of the ejector rod (1-6), repeat step S4 to continue increasing the spring force until the upper end face of the armature (2-7) contacts the lower end face of the ejector rod (1-6); Repeat step S5, twisting the rotating sleeve (1-2) in the opposite direction until the armature (2-7) just bounces back to the side of the upper stop (2-1); Measure the distance between the ring surface F of the fixed sleeve (1-1) and the ring surface N of the rotating sleeve (1-2), and denot it as x2; calculate the work W done by the spring force during this process based on x2 and the relationship between the compressive force F on the spring and the spring length x. s2 ; S8: The work W done by the spring force during the process when the upper end face of the armature (2-7) just separates from the lower end face of the ejection rod (1-6) s1 The work W done by the spring force during the process of the armature (2-7) just rebounding to the side of the upper stop (2-1) is the following. s2 , The mass of the armature (2-7), the moving block (3) and the ejection rod (1-6) are calculated to obtain the velocity v of the moving block (3) just before the collision with the stationary block (4) and the collision recovery coefficient e between the moving block (3) and the stationary block (4).

7. The method for measuring the collision recovery coefficient according to claim 6, characterized in that, In step S5, the work W done by the spring force is calculated based on x1 and the relationship between the compressive force F on the spring and the spring length x. s1 This includes: calculating the spring force f1 when the ejector rod (1-6) contacts the fixed sleeve (1-1) and the spring force f2 when the ejector rod (1-6) contacts the lower end cover (1-3) based on the relationship between x1 and the compressive force F on the spring and the spring length x; .

8. The method for measuring the collision recovery coefficient according to claim 7, characterized in that, The velocity v of the moving block (3) and the stationary block (4) just before they collide is: ; The collision recovery coefficient e between the moving block (3) and the stationary block (4) is: .

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