Emergency two-section valve shrinkage plug anti-drop fastening method

Abstract

The invention provides an anti-drop fastening method for a shrinkage plug of an emergency two-section valve, relates to the technical field of railway vehicle braking, and is used for preventing the shrinkage plug which is in threaded connection with a shrinkage hole position of a valve body of the emergency two-section valve from dropping. The anti-falling fastening method comprises the steps that the axial static loading force Fc of pressure air acting on the shrinkage plug is obtained; acquiring the frictional resistance F when the air flows out of the shrinkage cavity; according to the axial static loading force Fc and the frictional resistance F, calculating a shrinkage and plugging pre-tightening force FP; according to the shrinkage plug pre-tightening force FP, the shrinkage plug fastening torque T is calculated; according to the fastening torque T, a torsion tool is adopted to connect the shrinkage plug into the shrinkage hole in a threaded mode; by means of the fastening torque obtained scientifically and reasonably, the reliability of shrinkage, plugging and fastening of the emergency two-section valve is improved, and it is guaranteed that the 120 valve is stable and reliable in application performance.

Description

Technical Field

[0001] The invention belongs to the technical field of railway vehicle braking, and more specifically, relates to a method for tightening an emergency two-stage valve to prevent it from falling off. Background Art

[0002] The air brake device of railway vehicles is mainly composed of brake cylinder, 120 valve, auxiliary air cylinder, acceleration and deceleration air cylinder, automatic adjustment device for empty and loaded vehicles, brake pipe, etc. The interior of 120 valve is mainly composed of action part, deceleration part, acceleration relief valve, emergency two-stage valve, etc. The main function of emergency two-stage valve is to realize the two-stage pressure rise of brake cylinder, first fast and then slow, when the vehicle brakes. When the vehicle is relieved, it serves as a passage for the brake cylinder to communicate with the atmosphere to realize brake cylinder relief.

[0003] The 120 valve is divided into two types, 10 inches and 14 inches, according to the matching brake cylinder model. Compared with the 10-inch and 14-inch 120 valves, the 10-inch 120 valve mainly has a reduction hole installed on the valve body of the emergency two-stage valve and between the two vents of the emergency two-stage valve. When the improved 14-inch 120 valve is developed and produced, each reduction plug is optimized and improved from the original independent structure to an integrated conversion reduction plug. Therefore, when inspecting the emergency two-stage valve of the 120 valve, there are two structures: the independent reduction plug of the existing 120 valve and the integrated conversion reduction plug of the improved 120 valve.

[0004] like Figure 1 As shown, the emergency two-stage valve includes a valve body 1, a spring 4, an O-ring 5, a shrinkage hole 2 and a shrinkage plug 3 threadedly connected to the shrinkage hole 2. When the emergency two-stage valve is assembled inside the 120 valve 6, a brake cylinder filling and exhaust passage, two ventilation interfaces 7 connected to the brake cylinder and the air source respectively, and a vehicle pipe passage 8 on the upper part of the valve body are formed around the valve body 1.

[0005] The shrink plug of the emergency two-stage valve is a 55° sealing pipe thread. The main function of the existing 55° sealing pipe thread connection structure is sealing, and there is no self-locking function after the thread is tightened.

[0006] The existing regulations on the inspection and assembly of shrinkage plugs only stipulate that "the shrinkage plugs should be installed at the corresponding shrinkage hole positions". There are no measures to increase the tightening force during assembly, and there are no regulations related to the tightening force of the shrinkage plugs.

[0007] The shrinkage plug of the emergency two-stage valve tightened according to the existing process (tightened in place) varies due to the different arm strength of different assemblers. When the actual tightening torque is small, there is a risk of the shrinkage plug falling off or loosening.

[0008] The shrinkage and plugging stress conditions of the emergency two-stage valve include:

[0009] When the brake is in the normal braking and emergency braking positions, the auxiliary air cylinder is connected to the brake cylinder, and the pressure air in the auxiliary air cylinder flows upward from the emergency second-stage valve to inflate the brake cylinder, and the plug is tightened upward;

[0010] When the inflation is relieved after normal braking, the brake cylinder is connected to the atmosphere, and the pressure air in the brake cylinder flows downward from the top of the emergency second-stage valve, through the middle shrinkage plug hole and the surrounding large section to the atmosphere. Part of the pressure air in the brake cylinder causes the shrinkage plug to be subjected to a downward loosening force;

[0011] When inflation is relieved after emergency braking, due to the sharp drop in train pipe pressure during emergency braking, the emergency second-stage valve moves up to the highest position under the action of the pressure difference and closes the surrounding large-section passage. After relief, as the train pipe pressure rises and the brake cylinder pressure drops, the emergency second-stage valve returns to its original position under the action of the spring. After the main piston moves down to the relief position, the pressurized air in the brake cylinder flows to the atmosphere through the middle shrinkage plug hole and the surrounding large section. Part of the pressurized air in the brake cylinder causes the shrinkage plug to be subjected to a force in the downward loosening direction.

[0012] Therefore, under the above shrinkage plug installation conditions and stress conditions, as the vehicle is relieved and vibrated during the use of the 120 valve, part of the shrinkage plug of the emergency two-stage valve of the two structures of the 120 valve will fall off or loosen.

[0013] The size of the shrinkage hole at the shrinkage point of the emergency second-stage valve directly affects the inflation and exhaust speed of the brake cylinder during braking and relief. In severe cases, the detached shrinkage blockage may cause the emergency second-stage valve to get stuck or malfunction, posing a safety hazard to the performance of the 120 valve and vehicle operation. Summary of the invention

[0014] The purpose of the present invention is to provide an emergency two-stage valve shrinkage and anti-detachment fastening method in view of the deficiencies in the existing technology, so as to solve the problem proposed in the above background technology that during the use of the 120 valve, as the vehicle is relieved and vibrated, the shrinkage and anti-detachment of the emergency two-stage valve of the 120 valve may fall off or loosen, posing a safety hazard to the use performance of the 120 valve and the operation of the vehicle.

[0015] In order to achieve the above-mentioned object, the present invention provides a shrinkage plugging and anti-dropping fastening method for an emergency two-stage valve, which is used to prevent the shrinkage plugging at the shrinkage hole position of the valve body of the emergency two-stage valve from falling off, wherein the emergency two-stage valve is used in a braking device of a vehicle, and the anti-dropping fastening method comprises:

[0016] Obtain the axial static load force F of the compressed air on the shrink plug c ;

[0017] Obtain the friction resistance F when air flows out through the shrinkage hole 阻 ;

[0018] According to the axial static load F c and friction resistance F 阻 Calculate the shrinkage preload force F P ;

[0019] According to the shrinkage preload F P Calculate the shrink plug tightening torque T;

[0020] According to the tightening torque T, a torque tool is used to connect the shrinkage plug thread into the shrinkage hole.

[0021] Preferably, the axial static load force F of the compressed air acting on the shrink plug is obtained. c include:

[0022] Select the axial static load F c Calculation formula:

[0023]

[0024] Where, d2 is the middle diameter of the external thread of the shrink plug, m;

[0025] P is the pressure borne by the thread pair, Pa.

[0026] Preferably, the friction resistance F when air flows out through the shrinkage hole is obtained. 阻 include:

[0027] Select the friction resistance F 阻 Calculation formula:

[0028]

[0029] Where: λ is the friction coefficient;

[0030] S is the cross-sectional area of ​​shrinkage cavity, m 2 ;

[0031] u is the average air velocity in the shrinkage cavity, m / s;

[0032] ρ is air density, kg / m 3 .

[0033] Preferably, according to the axial static load force F c and friction resistance F 阻 Calculate the shrinkage preload force F P include:

[0034] Select the shrink plug to bear the total axial load F during use c Calculation formula:

[0035] F c '=F c +F 阻

[0036] Select the residual preload F required for the shrink plug to withstand the total load P Calculation formula:

[0037] F P '=KF

[0038] Where: K is the axial preload coefficient;

[0039] Select the preload force F P Calculation formula:

[0040] F P =F P '+(1-λ)F c '

[0041] Where: λ is the relative stiffness of the shrinkage connection.

[0042] Preferably, according to the shrinkage preload force F P Calculation of shrink plug tightening torque T includes:

[0043] Select the calculation formula for the shrink plug tightening torque T:

[0044]

[0045] Where: l is the effective length of the torque tool, cm.

[0046] Preferably, according to the shrinkage preload force F P Calculating the shrinkage plugging tightening torque T also includes selecting a safety factor of 1.5-2 to obtain a shrinkage plugging safety tightening torque of 1.5T-2T.

[0047] Preferably, using a torque tool to thread the shrinkage plug into the shrinkage hole according to the tightening torque T includes: tightening with a torque screwdriver.

[0048] Preferably, the emergency two-stage valve shrinkage plugging and anti-disengagement fastening method further comprises: testing and verifying the reliability of the safe fastening torque used when the shrinkage plugging thread is connected in the shrinkage hole.

[0049] Preferably, testing and verifying the reliability of the safe tightening torque used when the shrinkage plug thread is connected in the shrinkage hole includes: performing an air filling test on the emergency two-stage valve.

[0050] Preferably, testing and verifying the reliability of the safe tightening torque used when the shrinkage plug thread is connected in the shrinkage hole also includes: performing a vibration test on the emergency two-stage valve.

[0051] Preferably, testing and verifying the reliability of the safe tightening torque used when the shrink plug thread is connected in the shrinkage hole also includes: conducting a full and vibration test on the emergency two-stage valve at the same time.

[0052] The present invention provides an emergency two-stage valve shrinkage and plugging anti-slipping fastening method, which has the beneficial effects of: the anti-slipping fastening method analyzes the emergency two-stage valve in the prior art, combines the shrinkage and plugging stress conditions of the emergency two-stage valve, and according to the axial static load force F c and friction resistance F 阻 Calculate the shrinkage preload force F P , according to the shrinkage preload FP The shrinkage and plugging tightening torque T is calculated and the shrinkage and plugging tightening torque of the emergency two-stage valve is worked out. By scientifically and reasonably obtaining the tightening torque, the shrinkage and plugging tightening reliability of the emergency two-stage valve is improved, ensuring the stable and reliable performance of the 120 valve.

[0053] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0055] Figure 1 The schematic diagram of the structure of the emergency two-stage valve in the prior art is shown.

[0056] Figure 2 A flow chart of an emergency two-stage valve shrinkage, plugging and anti-disengagement fastening method according to an embodiment of the present invention is shown.

[0057] Figure 3 A simplified diagram of force analysis of an emergency two-stage valve shrinkage, plugging and anti-disengagement fastening method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0058] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0059] like Figure 2 As shown, the present invention provides an emergency two-stage valve shrinkage plugging and anti-slipping fastening method, which is used to prevent the shrinkage plug at the shrinkage hole position of the valve body of the emergency two-stage valve from falling off. The emergency two-stage valve is used in the braking device of the vehicle. The anti-slipping fastening method includes:

[0060] Obtain the axial static load force F of the compressed air on the shrink plug c ;

[0061] Obtain the friction resistance F when air flows out through the shrinkage hole 阻 ;

[0062] According to the axial static load F c and friction resistance F 阻 Calculate the shrinkage preload force F P ;

[0063] According to the shrinkage preload F P Calculate the shrink plug tightening torque T;

[0064] According to the tightening torque T, a torque tool is used to connect the shrinkage plug thread into the shrinkage hole.

[0065] In order to solve the problem that the plugging of the emergency second-stage valve of the 120 valve may fall off or loosen due to the relief and vibration of the vehicle during the use of the 120 valve, which may cause safety hazards to the use performance of the 120 valve and the operation of the vehicle, the present invention provides an emergency second-stage valve plugging anti-loosening fastening method. The anti-loosening fastening method analyzes the emergency second-stage valve of the prior art, combines the plugging stress working conditions of the emergency second-stage valve, and according to the axial static load force F c and friction resistance F 阻 Calculate the shrinkage preload force F P , according to the shrinkage preload F P The shrinkage and plugging tightening torque T is calculated and the shrinkage and plugging tightening torque of the emergency two-stage valve is worked out. By scientifically and reasonably obtaining the tightening torque, the shrinkage and plugging tightening reliability of the emergency two-stage valve is improved, ensuring the stable and reliable performance of the 120 valve.

[0066] Preferably, the axial static load force F of the compressed air acting on the shrink plug is obtained. c include:

[0067] Select the axial static load F c Calculation formula:

[0068]

[0069] Where, d2 is the middle diameter of the external thread of the shrink plug, m;

[0070] P is the pressure borne by the thread pair, Pa.

[0071] Preferably, the friction resistance F when air flows out through the shrinkage hole is obtained. 阻 include:

[0072] Select the friction resistance F 阻 Calculation formula:

[0073]

[0074] Where: λ is the friction coefficient;

[0075] S is the internal surface area of ​​shrinkage cavity, m 2 ;

[0076] u is the average air velocity in the shrinkage cavity, m / s;

[0077] ρ is air density, kg / m 3 .

[0078] Preferably, according to the axial static load force F c and friction resistance F 阻 Calculate the shrinkage preload force F P include:

[0079] Select the shrink plug to bear the total axial load F during use c Calculation formula:

[0080] F c '=F c +F 阻

[0081] Select the residual preload F required for the shrink plug to withstand the total load P Calculation formula:

[0082] F P '=KF

[0083] Where: K is the axial preload coefficient;

[0084] Select the preload force F P Calculation formula:

[0085] F P =F P '+(1-λ)F c '

[0086] Where: λ is the relative stiffness of the shrinkage connection.

[0087] Preferably, according to the shrinkage preload force F P Calculation of shrink plug tightening torque T includes:

[0088] Select the calculation formula for the shrink plug tightening torque T:

[0089]

[0090] Where: l is the effective length of the torque tool, cm.

[0091] Preferably, according to the shrinkage preload force F P Calculating the shrinkage plugging tightening torque T also includes selecting a safety factor of 1.5-2 to obtain a shrinkage plugging safety tightening torque of 1.5T-2T.

[0092] Preferably, using a torque tool to thread the shrinkage plug into the shrinkage hole according to the tightening torque T includes: tightening with a torque screwdriver.

[0093] Preferably, the emergency two-stage valve shrinkage plugging and anti-disengagement fastening method further comprises: testing and verifying the reliability of the safe fastening torque used when the shrinkage plugging thread is connected in the shrinkage hole.

[0094] Preferably, testing and verifying the reliability of the safe tightening torque used when the shrinkage plug thread is connected in the shrinkage hole includes: performing an air filling test on the emergency two-stage valve.

[0095] Preferably, testing and verifying the reliability of the safe tightening torque used when the shrinkage plug thread is connected in the shrinkage hole also includes: performing a vibration test on the emergency two-stage valve.

[0096] Preferably, testing and verifying the reliability of the safe tightening torque used when the shrink plug thread is connected in the shrinkage hole also includes: conducting a full and vibration test on the emergency two-stage valve at the same time.

[0097] Example

[0098] According to the analysis of the shrinkage and plugging stress conditions of the emergency two-stage valve, the shrinkage and plugging tightening torque of the emergency two-stage valve is formulated with reference to the calculation method of the tightening force of the bolted connection structure and the relevant methods of aerodynamic calculation. A special air-filled vibration test device is used for test verification to ensure that the calculation process is scientific and reasonable. The shrinkage, plugging, tightening and testing specifications of the emergency two-stage valve are formulated to further guide standardized operations on site.

[0099] 1. Calculation of safety tightening torque for shrink plugging includes:

[0100] 1. Shrinkage and plugging force analysis

[0101] like Figure 3 As shown in the figure, according to the analysis of the operating conditions of the emergency two-stage valve, in order to ensure the reliable tightening of the shrink plug thread, the tightening force F of the shrink plug thread friction pair in the relief position must be ≥ the axial static load force F of the compressed air acting on the shrink plug end face c + Air Warp Friction resistance F during shrinkage outflow 阻 .

[0102] 2. Shrink plug bears axial static load F c calculate

[0103] The shrinkage plug and the shrinkage hole of the emergency two-stage valve are threaded. Refer to the calculation formula for the axial force load of the bolt group in the mechanical design manual.

[0104]

[0105] Where, d2 is the middle diameter of the external thread of the shrink plug, m;

[0106] P is the pressure borne by the thread pair, Pa.

[0107] When the heavy vehicle position is relieved, the theoretical maximum pressure that the threaded pair can withstand is 370KPa. According to GB / T7306.2-2000, the middle diameter d2 of the R21 / 8 reduced plug external thread of the F-type emergency two-stage valve is 9.147mm, and the middle diameter d2 of the R21 / 4 reduced plug external thread of the H-type emergency two-stage valve is 12.301mm.

[0108] According to (Formula 1-1), the maximum axial static load force on R21 / 8 is calculated as:

[0109]

[0110] According to (Formula 1-1), the maximum axial static load on R21 / 4 is calculated as:

[0111]

[0112] 3. Air friction resistance F at shrinkage hole 阻 calculate

[0113] 3.1. Calculation of total air flow volume at the relief position

[0114] When the vehicle in the heavy parking position brakes, the theoretical pressure air in the brake cylinder passage is 360±10KPa, and the pressure in the decompression chamber of the empty and heavy vehicle adjustment device is zero. When the vehicle in the heavy parking position is in the relief position, the brake cylinder passage (including DN20 pipe system, DN10 pipe system, and 120 valve) is connected to the atmosphere through the emergency second-stage valve and exhaust port of the 120 valve.

[0115] The calculation formula for the brake cylinder and pipe system volume is:

[0116]

[0117] Where: d is the inner diameter of the brake cylinder, m;

[0118] h is the brake cylinder stroke or pipe length, m.

[0119] Taking the C70 open car equipped with 305×254 brake cylinder as an example, the brake cylinder pressure in the heavy-duty position is about 360KPa, and the piston stroke is about 200mm; the DN20 pipe system of the current stainless steel brake pipe used in railway freight cars has an outer diameter of 27mm, a wall thickness of 3mm, and a total length of about 2135mm; the DN10 pipe system has an outer diameter of 17mm, a wall thickness of 2.2mm, and an effective length of about 3822mm in the heavy-duty position.

[0120] According to (Formula 1-2), the pressure air volume V of the brake cylinder passage is:

[0121] V=V 缸 +V 20管系 +V 10管系 =0.015864164m 3

[0122] 3.2. Calculation of air flow and speed

[0123] During the release process, the pressure air flow in the brake cylinder passage is calculated as follows:

[0124] Q=V / t (1-3)

[0125] Where: t is the pressure air flow time, s.

[0126] During the relief process, the flow rate of pressurized air passing through the emergency second-stage valve shrinkage blockage section is calculated as follows:

[0127] u=Q / S (1-4)

[0128] Where: S is the cross-sectional area of ​​the shrinkage cavity, m 2 .

[0129] Taking the C70 open wagon equipped with 305×254 brake cylinder as an example, the time for the heavy-duty brake cylinder to be completely released is about 49s.

[0130] According to (Formula 1-3), the air flow rate Q is calculated as follows:

[0131] Q=V / t=0.015864164 / 49=0.0003238m 3 / s

[0132] Assuming that all the pressure air is released through the emergency two-stage valve, The average pressure air velocity at the shrinkage hole is calculated according to (Formula 1-4):

[0133]

[0134] 3.3 Calculation of air friction resistance at shrinkage cavity

[0135] During the exhaust process, the emergency second-stage valve is blocked by air resistance at the same time. The air resistance calculation formula is:

[0136]

[0137] Where: λ is the friction coefficient;

[0138] S is the cross-sectional area of ​​shrinkage cavity, m 2 ;

[0139] u is the average air velocity in the shrinkage cavity, m / s;

[0140] ρ is air density, kg / m 3 .

[0141] The Reynolds number Re in the shrinkage cavity is calculated as:

[0142]

[0143] Where: u is the air velocity in the shrinkage cavity, m / s;

[0144] D is the inner diameter of the shrinkage cavity, m;

[0145] μ is the kinematic viscosity, m 2 / s.

[0146] At a temperature of 20°C and a standard atmospheric pressure, the kinematic viscosity of air is μ = 15.06 × 10 -6 m 2 / s, calculated according to (Formula 1-6):

[0147]

[0148] To calculate the friction coefficient λ, this paper adopts the Klebnikov formula (Klebnikov formula is widely used in circular tube calculation and is applicable to 4000 <Re<10 8 ):

[0149]

[0150] Where: K is the roughness of the inner wall of the shrinkage cavity, mm.

[0151] The wall roughness of the shrinkage hole is K = 0.1 mm, and the quadratic interpolation method (Formula 1-7) yields λ = 0.0629.

[0152] At a temperature of 20°C and standard atmospheric pressure, the air density is ρ = 1.29 kg / m 3 , calculated according to the air resistance formula (Formula 1-5):

[0153]

[0154] 4. Calculation of shrinkage preload force

[0155] 4.1. Calculation of total axial load borne by shrink plug

[0156] According to the above force analysis, the total axial load F that the shrink plug bears during use c The calculation formula is:

[0157] F c '=F c +F 阻 (1-8)

[0158] Then according to formula (1-8), we can calculate:

[0159] Total axial load force F of R21 / 8 shrink plug c1 '=F c +F 阻 =24.317N

[0160] Total axial load force F of R21 / 4 shrink plug c2 '=F c +F 阻=43.917N

[0161] 4.2 Calculation of residual preload required for shrink plug to withstand total load

[0162] Residual preload F required for axial load P The calculation formula is:

[0163] F P '=KF (1-9)

[0164] Where: K is the axial preload coefficient;

[0165] According to the Mechanical Design Manual, the K value of pressure vessels or important connections is 1.5-1.8. Taking the maximum K value of 1.8, we can calculate according to (Formula 1-9):

[0166] The residual preload required for R21 / 8 shrink plug under axial load is: F P1 '=KF c1 '=1.8×24.317N=43.7706N

[0167] The residual preload required for R21 / 4 shrink plug under axial load is: F P2 '=KF c2 '=1.8×43.917N=79.0506N

[0168] 4.3. Shrinkage preload force F P calculate

[0169] The calculation formula of shrinkage plugging preload is based on the bolt axial load preload:

[0170] F P =F P '+(1-λ)F c '

[0171] Where: λ is the relative stiffness of the shrinkage connection.

[0172] According to the Mechanical Design Manual, the λ value for metal or gasket-free working conditions is 0.2-0.3. Taking the minimum λ value of 0.2, we can calculate according to (Formula 1-10):

[0173] R21 / 8 shrink plug axial load preload force is: F P1 =F P1 '+(1-λ)F c1 '=43.7706+(1-0.2)×24.317=63.2242N

[0174] R21 / 4 shrink plug axial load preload force is: F P2 =F P2 '+(1-λ)F c2'=79.0506+(1-0.2)×43.917=114.1842N

[0175] 5. Calculation of tightening torque for shrinkage and plugging

[0176] After consulting the relevant information on torque screwdrivers suitable for tightening the plug of the emergency two-stage valve, it is found that the torque required for tightening the plug can be achieved with kilograms of force, that is, the force generated by every 1 kilogram of force added to a 1 cm long lever. Therefore, the calculation formula for tightening the plug torque is:

[0177]

[0178] Where: l is the effective length of the screwdriver, cm.

[0179] When tightening the plug of the F-type emergency two-stage valve, the lever length of the torque screwdriver acting on the plug is equal to the middle diameter of the plug. When tightening the plug of the H-type emergency two-stage valve, the lever length of the torque screwdriver acting on the plug is equal to the middle diameter of the plug. According to (Formula 1-11), we can calculate:

[0180] The theoretical tightening torque of R21 / 8 shrink plug is:

[0181] The theoretical tightening torque of R21 / 4 shrink plug is:

[0182] Due to the friction resistance between the nut and the connector of the bolt-free fastening structure, as well as factors such as vibration and temperature changes during vehicle use, in order to ensure safe use, a safety factor of 1.5 to 2 is taken to calculate:

[0183] R21 / 8 shrink plug tightening torque: 9Kgf.cm~12Kgf.cm

[0184] R21 / 4 shrink plug tightening torque: 14Kgf.cm~18Kgf.cm

[0185] That is: when the F-type emergency two-stage valve is shrunk and plugged, the tightening torque is controlled to be 9Kgf.cm~12Kgf.cm, and when the H-type emergency two-stage valve is shrunk and plugged, the tightening torque is controlled to be 14Kgf.cm~18Kgf.cm.

[0186] 2. Test verification includes:

[0187] According to the physical mapping and related dimension inquiry of the 120 valve main valve body and the emergency two-stage valve, and combined with the operating conditions of the emergency two-stage valve, a shrinkage and plugging air-filling vibration test device for the emergency two-stage valve was designed and manufactured for experimental verification.

[0188] 1. Test samples

[0189] Select three emergency two-stage valves whose shrinkage plugs fall off when entering the factory, and select one emergency two-stage valve each of which has its shrinkage plug flush with the shrinkage hole after assembly during the process, one shrinkage plug sunk into the shrinkage hole, and one shrinkage plug protruding out of the shrinkage hole and number them.

[0190] 2. Test methods

[0191] The emergency two-stage valve is tightened or screwed in by the calculated safe tightening torque (8.9Kgf.cm for F-type emergency two-stage valve / 14Kgf.cm for H-type emergency two-stage valve), small torque (0.5Kgf.cm or 1.0Kgf.cm) and 4-button tightening. The three test methods of air filling only, vibration only and air filling + vibration are used to simulate its shrinkage and blocking stress conditions and conduct cyclic tests of braking, stillness, relief and stillness.

[0192] 3. Test results

[0193] 3.1. Safe tightening torque obtained through calculation of tightening test results

[0194] The emergency two-stage valves were tightened with the calculated safety tightening torque (8.9Kgf.cm for F-type emergency two-stage valve / 14Kgf.cm for H-type emergency two-stage valve). After the three test methods were used for 100 and 300 cycles, the tightening marks of the emergency two-stage valves did not show any misalignment.

[0195] 3.2. Passing the small torque tightening test

[0196] The emergency two-stage valve was tightened with a small torque (0.5Kgf.cm or 1.0Kgf.cm). After the above test method was used for 100, 200 and 300 cycles, the tightening marks of the emergency two-stage valves did not show any misalignment.

[0197] 3.3. By screwing in the 4-button emergency two-stage valve's shrink plug, after only the air filling cycle test for 100 times, 200 times, and 300 times, the shrink plug positioning marks of each emergency two-stage valve were obviously misaligned, but no falling off occurred; after only the vibration test for 100 times, 200 times, and 300 times, the shrink plug of one emergency two-stage valve fell off; after the air filling + vibration test for 100 times, 200 times, and 300 times, the shrink plugs of four emergency two-stage valves fell off (three of them fell off after 100 times).

[0198] After the test, the number of remaining connecting thread buckles of the shrink plugs that have not fallen off showed the overall trend of: air filling only > vibration only > air filling + vibration.

[0199] 4. Analysis of test results

[0200] 4.1. Comparative tests on the emergency two-stage valve screwed in from 4 buttons found that the vehicle's brake relief air filling, the vehicle's high-frequency vibration, and the simultaneous action of the two are all factors that cause shrinkage, blocking, and falling off.

[0201] 4.2. A comparative test of the emergency two-stage valve screwed in from 4 buttons found that the high-frequency vibration during vehicle operation has a greater impact on shrinkage and plugging.

[0202] 4.3. From the results of the small torque tightening test, it is found that the emergency two-stage valve shrinkage, plugging and air filling vibration test scheme adopted by the present invention basically meets the requirements of the emergency two-stage valve operating conditions, and the test scheme is feasible.

[0203] 4.4. Test results show that when using fixed torque tightening, the safety factor of 1.5 to 2 for calculating torque and considering vibration can theoretically meet the application requirements.

[0204] 3. Shrinkage and plugging fastening specifications include:

[0205] When the shrink plug is tightened with the calculated safe tightening torque, a qualified torque screwdriver should be used for tightening; after the F-type emergency two-stage valve shrink plug is tightened, the depth of the shrink plug sunk into the shrinkage hole should be less than 2mm; after the H-type emergency two-stage valve shrink plug is tightened, the depth of the shrink plug sunk into the shrinkage hole should be less than 1mm.

[0206] When tightening with a torque screwdriver, it is advisable to use a special conversion joint for converting between the hexagonal interface and the slotted nozzle, and the width of the slotted nozzle for tightening the F-type emergency two-stage valve should be controlled to 9mm, and the width of the slotted nozzle for tightening the H-type emergency two-stage valve should be controlled to 11mm.

[0207] In summary, this application combines the operating conditions of the emergency two-stage valve, refers to the calculation methods of bolt tightening force, aerodynamic friction resistance, etc., and considers factors such as the vibration of the emergency two-stage valve to determine the safety factor. The comprehensive calculation is determined, and the calculation process is scientific and reasonable, providing a technical basis for determining the tightening torque of the emergency two-stage valve.

[0208] The emergency two-stage valve shrinkage, plugging and anti-slip fastening scheme determined in this application uses a special air filling test device to verify its reliability under three working conditions: air filling only, vibration only, and air filling + vibration. The test results show that the shrinkage, plugging and anti-slip are reliable.

[0209] The emergency two-stage valve shrink plug tightening formulated in this application adopts a torque screwdriver to tighten according to the specified torque. The torque screwdriver used is regularly calibrated and easy to operate, which can effectively ensure that the emergency two-stage valve shrink plug is reliable and prevented from falling off.

[0210] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preventing a second-stage emergency valve from falling off by plugging and fastening, which is used to prevent the plugging and plugging threadedly connected to the shrinkage hole of the valve body of the second-stage emergency valve from falling off, wherein the second-stage emergency valve is used in a braking device of a vehicle, and is characterized in that: The anti-slip fastening method comprises: Obtain the axial static load force F of the compressed air on the shrink plug c ; Obtain the friction resistance F when air flows out through the shrinkage hole 阻 ; According to the axial static load F c and friction resistance F 阻 Calculate the shrinkage preload force F P ; According to the shrinkage preload F P Calculate the shrink plug tightening torque T; According to the tightening torque T, a torque tool is used to connect the shrinkage plug thread into the shrinkage hole.

2. The method for tightening an emergency two-stage valve according to claim 1, characterized in that: Obtain the axial static load force F of the compressed air on the shrink plug c include: Select the axial static load F c Calculation formula: Where, d2 is the middle diameter of the external thread of the shrink plug, m; P is the pressure borne by the thread pair, Pa.

3. The method for tightening an emergency two-stage valve according to claim 1, characterized in that: Obtain the friction resistance F when air flows out through the shrinkage hole 阻 include: Select the friction resistance F 阻 Calculation formula: Where: λ is the friction coefficient; S is the cross-sectional area of ​​shrinkage cavity, m 2 ; u is the average air velocity in the shrinkage cavity, m / s; ρ is air density, kg / m 3 .

4. The method for tightening an emergency two-stage valve according to claim 1, characterized in that: According to the axial static load F c and friction resistance F 阻 Calculate the shrinkage preload force F P include: Select the shrink plug to bear the total axial load F during use c Calculation formula: F c ′=F c +F 阻 Select the residual preload F required for the shrink plug to withstand the total load P Calculation formula: F P ′=KF Where: K is the axial preload coefficient; Select the preload force F P Calculation formula: F P＝ F P '+(1-λ)F c ' Where: λ is the relative stiffness of the shrinkage connection.

5. The method for tightening an emergency two-stage valve according to claim 1, characterized in that: According to the shrinkage preload F P Calculation of shrink plug tightening torque T includes: Select the calculation formula for the shrink plug tightening torque T: Where: l is the effective length of the torque tool, cm.

6. The method for tightening an emergency two-stage valve according to claim 5, characterized in that: According to the shrinkage preload F P Calculating the shrinkage plugging tightening torque T also includes selecting a safety factor of 1.5-2 to obtain a shrinkage plugging safety tightening torque of 1.5T-2T.

7. The method for tightening an emergency two-stage valve according to claim 1, characterized in that: Using a torque tool to connect the shrinkage plug thread into the shrinkage hole according to the tightening torque T includes: tightening with a torque screwdriver.

8. The method for tightening an emergency two-stage valve according to claim 6, characterized in that: The emergency two-stage valve shrinkage plugging and anti-disengagement fastening method also includes: testing and verifying the reliability of the safe fastening torque used when the shrinkage plugging thread is connected in the shrinkage hole.

9. The method for tightening an emergency two-stage valve according to claim 8, characterized in that: The reliability of the safe tightening torque used when the shrinkage plug thread connection is in the shrinkage hole is verified by testing, including: filling the emergency two-stage valve with air.

10. The method for tightening an emergency two-stage valve according to claim 8, characterized in that: The test verification of the reliability of the safe tightening torque used when the shrink plug thread connection is in the shrinkage hole also includes: a vibration test on the emergency two-stage valve.

11. The method for tightening an emergency two-stage valve according to claim 8, characterized in that: The test verification of the reliability of the safe tightening torque used when the shrink plug thread connection is in the shrinkage hole also includes: conducting a full and vibration test on the emergency two-stage valve at the same time.

Images