Buffer system parameter design method for electromagnetic forming, buffer system and electromagnetic forming system

Abstract

The invention discloses a buffer system parameter design method for electromagnetic forming, a buffer system and an electromagnetic forming system.The buffer system is used for buffering acting force of electromagnetic pulse force of a forming coil on a machine tool and comprises a hydraulic buffer unit, a gas-liquid buffer unit and a one-way throttling unit; the hydraulic cylinder is arranged on the machine tool, and the forming coil is arranged on the end face of the end, extending out of the hydraulic cylinder, of the piston. And designing the buffer system parameters according to the buffer system design performance indexes. The acceleration of the piston and the forming coil is limited through the inertia of the piston and the oil pressure together, the pulse electromagnetic force is buffered, the back-off amount of the piston and the forming coil in the pulse electromagnetic force acting stage and the buffering stage can be reduced, the stability of the distance between the forming coil and a workpiece is guaranteed, and the change of the pulse electromagnetic force is avoided; the forming effect is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic forming, and in particular relates to a buffer system parameter design method for electromagnetic forming, a buffer system and an electromagnetic forming system. Background Art

[0002] Electromagnetic forming, also known as magnetic pulse forming, is a high-efficiency forming technology that enables the rapid deformation of sheet metal. During the electromagnetic forming process, a high pulsed current flows through the forming coil, subjecting the nearby sheet metal to a high pulsed electromagnetic force, causing plastic deformation.

[0003] At the same time, the forming coil will be subjected to pulse electromagnetic forces of the same magnitude and opposite direction. Due to the short electromagnetic forming cycle and concentrated energy release, the pulse electromagnetic force on the forming coil has the characteristics of high amplitude and short duration. The typical pulse electromagnetic force curve over time is as follows: Figure 1 As shown, its peak value can reach 25 tons and its duration is less than 0.5 microseconds, i.e. 0.0005s.

[0004] Typically, the forming coil in an electromagnetic forming device is mounted on a rigid mold frame. The reaction force acting on the forming coil during electromagnetic forming is transmitted to the mold frame, which does not affect the normal operation of the electromagnetic forming device in this scenario. However, if the forming coil is mounted on a movable device, such as the Z-axis of a machine tool, the instantaneous pulse electromagnetic force, if transmitted directly to the machine tool, can cause impact damage to various machine tool mechanisms. Furthermore, the pulse electromagnetic force can significantly displace the machine tool's mounting axis, moving the forming coil away from the workpiece. This reduces the pulse electromagnetic force's effect on the workpiece, affecting the forming effect. Summary of the Invention

[0005] The object of the present invention is to provide a buffer system parameter design method for electromagnetic forming, a buffer system and an electromagnetic forming system, so as to solve the above-mentioned problems existing when the electromagnetic forming device is applied to mobile devices.

[0006] The present invention is achieved through the following technical solutions: A method for designing parameters of a buffer system for electromagnetic forming, wherein the buffer system is used to buffer the effect of the electromagnetic pulse force of the forming coil on the machine tool, and includes a hydraulic buffer unit, a gas-liquid buffer unit, and a one-way throttling unit; the hydraulic buffer unit includes a hydraulic cylinder and a piston with a counterweight, the piston dividing the hydraulic cylinder into a rod chamber and a rodless chamber; the gas-liquid buffer unit includes a pressure accumulator cylinder and a floating piston, the floating piston dividing the pressure accumulator cylinder into an air chamber and a liquid chamber, the liquid chamber being connected to the rodless chamber via a pipeline; the one-way throttling unit includes a one-way valve and a throttle valve, and the one-way throttling unit is arranged on the pipeline connecting the rod chamber and the rodless chamber; The hydraulic cylinder is arranged on the machine tool, and the forming coil is arranged on the end surface of one end of the piston extending out of the hydraulic cylinder; the buffer system parameters are designed according to the buffer system design performance indicators, and the buffer system design performance indicators include the force exerted by the pulse electromagnetic force on the machine tool after buffering and the displacement of the forming coil during the buffering process. The buffer system parameters include the initial pressure of the air chamber, the diameter of the hydraulic cylinder, the piston mass, and the size of the air chamber.

[0007] In some embodiments, the step of designing buffer system parameters according to the buffer system design performance index includes: S1. Set the initial pressure of the air chamber; S2. Calculate the force exerted by the hydraulic cylinder on the machine tool based on the initial pressure of the air chamber, determine the allowable range of the hydraulic cylinder diameter based on the allowable range of the force exerted by the hydraulic cylinder on the machine tool, and select the hydraulic cylinder diameter based on the allowable range of the hydraulic cylinder diameter; S3. Calculate the piston displacement during the pulse electromagnetic force action phase based on the piston force relationship and the motion equation. Obtain the allowable range of the piston mass based on the allowable range of the piston displacement during the pulse electromagnetic force action phase. Select the piston mass based on the allowable range of the piston mass. S4. Select the size parameters of the gas chamber and calculate the total displacement of the piston during the pulse electromagnetic force action stage and the buffer stage according to the gas compression equation; S5. Based on the force analysis of the piston, check the force exerted by the hydraulic cylinder on the machine tool after buffering; when the force exerted on the machine tool after buffering is greater than the allowable value, reduce the initial pressure value of the air chamber and return to step S1; or select a smaller hydraulic cylinder diameter and return to step S2; cycle in sequence until the force exerted on the machine tool after buffering is less than the allowable value, and obtain the buffer system parameters.

[0008] In some embodiments, the method further includes determining the total length of the hydraulic cylinder according to the total displacement of the piston during the pulse electromagnetic force action phase and the buffering phase, wherein the total length of the hydraulic cylinder is greater than the total displacement of the piston.

[0009] In some embodiments, the method further includes a step of obtaining the piston movement time, where the piston movement time is the sum of the piston movement time during the pulse electromagnetic force action stage, the buffer stage, and the reset stage.

[0010] On the other hand, the present invention also provides a buffer system, comprising: A hydraulic buffer unit includes a hydraulic cylinder and a piston with a counterweight, wherein the piston divides the hydraulic cylinder into a rod chamber and a rodless chamber; The gas-liquid buffer unit includes a pressure accumulator cylinder and a floating piston. The floating piston divides the pressure accumulator cylinder into an air chamber and a liquid chamber. The liquid chamber is connected to the rodless chamber through a pipeline. A one-way throttling unit includes a one-way valve and a throttle valve. The one-way throttling unit is arranged on a pipeline connecting the rod chamber and the rodless chamber. The buffer system parameter design method is adopted to determine the initial pressure of the air chamber, the diameter of the hydraulic cylinder, the mass of the piston, and the size of the air chamber of the buffer system according to the design performance index of the buffer system.

[0011] In some embodiments, when the piston is pushed to move toward the rod chamber, the one-way valve opens, allowing the oil in the rodless chamber to flow into the rod chamber through the one-way valve; when the piston is pushed to move toward the rodless chamber, the one-way valve closes, and the oil in the rod chamber can flow into the rodless chamber through the throttle valve, and the throttle valve generates a damping force on the oil.

[0012] In some embodiments, the opening size of the one-way throttling unit can be adjusted.

[0013] On the other hand, the present invention also provides an electromagnetic forming system, comprising the buffer system.

[0014] In some embodiments, the hydraulic cylinder of the buffer system is arranged on the Z axis of the machine tool, and the forming coil of the electromagnetic forming system is arranged on the end surface of one end of the piston extending out of the hydraulic cylinder.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: The buffer system of the present invention adopts a hydraulic cylinder with a counterweight piston and a gas accumulator cylinder. After the pulse electromagnetic force is completed, the piston and the forming coil compress the liquid in the hydraulic cylinder under the action of inertia, converting the impact energy into piston kinetic energy and liquid potential energy, and the oil compresses the gas in the air chamber of the accumulator cylinder to do work, thereby achieving buffering of the external pulse electromagnetic force and avoiding damage to the various mechanisms of the machine tool caused by the impact.

[0016] The present invention uses the inertia of the piston and the oil pressure to jointly limit the acceleration of the piston and the forming coil, buffer the pulse electromagnetic force, and reduce the retreat amount of the piston and the forming coil during the pulse electromagnetic force action stage and the buffering stage, thereby ensuring the stability of the distance between the forming coil and the workpiece, avoiding changes in the pulse electromagnetic force, and ensuring the forming effect.

[0017] The present invention is based on the working principle of the buffer system and the design requirements of the buffer performance indicators. By setting the initial pressure of the air chamber, the hydraulic cylinder diameter, piston mass, and the total displacement of the piston in the pulse electromagnetic force action stage are designed in turn. The force on the machine tool after buffering is checked according to the designed parameters, and the parameters of the buffer system are designed so that the buffer system can effectively buffer the instantaneous impact of the pulse electromagnetic force, control the force on the machine tool within the design range, and effectively control the displacement of the formed coil during the buffering process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is the curve of pulse electromagnetic force changing with time.

[0020] Figure 2 Schematic diagram of the buffer system structure in an embodiment of the present invention.

[0021] Figure 3 Schematic diagram of the force relationship of the buffer system in an embodiment of the present invention.

[0022] Figure 4 This is a flow chart of a buffer system parameter design method in an embodiment of the present invention.

[0023] Figure 5 This is a schematic structural diagram of an implementation scheme of a buffer system in an embodiment of the present invention.

[0024] Figure 6 These are the design parameters of the buffer system designed in the embodiment of the present invention.

[0025] in: 1. Piston, 11. Forming coil mounting end surface, 2. Hydraulic cylinder, 21. Rod chamber, 22. Rodless chamber; 3. One-way throttling unit; 4. Accumulator cylinder, 41. Air chamber, 42. Floating piston, 43. Liquid chamber. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0027] In response to the problems existing in the application of electromagnetic forming devices on mobile devices, the present invention proposes a buffer system that can withstand pulse electromagnetic forces with a peak value of more than 25 tons. Through the setting of the buffer system, the force acting on the machine tool during the electromagnetic forming process can be reduced to less than 1 ton, while limiting the moving distance of the forming coil to no more than 0.5 mm.

[0028] Based on the above technical requirements, refer to Figure 2 and Figure 5 , the buffer system of the present invention includes a hydraulic buffer unit, a gas-liquid buffer unit and a one-way throttling unit; The hydraulic buffer unit includes a hydraulic cylinder 2 and a piston 1 with a counterweight. The piston 1 divides the hydraulic cylinder 2 into a rod chamber 21 and a rodless chamber 22. The forming coil is arranged on the forming coil mounting end surface 11 of the piston. The gas-liquid buffer unit includes a pressure accumulator cylinder 4 and a floating piston 42. The floating piston 42 divides the pressure accumulator cylinder 4 into an air chamber 41 and a liquid chamber 43. The liquid chamber 43 is connected to the rodless chamber 22 through a pipeline. The one-way throttling unit includes a one-way valve and a throttle valve. The one-way throttling unit is arranged on the pipeline connecting the rod chamber and the rodless chamber; when the piston is pushed toward the rod chamber, the one-way valve opens, allowing the oil in the rodless chamber to flow into the rod chamber through the one-way valve; when the piston is pushed toward the rodless chamber, the one-way valve closes, and the oil in the rod chamber can flow into the rodless chamber through the throttle valve, and the throttle valve generates a damping force on the oil.

[0029] When the one-way valve is opened, the oil in the rodless chamber enters the rod chamber through the one-way valve. In addition, some oil enters the liquid chamber of the accumulator cylinder, compressing the gas in the gas chamber.

[0030] Under ideal static loading conditions, the rod chamber and the rodless chamber are always in a state of equilibrium. The oil in the rodless chamber enters the rod chamber through the one-way valve, and the volume change of the rodless chamber is consistent with that of the rod chamber.

[0031] Because electromagnetic forming involves high-speed deformation, the volume of the rodless chamber decreases rapidly during high-speed piston movement, instantly pressurizing the oil in the rodless chamber. Meanwhile, the volume of the rod chamber increases rapidly, generating negative pressure. The pressure differential between the rod and rodless chambers causes the check valve to open, allowing the oil in the rodless chamber to flow into the rod chamber. However, due to the extremely short duration of time, during the electromagnetic force application phase or piston movement, the amount of oil flowing from the rodless chamber through the check valve into the rod chamber is less than the volume change between the two chambers.

[0032] In the above dynamic process, if the gas-liquid buffer unit is not set, the amount of oil in the rodless chamber flowing into the rod chamber through the one-way valve is limited, and the oil quality changes slightly. When the piston moves upward and compresses the volume, the pressure in the rodless chamber will increase sharply, causing the impact force acting on the hydraulic cylinder and on the Z-axis of the machine tool through the upper end face of the hydraulic cylinder to increase sharply, which is equivalent to directly applying the impact force of electromagnetic forming to the Z-axis of the machine tool.

[0033] By setting up a gas-liquid buffer unit, the liquid chamber is connected to the large-diameter rodless cavity. Under the action of electromagnetic force, when the piston moves upward, part of the oil enters the liquid chamber, compressing the air in the gas chamber and maintaining the pressure in the rodless cavity, thereby reducing the impact force on the hydraulic cylinder and the Z-axis of the machine tool.

[0034] The damping force generated by the throttle valve can slow down the reset speed of the piston, ensuring that the piston and the forming coil are reset smoothly.

[0035] The air chamber of the accumulator cylinder is filled with nitrogen, and when the nitrogen in the air chamber is compressed, high pressure can be generated in the air chamber.

[0036] The forming coil is set at the end of the piston extending out of the hydraulic cylinder. Figure 1 , the buffering principle of the buffer device is as follows: During the forming operation, the inertia of the piston with the counterweight structure and the force provided by the compression of the oil in the rod chamber jointly limit the acceleration of the movement of the piston and the forming coil, thereby buffering the pulse electromagnetic force and making the piston and the forming coil have a smaller retraction amount during the pulse electromagnetic force action stage, reducing the position change of the forming coil, and the electromagnetic force generated on the workpiece will not be significantly reduced, ensuring the stability of the electromagnetic force.

[0037] After the pulse electromagnetic force is completed, the piston and the forming coil continue to compress the oil in the hydraulic cylinder under the action of inertia, converting the impact energy into piston kinetic energy and liquid potential energy, and then driving the floating piston to compress the gas in the air chamber through the oil entering the liquid chamber to perform work, so as to achieve buffering and reduce the impact force acting on the machine tool; when the pulse electromagnetic force is offset, the piston and the forming coil are reset under the action of the high-pressure gas in the air chamber.

[0038] Specifically, the hydraulic buffer unit converts the impact energy of the pulse electromagnetic force into piston kinetic energy and oil potential energy, and then performs work by compressing the gas in the liquid chamber to achieve buffering. Figure 3 shown.

[0039] like Figure 3 During the pulse electromagnetic force action stage, the forces acting on the piston include the axially upward pulse electromagnetic force F1, the downward thrust T exerted on the piston by the oil in the rodless chamber of the hydraulic cylinder, the friction force F2 between the hydraulic cylinder wall and the piston, and the gravity G of the piston.

[0040] During the electromagnetic forming process, when the piston is subjected to an instantaneous external force, the force quickly compresses the piston, and the oil in the rodless cavity enters the liquid chamber of the accumulator cylinder. The nitrogen in the compressed air chamber stores energy and generates high pressure, which forms a reaction force on the internal oil. Combined with the inertia of the piston with a counterweight, the instantaneous pulse electromagnetic force is balanced, and the movement of the buffer forming coil is slowed down and the movement of the forming coil is reduced.

[0041] At the same time, the oil in the rodless chamber enters the rod chamber through the one-way throttling unit. At this time, the one-way valve opens and the throttle valve does not work.

[0042] After offsetting the pulse electromagnetic force, under the action of high-pressure gas, the floating piston resets and presses the oil in the liquid chamber into the rodless cavity. At this time, the piston drives the piston rod to extend and the forming coil resets; the oil in the rod cavity enters the rodless cavity through the one-way throttling unit. At this time, the one-way valve is closed and the throttle valve throttles to generate damping force.

[0043] The opening size of the one-way throttling unit is adjustable. By adjusting the opening size, the size of the damping force and the extension speed of the piston are adjusted.

[0044] Based on the structure and working principle of the buffer system in the above embodiment, the present invention provides a buffer system parameter design method to reduce the impact of the pulse electromagnetic force on the machine tool and limit the moving distance of the forming coil.

[0045] In some embodiments, reference Figure 4 , the buffer system parameter design method includes the following steps: S1. Set the initial pressure of the air chamber According to engineering experience, set the initial pressure of the accumulator cylinder chamber.

[0046] S2. Determine the diameter of the hydraulic cylinder According to the initial pressure of the air chamber, calculate the force exerted by the hydraulic cylinder on the machine tool. According to the allowable range of the force exerted by the hydraulic cylinder on the machine tool, determine the allowable range of the hydraulic cylinder diameter. According to the allowable range of the hydraulic cylinder diameter, select the hydraulic cylinder diameter within the allowable range of the hydraulic cylinder diameter.

[0047] S3. Determine the piston mass According to the piston force relationship and motion equation, the piston displacement during the pulse electromagnetic force action stage is calculated. According to the allowable range of the piston displacement during the pulse electromagnetic force action stage, the allowable range of the piston mass is obtained. According to the allowable range of the piston mass, the piston mass is selected.

[0048] S4. Calculate the total piston displacement Based on engineering experience, the air chamber size parameters are selected, and the total displacement of the piston during the pulse electromagnetic force action stage and the subsequent buffering stage is calculated according to the gas compression equation.

[0049] S5. Check the force exerted by the hydraulic cylinder on the machine tool after buffering According to the force analysis of the piston, the force exerted by the hydraulic cylinder on the machine tool after buffering is checked; when the force exerted on the machine tool after buffering is less than the allowable value, enter step S6; when the force exerted on the machine tool after buffering is greater than the allowable value, reduce the initial pressure value of the air chamber and return to step S1, or select a smaller hydraulic cylinder diameter and return to step S2, and repeat the cycle to obtain the design parameters of the buffer system.

[0050] S6. Determine the total length of the hydraulic cylinder The total length of the hydraulic cylinder is determined according to the total displacement of the piston. The total length of the hydraulic cylinder should be greater than the total displacement of the piston.

[0051] S7. Calculate piston movement time According to the motion equation, the piston movement time in the buffer stage and the reset stage is calculated respectively; the piston movement time is the sum of the time of the pulse electromagnetic force action stage, the buffer stage and the reset stage.

[0052] The process of designing the parameters of the buffer system using the buffer system parameter design method of the present invention is described in detail below with reference to specific embodiments. When working, the buffer device mainly goes through the pulse electromagnetic force action stage, the buffer stage and the reset stage. The buffer system parameters are designed according to the performance indicators that the buffer system needs to meet in the pulse electromagnetic force action stage and the buffer stage, so as to achieve the design purpose of meeting electromagnetic forming and reducing impact damage to the machine tool.

[0053] 1. Pulsed electromagnetic force action stage To achieve optimal forming results, the piston retraction distance S1 should be controlled within a certain range during the duration t1 of the pulsed electromagnetic force F1 to ensure that the pulsed electromagnetic force provided by the forming coil is not significantly reduced. According to process tests, the piston retraction distance S1 should be controlled within 0.5mm or less during the pulsed electromagnetic force application period.

[0054] Therefore, the performance index of the buffer system is determined as follows: within the action time t1 of the pulse electromagnetic force F1, the piston retreat distance S1 should be controlled within 0.5 mm.

[0055] The pulse electromagnetic force is amplified and F1 is taken as a constant value in the design calculation, F1=25t=250000N, and its action time t1 is 0.0005s.

[0056] 1-1) Let the piston mass be m, the acceleration be a1, and the acceleration due to gravity be g = 10 kg·m·s -2 ; Both the hydraulic cylinder and the accumulator cylinder adopt cylindrical cylinder body, and the cavity diameters are D a and D b .

[0057] According to engineering experience, the initial pressure of the gas chamber is P G =0.35MPa.

[0058] When the pressure of the hydraulic cylinder and the accumulator cylinder are balanced, the pressures of the two are equal, that is, the hydraulic cylinder pressure P L =P G =0.35MPa.

[0059] Install the hydraulic cylinder on the Z-axis of the machine tool. According to Newton's third law, the liquid pressure on the rodless chamber of the hydraulic cylinder is equal to the force T exerted by the hydraulic cylinder on the machine tool. … (1-1); According to the design requirements, the force exerted by the hydraulic cylinder on the machine tool should not exceed 1t, that is, T≤10000N. Substituting into formula (1-1) we get: … (1-2); According to engineering experience, within the allowable range of hydraulic cylinder diameter, the hydraulic cylinder diameter is taken as 180mm; the calculated force exerted by the hydraulic cylinder on the machine tool is T=8906N.

[0060] 1-2) Reference Figure 3 , according to the force relationship of the piston, we can get: ………(1-3).

[0061] During the time t1, the piston motion can be approximated as uniformly accelerated linear motion, and the piston displacement can be expressed as: ………(1-4).

[0062] According to the design index requirements, the piston retreat distance S1 ≤ 0.5mm, and the combined equations (1-1), (1-3), and (1-4) yield: ……(1-5).

[0063] Ignoring friction, that is, F2=0, according to formula (1-5), we can obtain m≥60.12kg, which is the allowable range of piston counterweight. The piston mass is selected within this allowable range.

[0064] 2. Buffering stage after the pulse electromagnetic force After the pulse electromagnetic force has acted for a period of time, the piston has a certain amount of kinetic energy and will continue to move upward and backward, generating a certain impact force on the machine tool through the hydraulic cylinder.

[0065] If the impact force is too high, it will cause irreversible damage to the machine tool during multiple cycles of discharge forming, affecting the machine tool's accuracy and reducing its service life. Therefore, it is necessary to control the force directly acting on the machine tool within a limited range. Based on the machine tool's structural characteristics, the design requires that the force exerted by the hydraulic cylinder on the machine tool after buffering does not exceed 1 ton.

[0066] That is, the buffering stage needs to absorb the kinetic energy of the piston and limit the movement of the piston, and after buffering, the force exerted by the hydraulic cylinder on the machine tool does not exceed 1t.

[0067] 2-1) Assume the initial height of the air chamber is h, and the air pressure after compression is P2. During the buffering phase, the piston accelerates vertically downward. Based on the force relationship of the piston, we can obtain: … (2-1); Wherein, a2 is the acceleration of the piston during the buffering stage; It is the hydraulic pressure applied to the rodless chamber of the hydraulic cylinder during the buffering stage, which is equal to the force exerted by the hydraulic cylinder on the machine tool.

[0068] Similar to T, but will increase due to the compression of the gas in the air chamber. Close to T, the piston performs approximately uniformly accelerated linear motion. The piston displacement at this stage is: … (2-2); Among them, t2 is the time from the end of the pulse electromagnetic force to the piston moving to the highest point.

[0069] According to the speed transformation relationship: … (2-3); Combining equations (2-2) and (2-3), we get: ………(2-4).

[0070] 2-2) During the pulse electromagnetic force action stage and the buffer stage, the total displacement S of the piston is: … (2-5); Combining equations (2-1), (2-4), and (2-5), we get: … (2-6).

[0071] 2-3) The relationship between the air chamber before and after compression can be obtained: … (2-7); in, is the initial volume of the air chamber, is the volume of the air chamber after compression; P G 、D b 、D a , h are constants, we can get: … (2-8).

[0072] According to engineering experience, the diameter of the air chamber is 130 mm and the initial height h of the air chamber is 400 mm.

[0073] because ;available: .

[0074] Therefore, the force exerted by the hydraulic cylinder on the machine tool during the buffer stage does not exceed 1t, which meets the design index requirements.

[0075] 2-4) The total displacement of the piston in the pulse electromagnetic force action stage and the buffer stage can be obtained as follows: ; That is, the total retraction amount of the piston is 12.45mm, and the total stroke of the piston is 50mm. The total length of the designed hydraulic cylinder should be greater than 50mm.

[0076] 3. Reset stage: the piston returns to its initial position after reaching the highest point After the piston reaches its highest point, its speed drops to zero. Then, it moves downward under the action of gravity and hydraulic pressure and returns to its initial position.

[0077] The acceleration of the piston in the reset phase is a3, which can be obtained: … (3-1); The displacement S3 during the reset phase is expressed as: … (3-2) available: .

[0078] According to formula (2-3), we can get: .

[0079] Therefore, it can be obtained that the piston movement time from the start of the pulse electromagnetic force to the piston returning to the initial position is: .

[0080] Reference Figure 5 and Figure 6 In the buffer system of this embodiment, the medium in the hydraulic cylinder is YH-15 aviation hydraulic oil, and the medium in the air chamber of the accumulator cylinder is nitrogen.

[0081] The buffer system parameters designed using the above method are: piston diameter 150mm, piston length 550mm, weight 68.5kg; hydraulic cylinder bore diameter 180mm, stroke 60mm; accumulator cylinder bore diameter 130mm, initial air chamber pressure 0.35MPa.

[0082] The buffer system of this embodiment can withstand the pulse electromagnetic force with a peak value of 25t, a pulse width of 0.0002s, and a duration of more than 0.0005s, and the retraction distance of the formed coil does not exceed 0.5mm. After buffering, the impact force acting on the machine tool is less than 1t.

[0083] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. used to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0084] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of the present invention does not necessarily imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical" and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0085] It should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0086] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A parameter design method for a buffer system for electromagnetic forming, characterized in that: The buffer system is used to buffer the effect of the electromagnetic pulse force of the forming coil on the machine tool, and includes a hydraulic buffer unit, a gas-liquid buffer unit and a one-way throttling unit; the hydraulic buffer unit includes a hydraulic cylinder and a piston with a counterweight, the piston divides the hydraulic cylinder into a rod chamber and a rodless chamber; the gas-liquid buffer unit includes a pressure accumulator cylinder and a floating piston, the floating piston divides the pressure accumulator cylinder into an air chamber and a liquid chamber, and the liquid chamber is connected to the rodless chamber through a pipeline; the one-way throttling unit includes a one-way valve and a throttle valve, and the one-way throttling unit is arranged on the pipeline connecting the rod chamber and the rodless chamber; The hydraulic cylinder is arranged on the machine tool, and the forming coil is arranged on the end surface of one end of the piston extending out of the hydraulic cylinder; the buffer system parameters are designed according to the buffer system design performance indicators, and the buffer system design performance indicators include the force exerted by the pulse electromagnetic force on the machine tool after buffering and the displacement of the forming coil during the buffering process. The buffer system parameters include the initial pressure of the air chamber, the diameter of the hydraulic cylinder, the piston mass, and the size of the air chamber.

2. The buffer system parameter design method for electromagnetic forming according to claim 1, characterized in that: The steps for designing buffer system parameters according to the buffer system design performance indicators include: S1. Set the initial pressure of the air chamber; S2. Calculate the force exerted by the hydraulic cylinder on the machine tool based on the initial pressure of the air chamber, determine the allowable range of the hydraulic cylinder diameter based on the allowable range of the force exerted by the hydraulic cylinder on the machine tool, and select the hydraulic cylinder diameter based on the allowable range of the hydraulic cylinder diameter; S3. Calculate the piston displacement during the pulse electromagnetic force action phase based on the piston force relationship and the motion equation. Obtain the allowable range of the piston mass based on the allowable range of the piston displacement during the pulse electromagnetic force action phase. Select the piston mass based on the allowable range of the piston mass. S4. Select the size parameters of the gas chamber and calculate the total displacement of the piston during the pulse electromagnetic force action stage and the buffer stage according to the gas compression equation; S5. Based on the force analysis of the piston, check the force exerted by the hydraulic cylinder on the machine tool after buffering; when the force exerted on the machine tool after buffering is greater than the allowable value, reduce the initial pressure value of the air chamber and return to step S1; or select a smaller hydraulic cylinder diameter and return to step S2; cycle in sequence until the force exerted on the machine tool after buffering is less than the allowable value, and obtain the buffer system parameters.

3. The buffer system parameter design method for electromagnetic forming according to claim 2, characterized in that: The method also includes a step of determining the total length of the hydraulic cylinder according to the total displacement of the piston in the pulse electromagnetic force action stage and the buffering stage, wherein the total length of the hydraulic cylinder is greater than the total displacement of the piston.

4. The buffer system parameter design method for electromagnetic forming according to claim 2, characterized in that: The method further includes a step of obtaining the piston movement time, wherein the piston movement time is the sum of the piston movement time in the pulse electromagnetic force action stage, the buffer stage and the reset stage.

5. Buffer system, characterized in that, include: A hydraulic buffer unit includes a hydraulic cylinder and a piston with a counterweight, wherein the piston divides the hydraulic cylinder into a rod chamber and a rodless chamber; The gas-liquid buffer unit includes a pressure accumulator cylinder and a floating piston. The floating piston divides the pressure accumulator cylinder into an air chamber and a liquid chamber. The liquid chamber is connected to the rodless chamber through a pipeline. A one-way throttling unit includes a one-way valve and a throttle valve. The one-way throttling unit is arranged on a pipeline connecting the rod chamber and the rodless chamber. The buffer system parameter design method described in any one of claims 1 to 4 is adopted to determine the initial air chamber pressure, hydraulic cylinder diameter, piston mass, and air chamber size of the buffer system according to the buffer system design performance indicators.

6. The buffer system according to claim 5, characterized in that When the piston is pushed toward the rod chamber, the one-way valve opens, allowing the oil in the rodless chamber to flow into the rod chamber through the one-way valve; when the piston is pushed toward the rodless chamber, the one-way valve closes, allowing the oil in the rod chamber to flow into the rodless chamber through the throttle valve, and the throttle valve generates a damping force on the oil.

7. The buffer system according to claim 5, characterized in that The opening size of the one-way throttling unit can be adjusted.

8. Electromagnetic forming system, characterized in that, A buffer system comprising the buffer system according to any one of claims 5 to 7.

9. The electromagnetic forming system according to claim 8, characterized in that The hydraulic cylinder of the buffer system is arranged on the Z axis of the machine tool, and the forming coil of the electromagnetic forming system is arranged on the end surface of one end where the piston extends out of the hydraulic cylinder.

Images