CN206455041U - A kind of Tube Hydroforming machine of bulging pressure fluctuation loading - Google Patents

Abstract

The utility model is related to a kind of Tube Hydroforming machine of bulging pressure fluctuation loading, electrohydraulic servo valve control pressurized cylinder is first passed through linearly to be pressurized, move back and forth to form fluctuation pressure by servomotor and ball-screw driving pulsation cylinder piston rod again, back and forth retreated not against host computer system pressure change or pressurized cylinder and form fluctuation pressure, it is to avoid unstable state caused by the fluctuation of system pressure or the high frequency flutter of pressurized cylinder；Bulging pressure conventional linear is loaded when can realize internal high pressure forming, sinusoidal pulsation wave is loaded, triangle pulsation wave is loaded, four kinds of modes of the loading of rectangle pulsation wave and the above combine loading at times, and the fluctuating frequency of pressure and amplitude are adjustable within the specific limits, the technique scope of application of equipment is expanded, the forming quality of product is improved.

Description

A pipe hydroforming machine with bulging pressure pulsation loading

technical field

The invention relates to an internal high-pressure forming machine, in particular to a pipe hydraulic forming machine loaded with bulging pressure pulses.

Background technique

Internal high pressure forming technology is an advanced, special, precise (semi-precision) net forming technology used to produce thin-walled metal components with complex cross-sections. Technology, with the characteristics of low cost, less process, light weight and high strength, is widely used in aviation, automobiles, home appliances and other fields. For example, multi-pass oil pipes of aero-engines, exhaust pipes, sub-frames, chassis, etc. of automobiles, and multiple copper pipes in air conditioners are all formed by internal high-pressure forming methods gradually replacing traditional methods. The basic process of this technology is as follows: first pretreat the billet, then place the tube blank at the correct position in the lower mold, and close the upper mold to lock the mold; the axial feed cylinder drives the punch to seal the end of the tube blank, At the same time, the liquid forming medium discharged from the filling hole of the punch does not exhaust the air; then the punches at both ends are fed and replenished at the same time, and the internal pressure increases at the same time; under the combined action of pressure and axial thrust, the tube blank is tightly attached to the mold The inner cavity is formed into a component of the required complex shape; after the forming is completed, the punch returns to release the pressure, the upper die is opened, and the workpiece is taken out.

The loading path usually refers to the matching relationship between the axial feed and the bulging pressure during the forming process. The loading path has an important impact on the quality of the hydroforming product. A reasonable loading path can significantly improve the forming performance of the material, avoid or reduce product buckling, cracking, and wrinkling. Most of the existing bulging pressure loading methods of internal high pressure forming machines are linear loading. In 2001, Japanese scholar T Rikimaru found that if the forming pressure inside the pipe is cycled in a certain pulsating manner, sufficient bulging can be obtained with less pressure, and the deformation can be made more uniform, which can delay the occurrence of rupture. This new technology is referred to as pipe pulsation hydroforming technology for short, and it is also called fluctuating loading internal high pressure forming technology in China. Once the technology was discovered, it immediately aroused the research interest of many scholars at home and abroad. Prof. Mori from Toyohashi University of Technology in Japan, Prof. Hama from Waseda University, Prof. Yang Lianfa from Guilin University of Electronic Science and Technology in China, and researcher Zhang Shihong from Shenyang Institute of Metal Research, Chinese Academy of Sciences have carried out related research. The research of Professor Mori from Japan found that under the pulsating loading method, the pipe will produce tiny wrinkles during the forming process, and the wrinkles have the characteristics of repeated generation and flattening, which makes the wall thickness change in the deformation zone of the pipe more uniform, and can effectively prevent the occurrence of product rupture. , thus improving the pipe formability. Professor Yang Lianfa of Guilin University of Electronic Science and Technology studied the plastic forming process of stainless steel pipes under pulsating hydraulic loading. The results show that: when the time is constant, with the increase of the pressure pulsation frequency, the more uniform the wall thickness distribution of the pipe, the better the filling of the mold .

The research equipment used by the above scholars is almost always to add a pulsating hydraulic pressure generating device to the traditional internal high pressure forming machine, or to make a simple pulsating hydroforming test device. At present, there are few internal high pressure forming machines with bulging pressure pulse loading at home and abroad. Chinese patent CN102182728A discloses a method for generating pulsating pressure. In this method, in a closed liquid chamber, a preset pressure is obtained by setting one piston to perform linear motion to pressurize, and the other piston to perform reciprocating motion to generate pulsating pressure. pulsating pressure. This method is simple and easy to implement, and the required equipment cost is relatively low, but this method does not disclose in detail how to control the movement of the two pistons according to the predetermined law, and this method is only suitable for experimental research of medium and low pressure, not suitable for high pressure. Internal high pressure forming machine with bulging pressure and high degree of automation. Chinese patent CN102451868A discloses a hydroforming method in a fluctuating internal pressure controlled loading mode. This method relies on fluctuating oil sources to control the internal pressure to form products that meet the requirements. The process range includes hydroforming of pipes, hydroforming of shells, sheet metal Hydroforming, the oil source control loading mode is sine wave, rectangular wave, triangular wave or compound wave. However, this patent only proposes a pulsating internal pressure loading method, and does not involve specific pressure pulsating loading internal high pressure forming equipment, nor does it disclose how to specifically realize the generation mechanism and control method of pulsating pressure. Chinese patent CN202123142U discloses a fluctuating loading pipe hydroforming ultra-high pressure system, which can realize fluctuating loading of forming pressure, and has good sealing effect and high forming efficiency. This patent is to control the overflow pressure of the pilot proportional electromagnetic overflow valve through the PID controller, and realize the pressure pulsation through the closed-loop feedback control of the pressure sensor, and realize the pressure linear loading and pulsating loading at the same time. However, the pressure at the input end of the low-pressure oil of the pressurized cylinder of this system fluctuates continuously, resulting in the instability of the system pressure; the dynamic performance of the ordinary pilot-operated proportional electromagnetic relief valve is difficult to meet the high-frequency pulsation requirements, and the long-term overflow leads to low energy utilization efficiency. Low. At the same time, this patent only discloses the pulsating loading hydraulic system, and does not clearly explain the complete machine equipment.

Contents of the invention

The purpose of the present invention is to solve the problem that the existing internal high pressure forming machine can only realize the linear loading of the bulging pressure, but cannot realize the pulsating loading. The electric motor drives the piston of the hydraulic cylinder to reciprocate to generate pulsating pressure, which is a combined loading small and medium-sized internal high pressure forming machine.

The technical scheme that the present invention takes for solving the above problems is:

A pipe hydroforming machine with bulging pressure pulsation loading according to the present invention, comprising: an upper beam, a guide post, a fast cylinder, a main cylinder, a movable beam, an upper die, an axial feed cylinder, and punches in the same quantity as the above, Workbench, frame, lower mold, lower cylinder, electrical control cabinet, PLC, servo driver, multiple button switches, control panel, touch screen, low-pressure liquid filling system, host hydraulic system, system oil pipe, booster cylinder, pressure transmitter Devices, pulsation hydraulic pressure generating devices, high-pressure water pipes and pressure transmitters;

The pulsating hydraulic pressure generating device includes: servo motor, screw, ball, nut, countersunk screw, connecting flange, pulsating cylinder piston rod, pulsating cylinder cylinder, high-pressure check valve at liquid inlet, pressure transmitter, cut-off Valve and outlet high pressure check valve. The servo motor is fixedly connected to the lead screw; the lead screw, multiple balls and nuts together constitute the ball screw transmission pair; multiple through holes are evenly distributed on the circumference of the nut base, and the same number of through holes are distributed at the corresponding positions on the circumference of the connecting flange. A large number of countersunk screws connect the two; the upper end of the piston rod of the pulsation cylinder is fixedly connected with the connecting flange, and the lower end forms a variable volume chamber with the cylinder body; the two sides of the cylinder body are respectively connected with high-pressure check valves to control the one-way flow of high-pressure liquid ;The liquid outlet of the pulsating hydraulic cylinder is connected with the pressure transmitter through the shut-off valve;

The main engine hydraulic system includes: main engine oil tank, main motor, remote pressure regulating valve, constant pressure variable pump, system overflow valve, at least one accumulator, electro-hydraulic servo valve, two-position four-way electromagnetic reversing valve and pressure gauge , the oil tank of the main engine is filled with hydraulic oil, and the main motor is connected to the constant pressure variable pump through a coupling; the oil inlet of the constant pressure variable pump is connected to the oil tank, and the oil outlet is connected to one interface of the four-way joint of the system; the other three four-way joints The ports are respectively connected to the accumulator, the oil inlet P of the electro-hydraulic servo valve, and other oil circuits of the main engine; the A and B oil ports of the electro-hydraulic servo valve are respectively connected to the P and T ports of the electromagnetic reversing valve; The A and B oil ports of the directional valve are respectively connected to the middle oil port and the end oil port of the booster cylinder;

The low-pressure liquid filling system includes: a high-pressure check valve, an overflow valve, a liquid-filling motor, a liquid-filling pump, a filter, and a water tank. The water tank is filled with a forming liquid medium; , the liquid outlet quickly fills the booster cylinder; the overflow valve is used as a safety valve for the filling system, and the high-pressure check valve prevents the high-pressure liquid in the booster cylinder from flowing back into the low-pressure filling pump.

There are 4 cylindrical guide pillars, which respectively pass through the four holes corresponding to the movable beam, the upper end is fixedly connected with the upper beam, and the lower end is fixedly connected with the workbench; the main cylinder is a large-diameter plunger cylinder, and the two quick cylinders are symmetrically distributed on the The left and right sides of the master cylinder; the cylinder body of the master cylinder and the two fast cylinders are fixedly connected to the lower end of the upper beam, the plunger rod of the master cylinder and the end of the piston rod of the quick cylinder are fixedly connected to the upper end of the movable beam; the upper end of the upper die is fixedly connected to the In the middle of the lower end surface of the movable beam, the lower die is fixed on the upper end face of the workbench corresponding to the upper die; there are two or three axial feed cylinders, which are respectively fixed on the left, right and rear sides of the workbench, and the third is fixed on the rear side, the punch is horizontally connected to the end face of the piston rod; the workbench is fixed on the frame, and the lower cylinder is set in the frame;

The control panel is fixedly connected to the upper beam, and the touch screen and the button switch are installed in it; the electrical control cabinet is fixedly connected to the right side of the frame, and the PLC (including AD/DA module) and the servo driver are installed in it;

The booster cylinder is fixedly connected to the right side of the frame, and the two oil ports of the low-pressure chamber are connected to the hydraulic system of the main engine through the system oil pipe, the liquid inlet of the high-pressure chamber is connected to the low-pressure liquid filling system through the high-pressure water pipe, and the liquid outlet is connected through the The high-pressure water pipe is connected to the pulsating hydraulic pressure generating device; the pressure transmitter is inserted at the liquid outlet of the booster cylinder; the liquid outlet of the pulsating hydraulic pressure generating device is connected to the liquid hole in the punch through a high-pressure water pipe;

The button switch, touch screen, low-pressure liquid filling system, host hydraulic system, pulsation hydraulic pressure generating device and pressure transmitter are respectively connected to the input or output interface of the PLC through cables; the input end of the servo drive is connected to the output interface of the PLC through cables, Its output end is connected with the servo motor in the pulsation hydraulic pressure generating device;

The touch screen can manually input the internal high pressure forming pressure loading program, the pressure linear loading part and the pulsating part input parameters independently; the program parameters are processed by PLC to control the actions of each system and components respectively; the electric signal is input into the electro-hydraulic servo valve, and the servo valve is controlled by the electric signal The flow rate to control the feed of the booster cylinder; the liquid forming medium supplemented by the low-pressure liquid filling system is pressurized by the booster cylinder and flows into the pulsation hydraulic pressure generating device, and the piston rod in the pulsation hydraulic pressure generation device is pressurized to form pressure pulsation through cyclic reciprocating motion. eventually flow into the tubing. A pressure transmitter is inserted at the outlet of the booster cylinder to detect the pressure, and the pressure is converted into an electrical signal and fed back to the PLC, and the PID controller in the PLC forms a semi-closed loop adjustment of the pressure.

The beneficial effects of the present invention are:

1. The small and medium-sized internal high pressure forming machine involved in the present invention can realize the conventional linear loading, sinusoidal wave pulsating loading, triangular wave pulsating loading, rectangular wave pulsating loading and combined loading of the above four loading methods in the forming process, The scope of application of the forming process of the equipment is expanded, and the forming quality of the product is improved.

2. The frequency and amplitude of the pulsating pressure of the small and medium-sized internal high pressure forming machine involved in the present invention can be continuously adjusted within a relatively large range, and the two parameters can be adjusted independently of each other.

3. The pressure pulsation device provided in the present invention adopts independent electrical control, which does not depend on the fluctuation of the main system pressure or the small flutter of the pressurized cylinder to form pressure pulsation, which improves the stability of the system.

4. The present invention uses PLC and servo driver to control the servo motor to form pressure pulsation, with simple structure, relatively low cost, and convenient use and maintenance.

4. The hydraulic system of the main engine of the internal high pressure forming machine involved in the present invention uses a combination of a constant pressure variable pump and an accumulator as a power source, which ensures the stability of the hydraulic system pressure of the main engine, reduces the installed power of the motor, and improves energy utilization efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the host structure of the present invention;

Fig. 2 is the schematic diagram of the clamping state of the main engine of the present invention;

Fig. 3 is a schematic diagram of the hydraulic system of the present invention;

Fig. 4 is the flow chart of bulging pressure control of the present invention;

Fig. 5 is a schematic diagram of the internal structure of the pressurized cylinder of the present invention;

Fig. 6 is a schematic diagram of the internal structure of the pulsating hydraulic pressure generating device of the present invention;

Fig. 7 is a comparison curve of bulging pressure sinusoidal pulsation loading and conventional linear loading in the present invention;

Fig. 8 is a graph showing the comparison between rectangular pulsating loading of forming pressure and conventional linear loading in the present invention;

Fig. 9 is a graph showing the comparison between triangular pulsating loading and conventional linear loading of the forming pressure of the present invention;

In the figure: 1. Upper beam; 2. Guide column; 3. Fast cylinder; 4. Master cylinder; 5. Movable beam; 6. Upper die; 7. Punch; 8. Axial feed cylinder; ;10. Rack; 11. Lower mold; 12. Lower cylinder; 13. Electrical control cabinet; 14. PLC (including AD/DA module); 15. Servo driver; 16. Button switch; 17. Control panel; 18. Touch screen; 19. Low-pressure liquid filling system; 20. Main engine hydraulic system; 21. System oil pipe; 22. Booster cylinder; 23. Pulse hydraulic pressure generating device; 24. High-pressure water pipe; 25. Pressure transmitter; .Oil tank of main engine; 28. Main motor; 29. Remote pressure regulating valve; 30. Constant pressure variable pump; 31. Relief valve; 32. Accumulator; 33. Electro-hydraulic servo valve; Directional valve; 35. Pressure gauge; 36. High-pressure one-way valve; 37. Relief valve; 38. Liquid-filled motor; 39. Low-pressure pump; 40. Filter; 41. Water tank; 42. Liquid outlet; 43. Inlet Liquid port; 44. High pressure chamber; 45. Middle oil port; 46. Piston rod; 47. Cylinder body; 48. End oil port; 49. Servo motor; 50. Screw rod; 51. Ball; 52. Nut; 53 .Sunk head screw; 54. Connecting flange; 55. Piston rod of pulsation cylinder; 56. Cylinder body of pulsation cylinder; Liquid port high pressure check valve.

Wherein: parts 27-35 form the main engine hydraulic system 20 in Fig. 1, and parts 36-41 form the low-pressure liquid filling system 19 in Fig. 1, in Fig. 3, except that the icon connected with overflow valve 37 is a water tank, other unidentified The marked oil tank icons are all main engine oil tanks 27 .

detailed description

The following descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention, such as increasing the number of axial feed cylinders If there are 3 or more, changing the clamping mode of the main cylinder, changing the quantity and size of the pressurized cylinder and the pulsating hydraulic cylinder, the specifications of the servo motor, etc., should all be included in the protection scope of the present invention.

Example 1:

This embodiment is internal high pressure forming with conventional linear loading of bulging pressure, and this embodiment will be described with reference to Figs. 1-6.

A pipe hydroforming machine with bulging pressure pulsation loading of the present invention comprises: an upper beam 1, four guide columns 2, two fast cylinders 3, a master cylinder 4, a movable beam 5, an upper die 6, two (or Three) Axial feed cylinder 8 and the same number of punches 7, workbench 9, frame 10, lower die 11, lower cylinder 12, electrical control cabinet 13, PLC (including AD/DA module) 14, Servo driver 15, multiple button switches 16, control panel 17, touch screen 18, low-pressure liquid filling system 19, host hydraulic system 20, system oil pipe 21, booster cylinder 22, pulsation hydraulic pressure generating device 23, high-pressure water pipe 24, pressure transmission device 25.

The pulsation hydraulic pressure generating device 23 includes: a servo motor 49, a lead screw 50, a plurality of balls 51, a nut 52, a plurality of countersunk screws 53, a connecting flange 54, a pulsation cylinder piston rod 55, a pulsation cylinder body 56, and Liquid port high-pressure one-way valve 57, pressure transmitter 58, stop valve 59, liquid outlet high-pressure one-way valve 60. The servo motor 49 is fixedly connected to the lead screw 50; the lead screw 50, multiple balls 51, and nuts 52 form a ball screw transmission pair; the circumference of the base of the nut 52 is evenly distributed with a plurality of through holes, and the corresponding positions on the circumference of the connecting flange are also distributed the same number of through holes, the two are connected by a corresponding number of countersunk screws 53; the upper end of the pulsation cylinder piston rod 55 is fixedly connected with the connecting flange 54, and the lower end forms a variable volume chamber with the cylinder body 56; the two sides of the cylinder body 56 are respectively Connect the high-pressure one-way valve 57 and 60 to control the one-way flow of high-pressure liquid; the liquid outlet of the pulsating hydraulic cylinder is connected to the shut-off valve 59, and the shut-off valve 59 is connected to the pressure transmitter 58.

The main engine hydraulic system 20 includes: main engine oil tank 27, main motor 28, remote pressure regulating valve 29, constant pressure variable pump 30, system overflow valve 31, at least one accumulator 32, electro-hydraulic servo valve 33, two-position four Through electromagnetic reversing valve 34, pressure gauge 35. The main engine oil tank 27 is equipped with hydraulic oil, and the main motor 28 is connected with the constant pressure variable pump 30 through a coupling; the oil inlet of the constant pressure variable pump 30 is connected to the oil tank 27, and the oil outlet is connected to an interface of the four-way pipe joint of the system; The other three ports of the pipe joint are respectively connected with the accumulator 32, the oil inlet P of the electro-hydraulic servo valve 33, and other oil circuits of the main engine; The P and T oil ports are connected; the A and B oil ports of the electromagnetic reversing valve 34 are respectively connected with the middle oil port 45 and the end oil port 48 of the booster cylinder 22 .

The low-pressure filling system 19 includes: a high-pressure check valve 36 , an overflow valve 37 , a filling motor 38 , a filling pump 39 , a filter 40 , and a water tank 41 . The forming liquid medium is installed in the water tank 41; the filter 40 is installed at the liquid inlet of the low-pressure and large-flow liquid charging pump 39, and the liquid outlet is quickly filled with the liquid to the pressurized cylinder 22; the overflow valve 37 is used as a safety valve for the liquid filling system, and the high-pressure one-way The valve 36 prevents the high-pressure liquid in the booster cylinder 22 from flowing back into the low-pressure charging pump 39 .

The four cylindrical guide posts 2 pass through the movable beam 5 and correspond to four holes, the upper end is fixedly connected with the upper beam 1, and the lower end is fixedly connected with the workbench 9; the main cylinder 4 is a large-diameter plunger cylinder, and two fast The cylinders 3 are symmetrically distributed on the left and right sides of the main cylinder 4; the cylinder bodies of the main cylinder 4 and the two quick cylinders 3 are fixedly connected to the lower end surface of the upper beam 1, and the plunger of the main cylinder and the end of the piston rod of the quick cylinder are fixedly connected to the movable beam 5 end face; the upper end face of the upper die 6 is fixedly connected to the middle part of the lower end face of the movable beam 5, and the lower die 11 is fixed on the upper end face of the workbench 9 corresponding to the upper die 6; the two or three axial feed cylinders 8 are fixed On the left, right, and rear sides of the workbench 9 (the third is fixed on the rear side), the punch 7 is horizontally connected to the end face of the piston rod; the workbench 9 is fixed on the frame 10, and the lower cylinder 12 is arranged on the machine in rack 10;

The control panel 17 is fixedly connected to the right side of the upper beam 1, and the touch screen 18 and the button switch 16 are all installed in it; The drivers 15 are all installed inside it; the booster cylinder 22 is fixedly connected to the right side of the frame, and the two oil ports 45 and 48 of the low-pressure chamber are connected to the main engine hydraulic system 20 through the system oil pipe 21, and the liquid inlet 43 of the high-pressure chamber is connected through the high-pressure water pipe 24 is connected to the low-pressure liquid filling system, and its liquid outlet 42 is connected to the pulsating hydraulic pressure generating device 23 through a high-pressure water pipe; the pressure transmitter 25 is inserted at the liquid outlet 42 of the pressurized cylinder; Connect with the liquid hole in the punch 7 through the high-pressure water pipe 24;

The button switch 16, the touch screen 18, the low-pressure liquid filling system 19, the host hydraulic system 20, the pulsation hydraulic pressure generating device 23 and the pressure transmitter 25 are respectively connected to the input or output interface of the PLC 14 through cables; the input end of the servo driver 15 is connected through The cable is connected to the PLC output interface, and its output end is connected to the servo motor 49 in the pulsation hydraulic pressure generating device;

The touch screen 18 can manually input the pressure loading program of the internal high pressure forming, the normal linear loading part of the pressure and the pulsating loading part input parameters independently, and there is no pulsating loading parameter in this embodiment; the program parameters are processed by PLC14 to control the actions of each system and component respectively; The electrical signal is input to the electro-hydraulic servo valve 33, and the feed of the booster cylinder 22 is controlled by controlling the flow rate of the servo valve; the liquid forming medium supplemented by the low-pressure liquid filling system 19 is pressurized by the booster cylinder 22 and flows into the pulsation hydraulic pressure generating device 23; The piston rod in the hydraulic pressure generating device 23 is locked, and the high-pressure forming medium finally flows into the pipe 26 . A pressure transmitter 25 is installed at the outlet of the booster cylinder 22 to detect the pressure, and the pressure is converted into an electrical signal to be fed back into the PLC 14, and the PID controller in the PLC forms a semi-closed-loop control of the pressure.

In this embodiment, the linear function of internal pressure changing with loading time is:

P ₀ (t) = 10t (0≤t<5);

P ₀ (t) = 25t-75 (5≤t<15);

P ₀ (t)=300 (15≤t≤20).

Before processing, input the forming process program in the touch screen 18 as shown in the following table:

In the above table, the time point is the starting point or turning point of linear loading of internal pressure; the pressure is the bulging pressure at this moment; the pulsation mode is: 0 no pulsation, 1 sine wave pulsation, 2 rectangular wave pulsation, 3 triangular wave pulsation; amplitude h is the amplitude of the reciprocating motion of the piston rod 46 of the pulsation cylinder at the corresponding moment, and the frequency is the reciprocating frequency of the piston rod 46 .

Subsequently, the pretreated pipe 26 is placed in the correct position of the lower mold 11, and the corresponding button switch 16 in the control panel 17 is pressed to start semi-automatic forming. The main cylinder 4 drives the movable beam 5 to go down quickly until the upper mold 6 is close to the lower mold 11. Turn to slow mold clamping; the axial feed cylinder 8 is positioned quickly and axially, and at the same time, the motor 38 of the liquid filling system is started, and the low-pressure forming liquid discharged from the pump 39 passes through the booster cylinder 22 and the pulsation hydraulic pressure generating device 23 in sequence, and then enters the punching chamber. The liquid hole in the head 7; after the axial feed cylinder is positioned at the predetermined position, seal the ends of the pipe 26 and exhaust the air inside; then the axial feed cylinder 8 turns to slow feed, and according to the set Program feed; at the initial moment of feed, the high-pressure chamber 44 of the pressurized cylinder 22 is in the maximum volume state and is filled with low-pressure liquid; the main motor 28 drives the constant-pressure variable pump 30 to provide power for the hydraulic system, and the PLC14 controls the electro-hydraulic servo according to the set program The spool of the valve 33 moves, and at the same time the spool of the reversing valve 34 is in the right position, and the hydraulic oil enters the low-pressure chamber of the pressurized cylinder 22 from the oil port 38, and pushes the piston rod 46 to move toward the high-pressure chamber 44; After the forming liquid is pressurized, it flows through the one-way valves 57 and 60 in the pulsation hydraulic pressure generating device 23 in sequence. At this time, the servo motor 49 is in a stop state and does not generate pulsating pressure; the high-pressure liquid finally enters the pipe through the liquid filling hole in the punch 7 26 inside, under the coordination of axial feed, the pipe material 26 is closely attached to the inner wall of the upper die 6 and the lower die 11 of the mold, and a product of the required shape is formed.

During this forming process, the output pressure of the constant pressure variable pump 30 can be controlled by adjusting the pressure of the remote pressure regulating valve 29; the overflow valve 31 controls the maximum pressure of the hydraulic system of the main engine, and plays a role of pressure limiting safety; The hydraulic oil is absorbed in the working gap, and when the forming pressure rises rapidly, a large flow of hydraulic oil is quickly supplied to the electro-hydraulic servo valve 33 to reduce the installed rated power of the motor 28; the pressure gauge 35 can display the pressure of the low-pressure chamber of the booster cylinder 22 in real time, It is convenient for equipment operators to observe and monitor the forming process in real time; the pressure transmitter 25 collects the pressure of the liquid outlet 42 of the high-pressure chamber of the pressurized cylinder 22 in real time, and converts it into an electrical signal and feeds it back to the PLC14 to form a pressure closed-loop feedback control and control the electro-hydraulic pressure in real time. The spool of the servo valve 33 moves; at the same time, the change of the bulging pressure is displayed on the touch screen 18 in real time; the high-pressure check valve 36 prevents the high-pressure forming liquid from backflowing back to the low-pressure filling pump 39 .

After the execution of the high pressure forming program is completed, the axial feed cylinder 8 quickly returns to the initial position, the pressure of the pipe 26 is released, the fast cylinder 3 drives the movable beam 5 to open the mold quickly, and finally the formed pipe 26 is taken out to prepare for the next workpiece forming.

Example 2:

This embodiment is internal high pressure forming with sinusoidal pulsation loading of bulging pressure, and this embodiment will be described with reference to Figs. 1-7.

In this embodiment, the internal pressure loading curve function is:

P ₁ (t)=P ₀ (t)+ΔP·sin(2πω·t).

In the formula, P ₀ (t) is the conventional linear loading curve in Example 1, ΔP is the pulse wave amplitude, which is 5 MPa in this embodiment; ω is the pulse frequency, which is 1 Hz in this embodiment.

Compared with Example 2, the pulsating loading method is selected as 1, and the amplitude h needs to be manually measured before the part is formed. Because the system only feeds back and controls the conventional linearly loaded pressure, the pulsating pressure is partially open-loop controlled, and the input program is the amplitude h of the piston rod of the pulsating cylinder, not the amplitude ΔP of the pulsating pressure. Knowing the hydrodynamic properties of the forming medium, the pulsating cylinder, high-pressure water pipe, pipe size, etc., the piston rod amplitude h corresponding to the amplitude ΔP can be calculated through theoretical derivation. However, due to too many assumptions and uncontrollable factors such as leakage in the system, there are relatively large big error. Therefore, it is more accurate to manually measure the amplitude of the piston rod of the pulsation cylinder on the equipment.

The present invention is a small and medium-sized internal high-pressure forming machine. Under the condition that the pressure pulsation amplitude ΔP is constant and the pressure control accuracy is not high, a constant value of the amplitude h can be set. If after forming, it is found that the pressure amplitude ΔP attenuation exceeds the required pressure control accuracy, then the amplitude h of the piston rod of the pulsation cylinder can be compensated by comparing the real-time pressure value recorded on the touch screen 18, and the starting point of each period is set to a different amplitude. According to the h value at the initial moment, the piston rod vibration amplitude of each pulsation cycle is automatically determined according to the linear interpolation method.

The method for manually measuring the amplitude of the pulsation cylinder piston rod 46 is: set the equipment in the touch screen 18 to be in the manual operation state; press the corresponding button switch 16 to manually control the master cylinder 4 mold closing and the punch 7 to quickly locate; The pressurization cylinder 22 pressurizes in a jog manner. Under the condition that the pipe material does not break and fail (the pressure changes suddenly when the pipe material breaks), the theoretically calculated h value is input into the touch screen as a benchmark, and then the pulsation hydraulic pressure generating device 23 is manually controlled to operate. The pressure transmitter 25 collects the outlet pressure of the one-way valve 60 in real time and displays it on the touch screen 18 . Observe the actual pressure pulsation value and compare it with the theoretical value, make multiple feedback corrections, and finally determine the reasonable value of h.

Another difference between the forming process of this embodiment and Embodiment 1 is that in the semi-automatic forming process, the pulsating hydraulic pressure generating device 23 is in the running state, and the piston rod 55 of the pulsating cylinder is at the equilibrium point at the initial moment, and the high-pressure liquid flows from the booster cylinder 22 into a sinusoidal pulsating pressure after entering. The mechanism of sinusoidal pulsating pressure generation is: PLC14 outputs control electrical signal, after being amplified by servo driver 15, it drives servo motor 49 to rotate, its rotational angular velocity changes sinusoidally, and the maximum value is automatically calculated by the system according to the pulsation frequency ω and the amplitude h of the piston rod . The servo motor 49 drives the ball screw nut pair to convert the rotary motion into a linear motion, and the nut 52 drives the piston rod 46 to make a reciprocating sinusoidal motion up and down, so that the pressure in the rodless chamber fluctuates; the one-way valves 57 and 60 prevent the high-pressure liquid from reversing when pulsating. flow, reducing interference; the cut-off valve 59 is opened when forming with pulsating loading, and closed when forming without pulsating loading, so as to improve the service life of the pressure transmitter 58.

Example 3

This embodiment is internal high pressure forming with rectangular pulsating loading of bulging pressure, and this embodiment will be described with reference to Fig. 1-9 and Fig. 8 .

In this embodiment, the internal pressure loading curve function is:

In the formula, P ₀ (t) is the conventional linear loading curve in Example 1, ΔP is the pulse wave amplitude, which is 5 MPa in this embodiment; ω is the pulse frequency, which is 1 Hz in this embodiment.

Compared with Embodiment 2, the servo motor 49 drives the piston rod 46 to move at the maximum rotational speed in each pulsation period. The piston rod 46 moves quickly from the balance point to the maximum amplitude h, pauses for a period of time, then descends to the position h below the balance point, and quickly returns to the balance point when the pause is the same.

Example 4

This embodiment is internal high pressure forming under triangular pulsation loading of bulging pressure, and this embodiment will be described with reference to Fig. 1-6 and Fig. 9 .

The triangular wave in this embodiment has amplitude ΔP=5 MPa and period ω=1 Hz. Compared with the second embodiment, the servo motor 46 drives the piston rod 47 to move up and down at a constant speed from the balance point in each pulsation period.

Example 5

In this embodiment, multiple loading methods are combined loading in different time periods, and this embodiment will be described in conjunction with FIGS. 1-9 .

The input procedure is shown in the table below:

The pulsating hydraulic pressure generating device outputs sine wave pulsating pressure within 0-5s, rectangular wave pulsating pressure within 5-15s, and triangular wave pulsating pressure within 15-20s, realizing multi-loading methods combined loading in different periods. The amplitude h is fine-tuned from 5mm to 5.3mm to properly compensate for the attenuation of pressure pulsation.

Claims (7)

1. a kind of Tube Hydroforming machine of bulging pressure fluctuation loading, including：Entablature, guide pillar, fast cylinder, master cylinder, activity Crossbeam, upper mould, axial feed the cylinder drift consistent with quantity therewith, workbench, frame, lower mould, lower cylinder, electrical control cabinet, PLC, servo-driver, button switch, control panel, touch-screen, system oil pipe, pressurized cylinder, pressure transmitter, high-pressure water pipe and Pressure transmitter；It is characterized in that：Also include：

Pulse hydraulic generation device：The pulse hydraulic generation device includes：Servomotor, leading screw, ball, nut, countersunk head spiral shell Nail, adpting flange, pulsation cylinder piston rod, pulsation cylinder cylinder body, inlet high pressure check valve, pressure transmitter, stop valve and go out liquid Mouth high pressure check valve, servomotor is fixedly connected with leading screw；Leading screw, many balls, nuts collectively form ball-screw-transmission pair； Nut base even circumferential is distributed multiple through holes, and adpting flange circumference correspondence position is also distributed the through hole of identical quantity, by right The sunk screw of quantity is answered to connect the two；Pulsation cylinder piston rod upper end is fixedly connected with adpting flange, lower end and cylinder body shape Into variable volume cavity；Cylinder body both sides connect high pressure check valve respectively, control highly pressurised liquid one-way flow；At pulse hydraulic cylinder liquid outlet It is connected by stop valve with pressure transmitter；

Host hydraulic system：The host hydraulic system includes：Main sump, main motor, remote pressure regulating valve, constant pressure variable displacement pump, System overflow valve, at least one accumulator, electrohydraulic servo valve, two-position four-way solenoid directional control valve and pressure gauge, main sump are equipped with Hydraulic oil, main motor is connected by shaft coupling with constant pressure variable displacement pump；The oil inlet of constant pressure variable displacement pump is connected with fuel tank, and oil-out is extremely One interface of system four-way connection；Four-way connection the other three interface respectively with accumulator, the oil inlet P of electrohydraulic servo valve, master Machine other oil circuits connection；A, B hydraulic fluid port of electrohydraulic servo valve correspond to be connected with P, T hydraulic fluid port of solenoid directional control valve respectively；Electromagnetic switch A, B hydraulic fluid port of valve correspond to be connected with middle part hydraulic fluid port, the end hydraulic fluid port of pressurized cylinder respectively；

Low pressure hydromechanical system：The low pressure hydromechanical system includes：High pressure check valve, overflow valve, topping up motor, charging pump, filtering Shaping liquid medium is housed in device and water tank, water tank；Low pressure and mass flow charging pump inlet installs filter, and liquid outlet is to supercharging The quick topping up of cylinder；Overflow valve makees hydromechanical system safety valve, and high pressure check valve prevents the highly pressurised liquid in pressurized cylinder from reversely flowing into low Press charging pump.

2. the Tube Hydroforming machine of bulging pressure fluctuation loading according to claim 1, it is characterized in that：The guide pillar is 4 cylindrical guides, are each passed through four holes of moved cross beam correspondence, and upper end is fixedly connected with entablature, lower end and workbench are solid Fixed connection.

3. the Tube Hydroforming machine of bulging pressure fluctuation loading according to claim 1, it is characterized in that：The master cylinder is Major diameter plunger case, two fast cylinders are symmetrically distributed in the master cylinder left and right sides；Master cylinder, the cylinder body of two fast cylinders are fixedly connected on Entablature lower surface, master cylinder plunger piston bar, fast cylinder piston-rod end are fixedly connected on moved cross beam upper surface.

4. the Tube Hydroforming machine of bulging pressure fluctuation loading according to claim 1, it is characterized in that：On the upper mould End face is fixedly connected in the middle part of moved cross beam lower surface, and lower mould is fixed on workbench upper surface and upper mould correspondence position.

5. the Tube Hydroforming machine of bulging pressure fluctuation loading according to claim 1, it is characterized in that：The axial direction is entered It is multiple to cylinder, is separately fixed at workbench left and right side, drift is connected horizontally in its piston rod end face.

6. the Tube Hydroforming machine of bulging pressure fluctuation loading according to claim 1, it is characterized in that：The electric-controlled Cabinet processed is fixedly connected on the right side of frame, and PLC is mounted on inside it with servo-driver；It is right that pressurized cylinder is fixedly connected on frame Side, its hydraulic fluid port of low pressure chamber two is connected by system oil pipe with host hydraulic system, its high pressure chest inlet by high-pressure water pipe with Low pressure hydromechanical system is connected, and its liquid outlet is connected by high-pressure water pipe with pulse hydraulic generation device；Pressure transmitter is inserted into At pressurized cylinder liquid outlet；Liquid-through hole in the liquid outlet and drift of pulse hydraulic generation device is connected by high-pressure water pipe.

7. the Tube Hydroforming machine of bulging pressure fluctuation loading according to claim 1, it is characterized in that：The button is opened Pass, touch-screen, low pressure hydromechanical system, host hydraulic system, pulse hydraulic generation device and pressure transmitter pass through cable respectively It is connected with PLC input or output interface；The input of servo-driver is connected by cable with PLC output interfaces, and it is exported End is connected with the servomotor in pulse hydraulic generation device.