High-pressure heavy-load friction welding machine static pressure supporting friction pair temperature control method

Abstract

In order to solve the problem that the temperature change of the static pressure bearing friction pair under high pressure and heavy load working condition causes the change of the static pressure oil film shape and viscosity, thereby reducing the machining precision and service life of the friction welding machine, the application provides a high pressure and heavy load friction welding machine static pressure bearing friction pair temperature control method.The application starts from the environmental temperature and the local temperature of the static pressure bearing friction pair, first heats or cools the global oil liquid through the oil temperature control box, reduces the influence of the environmental temperature on the static pressure bearing friction pair of the friction welding machine, then feeds back the local temperature of the static pressure bearing friction pair through the temperature sensor on the oil pad, controls the variable frequency motor, the adjustable constant displacement pump and the PWM proportional electromagnetic speed regulating valve through the PWM signal modulator and the signal power amplification circuit, increases the flow of the local hydraulic oil, cools the local heating position of the friction pair, and realizes the dynamic regulation and control of the local temperature of the static pressure bearing friction pair.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of solid-phase welding, and particularly relates to a temperature control method for a static pressure supporting friction pair of a friction welding machine. BACKGROUND

[0002] In the fields of aviation, aerospace, military weapons, nuclear power, automobiles, etc., the friction welding technology has become the preferred technology for efficient and high-quality manufacturing of key components due to its good welding quality of joints, weldable dissimilar steel and dissimilar metals, high welding size precision, and other advantages. In the welding process, the main component of the static pressure support of the friction welding machine will bear a large amount of upsetting force and high speed, so the static pressure support will inevitably have temperature rise, and due to the influence of gravity or partial load, the local temperature of the static pressure support friction pair will be uneven. The local temperature rise of the friction pair will cause the deformation of the oil film to reduce the machining precision, and the dry friction between the friction pairs will damage the workpiece and the friction welding machine. In addition, because China has a vast territory, the temperature in different seasons in different places is different, so the influence of the environmental temperature must be considered when the friction welding machine is working. Too low or too high environmental temperature will change the viscosity of the hydraulic oil and the shape of the static pressure support friction pair, thereby affecting the machining precision and the service life of the machine. As the core component of the friction welding machine, it is necessary to study a method for controlling the temperature of the friction pair of the static pressure support within a reasonable range under high pressure and heavy load conditions. The traditional temperature control scheme for the friction pair of the static pressure support only cools the whole static pressure support, cannot control the local temperature of the static pressure support friction pair within a reasonable range, and ignores the influence of the environmental temperature on the static pressure support friction pair, so this application will focus on solving this problem. SUMMARY

[0003] The application proposes a temperature control method for the friction pair of the static pressure support of a friction welding machine to solve the problem that the temperature change of the friction pair of the static pressure support under high pressure and heavy load conditions changes the shape and viscosity of the static pressure oil film, and reduces the machining precision and service life of the friction welding machine.

[0004] The static pressure support of the friction welding machine is divided into a bearing side axial static pressure support friction pair, a non-bearing side axial static pressure support friction pair, and a radial static pressure support friction pair. Each of the bearing side axial static pressure support friction pair, the non-bearing side axial static pressure support friction pair, and the radial static pressure support friction pair has four evenly distributed oil pads, and a group of temperature sensors is installed on each oil pad.

[0005] The temperature control method for the friction pair of the static pressure support of the friction welding machine proposed by the application is implemented according to the following steps:

[0006] Step A, set up a global oil temperature control circuit in the oil tank, which is composed of a coarse oil filter, a vane pump, a one-way valve and an oil temperature control box. Before the main shaft is running, the oil temperature control box detects whether the oil temperature is within the preset reasonable range. If the oil temperature is not within the preset temperature range, the oil temperature control box starts.

[0007] Step A1, after the oil temperature control box starts, it is judged whether the oil temperature at this time is higher than the preset reasonable temperature. The corresponding temperature control module is turned on.

[0008] Step A2, if the oil temperature is higher than the preset temperature range of the oil temperature control box, the cooling module in the oil temperature control box automatically starts. At this time, the cooler in the oil temperature control box works. The cooler is forced to accelerate heat dissipation by a special fan, and the oil temperature is cooled to the preset temperature range.

[0009] Step A3, when the temperature of the hydraulic oil is lower than the preset reasonable temperature range of the oil temperature control box, the heating module is automatically started. The electric heater in the oil temperature control box works. The oil flows through the electric heater through the parallel pipeline, so as to shorten the heating time of the oil and quickly heat the temperature of the hydraulic oil to the preset temperature range, avoiding the influence of the environment temperature on the static pressure bearing friction pair.

[0010] Step B, after the oil temperature reaches the preset temperature range of the oil temperature control box, the static pressure bearing hydraulic system pumps the hydraulic oil into the static pressure bearing friction pair. The load side axial static pressure bearing friction pair, the non-load side axial static pressure bearing friction pair and the radial static pressure bearing friction pair generate load oil film. The main shaft starts to work and rotates.

[0011] Step C, the temperature of the oil seal edge in the oil pad of the static pressure bearing friction pair is the highest in the whole friction pair. This is because in the static pressure bearing, when the lubricating oil flows through the friction surface, high-speed injection will be generated, thereby generating strong friction and heat at the oil seal edge. In order to timely grasp the temperature change of the oil seal edge, a temperature sensor is arranged at this position and real-time monitors the temperature of the oil seal edge of the oil pad. When the temperature sensor detects the temperature change, it will transmit the temperature signal to the PWM signal modulator.

[0012] Step D, the PWM signal modulator is composed of a frequency adjustment circuit and a pulse width modulation circuit. After different temperature signals are transmitted to the PWM signal modulator, the frequency adjustment circuit will output different frequency pulse signals according to different temperature signals, and then the pulse signals are input into the pulse width modulation circuit. On the premise that the frequency does not change, the duty cycle of the pulse signal is adjusted, so that for each temperature signal input, a signal containing a specific frequency and pulse width is output from the PWM signal modulator.

[0013] Step E, after the pulse signal containing specific frequency and pulse width is output from the PWM signal modulator, it is output to the signal power amplifier circuit, and the pulse signal amplified by the signal amplifier circuit is output to the variable frequency motor and the PWM proportional speed regulating valve. In addition, the pulse signal amplified by the signal power amplifier is re-input into the pulse width modulation circuit to form a deep negative feedback loop. This loop can monitor the output signal of the power amplifier in real time and compare it with the set value to finely adjust and control the output signal, thereby improving the stability and response speed of the signal output. At the same time, due to the existence of some nonlinear distortion factors in the PWM signal modulator, such as saturation, dead zone, etc., this deep negative feedback loop can also reduce the influence of these distortions through dynamic compensation, thereby ensuring the output accuracy and reliability of the signal.

[0014] Step F, the PWM proportional electromagnetic speed regulating valve is arranged between the oil distributor and each oil pad of the friction pair. The PWM proportional speed regulating valve is composed of a force motor and a speed regulating valve. Different PWM signals can form different control current signals through the signal power amplifier, and these signals will eventually be converted into axial force by the force motor, which is proportional to the control current. This axial force will act on the throttle spool of the speed regulating valve, thereby changing the valve port coverage to achieve precise regulation of the output flow.

[0015] Step G, the pulse signal output by the signal amplification power circuit is transmitted to the variable frequency motor, and these pulse signals have different frequencies and widths, and the variable frequency motor can achieve precise control of its speed by receiving these pulse signals. When the frequency of the pulse signal changes, the variable frequency motor will respond accordingly to change its speed.

[0016] Step H, the output flow of the adjustable constant flow pump is controlled by the speed of the variable frequency motor. When the speed of the variable frequency motor changes, the output flow of the adjustable constant flow pump will also change accordingly. When the temperature of a certain oil pad of the friction pair increases, the speed of the variable frequency motor increases, and the output flow of the adjustable constant flow pump also increases. Conversely, when the temperature of a certain oil pad of the friction pair decreases, the speed of the variable frequency motor decreases, and the output flow of the adjustable constant flow pump also decreases, achieving dynamic control of the output flow of the oil pump.

[0017] Step I, since the loads of the bearing side axial static pressure supported friction pair, the non-bearing side axial static pressure supported friction pair and the radial static pressure supported friction pair are different, three sets of oil supply systems are used to supply oil to them respectively, and each friction pair is composed of four evenly distributed oil pads. The oil distributor is used to divide the hydraulic oil into four equal flow parts and supply them into the oil pads.

[0018] Step J, when the hydraulic oil passing through the oil separator passes through the PWM proportional electromagnetic speed regulating valve, the PWM proportional electromagnetic speed regulating valve changes its valve port covering amount due to the change of the local temperature signal of the friction pair, so that the oil flow passing through the PWM proportional electromagnetic speed regulating valve changes with the temperature, realizing the local dynamic control of the oil flow into the friction pair.

[0019] Step K, during the operation of the friction welding machine, the local temperature of the static pressure supported friction pair may be increased due to the influence of gravity or unbalanced load, and the temperatures are different, at this time, the flow into each friction pair oil pad will gradually increase the oil pump-in to cool the local temperature of the static pressure supported friction pair, and the flow into each friction pair oil pad will decrease the oil flow with the decrease of the temperature, so as to control the temperature of the friction pair within a reasonable range.

[0020] The case starts from the environmental temperature and the local temperature of the friction pair, so that the temperature of the static pressure supported friction pair is always maintained within a reasonable range, and the influence of the change of the environmental temperature and the local temperature of the friction pair on the machining precision and the service life of the main shaft is avoided.

[0021] The scheme realizes the control of the global oil temperature and the dynamic control of the local oil flow of the friction pair to achieve the best temperature control effect, reduces the labor amount of personnel and unnecessary energy waste.

[0022] The scheme only adds temperature sensors, PWM proportional electromagnetic speed regulating valves, oil temperature control boxes and PWM signal modulators on the original hydraulic system, and does not need to add a set of hydraulic cooling system, cooling tank and the like as in the traditional static pressure supported temperature control scheme, so the adaptability is good and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The static pressure supported friction pair temperature control flow chart.

[0024] Figure 2 The static pressure supported friction pair temperature control hydraulic system principle diagram.

[0025] Figure 3 The static pressure supported friction pair structure schematic diagram.

[0026] Figure 4 The oil pad temperature sensor position schematic diagram.

[0027] The temperature control hydraulic system of the hydrostatic bearing friction pair is composed of a vane pump 2, adjustable constant displacement pumps 6, 12, 18, variable frequency motors 7, 13, 19, coarse oil filters 1, 5, 11, 17, fine oil filters 8, 14, 20, oil temperature control boxes 4, one-way valves 3, 10, 16, 22, overflow valves 9, 15, 21, four-point oil distributors 23, 24, 25, PWM proportional electromagnetic speed regulating valves 26, temperature sensors 27, PWM signal modulators 28, signal power amplification circuits 29, and oil tanks 30. The hydrostatic bearing friction pair is composed of a load-bearing side axial hydrostatic bearing friction pair a, a radial hydrostatic bearing friction pair b, and a non-load-bearing side axial hydrostatic bearing friction pair c, wherein the load-bearing side axial hydrostatic bearing friction pair a has oil pads a1, a2, a3, and a4, the radial hydrostatic bearing friction pair b has oil pads b1, b2, b3, and b4, and the non-load-bearing side axial hydrostatic bearing friction pair c has oil pads c1, c2, c3, and c4. The temperature sensors 1 and 3 are arranged on the oil pad oil sealing edges 2 and 4. Embodiment

[0028] The present application considers the influence of ambient temperature and local temperature on the hydrostatic bearing friction pair, and designs a temperature control scheme for the hydrostatic bearing friction pair of a friction welding machine, so that the temperature of the hydrostatic bearing friction pair is always maintained within a reasonable range. The structure of the hydrostatic bearing friction pair is shown in Figure 3 , and the temperature control flow chart is shown in Figure 1 .

[0029] Since the temperature at the oil sealing edge on the radial outer side of the oil pad oil film is the highest, the sensor position is shown in Figure 4 . Since the oil pad temperature control structure of each friction pair is the same, the load-bearing side axial hydrostatic bearing friction pair oil pad a1 is selected to illustrate the control method of the friction pair temperature, and the principle diagram of the temperature control hydraulic system is shown in Figure 2 .

[0030] Step A: Set the temperature range of the oil temperature control box 4 according to the optimal working temperature of the hydraulic oil. When the friction welding machine starts to work, the global oil temperature control circuit is started, the oil is pumped out from the oil tank 30 by the vane pump 2, flows through the coarse oil filter 1, passes through the one-way valve 3, flows through the oil temperature control box 4, and then returns to the oil tank. At this time, the oil temperature control box 4 detects whether the oil temperature is within the pre-set reasonable range. If the oil temperature is not within the pre-set temperature range, the oil temperature control box 4 is started.

[0031] Step A1: After the oil temperature control box 4 is started, it is judged whether the oil temperature at this time is higher than the pre-set reasonable temperature, and the corresponding temperature control module is turned on.

[0032] Step A2, when the oil temperature flowing through the temperature control box 4 is higher than the preset temperature range of the oil temperature control box 4, the cooling module in the oil temperature control box 4 will automatically start to ensure that the operating temperature of the oil is within the appropriate range. At this time, the cooler in the oil temperature control box starts to work, and the cooler is forced to accelerate heat dissipation through a special fan, so as to reduce the temperature of the oil to the preset temperature range.

[0033] Step A3, when the temperature of the hydraulic oil is lower than the reasonable temperature range preset by the oil temperature control box 4, the heating module is automatically started. At this time, the electric heater in the oil temperature control box starts to work, and the oil flows through the heater through the parallel pipeline to shorten the time required for heating the oil, so that the temperature of the hydraulic oil can be quickly heated to the preset temperature range, thereby avoiding the adverse effects of the ambient temperature on the friction pair of the hydrostatic bearing.

[0034] Step B, after the oil temperature is adjusted by the oil temperature control box 4, the variable frequency motor 7, 13, 19 starts to work, and the adjustable constant displacement pump 6, 12, 18 pumps the oil from the oil tank 30. After the oil is filtered by the coarse filter 5, 11, 17 and the fine filter 8, 14, 20, it flows to the four-point oil distributor 23, 24, 25 through the one-way valve 10, 16, 22. The oil continues to flow through the PWM proportional electromagnetic speed regulating valve, enters the oil pad a1, a2, a3, a4 of the bearing side axial hydrostatic bearing friction pair a, the oil pad b1, b2, b3, b4 of the radial hydrostatic bearing friction pair, and the oil pad c1, c2, c3, c4 of the non-bearing side axial hydrostatic bearing friction pair c, and forms a bearing oil film. After that, the main shaft starts to work.

[0035] Step C, if the temperature of the friction pair oil pad a1 gradually rises, the temperature sensor 27 will send a series of temperature signals according to the temperature, and the temperature signals will be transmitted to the PWM signal modulator 28.

[0036] Step D, the PWM signal modulator 28 includes a frequency adjustment circuit and a pulse width modulation circuit. When the temperature sensor 27 receives different temperature signals, these signals will be transmitted to the PWM signal modulator 28. In this process, the frequency adjustment circuit will output pulse signals with different frequencies according to different temperature signals. These pulse signals are then input into the pulse width modulation circuit, which can adjust the duty cycle of the pulse signal while keeping the frequency unchanged. Therefore, each temperature signal will generate a PWM signal with a specific frequency and pulse width from the PWM signal modulator 28.

[0037] Step E, when the PWM signal modulator 28 outputs the pulse signal containing a specific frequency and pulse width, the pulse signal is transmitted to the signal power amplifier circuit 29. Under the action of the signal power amplifier circuit 29, the pulse signal is further enhanced, thereby generating an output signal with higher power. The output signal is then transmitted to the variable frequency motor 19 and the PWM proportional speed regulating valve 26.

[0038] Step F, the PWM proportional speed regulating valve 26 receives the control current of the signal power amplifier circuit 29, and the force motor in the PWM proportional electromagnetic speed regulating valve 26 outputs an axial force proportional to the control current, which acts on the spool of the PWM proportional speed regulating valve 26, thereby gradually increasing the flow output to the bearing side axial hydrostatic bearing friction pair oil pad a1.

[0039] Step G, the control current of the signal power amplifier circuit 29 is transmitted to the variable frequency motor 19, so that the rotating speed of the variable frequency motor 19 gradually increases.

[0040] Step H, as the rotating speed of the variable frequency motor 19 gradually increases, the output flow of the adjustable displacement pump 18 also gradually increases.

[0041] Step I, the oil enters the four-point oil distributor 23 through the coarse filter 17, the fine filter 20 and the one-way valve 22, and is divided into equal flow portions to enter the PWM proportional speed regulating valve.

[0042] Step J, as the opening of the PWM proportional speed regulating valve 26 increases at this time, the oil flow through the PWM proportional speed regulating valve 26 also increases.

[0043] Step K, at this time, the hydraulic oil flow in the bearing side axial hydrostatic bearing friction pair oil pad a1 gradually increases as the temperature gradually increases, cooling the bearing side axial hydrostatic bearing friction pair oil pad a1, and reducing the temperature of the bearing side axial hydrostatic bearing friction pair oil pad a1 to a reasonable range, thereby realizing dynamic and accurate control of the local temperature of the hydrostatic bearing friction pair.

Claims

1. A method of temperature control of a frictional pair of a friction welding machine static pressure support, characterized in that The static pressure bearing friction pair of the friction welding machine is divided into a bearing side axial static pressure bearing friction pair, a non-bearing side axial static pressure bearing friction pair and a radial static pressure bearing friction pair, wherein the bearing side axial static pressure bearing friction pair, the non-bearing side axial static pressure bearing friction pair and the radial static pressure bearing friction pair each have four uniformly distributed oil pads, and a group of temperature sensors are installed on each oil pad; a reasonable range of global oil temperature of the static pressure bearing friction pair is set, if the oil temperature is higher or lower than the set temperature range, the oil temperature control box cools or heats the oil accordingly, after the oil temperature reaches the specified range, the main shaft works, and the bearing oil film is generated in the bearing side axial static pressure bearing friction pair, the non-bearing side axial static pressure bearing friction pair and the radial static pressure bearing friction pair, thereby greatly reducing the influence of the environment temperature on the static pressure bearing friction pair; then the global oil is heated or cooled by the oil temperature control box to reduce the influence of the environment temperature on the static pressure bearing friction pair of the friction welding machine, and the temperature sensors on the oil pads feed back the local temperature of the static pressure bearing friction pair, the PWM proportional electromagnetic speed regulating valve is arranged between each oil distributor and each friction pair, the temperature sensors continuously transmit the temperature signals to the PWM signal modulator, different frequency and pulse width signals are modulated according to different temperature signals, the signals are continuously controlled by the power amplifier to control the variable frequency motor and the PWM proportional electromagnetic speed regulating valve, thereby dynamically controlling the flow of the adjustable quantitative pump and each PWM proportional electromagnetic speed regulating valve, and dynamic and accurate control of the local temperature of the static pressure bearing friction pair is realized; wherein each temperature sensor is arranged at the oil sealing edge of the oil pad of the static pressure bearing friction pair, three sets of oil supply systems are used to supply oil to the bearing side, the non-bearing side and the radial static pressure bearing friction pair, and each friction pair is composed of four uniformly distributed oil pads, and the oil distributor is used to divide the hydraulic oil into four equal flows and supply into the oil pads.

2. A method of temperature control of a friction pair of a friction welding machine supported by static pressure according to claim 1, characterized in that From the environment temperature and the local temperature of the friction pair, the temperature of the static pressure bearing friction pair is always kept within a reasonable range, and the influence of the change of the environment temperature and the local temperature of the friction pair on the machining precision and the service life of the main shaft is avoided.

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