| Deep oil and gas resource drilling projects,deep continental scientific drilling projects,and deep-water marine drilling projects are increasingly demanding performance from drill pipes.Traditional steel drill pipes cannot meet safety and efficiency requirements due to their shortcomings such as self-heavy weight and poor corrosion resistance.In order to improve the drilling efficiency and ensure the safety of drilling projects,it is urgent to develop light and high-strength drill pipes to meet the working conditions of high temperature,high pressure,complex alternating stress,and high corrosion at the bottom of future drilling projects.Compared with steel drill pipe,aluminum alloy drill pipe has the advantages of high specific strength,strong corrosion resistance and non-magnetism.It can complete drilling projects that conventional steel drill pipe cannot complete.Aluminum alloy body need to be used in conjunction with steel joints.Practical engineering applications have proven that the threaded connection of aluminum alloy drill pipes is the weakest part of aluminum alloy drill pipes.Therefore,the accuracy and quality of the assembly of aluminum alloy drill body and steel joints will directly affect the entire Reliability of the drill pipe.In this paper,the following research is carried out on the hot assembly technology of aluminum alloy drill pipe body and steel joints:The thermal assembly test bench was used to measure the actual temperature of the aluminum alloy drill pipe during the thermal assembly process.It was found that with only external cooling,the temperature of the threaded part of the aluminum alloy drill pipe increased rapidly,and the temperature was 84 s.It reached a peak value of 119? at the time of heating;in the case of internal cooling only,the heating rate was slightly lower than that of only external cooling,and the temperature reached a peak of 95? at 130s;in the case of simultaneous cooling inside and outside,the rising rate was slightly lower than only external cooling or only internal cooling.The temperature peak reached 94? at 90 s.The test proves that the external cooling can prevent the threaded part of the aluminum alloy drill pipe body from being at a relatively high temperature for a long time.The internal cooling can reduce the maximum temperature of the threaded part of the aluminum alloy drill pipe body during the assembly process by about 25?.Therefore,during the design of the thermal assembly device,the internal and external cooling mechanisms need to be reasonably designed.Using the structural static analysis module in the finite element analysis software ANSYS Workbench,a simplified two-dimensional model of the screw connection of the aluminum alloy drill pipe and the steel joint is established.The finite element analysis of the axial tension of the screw connection is obtained to obtain the aluminum alloy drill pipe.The law of the influence of the properties of the aluminum alloy material on the actual axial tensile performance of the aluminum alloy drill pipe at the threaded part of the pipe body,and a fitting formula for the relationship between the maximum stress at the root of the thread and the axial tensile force is obtained.The calculation shows that the high temperature conditions during the hot assembly process will reduce the maximum axial tensile force that the aluminum alloy drill pipe can withstand by about 65 KN,which further proves the necessity of rationally designing the internal and external cooling mechanisms in the hot assembly device.An automatic interference heat assembly device for aluminum alloy drill pipe body and steel joint is designed.The device is supported by the pipe body,holding and clamping mechanism,steel joint heating mechanism,slewing mechanism,feeding mechanism,aluminum alloy drill pipe body cooling mechanism,and external steel joint.Composed of cooling mechanism,detection and control mechanism.The equipment selection,structure design and strength check of each mechanism of the device were analyzed,the rationality of the design was fully demonstrated,and the performance parameters of each mechanism were given.In the detection and control mechanism,the schematic diagram of the electronic control system was reasonably designed.The Siemens S7-300 programmable controller was used.The STEP7 software was used to program the assembly process and assembly process to achieve automatic control.This device can realize automatic thermal assembly of ?147mm aluminum alloy pipe body and ?178mm standard steel joint.During the assembly process,the heating temperature of the steel joint can reach more than 400?,and the temperature of the aluminum alloy drill pipe body is lower than 90?,which can be improved to a certain extent.The assembly accuracy and quality of the aluminum alloy drill pipe body and steel joints,thereby improving the practical application reliability of domestic aluminum alloy drill pipes. |
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