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In view of the shortcomings of high peak of crank torque and polished rod load,short stroke and serious wear of steel wire rope,the structural characteristics of the conventional beam pumping unit are analyzed. On the basis of that,the post pulley mechanism that change with the displacement of the suspended point and adjust the balance arm is designed. The steel belt is used to replace the traditional steel wire rope to fix on the post pulley. In the process of changing the balance arm post pulley driven steel belt around it to increase the stroke and reduce the friction loss. And the kinematic characteristics of this oil pumping unit are analyzed and calculated. Using the conventional beam pumping unit of CYJ10-1. 8-200 to calculate and analysis and find that the post pulley mechanism that is used has made the peak displacement of suspended point increase about150%. The solid model of the oil pumping unit 1∶ 10 is built and tested. The results show that the calculation and analysis results of this oil pumping unit are in accordance with the experimental results. The correctness of the calculation and analysis results of suspension point kinematic characteristics is verified.

Circular crossbore as a common geometric construction exists widely in the engineering components. Its fatigue life is heavily decreased by the crack failure around the intersecting line. So, the typical analysis model of crossbores with mode I crack is built, and the influence of four main parameters, such as thickness–diameter ratio Y , crossbores diameter ratio Q , crack length a , and axis ratio of elliptical crack face b / a , on fracture parameter K I is presented. The results show that the distribution of K I is mainly influenced by Q and b / a , and the influence of b / a is more obvious. The value of K I is mainly influenced by Y, Q , and a , while the influence of b / a is not evident. For elliptical crack face, the K I max (maximum value of K I ) located at the short axis leads to higher crack growth rate. K I max is a crucial factor of fracture criterion, and the significance of factors on it is also analyzed here. A variance analysis of four factors is performed and their order is Y > Q > a > b / a . In addition, a calculation function of K I max is built based on 294 sets’ data and the error is analyzed by mean absolute percentage error with maximum error being less than 7.2%.

Based on the hypothesis of stretch small distortion and distortion congruity,the model and algorithm of meshing force analysis under theoretical conditions are given.According to the Hertz theory and geometric relation of meshing pair,the meshing rigidity models of the meshing pair are established,and the calculation formulas of the meshing rigidity and the principal curvature of the contact point are deduced.The presented methods is illustrated through an example,and the distributing characteristic of meshing forces,sum of principal curvature and meshing rigidity of this type of transmission device is acquired.The acquired result can be adopted as the analytical base for structure design,vibration analysis.

Aiming at the problem of the installation space of double cross universal joint steering transmission shaft is limited,it is difficult to meet the condition of constant speed drive,and need to adjust the phase angle to reduce the rotating speed fluctuation,the rotating speed ratio and rotating angle equations of steering transmission shaft are established by means of spatial geometric projection method,and the equation is verified by using the constant velocity condition. The influence of phase angle on rotating speed ratio are quantitatively analyzed,the results show that the input shaft and output shaft can realize constant speed drive while two transmission angle are equal and the phase angle is equal to the transmission plane angle,and the double cross universal joint transmission shaft can’t realize the constant speed drive while two transmission angle are not equal.However,the speed difference of input shaft and output shaft is the smallest while the phase angle is equal to the transmission plane angle. Therefore,this is the best phase angle when phase angle is equal to transmission plane angle and their phases are reversal. Then,the optimal solution formula of phase angle is deduced based on hard point of steering system and the computer program is compiled. The calculation result of the program is accurate by example verification. The conclusion and the program has theoretical and practical significance on system design of automobile steering and research on the transmission of other types universal joint.

In view of the problem that the conventional analysis method cannot directly solve reliability problem of the complex cylinder sine oscillating tooth transmission system,a simulation method based on minimal cut sets of fault tree is proposed,which can solves system reliability.According to the structural characteristics of cylinder sine oscillating tooth transmission,the function block diagram of the system is given and the fault tree of the system is built.The minimal cut sets of the fault tree are acquired,and the cumulative failure probability and the probability density are calculated.Different types life distribution function of the system are fitted out.The life distribution function is determined preliminarily based on the principle of minimum residual sum of squared,and the K-S hypothesis testing is carried out for the life distribution function,which ultimately determine life distribution function of cylinder sine oscillating tooth transmission is Weibull distribution.The weak links of cylinder sine oscillating tooth transmission system are determined by analysis of model importance.

A statically designed derrick of deep oil well drilling rig may have poor dynamic characteristics, which can cause earlier structure failure of the drilling rig and harsh working condition. One such designed derrick is found to vibrate severely in operation while the rotation speed of rotary table is about 120 r/min with the working frequency of 2.0 Hz. To solve this problem, an experimental modal test of the derrick is conducted and the modal frequencies and vibration shapes are obtained. Through comparison of modal frequencies with that of exciting devices, it is found that the severe vibration of the drilling rig is caused by the resonance of second modal frequency (1.96 Hz) and the working frequency of rotary table. Based on principles of sensitivity analysis and structural dynamics modification method, the frequency sensitivities of all nodes on the derrick are calculated and compared, and then seven nodes with high-frequency sensitivity are selected on which corresponding mass are added to vary the modal frequency. Result shows that the second modal frequency of the derrick is reduced to 1.42 Hz and is out of the normal working frequency range of rotary table, which demonstrates that the dynamic characteristics of the derrick is improved and severe vibration can be avoided.

Heavy K-type derrick is one of the most important load-carrying parts in deep well oil drilling rig. Field test is a useful way of obtaining the dynamic characteristic parameters of the derrick but inherent disadvantages such as high cost, site condition limit its application. It is economical and effective to make reduced-scale dynamic model and do experiments for improving design of the derrick prototype. Based on similarity principle, we develop a reduced-scale dynamic model of the derrick prototype with geometric similarity ratio of 10. Dynamic test for the model and harmonic-response analysis for the derrick prototype have been conducted, respectively. The result shows that the maximum deviation of frequency and displacement between test and analysis is small, which proves the rationality and validity of the design and manufacturing of the dynamic model. Also, the test and harmonic-response analysis data indicate that in drilling process, the rotation of the rotary table can hardly ever cause the severe vibration of the derrick. The experimental dynamic test of reduced-scale derrick model can replace the field test of the derrick prototype and provides reference for dynamic characteristic research of the derrick prototype. [ABSTRACT FROM AUTHOR]

According to the main failure mode of fracturing pump head, the finite element model of pump head with crack defect was built. The plastic zone length of crack front was analyzed under different initial crack and working pressure, and the formulae for calculating the plastic zone length of the crack front at θ=0° and θ=90° were fitted according to the maximum crack opening displacement (MCOD). The results show that the stress state of crack front at 3°≤θ≤87° is close to plane strain state, and the crack tip plastic zone size is positively correlated with the crack length and the working pressure. The plastic zone size under plane strain calculated by the Irwin formula can be in good agreement with the finite element results. The stress state of crack front at θ=0° and θ=90° is between plane stress state and plane strain state. The fitted formulae of the plastic length are influenced by the MCOD and initial crack, which provides a method for studying the plastic zone effects on the crack growth of pump head. [ABSTRACT FROM AUTHOR]