Key Engineering Materials Vol. 522

Abstract: Realization of longitudinal-torsional complex vibration by conical compound horn has more engineering application value with respect to the conventional longitudinal-torsional complex vibration converting devices. The frequency equations of longitudinal vibration and torsional vibration for the conical compound horn made up of cone and circular cylinder were given based on the wave theory of longitudinal vibration and torsional vibration of ultrasonic horn. The mechanism of the realization of longitudinal-torsional complex vibration by conical compound horn under single acoustic excitation was explained. And a numerical example indicated that longitudinal-torsional complex vibration could be realized by conical compound horn when the length and diameter of such horn were well chosen. The results of this study may be used in the field of longitudinal-torsional complex vibration ultrasonic machining.

Abstract: Hydraulic stretch forming is a very important technology. Punch press has achieved multi-station automatic processing in the press area, which has greatly improved the efficiency. However, the main domestic stretching machine is single-stretching hydraulic machine at present. Compared with punch press, hydraulic stretching machines take less space and have better security, but they make less efficiency and have lower degree of automation. Hence, in order to take the advantage of hydraulic stretching machines and enhance the automation level, studies on multi-position automatic stretching machine occupies an important position. This paper proposes a design scheme of Six-station Automatic Hydraulic Stretching Machine (SAHSM) according to the practical production. The overall 3D structure of SAHSM is designed based on Solidworks to prove the theoretical possibility of the program. Then modal analysis is operated based on FEA of the key components of stretching machine module to improve reliability of the product and overcome the disadvantage of the traditional checking method, the first two-order modes are obtained to prove the impossibility of the resonance. At last, ADAMS-based virtual prototype is analyzed to demonstrate the feasibility and effectiveness of the SAHSM dynamic design proposed in this paper

Abstract: In this paper, some experiments was implemented for analyzing the affecting factors on allowable contact stress of four-point-contact slewing rings with single row including the hardening depth, hardness and the osculation between the steel ball and the raceway. Firstly, the common material 42CrMo was chosen and heat-treated with some process of heat treatment for getting different hardening depth. And then, the indentation tests were conducted with the test-rig, followed by the data process. Finally, some conclusions can be obtained by comparing and analyzing the data. It concludes that when the hardening depth beyond 0.3 and the hardness is not lower than 57HRC, a better allowable contact stress can be got, besides, the better osculation 0.52 is better for the load capacity.

Abstract: ntegrated design theory and method oriented to the product generalized quality is one design method facing to the full-function and whole performance. Design theory of barrel finishing equipment is put forward by the design of crankshaft barrel finishing equipment, function optimization and visual optimization design are mainly discussed, which can provide the design thought for developing new barrel finishing equipment.

Abstract: Spin-forming of part with internal tooth is a new technology of the near-net forming in gear manufacturing field. And the main purpose of the parts spin-forming is to shape teeth on the internal surface of blank. In order to improve the forming quality of internal tooth, the effect of roller on tooth height of spline was investigated by processing experiments and finite element simulation. The result indicates that, for full-radius roller, a large nose radius has also witnessed a discernible growth in spinning force and tooth height; considering the uniformity of tooth height distribution of spun part and decrease in forming force, the bio-conical roller is more suitable for this forming process

Abstract: Aiming at the difficulty of online measurement for three-dimensional deformation of large overhead crossbeam in gantry CNC machining centre, this paper proposes a measuring method based on multi-points attitude of crossbeam-body. Real-time measuring the attitudes of some equidistant points on crossbeam-body, dealing with the measurement information by adopt shockproof filtering, wavelet denoising and smoothing. Then infer the formulas to calculate deformation of each point along different directions of x-axis, y-axis, z-axis. The experiment uses triaxial acceleration sensor modules to measure crossbeam attitude. Experimental results show that the minimum deformational angle can be measured low to 0.06°. And if the spacing between sensor modules has mm level accuracy, the precision of calculation about deformation can reach up to 10^-3mm level. In addition, this method is strongly suitable for on-site environment, and it can lay a foundation for further researching about prediction and compensation in the CNC processing.

Abstract: This study was focused on the theoretical modeling and numerical investigation about the dynamic and static stiffness of coupled double-rotor spindle system of high speed grinder. The moment balance and the transition matrix, the state vector, field matrix of spindle system of high speed grinder were analyzed and deduced. The theoretical models about dynamic and static stiffness were established using the transfer matrix method. The numerical results showed that increased rigidity of front bearing significantly increased static and dynamic rigidity of spindle end and the rigidity of front bearing increased, dynamic rigidity increased more significantly than static rigidity. Furthermore, it can be conclued that increased overhang length reduced dynamic and static rigidity of spindle end at an increasingly slower rate and the span of bearing increased, static and dynamic rigidities of spindle end were reduced

Abstract: Armature components are the core component of the electro-hydraulic servo valve, and all the components of the armature components require high precision and assembly accuracy. Now, the armature components assembly uses an old-fashioned pressing machine, whose success rate and efficiency are low. This situation wastes a great deal of economic costs and time costs. To improve this situation, the authors develop a new type of automatic assembling machine to achieve automatic and high-precision assembly of the armature component.

Abstract: Advantages and disadvantages of present tower crane's upper structures are analyzed in this paper. According to the theory of prestressing jib, through combination design, a kind of structure is presented which can realize multiple use and greatly improve the hoisting capacity. Mechanical analysis and contrasts are done for old and new designs by finite element analysis software ALGOR. Finally, an example is given to verify the validity and feasibility of the design

Abstract: In order to find the vibration frequency when the workpiece obtains optimum vibration effect, the structural dynamic analysis were conducted in this paper, using finite element dynamic analysis methods on the horn and the workpiece combination. Through the vibration mode analysis, the resonant frequency of the horn and workpiece combination along the workpiece axial direction (y) is 20.845KHZ, along the x, z direction are respectively 22.373KHZ and 22.375KHZ, which are in the range of the ultrasonic generator frequency adjustment. Through the harmonic response analysis, the displacement amplitude in the big end of the horn is substantially equal, the displacement of each node on the symmetry axis of the horn increases firstly and then decreases along the axial, reaching the minimum at the wave node, and then gradually increases, reaching the maximum on the free end. The magnification is up to 18.84um, which can meet the requirements of ultrasonic vibration. In addition, it can be seen from the model graph of the workpiece thin segment that in the ultrasonic loading conditions, the thin segment of the workpiece at the middle position are mostly easy to break, which is consistent with the theoretical analysis. These findings and follow-up of test results are consistent, which proved the validity and reliability of software analysis.