Xinggang Jiang

Study on the separation effect of high-speed ultrasonic vibration cutting

&NA; High‐speed ultrasonic vibration cutting (HUVC) has been proven to be significantly effective when turning Ti‐6Al‐4V alloy in recent researches. Despite of breaking through the cutting speed restriction of the ultrasonic vibration cutting (UVC) method, HUVC can also achieve the reduction of cutting force and the improvements in surface quality and cutting efficiency in the high‐speed machining field. These benefits all result from the separation effect that occurs during the HUVC process. Despite the fact that the influences of vibration and cutting parameters have been discussed in previous researches, the separation analysis of HUVC should be conducted in detail in real cutting situations, and the tool geometry parameters should also be considered. In this paper, three situations are investigated in details: (1) cutting without negative transient clearance angle and without tool wear, (2) cutting with negative transient clearance angle and without tool wear, and (3) cutting with tool wear. And then, complete separation state, partial separation state and continuous cutting state are deduced according to real cutting processes. All the analysis about the above situations demonstrate that the tool‐workpiece separation will take place only if appropriate cutting parameters, vibration parameters, and tool geometry parameters are set up. The best separation effect was obtained with a low feedrate and a phase shift approaching 180 degrees. Moreover, flank face interference resulted from the negative transient clearance angle and tool wear contributes to an improved separation effect that makes the workpiece and tool separate even at zero phase shift. Finally, axial and radial transient cutting force are firstly obtained to verify the separation effect of HUVC, and the cutting chips are collected to weigh the influence of flank face interference. HighlightsA high‐speed ultrasonic vibration turning titanium alloys method is proposed.A partial separation effect model due to flank face interference is built.20 kHz transient cutting force signals are gained to verify the separation effect.Separated broken chips due to tool vibration are collected and monitored.

Study of Phase Shift Control in High-Speed Ultrasonic Vibration Cutting

High-speed ultrasonic vibration cutting (HUVC) applies an ultrasonic vibration to a cutting tool transverse to the cutting direction. The advantage of this method is that the high-speed cutting exceeds the critical cutting speed restrictions of ultrasonic vibration cutting. However, irregular dimple arrays are machined on the work-piece surface, increasing the surface roughness. In this paper, a phase shift control method is proposed, which aims to overlap dimples in a regular pattern to decrease the surface roughness for HUVC. First, this paper investigates the theory of phase shift control to guarantee the surface quality of HUVC. Then, a closed-loop direct digital synthesis (DDS) system is designed to keep the phase shift of the machined dimples stable and controllable. A contrast experiment is conducted to compare the performance of the closed-loop DDS and the open-loop DDS methods in HUVC process. The results show that the closed-loop DDS method can render the dimple phase stable and controllable during the HUVC process. The phase shift value influences the surface roughness. Setting the phase shift to 0.94π with an appropriate feed-rate, the surface roughness is reduced to 0.303, compared to a surface roughness of 0.785 when using the open-loop DDS method.

Effect of speed ratio in edge routing of carbon fiber-reinforced plastics by rotary ultrasonic elliptical machining

Edge routing carbon fiber-reinforced plastic structures is the first and mandatory operation after demolding. In order to solve the problems such as tool clogging and mechanical damages at the machined surface in edge routing of carbon fiber-reinforced plastics by grinding tools, the rotary ultrasonic elliptical machining technique was used in edge routing carbon fiber-reinforced plastics for the first time. First, the rotary ultrasonic elliptical machining principle and an analysis of the effect of the speed ratio, Rs (i.e., the ratio of the nominal cutting speed to the maximum tool vibration speed in the cutting direction), on the relative motion of the tool and workpiece were presented as the speed ratio greatly influences the rotary ultrasonic elliptical machining performance. Then, the edge routing experiments by rotary ultrasonic elliptical machining were conducted to study the machining quality at different speed ratios. The results showed that the grinding forces at Rs 0.1 decreased about 19% (normal grinding force) and 17% (tangential grinding force) than that at Rs 0.8 after cutting 100min. The tool diameter reduction at Rs 0.1 was 34% lower than that at Rs 0.8 after cutting 100min and the machined surface integrity at Rs 0.1 was also modified at the end of the experiments. The experimental findings suggest that the optimal integrated surface could be achieved by applying the rotary ultrasonic elliptical machining method with the fine size diamond grinding tool and the low speed ratio.

Improving anti-adhesion performance of electrosurgical electrode assisted with ultrasonic vibration

HighlightsA novel ultrasonic vibration‐assisted (UV‐A) electrosurgical electrode was firstly proposed.The adhesion force with UV‐A was decreased 60–75% without affected by load.The mass of adhesion tissue was decreased by 80% with UV‐A.The underlying mechanism with UV‐A for soft tissue anti‐adhesion was revealed. ABSTRACT The electrosurgical electrode currently stands out as one of the most commonly used tools in minimally invasive surgery. In order to facilitate tissue cutting and accelerate wound healing, tissue adhesion to the electrosurgical electrode is considered as an extremely urgent problem to be solved. In this paper, a novel ultrasonic vibration assisted (UV‐A) electrosurgical electrode is firstly proposed to overcome the problem of tissue sticking. The anti‐adhesion effects were evaluated by measuring the adhesion force and the weight of tissue adhesion using the electrosurgical electrode with and without UV‐A comparatively. Experimental results show that the average adhesion force and the tissue adhesion mass with UV‐A were decreased by approximately 60% and 70% respectively, accompanied by smaller thermal injury area compared with that without UV‐A. Moreover, the underlying mechanism of anti‐adhesion effect with UV‐A was revealed by investigating the influence of ultrasonic vibration on electric current, tissue removal and spark discharge. This research suggests that UV‐A is a promising and practical method for improving the anti‐adhesion performance of electrosurgical electrode.