Deflection (engineering)

About: Deflection (engineering) is a research topic. Over the lifetime, 30862 publications have been published within this topic receiving 298849 citations.

Evaluation of the stiffness chain on the deflection of end-mills under cutting forces

Abstract: This study presents the investigation of the stiffness of the system formed by the machine-tool, shank and toolholder, collet and tool. Cutting forces induce the deflection of the system, and consequently an error appears on the machined surface. Comparing values obtained from cantilever beam models applied to the cutting tool, analytical or FEM, with those experimentally obtained, large differences have been observed, which in some cases are more than 50%. For this reason, we have proceeded to evaluate the stiffness of each of the existing elements between the machine bed and the tool tip. Thus, deflections of the machine-tool, toolholder and toolholder clamping in the spindle, tool clamping in the toolholder, and tool itself, were measured experimentally under the effects of known forces. The final application is the ball-end milling of complex surfaces, an operation commonly performed in the finishing of moulds or forging dies, where errors of more than 70 μm are not unusual. A great part of this error comes from the deflection of the machine-tool assembly, spindle, shank and tool, due to the high cutting forces of the high speed machining of tempered steels. Cutting forces can be estimated using a semi-empirical approach, and from here some values of probable errors may be taken into account to check if the CNC programs are sufficiently adapted. However, a previous study of the deflection chain in the cutting process is needed, as is presented in this work. Results show that stiffness of the slender and flexible tools is 15 times lower than that of the machine and toolholder system. But this correlation is only 5–7 times lower for shorter and thicker tools.

A Simple and Accurate Method for Determining Large Deflections in Compliant Mechanisms Subjected to End Forces and Moments

Abstract: Compliant members in flexible link mechanisms undergo large deflections when subjected to external loads. Because of this fact, traditional methods of deflection analysis do not apply. Since the nonlinearities introduced by these large deflections make the system comprising such members difficult to solve, parametric deflection approximations are deemed helpful in the analysis and synthesis of compliant mechanisms. This is accomplished by representing the compliant mechanism as a pseudo-rigid-body model. A wealth of analysis and synthesis techniques available for rigid-body mechanisms thus become amenable to the design of compliant mechanisms. In this paper, a pseudo-rigid-body model is developed and solved for the tip deflection of flexible beams for combined end loads. A numerical integration technique using quadrature formulae has been employed to solve the large deflection Bernoulli-Euler beam equation for the tip deflection. Implementation of this scheme is simpler than the elliptic integral formulation and provides very accurate results. An example for the synthesis of a compliant mechanism using the proposed model is also presented.

Anorectal angle measurement

Abstract: Apparatus (10) for measuring the anorectal angle comprises an outer rubber-like sheath (12), which may be a suitably modified catheter, within which is disposed an elongate angular deflection detector (14) which provides on display (16) a read-out of the angular deflection of the apparatus. The sheath (12) may include pressure ports with associated pressure lines back to the proximal end of the sheath to allow the pressure to be read at different points along the anal canal.

Endoscope deflection control

Abstract: An endoscope deflection control is described whereby enhanced one-hand control of the tip of a polydirectionally deflectable endoscope is obtained. The deflection control is mounted external to the head of the endoscope in such manner that convenient single-hand manipulation of deflection control wheels mounted on the head provides tip deflection in either a freewheeling deflection mode or an incremental mode characterized by discrete stable incremental tip deflections. Single-hand operation of the endoscope deflection control is obtained by locating incremental deflection position elements in a compact structure which is wholly or partly external to the head while the control wheels remain within manipulatable reach of the single hand's fingers. The deflection control wheels are under continuous control by the operator whose single hand may rotate either or both wheels in either mode and selectively, at any time, with the fingers of the same hand, may switch either or both control wheels into either of the modes by axially sliding the wheels into or out of engagement with associated incremental deflection position elements.