• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.10a
• /
• pp.264-264
• /
• 2003

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.10
• /
• pp.897-904
• /
• 2008

Egg grading machine is used in poultry raising industry to classify eggs by their weight and to pack up them. Packer holder mechanism is a main part of the egg grading machine, of which role is to take eggs fallen from conveyor belt, and afterward to transfer eggs vertically to mold tray. The vertical motion of packer holder is usually driven by slider-crank mechanism or cam. This paper describes development of the cam in packer holder based on kinematic analysis of packer holder mechanism and measurement of acceleration and noise of the cam to verify performance of it. Several cams that are designed and manufactured by the author of this paper according to different design specification are compared to determine the best solution for egg transfer in the packer holder mechanism.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.4
• /
• pp.129-140
• /
• 1998

A numerical method is proposed to optimize automotive cam profiles. An acceleration curve of a cam follower motion is described by Hermite spline curves. Because of the intrinsic characteristics of the Hermite curve, it is possible to design an acceleration curve with arbitrary shape. Design variables in the optimization problem are location of control points which define the acceleration curve. Objective function includes dynamic performances as well as kinematic properties of a valve train. Similar optimization procedure was also performed using Polydyne cam profile synthesis method. Optimized profiles using the Hermite curve are proved to be superior to those using the Polydyne method.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.9
• /
• pp.59-65
• /
• 1995

The cam is used to a main component in a variety of automatic machines and instruments. To meet the demand of a complicated operation and of reducing weight for automatic machine, Curve Blending Technology, in which each of the basic curves suitable for individual interval is connected, is used for the cam design. In the curve blending, it is necessary to select appropriate elementary curve for each interval and to confirm the dynamic continuity at connecting points between adjoining elementary curves. This paper represented the elementary curve selection method to select an appropriate curve for each interval, and executed computation for the follower displacement and angular displacement of each interval. The paper made an analysis and examine closely for elementary curves to synthesizing curve blending, and it performed dynamic conditions clearly at every points on the cam motions. Therefore the curve blending technology presented by the paper turned into easier work.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.2
• /
• pp.247-254
• /
• 2003

The paper presents the influence of spring dynamics and friction on dynamic responses in a spring-driven cam system. The characteristics of the friction on the camshaft are analyzed using the nonlinear pendulum experiment while the parameters of the friction model are estimated using the optimization technique. The analysis reveals that the friction of the camshaft depends on stick-slip, Stribeck effect and viscous damping. Spring elements are found to have much influence on the dynamic characteristics. Hence, they are modeled as four-degree-of-freedom lumped masses with equivalent springs. The appropriateness of the derived friction model and spring model is verified by its application to a vacuum circuit breaker mechanism of the cam-follower type.

• Fibers and Polymers
• /
• v.6 no.2
• /
• pp.151-155
• /
• 2005

A twisting machine is to twist yarns for improving yam strength. After twisting yams, the twisting machine winds yams into a bobbin. The traverse mechanism is very important part of winding mechanism. Because it performs uniform winding onto the bobbin. the traverse cam is the main part of the traverse mechanism. This paper proposes design method of the traverse cam using the relative velocity method [4,5]. The relative velocity method is used to calculate the relative velocity of the follower versus the cam at the center of roller, and then to determine the contact point using the geometric relationship and kinematical constraints. Finally, we present examples verifying the accuracy of the proposed methods.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.3
• /
• pp.526-533
• /
• 1990

The dynamic stability of a single cam drive mechanism is investigated by an analytical approach. The nonlinear differential equation describing the motion of a single cam drive mechanism is linearized with respect to the imput power angle, and results a linear parametric differential equation. The instability region is examined by applying the harmonic balance method to linearized parametric equation having periodicity. Through the dynamic stability analysis of a single cam drive mechanism, it is observed that the parametric resonances exist and the instability regions tend to become wide as increasing the drive speed and follower mass.

• Tribology and Lubricants
• /
• v.16 no.3
• /
• pp.201-207
• /
• 2000

The numerical procedure to analyze a non-steady 3-dimensional elastohydrodynamic lubrication on the cyclically loaded contact has been newly developed. The procedure was applied on the cam-roller contact of the valve mechanism for the marine diesel engine. Both the pressure distribution and the film thickness between the cam and roller follower were calculated for each time step of the whole cycle. The pressure spike is shown at the outlet of the roller edge and it is getting higher as the external load is increased. The film thicknesses in the result of the non-steady analysis have a tendency to increase compared to those in the result of the analysis with the assumption of steady state. Therefore, the surface roughness of the non-steady contact need not be limited below that of the steady contact of the equivalent operating conditions.

• Tribology and Lubricants
• /
• v.15 no.4
• /
• pp.343-353
• /
• 1999

The role of viscosity index improver's(Ⅶ) additives for modem engine lubrication is complex. Under the condition of atmosphere or low shear rate, the characteristics of Ⅶ added lubricant is verified and quoted frequently for mathematical model of lubricant behavior. However, recent research shows that added lubricant has the characteristics of shear thinning at high shear rate condition although it performs well enough over the whole range of working temperature. At high shear rate, they show significant decrease of apparent viscosity irrespective of temperature. Many experimental researches verify that Ⅶ added lubricant shows boundary film layer formation on the solid surface as well as shear thinning effect by its polymeric molecular characteristics. The intend of our research is to verify the effects of Ⅶ from the viewpoint of continuum mechanics, because conventional Reynolds'equation with only pressure-viscosity relation cannot fully predict the lubricant behavior under the Ⅶ added condition. In these aspects, Reynolds'equation of Newtonian fluid model lacks the reflection of real fluid behavior and there is no way to explain the non-linear characteristics of Ⅶ added lubricant. In this research, we mathematically modeled the Ⅶ added lubricant behaviors which are the characteristics of non-Newtonian fluid behavior at high shear rate and boundary film formation on the solid surface. The consideration of elastic deformation in the contact region is also included in our computation and finally the converged film pressure and the film thickness with elastic deformation are obtained. The results are compared with those of Newtonian fluid model.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2004.11a
• /
• pp.261-268
• /
• 2004

For cam and roller-follower contacting surfaces, the effect of tangential loading on the subsurface stress field at an elaso-hydrodynamic lubrication condition has been studied numerically. As tangential load increases, the subsurface stress field extended more widely to the direction of the tangential load. The positions of the maximum shear stress and the maximum effective stress are getting closer to the surface with the increasing tangential load. The tangential load at the elasto-hydrodynamic lubrication condition is of little consequence to the subsurface stress field.