• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1299-1302
• /
• 2005

Current mechanical devices are trending toward being a small size, high speedy, automation. For performing these functions, machinery elements organizing a machine should be designed exactly. Cams have high confidence and economics in ablility to transmit a motion. Accordingly, A cam mechanism is very important for processing the machine automatically. This paper introduce an inverse cam mechanism. A square shaped cam which cannot be commonly analyzed is designed and manufactured by using the NURBS interpolation algorithm. The objective of this paper is to develop a computer-aided design program. In this paper, a displacement curve of oscillating motion inverse cam mechanism with square shaped follower is analyzed. The data is redistibuted by the NURBS algorithm. A cam shape is designed by the instant velocity center method, and simulated to verify the validity of the operation state.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.8
• /
• pp.47-54
• /
• 2002

A barrel cam is used as a very important part of an index drive unit. The index drive unit must have an intermittent-rotational motion. The barrel typed cam and roller gear mechanism has the advantages of high reliability to perform a prescribed motion of a follower. This paper proposes a new method for the shape design of the barrel cam and also a CAD program is developed by using the proposed method. As defined in this paper, the relative velocity method for the shape design calculates the relative velocity of the follower versus cam at a center of roller, and then determines a contact point by using the geometric relationships and the kinematic constraints, where the direction of the relative velocity must be parallel to a common tangential line at the contact point of two independent bodies, i.e. the cam and the follower Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. This paper presents two examples for the shape design of the barrel cam in order to prove the accuracy of the proposed methods.

• International Journal of Automotive Technology
• /
• v.8 no.1
• /
• pp.59-66
• /
• 2007

High frequency excitation terms in a cam profile can excite vibration of a cam follower system. In this paper, modified smoothing spline curves are used to reduce the high frequency terms. The essential difference between the proposed method and other existing approaches is its ability to make the principal cam motions smooth while still exactly satisfying boundary conditions of follower displacement, velocity and acceleration. The boundary values usually depend on the ramp properties of a cam. Our method, thus, allows designers to smooth the existing cam motion without any damages on its ramp areas. Because the ramp height, velocity and acceleration are maintained exactly, more radical smoothing is possible. An example shows that the proposed method can be a powerful tool of cam profile smoothing, which removes high frequency components in the cam profile excitations without any changes in ramp properties.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.813-817
• /
• 2000

Cam mechanism is one of the common devices used in many automatic machinery. Specially cylindrical cam generates three dimensional motions. Thus, the shape design procedure must have high accuracy. This paper proposes the shape design procedure for a cylindrical cam and follower mechanism using a relative velocity method. The relative velocity method and coordinate transformation are used to find a contact point between cam and follower. Also, the full shape of the cylindrical cam can be generated by using the geometric relationships and the contact constraints. As a result, this paper presents an example for the sape design of the cylindrical cam in order to prove the accuracy of the design procedures.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.6
• /
• pp.1361-1371
• /
• 1993

The effort of this paper is to develop a methodology of computer aided design and manufacture of spatial cams. The integrated CAD/CAM systems for spatial cams are developed to enable manufacturer to design and machine them readily. The contour of spatial cams can be obtained by applying envelope theory to the cam/follower motion. The mathematical cam contour is evaluated at some increment to generate the numerical data for the CNC programming. Incremental generation of points along a cam contour can be accomplished in consideration with the specified tolerance. The computerized procedure is described in detail with accompanying examples.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.5
• /
• pp.112-119
• /
• 2009

Cam mechanisms are one of the most popular devices for generating irregular motion and are widely used in many automatic equipments, such as textile machinery, internal combustion engines and other automatic devices. In order to obtain the positive motion of follower by rotating cam, its shape should be correctly designed and manufactured. However, complex engineering tasks are required in a design and manufacturing of cams. And also, the manufacturing of general cam is demanded high costs. For the designing of cam, it must be decided that what kind of motion has to be transmitted to follower before selecting the curve of cam and designing profile of cam. However, even though the exact profile of cam is designed at the progress of design, if it doesn't have precision at the manufacturing progress, it's impossible to get expected result. We will develop cam simulation apparatus for measuring cam curve and get profile data before analyzing an error through comparison with design data of cam.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.11
• /
• pp.924-929
• /
• 2008

The rate of wear of cam followers in a valve train system is mainly a function of contact stress between the cam and the follower, sliding velocity and hydrodynamic film thickness between the two mating surfaces. The wear or surface fatigue can be reduced by maximizing the elastohydrodynamic film thickness. In this paper, an attempt has been made to estimate the optimal specific film thickness of cam-follower system quantitatively. A general TES polynomial function with real values of exponents is developed and genetic algorithm (GA) is used as optimization techniques for maximizing the minimum specific film thickness. The optimization programs enumerate values of the exponents for synthesis of cam displacement curves. The results show that the minimum film thickness can be increased considerably, e.g. approximately 7% in this paper.

• 연구논문집
• /
• s.22
• /
• pp.75-83
• /
• 1992

The beating motion of a high speed shuttleless loom is driven by cams. Two cams become one system and their shaft laid across each other. Moreover, the shape of the cams is very complex and requires high precision for successful weft insertion and good interlacing with warp yarn. The iterative contact method is developed for use in design and analysis of the driving mechanism of a disk type cam with oscillating roller follower. The optimum design is performed by utilizing a CAD program, DISKCAM. The 8th order polynomial is selected to interpolate the desired shape trajectory of the cam, the optimal shape of the cams is defined based on the demension of the follower. The kinematic motion of the beating cam mechanism is investigated. The phase angle is determined to achive harmonious cam motions

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.3 no.2
• /
• pp.86-94
• /
• 2004

The flash temperature distribution on the contact surfaces between cam and roller-follower mechanism was analysed numerically. The elasto-hydrodynamic lubrication pressure and film thickness were used to get the accurate analysis results. The temperature distribution was obtained by numerical integration by making use of Carslaw and Jaeger's formulation to the whole contact surfaces. The maximum flash temperature was increased with both the increasing slip ratio of the contact surface and increasing external load Profile of the temperature distribution was affected by the sliding velocity of the surface.

• Tribology and Lubricants
• /
• v.19 no.4
• /
• pp.195-202
• /
• 2003

Many computational researches have been performed about EHL film thickness in the contact between cam and follower in the engine valve train system. However, those computations do not explain the characteristics of dynamic film thickness which means squeeze film effect. Without the consideration of transient term in the Reynold's equation, the predicted film thickness from steady state condition has large difference from the actual film thickness. In this study, we have investigated the kinematic and dynamic simulations of rocker-arm valve train system. From the dynamic simulation, the applied load and the entraining velocity of the lubricant between cam and follower are obtained and with these values the dynamic film thickness is computed by Newton-Raphson method and compared with the steady state film thickness.