Carl F. Zorowski

An analysis of cold strip rolling

Abstract A method of analysis is presented for investigating the mechanics of cold strip rolling. This method takes into account the elastic deformations of the strip and the rolls and the effect of applied strip tensions, as well as the plastic strip deformations. Predictions of load and torque requirements for reducing strip of any material and dimensions are obtainable along with the pressure distributions between the rolls and the strip, the shape and length of the contact arc, and the resulting roll flattening. The only information required for the application of this method is the dimensions and elastic-plastic material properties of the roll and strip. The results of a number of numerical examples are presented and compared with experimental results to indicate limits on the accuracy of the method.

The stresses, deformations and bending of a simply supported cylinder subjected to a symmetric normal surface loading

Abstract By using Papcovitch-Neubers three-function theorem, this paper considers the general elastostatic problem of a solid cylinder with simple supports on each end subjected to any distribution of surface loading provided the distribution is symmetric with respect to a set of perpendicular planes, one of which contains the cylinder axis and the other passes through the cylinders central cross-section. Numerical examples are presented for a uniformly distributed normal surface pressure over a circumferential arc of 6° and extending a finite distance along the cylinder axis. This approximates the loading on the work roll in a 2-high metal rolling mill.

Mathematical Prediction of Dynamic Tire Behavior

The subject of the problems and progress in predicting the mechan- ical behavior of tires subjected to dynamic loading is treated in two parts. The difficulties associated with this problem and various methods that have been pro- posed for its treatment are first discussed. The application of finite element tech- niques is emphasized, both with respect to current success and future potential. The second part presents a detailed analysis of this same problem using classical membrane theory. Although the model is developed using the same basic considera- tions employed by earlier investigators, its final formulation provides for greater generality and flexibility in application. It has the capability of defining meridian profiles and, consequently, cord strains under a condition of inflation and centrifugal loading as a function of geometric and cord load parameters designated at any point on the tire carcass. The result is a method of analysis which can be easily applied to study the effects of a variety of tire design and constructional constraints on carcass shape and cord tensions.

Onset of Mechanical Separation in Bellows-Supported Rotary Face Seals

The problem of incipient dynamic mechanical separation in bellows-supported rotary face seals is analyzed assuming the bellows to be represented by a series of distributed springs and dampers supporting a rigid seal carrier. An expression is developed for the distribution of contact forces between the seal and mating rings generated by the coupled effects of shaft pulsation and mating-ring wobble. This expression is used to determine the operating conditions which will produce the onset of separation by applying the criterion that the contact force distribution will go to zero at some point on the seal when separation is imminent. Results are presented in the form of equations and graphs which define the minimum initial compression necessary to maintain continuous contact in terms of system resilience and damping, amplitude of mating-ring wobble and shaft pulsation, and operating frequency.Copyright

Post Mechanical Separation in Elastically Supported Rotary Face Seals

Results are reported of an analytical study of the character and magnitude of post mechanical interface separation in elastically supported rotary face seals subjected to particular types of input excitation. The seal system is approximated by lump system parameters which permit simulation of its dynamic response. Input forcing functions assigned to the mating ring include harmonic axial shaft pulsation and wobble due to misalignment. The equations of motion governing the seal carrier are solved to determine the character (stable or unstable) and magnitude (relative displacement at seal interface) of post mechanical separation for combinations of system parameters (spring constants, damping ratios, preset, inertia, etc.) and operating conditions (speed, degree of misalignment, amplitude of end play, etc.). For combinations of parameters normally encountered no unstable behavior was observed. However, a reversal of the effects of system damping between pre and post separation behavior did occur. Presented ...

Deformation of the Pneumatic Tire

Abstract A finite element model is presented for analysis of axisymmetric static loadings of a bias ply pneumatic tire. The model can predict deformed shapes and the resulting cord forces in the tire. The tire is considered as a thin shell of revolution with membrane and bending stiffness. Its material properties are assumed to be linearly orthotropic. Large axisymmetric deformations studied with the proposed model gave very close approximations to the actual situation. The predicted cord forces matched the experimental values very closely.

INFLUENCE OF MILL SETUP ON HOLLOW GEOMETRY PRODUCED BY ROTARY PIERCING

As the first part of a planned three phase analytical study of the rotary piercing process a mathematical analysis of the pass geometry in terms of the mill setup parameters on a cone type piercing mill is performed to predict the wall thickness and outer diameter of pierced hollows. In investigating the outer diameter variation through the pass three distinct regions are defined and analyzed. A condition of skew rolling of the billet occurs from first roll contact to just ahead of the piercer point tip. This is followed by free billet expansion until shoe contact is made. Thereafter the shoes constrain the hollows outer diameter growth. Predictions of the hollows shape along the pass line based on the geometry of the pass as dictated by these three forming regions and the mill setup parameters are compared with experimental results obtained from a model mill piercing clay billets as well as with measurements of production mill steel hollows.

IMSEI: a graduate education, research, and technology transfer program in integrated manufacturing systems supported by a university/industry consortium

A cooperative industry/university graduate education research, and technology transfer program in computer integrated manufacturing systems at North Carolina State University is described. Administrated through the Integrated Manufacturing Systems Engineering Institute (IMSEI), the program draws its resources from six academic departments in the College of Engineering and a consortium of industrial associates. Details are presented on the organization, structure, and operation of the Institute, including university and industry participation, the academic program, research mechanisms and areas of interest, laboratory facilities, technology transfer activities, and program funding.<<ETX>>

Dynamic Moduli of Continuous Filament Yarns Subjected to Low Frequency Excitation Superimposed on High Initial Longitudinal Strain

Reported are the results of an experimental and theoretical investigation of the dynamic viscoelastic properties of twisted continuous filament yarn subject to low frequency longitudinal excitation superimposed on high initial strain. The object is to relate the effective dynamic mechanical properties of the constituent filaments and the geometry of the filaments in the structure. An analytical model is presented which defines this relationship based on the following principle assumptions: (I) the imposed dynamic longitudinal strain is propagated as a plane wave in the twisted yarn structure, (2) filament locations within the yarn structure are constant radius helical paths, and (3) filament dynamic mechanical properties can be represented by a generalized Maxwell model. An analysis of the effects of filament to filament interactions within the yarn structure represented by a simple coulomb friction is also included in the model development. Experiments performed on 70 denier, 34 filament nylon 66 yarn using the Rheovibron DDV II Viscoelastometer shown that yarn dynamic mechanical properties are predictable in terms of the dynamic mechanical properties of the filaments and the geometry of the yarn structure using the developed model at levels where sufficient static strain is imposed to eliminate coulomb friction effects.

Reduction of shock transmission by equipment damping

Results are presented of an analog study of the effect of viscous damping on the response of an idealized two degree of freedom series system subjected to a uniform velocity shock. Response characteristics are presented in curves which indicate how shock transmissability varies with the amount of damping present, the ratios of the uncoupled frequencies of the system and the mass ratio of the two bodies responding to the input.