Wall friction and lubrication during compaction of coal logs

Li, Y.; Liu, H.; Rockabrand, A.

doi:10.1016/0032-5910(96)03110-5

Cited by 20 publications

(14 citation statements)

References 18 publications

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“…Therefore die wall friction force can be obtained by substituting (1), (2), and (3) into (4), and integrate along the height of the compact, leading to [9]. of the passive shaping surface will be uniform.…”

Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

“…3a the force F 0 acting on the top face of the layer with thickness dh, hydraulic area S 0 , and the reaction force h F P dP S = − (9) where P is the compaction pressure, dP is the pressure decrease at a height dh. The die-wall friction forces developed at the passive shaping surface that moves in concert with the upper and lower active shaping surfaces are determined respectively as .…”

Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

“…Their work remains an analysis still used in many powder compaction studies today to consist a force balance on an axial slice of a granular cylinder. It is difficult to eliminate die wall friction force of conventional compaction and there are many research studies about it [9][10][11][12][13]. Let us consider the powder disc of deformation of the cylinder shape with diameter D=2r in Fig.…”

Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

See 2 more Smart Citations

The comparison of model compaction method to make uniformly dense ceramic bodies

Хасанов

Edgar

Sokolov

et al. 2012

2012 7th International Forum on Strategic Technology (IFOST)

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The "collector" method of uniaxial dry compacting homogeneously dense powdered bodies of complex shape without macroscopic defects has been developed. It was based on the selfalignment of uniform density regions within a green compact by design of special mold to reduce die-wall friction effects. An equation was proposed that determined the density differential throughout the height of a green compact, which depended on geometrical parameters, and required the controlled movement of die parts. The technique of pressing with the collector method has been developed and patented by TPU. Based on the principles of the collector method a compaction mold of spiral type was modeled for compaction of cylindrical compacts with two alternating, oppositely-moving parts of the passive shaping surface with sliders, twisted at an angle of 36 degrees. The process of powder compaction was simulated by finite element method. The simulation results of the deformation process in the compacts showed that the density of each layer distributed irregularly with the curvature of isosurfaces in the direction of movement of the punch. The results of comparative simulation showed that the statistical dispersion of local values of the deformation of the green compacts made by collector method with the mold of spiral type is reduced to 48% when compared with conventional static compaction and reduced to 5% when compared with collector compaction using the mold of non-spiral type. This method decreases the density gradients. It can be applied to manufacture ceramic articles from nanopowders like impellers and plates with longitudinal holes.

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Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

Section: A Case Of the Conventional Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The comparison of model compaction method to make uniformly dense ceramic bodies

Хасанов

Edgar

Sokolov

et al. 2012

2012 7th International Forum on Strategic Technology (IFOST)

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“…The friction index (f) gives the ratio of the shear stress to axial stress and is an indication of the friction effect [21,22]. Thus, it is a significant parameter for powder compaction.…”

Section: Friction Indexmentioning

confidence: 99%

X-ray tomography analysis of aluminum alloy powder compaction

Yang

Zhang

2015

Rare Met.

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Aluminum alloy green compacts obtained by single-action compaction in lubricated and unlubricated dies were investigated by X-ray tomography. For the purpose of obtaining the relationship between the density of green compact and the gray value of reconstructed images, linear fitting was performed. The results show that these data have excellent linear relationship. Then, a new method for analysis of compaction process was presented in this paper. Detailed quantitative analysis of the density and compressive pressure distribution in green compacts was performed. The compressive pressure transmitted ratio and friction index were also discussed. It is found that the lubricated die wall has better effects on the density homogeneity at lower applied compressive pressure. During compaction process, the densification of powder particles in the die mainly occurs in the lower part of the green compact and the factor which mainly influences the friction between die wall and green compact is the applied compressive pressure.

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“…The friction interaction between compact powder and die wall those has an important roles of powder compaction lead to density changes, increasing press, material removal force from die and die corrosion [4]. It is difficult to eliminate die wall friction in the process of conventional compaction and there are several study cases in article [5][6][7][8][9]. The nonuniform density is the major problem in creating compact bulk nanostructured materials from nanoparticles in conventional pressing.…”

Section: Introductionmentioning

confidence: 99%