Rotary Mill Research Articles

Automating the operation of a rotary mill feeder

Automating the operation of a rotary mill feeder

Calculation of the power expended by a centrifugal rotary ball mill for the grinding of soft and brittle granular materials

Calculation of the power expended by a centrifugal rotary ball mill for the grinding of soft and brittle granular materials

Pulverization of granules of Diphenylguanidine in a vertical centrifugal rotary mill

Pulverization of granules of Diphenylguanidine in a vertical centrifugal rotary mill

Dispersion of ceramic clays in a rotary mill

Dispersion of ceramic clays in a rotary mill

Effects of niobium carbide additions upon the production and properties of sintered high-speed steel

1. A study was made of the comminution to powder, in a rotary ball mill, of R18 high-speed steel swarf containing niobium carbide additions and of the subsequent processing of the resultant composite powders to dense blanks. 2. Niobium carbide was found to intensify the swarf comminution process: In powder milled for 48 h, the presence of 5 vol.% NbC increased the yield of the −0.25-mm fraction from 46 to 81% and that of the finest (−0.04-mm) fraction from 35 to 45.5%. At the same time, the mean particle size decreased from 0.31 to 0.18 mm. 3. A study was made of the pressing and sintering of the high-speed steel powder with niobium carbide additions. Strong compacts with a relative density of 70–73% were produced by pressing the powder, with a rubber addition, under a pressure of 8–10 tons/cm2. 4. Sintering, in the absence of a liquid phase, for 60 min at 1250°C in very dry hydrogen was found to yield blanks with a relative density of more than 95%. The blanks were characterized by a fine-grained structure and a mean carbide grain size of 1.5–2μ. 5. The addition of niobium carbide affected the size of the austenitic grain, reducing it from 18μ at 1 vol.% NbC to 7μ at 5 vol.% NbC. 6. The introduction of niobium carbide raised the hardness of the sintered steel, from 59 HRC (without NbC) to 65 HRC at a NbC content of 5 vol.%.

Rotary Grinding Mill and Drive Motor Torque Relationships

An understanding of torque relationships in the operation of rotary grinding mills necessitates a complete analysis of the mill, gear train, and drive motor insofar as torsional load, inertia, and frictional losses are concerned. Ability of a drive motor to develop the required torque is dependent upon its inherent torque characteristics in combination with its electrical supply system. A complete evaluation of both the drive motor and power system is therefore necessary to assure that proper torque will be supplied by the drive motor for the mill requirements.

Study of the dispersion kinetics of plastic clays in a rotary mill mixer

Study of the dispersion kinetics of plastic clays in a rotary mill mixer

A Continously Recording Flight Mill for Investigating the Effect of Volatile Substances on the Flight of Tethered Insects1

An apparatus was developed to test and record the effect of volatile substances on the flight of tethered insects. It consists of a rotary flight mill within a glass chamber through which there is a continuous air flow, and a photocell-ratemeter-paper chart recording system. This system provides a permanent quantitative record of flight speed and duration and shows immediate and subtle changes in flight speed. The apparatus can be adapted for computer programming by a digital voltmeter and tape punch. Introduction of sex pheromone (as female frass) into the flight chamber caused male Douglas-fir beetles, Dendroctonus pseudotsugae Hopkins, and striped ambrosia beetles, Trypodendron lineatum (Olivier), to cease flight abruptly. This is considered to be strong evidence for the arrestant effect of pheromones on flying scolytids. The apparatus has promise as a tool in the study of the effect of pheromones and volatile host attractants on flying insects.

Grinding of WCrV steel shavings

1. With the aim of using powder for making compact billets and tools, the authors studied the grinding of WCrV steel in ball mills and vibromills with addition of surfactants- machine oil and solutions of oleic acid in oil and CCl4. 2. Addition of pure CCl4 retards grinding in comparison with dry grinding. Addition of oleic acid to CCl4 accelerates grinding. The optimum additive was found to be a 10% solution of oleic acid in 0.05 liter of CCl4 per kg of shavings; this corresponds to a virtually monomolecular film of adsorbed oleic acid on the powder. Grinding for 40 h in a rotary mill gives a powder with a mean particle size of 0.193 mm (in place of 0.277 mm with dry grinding). 3. In the case of grinding in oil, the optimum addition was 0.15 liter/kg of shavings; grinding for 40 h gave a powder with a mean particle size of 0.171 mm. With an increase in the amount of oil to 0.05 liter or an increase to 0.5 liter, the grinding rate was less than with dry grinding. 4. Addition of 10% of oleic acid to the oil, with a total solution volume of 0.15 liter/kg of shavings, retards grinding; however, if the volume of 10% acid solution is reduced to 0.05 liter/kg of shavings, the grinding rate is somewhat greater than with 0.15 liter of oil without oleic acid (after 40 h the mean particle size is 0.166 mm). 5. The duration of grinding in a vibromill is approximately six times greater than in a rotary mill. 6. The hardness of particles ground to a given particle size in a vibromill is less than in the case of a rotary mill. 7. Industrial shaving scrap from R18 WCrV steel contains oil (the cooling liquid used in machining). Therefore the simplest method of accelerating grinding of shavings in ball mills and vibromillis is addition of 0.15 liter/kg of oil or a 10% solution of oleic acid in oil (0.05 liter/kg), which is more effective.

142. The influence of the gas atmosphere on the pulverisation process in vibratory and rotary mills: W. Batel, Chemie-Ingenieur-Technik30, 651–660, 1958

142. The influence of the gas atmosphere on the pulverisation process in vibratory and rotary mills: W. Batel, Chemie-Ingenieur-Technik30, 651–660, 1958

Rotary Vibrating Ball Mill

After reading a publication by B. Claus, we have tried to apply an analogous principle as used in this device to an existing type of vibrating ball mill (Vibratom).

Rotary Querns on the Continent and in the Mediterranean Basin

In his two articles on querns (1) Dr Cecil Curwen has given us a really epoch-making contribution to prehistory and history. Not only has he provided the prehistorian with a new instrument for the establishment of chronology, but he has drawn the attention of excavators to a revolutionary but curiously neglected advance in technology. For the rotary mill is the first major application of rotary motion since the invention of the potter's wheel and the lathe in the remote Oriental Copper Age; it led on directly to the invention of geared machinery and the water-wheel and so to the first employment of inanimate motive power apart from the harnessing of the winds to the sail. Though this invention took place in the full light of history, the sole evidence for its origin, apart from a single reference in a writer so late as Pliny (2), is purely archaeological. Unfortunately it is still rather thin; excavators of classical and barbarian sites have generally been too preoccupied with statuary and art-objects on the one hand, with types accepted as chronologically significant on the other, to provide the historian of science with the data he craves. Truhelka for instance, generally so scrupulous in the full publication of all his finds, does not illustrate nor even describe a single quern from Dolja Dolina in Bosnia where he found plenty (3).

Alloy Tubes for Aeroplanes

MINIMUM weight with no decrease of strength is the maxim governing the specifications to which seamless alloy‐tubes and sections, used in the construction oi aeroplanes, are made and research work on the behaviour of alloys under any possible conditions is included in the day's work of the technical staffs of the various factories. No other branches of the ferrous and non‐ferrous trades are subjected to such severe treatment of material as is the seamless tube section. In the larger diameters the material has to with‐stand the tremendous torsional strains of the rotary piercing mill, and for the smaller sizes the equally exacting high pressures of the extrusion press. As the principles of methods of manufacture vary little for ferrous and non‐ferrous, the author proposes to deal broadly with the last‐named metals, in which outstanding progress has been made in recent times.