Cutter heads

Bucketwheel excavators are used for overburden removal at phosphate mines in eastern North Carolina, Senegal, and Togo. One mine in central Florida has used cutter head dredges for both overburden removal and ore excavation. 

Figure 142. (a) Lodige mixer equipped with cutter heads. (Courtesy of Gebr. Lodige, Paderborn, FRG)... 

FIGURE 7.20. Heavy metal boring bars with simple and multiple cutter heads. By courtesy of Plansee AG, Austria. 

Boring Onn BarmU.—The tool used for this pur pose consists of a rod a little longer than the barrel to be bored, with a cutter head at one end. Thu cutter is about onn.half or three-quarters of an inch long, and of a diameter a little larger than the bore... 

At the Faido multifunction station of Gotthard base tunnel project (Ehrbar 2008), the cutterhead had been changed from 8.80 m to 9.40 m in order to obtain more space for deformations and rock support. The deformation behind the cutter head became locally big, and there was a risk that the back-up installation could not pass through the excavated hole. Due to very large radial deformations and an influence of the second tube on the first (eastern) tube, some heavy damage unexpectedly presented in the rock support and lifting of the concrete floor (see Fig. 3). 

In continuous cutting of bevel gears, cutter head and gear rotate in a fixed ratio. Hereby all... 

In both process variants, the cutter head has to fulfill a generating feed movement to cut the profile curvature, which is necessary for a meshing gear pair. However, in applications... 

In the vibrating reed technique one end of a small sample is clamped in a gramophone record cutter head driven by a variable frequency oscillator. The amplitude of vibration is measured opto-electrically. enabling tan <5 to be calculated from the width of the resonance, sihce tan = Af. fr where f is the resonant frequency and A/ the bandwidth. 

The last unit in our design problem is the drive belt. If the cutter were electrically driven by a constant speed motor, the major function of the belt would be the uniform transmission of power to the cam and, subsequently, to the cutter head. In this design, the cutter is driven by a gasoline motor which has pulsations in power output particularly a small motor of the type used in hand held units. The amount of flywheel effect that can be built into such a unit is limited and the pulsations caused by the individual firings in the motor cylinders is transmitted to the output shaft. 

Interlocks are fitted to the cutter head so that the machine is switched off when the waste bin is emptied. 

Line sliafts Light motion) Dredges — Cutter head drives, jig drives. 

When changig the mandrel, the lead slug behind the die must be removed. This is done by turning the screw-fitting h completely out of the thread and dismounting the die towards the rear. As may be seen in Fig. 42, the lead slug is milled out by a cutter-head v set on a tube w and advanced and rotated by a motor, the worm drive x and the threaded ring y. 

The appropriate milling tools particularly contribute to economic machining of workpieces. A wide range of tools are available, e.g., cutter heads with as-large-as-possible infeed, to end mills for the smallest inaccessible areas. These can be applied with replaceable cutters made from alloyed special steel/carbides/ceramic and for example as inserts. 

The spray fan system was designed for use with exhaust ventilation only. A different system, designed for use with blowing ventilation, was designed by Volkwein and Wellman (1989). It also uses directional sprays to induce air movement around the cutter head. The authors report an improvement in ventilation by a factor of 2 to 3. 

Three basic wet-bar techniques are used (Figure 20.6). Water-trickle system A uses a gravity-feed or low-pressure (less than 345 kPa or 50 psi) pump to send water through the bar and to discharge it at the bar tip. Water-spray system B uses a low-pressure spray nozzle located at the front of the cutter head. For protection, the nozzle can be located within the cutter head. Water-trickle system C used a gravity-feed or low-pressure pump to discharge water onto the cutter chain on either or both sides of the cutter head. 

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