Hydraulic Ram

A separate control is exerted over the screw cushion. The cushion is the volume of liquid that remains in front of the screw after injection (see Figure 7.37) the cushion affects the pressure transmitted from the system (ram hydraulics and ram) to the cavity during packing. The ram position sensor measures the cushion if it is low the screw is withdrawn funher during the rotation phase of the next cycle. 

An indatable diaphragm or membrane has been used in membrane plate presses closely related to the conventional plate and frame presses. A pressure filtration period is foUowed by compression with the hydraulically operated membrane or by a hydraulically operated ram if dexible rim seals are fitted. This principle also is used in vertical presses that use either one or two endless cloth belts indexing between plates. Indatable membrane also may be used on a cylindrical filtration surface with or without a preceding pressure filtration stage. 

When the bulk containing the binder is uniform, it is compressed on pneumatic, hydraulic, or ram-type presses. Compression can be carried out in presses provided with suitably designed cavities or in metallic pans. The pans ate filled with the powder mass, and a plunger with a cross-sectional shape similar to that of the pan is used to compress the tablet. The resulting tablets ate commonly used with powder puffs or cosmetic bmshes. 

Viscous Drag Jet (Ejector-boosted) Gas Lift Hydraulic Ram Electromagnetic Screw Centrifugal Rotating Casing (Pitot)... 

A die stamping was produced in just one action. Stock (2) was fed into die (1) and the deformation to obtain a cup was performed by a stamp (3) which moved in a sleeve (4) driven by a piston of a hydraulic cylinder. The strain obtained was measured with strain gauge (5). The temperature of the deformed alloy was maintained by heating device (7) and controlled with sensor (8). After the deformation was completed shedder (9) driven by a piston (10) of hydraulic cylinder (11) ejected the cup. The whole press ram rested upon base (12). 

Figure 40.2 illustrates the transmission of forces through liquids. For Pascal s law to become effective for practical applications, a piston or ram confined within a close tolerance cylinder was needed. It was not until the latter part of the eighteenth century that methods were developed that could make the snugly fitted parts required making hydraulic systems practical. 

The hydraulic press, invented by an Englishman, John Brahmah, was one of the first workable machines that used hydraulics in its operation. It consisted of a plunger pump piped to a large cylinder and a ram. This press found wide use in England because it provided a more effective and economical means of applying large, uniform forces in industrial uses. 

Hot pressing requires a refractory die, pressure and heat sources and temperature- and pressure-indicating devices. For many applications the die containing the sample to be hot pressed is heated either by a separate furnace (for < 1000°C) or by inductive or resistance heating of the die body itself. Uniaxial pressure is applied through the ram of a hydraulic or pneumatic press. 

A device for storing hydraulic pressure in its simplest form it is a long vertical hydraulic cylinder, on top of the ram on which weights may be placed or suspended. 

A pressure vessel constructed of steel, used for the vulcanisation of rubber products by the open steam method. The autoclave may be horizontal (vulcanisation of footwear, cables, hose), or vertical and fitted with a hydraulic ram (e.g., moulding pneumatic tyres). 

The total pressure in tons exerted by the ram on the platens of a hydraulic press. It is calculated by multiplying the area of the ram by the hydraulic pressure and converting to tons sometimes called press capacity or ram pressure. 

The second area of advance is in mechanisation which enables the opening and closing to be done automatically by a ram driven hydraulically or by an electric motor. Plate transportation is effected by fitting triggers to two endless chains operating the plates, and labour costs have consequently been reduced very considerably. Improved designs have... 

Hj) Height of Burst (Sonic) Test. The purpose of this test is to det the height of burst of a fuze using sonic techniques. This technique requires the measurement of the time of arrival of sound at directional microphones precisely placed in a plane. A brief description of this test is given on p IIIB-20 Ref 39 Addnl info can be obtd from "Instrumentation Section, Technical Services Laboratory, Ammunition Development Division, Ammunition Engineering Directorate, Picatinny Arsenal, Dover, NJ 07801 H2) Hydraulic Ram and Vibrator Test. This test could be used to simulate impact shock on bombs or rockets assembled with fuzes that are launched from aircraft. It also could check the transportability of fuzes that experience this environment. This test is listed, but not described in Ref 39, p IIB-37... 

Specialty Refractories. Bulk refractory products include gunning, ramming, or plastic mixes, granular materials, and hydraulic setting castables and mortars. These products are generally made from the same raw materials as their brick counterparts. 

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