Down-stroking press

A plastics material of particular application in electrical components. It consists of a thermosetting polyester resin, mineral fillers, fibrous reinforcement and a hquid crosslinking medium such as diallyl phthalate. Down-Stroking Press... 

In a conventional rubber moulding press the main ram travels upwards. In a down-stroking press the main ram is situated above the movable top platen to which pressure is applied by a downward movement of the ram. 

Fig. 44 illustrates a billet-fed lead cable press. The up-stroking design, as shown in Fig. 18, is the most suitable type, because the ram must be traversed to permit of charging the billet, for which purpose a small hydraulic cylinder with plunger and guide-frame is fixed on the face of the upper platen. With a down-stroking press, this drive unit would have to be mounted on the movable crosshead which would call for connection by hoses or telescopic tubes. 

Tablet Press. The main components of a tablet compression machine (press) are the dies, which hold a measured volume of material to be compressed (granulation), the upper punches which exert pressure on the down stroke, and the lower punches which move upward after compaction to eject the tablets from the dies. Mechanical components deflver the necessary pressure. The granulation is fed from a hopper with a feed-frame on rotary-type presses and a feeding shoe on single-punch presses. A smooth and even flow ensures good weight and compression uniformity. Using the proper formulation, demixing in the hopper is minimized.

A piston eylinder high pressure press is not excepted from the above problems, unless only the sample is set in its cylinder. There are experimental difficulties even in the simplest high pressure piston-cylinder press concerning the relation among the true pressure on the sample, the up-stroke gauge pressure, and the down-stroke gauge pressure. 

The press is suitably of the down-stroking two-column type, as shown in Fig. 7. The two columns are connected to the cylinder- and bottom platens by split nuts and check nuts. The pullback cylinder is suspended in the main cylinder so as to reduce the overall height. The pullback plunger acts on a crosshead which is connected to the plunger crosshead by two tie-rods. The plunger head carries the extrusion ram, on the bottom of which is fixed the die. The ram is bored out and provided at its bottom end with a curved outlet, through w hich it is possible to push out the die w ith the help of a rod. 

The design of the early vertical tube extrusion presses was simple and cheap. They were of the down-stroking type and built in frame construction. No special piercing equipment was provided since the billets extruded were only small ones. The mandrel w as rigidly inserted in the extrusion ram and extrusion is performed on the without shell method, when the ram has only a little clearance in the container. The heavy metal... 

With mechanical presses, the maximum force is available at the bottom of the slide stroke. In blanking and piercing operations, the work is done very near to the bottom of the stroke. However, where a part is blanked and then taken further down the stroke, e.g. to form a bend, less force will be available for the blanking operation which will have been carried out some distance above the bottom of the stroke. For example, a 500 kN press with a stroke of 120 mm will exert a force of only 120 kN half-way down its stroke. 

If it is a production application, one should define the cycle and calculate the cycle time to confirm the production rate. To define the cycle, one should first find out the minimum stroke to accomplish the task, then break down the stroke into the various elements where distance divided by velocity equals time as discussed in Section II.D. This process will reveal the speeds that will be required to provide the production rate. The speeds, in turn, will allow the press builder to establish the size of the pumping unit and determine the proper hydraulic circuit for the application. 

The top priorities of press maintenance are Housekeeping and Safety for the protection of the maintenance personnel and the press operator. The proverbial loaded guns such as electrical, air/pneumatics, and flywheel energy can cause serious injury to the maintenance personnel or press operator. Before any press maintenance work is started, the slide must be placed on the bottom of the stroke (to protect personnel from the slide, gears, or any press parts rolling), and the press must be shut down per Occupational Safety and Health Administration (OSHA) Lockout/Tagout standards (Fig. 1). 

One procedure for tightening tie rods is to put the press slide at the bottom of the stroke the press must be shut down per OSH A Lockout/Tagout standards. It is very important to have the gibs loosened on the press. When the tie rods... 

The punching power for the machine shown is derived from an electric motor in combination with a suitably sized flywheel. The kinetic energy of the flywheel is transmitted to the ram by way of a clutch mechanism, eccentric shaft, and pitman assembly. In this way, the rotational motion of the flywheel is converted to the stroke of the press, causing the machine ram to move down and up again to complete a single punching cycle. 

The flow of metals may easily be ascertained from experiments ) run on a 1,500-ton capacity rod extrusion press, in which - as illustrated in Fig. 108 - a 100 mm rod was extruded from a 163 mm container. The billet was made up with disks of 50 mm thickness and 150 mm diameter (sketch a) alternatively of copper and brass, and first of all compressed to a diameter of 163 mm and a total billet length of 592 mm (sketch b). Sketches c-e show clearly how the speed of flow is slowed down by the friction of the billet on the container wall and how the various disks bulge out towards the die aperture. From the movement of the various disks it is seen that disk no. for example, is dislodged for a distance of 205 mm from the die after a ram stroke of 92 mm (see sketch c). In sketch b the distance between this very edge and the die - in the com-... 

SHIRT FRONT. Start around the buttons, carefully working the iron point around the buttons on the placket. Move back up to the top of the shoulder and work your way down the front of the shirt, pressing the iron in long, smooth strokes. Repeat on the other side. It s worth spending a bit more time on the front placket and areas near the collar to make them perfect, especially if you re not planning on wearing a jacket over the shirt. 

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