Stroke limitation

During the plasticating process, the screw is rotated by a hydrauhc motor. The material descends from the hopper and enters the feed zone. The rotation of the screw then conveys the material toward the screw tip and through the open non-return valve. The screw is forced backward by the material accumulating in the injection chamber (ante-chamber) in front of the screw tip. As soon as the introduced melt has pushed the screw back to trigger the adjustable feed stroke limit switch, screw rotation is stopped. 

In the end position of the ram the main crosshead rests against the container with the stroke limiting sleeve w hich is attached to the ram-holder. The thickness of the billet discard is read on a graduated scale a stroke limiting sliding bar as with the press shown in Fig. 59 and 73, is therefore not required. 

The container is symmetrical and may be used from either end. It is centered to the container support in an annular groove. The container is held in the holder by a bayonet lock. When dismounting the container, the crosshead is lowered until the stroke limiting collar / makes contact. Then the clamping bolts are screwed in tap-holes specially provided for this purpose in the container, and with the crosshead moving up the container is lifted out. The container-holder is provided with a resistance heating system to heat the relatively small container. Its outer jacket is well insulated to prevent thermal losses. 

The effect of such stripper cylinders can also be attained by eliminating the distance between the surfaces c and d and providing a flexible stroke limiting device on the columns of the piercer device, the power of which must, however, be greater than that of the piercer, or by arranging the stops in such a way as to provide for their respective position to be adjusted or to be changed by means of spacers quickly. 

Tools used for this operation are illustrated in sketch c. Extrusion power and piercing power are coupled, the stroke limiting stops for the... 

Mechanically, the work press to which the electrodes are attached is conventional in as much as the requirements are basic, ie application of pressure by pneumatic, hydraulic or motorised means, or a simple pedal action. In practice, high frequency (hf) plastics welding presses are somewhat more sophisticated in as much as most presses are used for a variety of applications requiring varying controls, such as pressure adjustment, accurate stroke limiting stops and timed cycles. It is imperative that platens, which currently can be as large as 2.5 m x 1.8 m, are accurately made and aligned parallel to each other to limits of less than 0.075 mm. As pressures of up to 80 tons are sometimes required, it can be seen that substantial press frame and platen structures are necessary. 

Plunger Swing arm -Stroke limited disk with integral gear... 

Closing motion displaces an additional amount of adhesive can be minimized with stroke limiter... 

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