Pipe Presses

Decades had still to pass since the publication of this invention, until the first hydraulic presses were constructed and it was not until 1867 that the lead pipe press, as shown in Fig. 2, by the Frenchman Hamon became known. The principles of this early invention are still embodied in presses at the present time. 

In order to render possible casting of the molten lead into the container, a lifting cylinder a with piston b for the lifting of the crosshead c is arranged on top of the press. The nuts d are provided with bayonet-type threads. When changing tools, the crosshead / may be lifted with the help of the clamps e. Casting of the liquid lead is followed by an interval of five to ten minutes to allow for the solidification of the metal. The extrusion temperature is about 210 °C. 

Pearsox, C. E. The Extrusion of Metals. London Chapman Hall 1953. 

The commercial weight of a pipe bundle is about 75 kg with a maximum pipe diameter of about 60 mm. The bundle is lifted out of the coiler, wrapped with straw ropes and prepared for shipment. For the purpose of roughly determining the weight of a pipe bundle, the press is provided with a dial gauge indicating the extruded weight in dependence of the ram stroke. 

An extrusion pressure p = 1,600 kg/cm is chosen to allow for alloys for pure lead an extrusion pressure p = 1,200 kg/cm would be sufficient. 

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The triumphal march of the auger extruder however was not to be stopped. For all that, a great deal of design work and detail development had to be undertaken to reach today s state-of-the-art technology, which will be dealt with separately in Chapter 2 in much more detail. Around 1870 vertical auger extruders, the so-called suspended extrusion machines , were brought onto the market, to become forerunners of the later sewer pipe presses (Fig. 18). 

Experiments studying the corrosion behaviour of pipes and pipe connections made of the steel 1.4301 (SAE 304 UNS S30400) were carried out in cold drinking water in field tests lasting five years [34]. Table 20 contains data for pipes in various heat treatment states. The pipe connections were made of the same material as the pipes. Pressed fittings with a non-metallic seal and solder fittings were tested. The chemical composition of the solders used is shown in Table 21. 

For a long time there was an ever increasing demand for lead pipe presses. However, this development came to a stop about fifteen to twenty years ago, when pipes made of steel, non-ferrous and light metals, as well as pipes of plastic or synthetic materials made their appearance on the market. 

Apart from the lead pipe press, there was also designed a series of smaller presses, the most important types of which being employed for the manufacture of curved lead pipes for use as bends or syphons, of lead wire of round or profiled cross-section, and of tin solder wire. 

Fig. 3 shows the design of a modern lead pipe press. It has a bottom cylinder platen a which is positively connected to the top counterplaten c by means of four columns 6. The plunger d runs in a bronze bush in the cylinder and travels over a mandrel-bar holder e which is rigidly secured in the base of the cylinder. Sealing of the plunger in the cylinder and on... 

In size lead pipe presses range from 250 to 1,250 tons total pressure capacity. Materials employed are cast steel GS 50 for cylinder-platens, GS 45 for counterplatens and crossheads, steel St 60 for plungers and... 

Fig. 4. Hydraulic circuit diagram of a lead pipe press with tlirect pump drive...

The design of a lead trap press is illustrated in Fig. 5. Contrary to lead pipe presses, they are in horizontal design. They are provided with... 

Trap presses are operated like pipe presses directly off one pump which - in connection with a control gear - delivers the pressure water or the pressure oil either simultaneously to the two main cylinders or... 

Like lead pipe presses, the lead wire presses are driven directly off the pumps. The pump output is dependent on the ram speed and the... 

The press is driven - like wire- and pipe presses - directly by a pressure water or pressure oil pump at a maximum operating pressure of about 315 atm. The pump output is about 10 to 12 H.P. giving a ram speed of about 1.4 mm/sec the control gear is as described on p. 10. 

A horizontal press of this type is shown in Fig. 41. The lead is charged in a container disposed concentrically to the mandrel and the mandrel-holder respectively, and after solidification it is forced through the die in a manner similar to that used in a lead pipe press, see p. 4. 

With presses operating at slow speed rates, i. e. lead wire- and lead pipe presses, cable presses and rod extrusion presses, the working stroke is of relatively long duration - 10 to 20 minutes not being extraordinary -so that the accumulation of pressure fluid would make no sense. For tube extrusion presses, especially those working on heavy metals and at speed rates of up to 200 mm/sec, the accumulator drive will be preferred as the direct pump drive would be very expensive on account of the high pump capacity required. 

The Railroad Commission of Texas investigated a natnral gas explosion and fire that resulted in one fatality in Lake Dallas, Texas, in Angnst 1997 [5]. A metal pipe pressing against a plastic pipe generated stress intensification that led to a brittle-like crack in the plastic pipe. 

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