US3380270A - Plugging system for extrusion containers - Google Patents

Description

April 30, 1968 c. SAUVE 3,380,270

PLUGGING SYSTEM FOR EXTRUSION CONTAINERS Filed June 23, 1965 2 Sheets-Sheet 1 April 30, 1968 c. SAUVE 3,380,270

PLUGGING SYSTEM FOR EXTRUSION CONTAINERS Filed June 23, 1965 2 Sheets-Sheet 2 United States Patent @fice 3,380,270 PLUGGING SYSTEM FOR EXTRUSIGN CONTAINERS Charles Sauve, Versailles, France, assignor to Commissariat a lEnergie Atomique, Paris, France Filed June 23, 1965, Ser. No. 466,225 Claims priority, appligcatigrz gl rance, July 3, 1964,

3 Claims. (or. 7245 ABSTRACT OF THE DESCLOSURE This invention relates to a plugging system for extrusion containers whereby a container of this type can in particular be temporarily closed oft on the one hand on the front side of its die and on the other hand at the rear end of the body or billet to be extruded which is placed within said container, namely between said body and an extrusion ram. The primary object of said system is to ensure a uniform distribution of a lubricating material which has been previously introduced within the container so as to surround the billet entirely between this latter and the container wall.

The underlying principle of an extrusion method of this type and specifically of the lubrication process referred-to has already been described in US. Patent No. 3,072,251 as filed by Commissariat a lEnergie Atomique, wherein the apparatus employed was designed for use in conjunction with obturators or shutters consisting of metal parts having suitable mechanical strength, the rear shutter being formed by a stamped plate, the edges of which are applied by the pressure of the lubricant against the walls,

of the extrusion container, whereas the front shutter consists of a small plate which is held in position between the die and the die-holder and is designed to fail under the pressure exerted by the billet at the commencement of the extrusion process proper.

By reason of their very nature and design, obturators or shutters of the type referred-to above have to be replaced at the end of each extrusion operation. As can be understood, it is therefore of interest to replace such obturators by another sealing system consisting of removable members which can either be positioned or withdrawn at predetermined moments, on the one hand in front of the die and on the other hand behind the body to be extruded, one particular result thereby achieved being to permit of suitable injection and distribution of the lubricant within the extrusion container. Accordingly, it is possible in particular to employ on the one hand a simple front plug which is adapted to engage to a slight extent within the end of the die and, on the other hand, a rear plug which is connected in leak-tight manner to the extrusion ram without preventing this latter from sliding within the container for performing the extrusion operation proper. Preferably, and in a manner which is well known to those skilled in the art, said rear plug consists of a metal block designed to slide along the stem of the extrusion ram with interposition of packing glands, said block being fitted with means for applying this latter in leak-tight manner against the extremity of the extrusion container, preferably in synchronism with the movement of displacement of the ram.

3,38%,270 Patented Apr. 30, 1968 The object of this invention is to improve the arrangements noted above, in particular by making it possible to ensure that hydrostatic pressure of the lubricant is maintained within the extrusion container while the rear plug is applied at the same time against the extremity of said container during the entire movement of displacement of the ram which effects the extrusion operation.

To this end, the improvement proposed mainly consists in utilizing the relative motion of the ram rod and the metal block which constitutes the rear plug for the purpose of effecting an injection of lubricant under very high pressure into the extrusion container, said lubricant being preferably maintained in the plastic state and at a suitable temperature inside an annular feed reservoir which is formed between the ram rod on the one hand and the metal block on the other hand.

Under these conditions, the rear portion of the ram rod which has a larger diametrical cr0ss-secti0n serves to force the lubricant out of its reservoir towards the interior of the extrusion container after application of the rear plug and at a suitable pressure, the quantity of lubricant injected being exactly the quantity which is necessary for the purpose of filling under the desired extrusion conditions, the space which is left free between the internal Wall of said container and the body to be extruded. The injection of lubricant is effected at the pressure of extrusion of the body to be extruded, the volume of lubricant injected being very small if it is compared with that which would be necessary in order to fill the chamber if no ram at all were present. In any case, the ram has the intended function of thrusting the billet into its position of readiness for extrusion in contact with the die, the injection of lubricant being thus performed partly at the moment when the billet is in the extrusion position after bein thrust therein by the ram.

Consequently, the ram rod moves relatively to the rear plug to an extent which is equal to the displacement within the container as required for extrusion, and as increased to an extent which is necessary for the preliminary injection of a given quantity of lubricant.

All of the above features will become more readily apparent from a perusal of the following description of one example of embodiment which is given by way of indication and not in any limiting sense.

In the accompanying drawings, FIGS. 1, 2, 3 and 4 are diagrammatic views in partial cross-section of a horizontal extrusion press which entails the application of the improvement considered.

As can be seen from FIG. 1, the press which is illustrated comprises a header 1 which serves to hold in position by means of a support member 2 a die-holder 3 for a die 4; said die is placed at the end of the cavity 5 of an extrusion container 6.

The preliminary closure at the front end of the die 4 is effected by means of a removable plug 7 which can be withdrawn at the beginning of the extrusion operation by any suitable means. As to the other end of the cavity 5, the closure means consist of a metal block 8, the corresponding end of which is adapted to fit within a conical flare 9 formed in the end of the cavity 5.

The rod 10 of a ram 11 is adapted to pass axially through the metal plugging block 8 and is extended towards the right hand side of the drawing by a portion 12 having a transverse cross-section which is slightly larger than that of the central portion of the rod. Inside the block 8, there is accordingly formed around said rod 16 an annular recess 13 which can be filled with a quantity of suitable lubricant introduced through an admission duct 14 formed through the body of the block 8. The complete or partial filling of the annular space 13 by the lubricant is obtained by means of a high pressure pump (not shown in the drawings) which comes into action when the ram 3 and the rear block 8 are in the open position which is shown in FIG. 1.

In FIG. 1, the different members referred-to above are shown in the position corresponding to the beginning of an operation involving the extrusion of a body or billet 15 which is carried in a cradle support 16.

In a first step, the billet 15 is thrust into the cavity 5 of the container 6 under the action of the ram 11 as this latter moves forward together with the metal block 8 which forms a rear plug. When the forward end of the plug 8 engages within the conical portion 9 of the cavity 5 and thus effects the closure of this latter, the billet 15 is thrust forward by the ram 11 and thus brought into a position such that the front face of said billet is located at a distance of a few centimeters from the die 4, as shown in FIG. 2.

In a second step, a suitable pressure is applied to the metal block =8 by conventional means (not shown) which can either be jacks secured to the press header, screwtype breech-blocks, or any other device designed to ensure leak-tightness between the block and the extrusion container 6. Then, in a third step, the ram 11 continues to move from the right hand side to the left hand side in the drawing and, during the initial part of this movement, causes the lubricant to fill the entire space which is left free between the billet 15 and the internal wall of the cavity 5, as shown in FIG. 3. The injection of lubricant takes place under the effect of the movement of the portion 12 of the end of the ram rod within the annular space 13. It should be noted that, at this stage of operations, the pressure at which the lubricant is injected is maintained by the front plug 7 which is placed in front of the die and which therefore closes off said die in a leak-tight manner.

In a fourth step, as the forward movement of the ram 11 proceeds, the ram places the billet l5 opposite the die 4. The extrusion process proper commences at this moment at the same time as the plug 7 withdraws. During these operations, the lubricant continues to be injected at very high pressure as a result of the forward displacement of the ram.

Finally, in a fifth step, when a sufiicient quantity of lubricant has been injected into the cavity 5, a by-pass system (not shown in the drawings) permits the evacuation of excess lubricant while the quantity which is necessary for the extrusion process itself continues to be injected into the extrusion container at the pressure which is required in .order to force the metal through the die, as shown in FIG. 4.

It should be noted that, in the example described above, the seals employed, in particular for the purpose of providing leak-tightness between the metal block which forms a rear plug and the different parts of the ram rod are sliding seals having good mechanical properties for the purpose of affording resistance both to attrition and to heat. As an advantageous feature, the seals employed consist of O-ring seals formed of stamped metal members which have a sufiicient degree of elasticity to allow the liquid lubricant to flow in one direction only. With this object in view, the rubbing portions .of said seals are preferably formed of a metal which is softer than the steel of which the extrusion container and the ram rod are usually fabricated. As another preferable feature, said Oring seals can consist of two or a number of layers of bonded metals, the outer layer having suitable mechanical characteristics for the purpose of ensuring a good contact with the steel whilst the inner layer is formed of a metal having a higher yield strength at operating temperatures.

Finally, it is of interest to mention the notable resistance of the extrusion container to tangential stresses which could otherwise result in fast fracture. The hydrostatic pressures which are usually developed in conventional extrusion processes could in fact attain 12,000 to 15,000 bars.

As will be readily understood, the invention is not limited in any sense to the form of embodiment which has been described and illustrated herein and which has been given solely by way of example.

What I claim is:

1. An extrusion device comprising an extrusion container, a cylindrical chamber opening through said container containing the body to be extruded, a die at .one end of said chamber, an extrusion ram, a ramrod for said ram, a slidable plugging block closing the other end of said chamber and slidably mounting said ram and said ramrod, the relative motion of said ramrod and said plugging block producing an injection of lubricant under very high pressure into said chamber and an annular feed-reservoir between said ramrod and said plugging block, said lubricant being maintained in the plastic state and at a suitable temperature in said reservoir.

2. A device as described in claim 1, the rear portion of said ramrod having a larger diametrical cross-section than the front portion of said ramrod to force lubricant out of said reservoir into said chamber when said plugging lock engages said extrusion container, the quantity of lubricant injected filling the space between the internal wall of said chamber and the body to be extruded.

3. A device as described in claim 1, said ramrod moving relatively to said plugging block a distance equal to the displacement within said chamber for extrusion and for a preliminary injection of a given quantity of lubricant.

References Cited UNITED STATES PATENTS 1,321,096 11/1919 Geer 72--27l 3,072,251 1/ 1963 Sauve 72--42 CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner.

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