US2675125A - Direct and indirect extrusion of metals - Google Patents

Description

April 13, 1954 R, GENDERS DIRECT AND INDIRECT EXTRUSION 0F METALS 2 Sheet-Sheet l Filed Jan. '7. 1949 April 13, 1954 R. GENDERS 2,575,125

DIRECT AND INDIRECT EXTRUSION OF' METALS Filed Jan, 7. 1949 2 Sheets-Sheet 2 F/G. Q.

IMM e6/maw Germans 1L www1 Patented Apr. 13, 1954 OFFICE DIRECT AND INDIRECT EXTRUSION OF METALS Reginald Genders, Kent, England Application January 7, 1949, Serial No. 69,755

Claims priority, application Great Britain January 14, 1948 9 Claims.

This invention relates to the extrusion of metals and is concerned with apparatus for, and a method of, extruding plastic masses of, for example, steel, non-ferrous alloys or non-metallic materials into, for example, bars or rods of any desired cross section.

The two methods of extrusion known as the direct and the indirect methods possess individual characteristics providing differing advantages. Thus, in the case of the direct process in which the billet container is stationary and a moving ram forces the billet through a die, so that the billet moves relatively to the container, a high pressure is required and while the extruded product exhibits good surface qualities, the type of flow involved in the direct process may introduce defects within the product.

In the case of the indirect process, in which the container travels towards the die with the billet, so that the billet does not move relatively to the container, a lower pressure is required than in the direct process and an internally sound extruded product results, although the surface quality is not so good as in the direct process if an unmachined billet is used.

The object of the present invention is to provide extrusion apparatus and a method of operating such apparatus in a manner which will ensure both good surface quality and internal soundness of the extruded product, together with economical control of pressure.

According to the present invention, apparatus for eifecting extrusion of metals comprises a billet container, a die, means forl forcing the billet through the die and means enabling extrusion to be effected by either the direct or the indirect process or by a mixture of these processes. The billet container is movable and means are provided for starting and stopping the movement of the container at any desired stage of the extrusion operation. Preferably, means are provided for eiecting the movement of the container independently of the movement of the means for forcing the billet through the-die.

In particular forms of apparatus embodying the invention, the means for starting and stopping the movement of the container, or additional means, serve to control the relative speeds of movement of the container and the means for forcing the billet through the die. One or more hydraulically operated rams are used for eecting the desired movements.

In order that the invention maybe more clearly understood and readily carried vinto effect, alternative forms of apparatus constructed and designed to operate in accordance therewith, will now be described in greater detail by Way of example with reference to the accompanying drawings in which:

Fig, l is a plan View of one form of apparatus including a diagrammatic representation of the hydraulic means, and

Fig. 2 is a similar view of an alternative form.

Referring to the drawings, a main hydraulic ram I driven from a cylinder 2 and controlled from a valve box 3 having a control handle 4, is mounted to slide with a cross head 5. The ram Carries a holder B for a thrust rod I which is dimensioned to have a clearance t in the entrance to a container 8 for a billet 9. A thrust tlc is interposed between the rod 'I and the A die II is rigidly held in a hollow support I2 carried by a holder I3 on the front housing It. A container housing I5 is carried by pistons I6, II which slide in cylinders I8, I9 and 2l), 2I respectively. The cylinders I8 and 20 are mounted on the cross head 5 and the cylinders I9 and 2l are mounted on the front housing I4. Hydraulic feed pipes 22, 23 are connected to the cylinders I9, 2l and `to the cylinders I8, 20 respectively from a valve box 24 supplied with a hydraulic medium from an accumulator 25.

For convenience, Fig. 1 shows the position of the cooperating parts reached at an advanced stage of extrusion, the hydraulic system being shown under indirect extrusion conditions, that is to say conditions in which the container 8 is moving. The valve control handle 251 is thrown into a position in which valves 21, 28 and 29 permit the cylinders I9 and 2I to exhaust through the pipe 39, While the valve control handle 3l is in a position in which valves 32, 33 and 3d trap the fluid in the cylinders I8 and 29.

On the commencement of extrusion by one method of pressure and now control, the apparatus is in the condition shown in Fig. 1 except that no part of the billet 9 will have been extruded, andthe container will be full. The ram I is brought into operation, compressing the billet into contact with the walls of the container 8 and when the pressure at the die II has risen to about half that necessary to extrude with a fixed or stationary container, as in ordinary direct extrusion, the friction between the billet and the container will move the latter in the direction of the die and extrusion will begin with the flow characteristic of indirect extrusion. It will be understood that as the cylinders I9, 2| are ex- 3V hausting, there is no impediment to the movement of the container. Y

Once extrusion has commenced under the lower pressure required for indirect extrusion, the conditions may be changed at any desired point of the stroke to those of direct extrusion with the accompanying advantages of good surface quality of the extruded product. In order to achieve direct extrusion the position of the valve rods 2'6 and 3l are reversed to bring the valves they control into positions in which iiuid inthe cylinders I9, 2l is trapped and the cylinders I8 and 20 are exhausting. prevented from moving and the ram l continues to force the billet through the die by direct' extrusion.

When about 60% of the billet length has been extruded, there is a danger of this mode of flow introducing internal defects in the product, and at a later stage the pressure required to continue the direct process begins to rise rapidly. The mode of flow may therefore again be changed to that of the indirect method by restoring the valve rods 25 and 3l to their initial positions inl which the container housing again'becomes free to move in the direction of extrusion.

The completion of the operation under the conditions of, indirect extrusion results in lower pressure being required and a' flow which does not introduce internal defects in the product, both of these consequences rendering it possible to extrude an increased percentage of the billet before extrusion stops, with a proportionate gain in efliciency as well as in quality.

Although in the preceding description it has been assumed that the container is quite stationary or moves at the same speed as the billet, it is to` be understood that if desired, during movement of the container housing, its speed relatively to the main ram I may be controlled so as to produce the maximum advantageous results by setting the valves controlling thefhydraulic fluid at selected positions intermediate those whichthe cylinders I8, 20' and' I9, 2l are wholly exhausting or under maximum pressure.

Referring now to Fig. 2 of the drawings, alter- The container housing t5: is thus" native means for moving the container housingV are shown comprising an annular ram 35 which abuts against the container housing aiiand which, with an inner concentric ram 31', is mounted for movement on a cross head 38. A billet 39 shown before commencement of extrusion lls the container 40, the apparatus being shown in the condition prior to the commencement of extrusion. A die lil and a hollow die support 42 are carried by a' holder 43 on the front housing 44 and the container housing 36 is carried by pistons 45, 46

operating in cylinders 41, 43 mounted on the front housing 44.

Hydraulic feed pipes 49, are connected to the cylinders 41, 48 the supply of hydraulic iluid from a valve box 5l being controlled by a handle 52. In one extreme position of the valve handle iiuid so that the rams may be moved independently of each other and at variable speeds.

In order to commence extrusion, the valve handle 52 is placed in the position in which the cylinders 41 and 48 are exhausting. The ram 31 is then first drivenj into contact with' the billet 39 and this is followed by driving the ram' 35 to move the container with its housing at the same rate as the ram 31. Extrusion thus commences at a relatively low pressure by indirect ow and the movement of the centre ram 31 is then accelerated so that the resulting relatively slow movementiof the container produces a condition of mixed direct and indirect ow. IThe mixture of the two types of flo-w provides the advantages of a low pressure drive, good surface quality and internal soundness of the extruded product.

Preferably, in order that there shall be a minimum of discard or residue of the billet in the container at the conclusion of the operation, the final stage'is carried out under indirectfflow conditions.V in the usual way;

The apparatus described, when operated in the the extrusion of steel, nickelalloys or other metals.

which are diidcult to extrude.

It will be understood that the arrangement de` scribed enables varying degrees of mixture ofthe direct and indirect typesof flow to be achieved', simply by appropriate control of the rates of movement of the two concentric rams. Ify desired the apparatus may be pre-setto produce any desired variation or` pressureand type of flow during the extrusionstroke.Y It willbe seen also that the apparatus may be operated'to follow a predetermined shape of pressure/flow curve as selected by a user. Further, at any desired stage, the movement of the outer-.ram 35 may be stopped altogether if direct. extrusion only is desired or the centre ram, that is 31, may be moved constantly at the same rate as the' outer ram if purely indirect flow is required. Again the construction shownY inFig. 2 may be modied'so that the centre ram' 31 serves, through appropriate means, to propel the., container housing, while the outer ram provides the drive through a thrust rod toi the v to be effected by mixture of'thedirect and indirect means of low'comprising a hydraulic mechanism lfor moving saidfcontainer towards the die' at various speedsV and a hydraulic mechanism. for

moving the billet towards the die at. various speeds. v

2. Apparatus for eiecting extrusion of material in a plastic condition comprising a billet container, a die, a hydraulic ram for forcing said billet through said die, a second hydraulic ram for moving said container and means controlling saidrams to enabletheI extrusion operation tob'e The residue is-removed by known meansA manner indicated, enables a pressure to be used effected at any selected stage by the direct mode of flow and at another stage by the indirect mode of iiow, and means for causing said rams to move simultaneously in the same direction at relatively diierent speeds, whereby the billet container and the billet are moved at diierent speeds in the same direction to produce a condition of mixed direct and indirect flow and comprising hydraulic mechanism for operating each ram and a manually operated control for each mechanism.

3. Apparatus according to claim 2 and cornprising means for mounting said hydraulic rams concentrically with respect to each other.

4. An apparatus for eiecting extrusion of material in a plastic condition comprising a billet container, a support for said container, hydraulic means for moving said support, a die, means for forcing said billet towards said die for direct extrusion of the billet through said die, means for urging said container towards said die, whereby the billet is extruded therethrough by indirect flow, manually operated means for correlating said direct and indirect means for controlling the extrusion of said billet through said die to enable the direct mode of flow to be obtained at any desired stage of the extrusion operation and to enable the indirect mode of flow to be obtained at another stage of the extrusion operation, hydraulically operated means for moving said container urging means at a slower speed than said billet forcing means, whereby a mixed indirect and direct extrusion of the billet is obtained, and means for maintaining the indirect pressure substantially lower than said direct pressure during sequential application of said direct and indirect extrusions.

5. An apparatus as claimed in claim 4 wherein said billet container is supported by two hydraulically operated pistons disposed in cylinders and wherein a valve is `provided for supplying the hydraulic medium to said cylinders for controlling the supply of hydraulic medium to effect movement of said container in one direction and to prevent movement of said container in the opposite direction.

6. A method of effecting extrusion of material in a plastic condition in which extrusion of a given billet is initially eiected with the pure indirect process and is then continued with the pure direct process, and in which during at least one period of the extrusion operation on the billet a mixture of the direct and indirect process of extrusion is employed.

7. The herein described method of extruding metals consisting of placing a billet of the metal to be extruded in a billet container, placing a die at one end of the container and a ram at the other end of the billet container, applying pressure on the ram to compress the billet within the container and to extrude a portion of the billet through the die and upon extrusion of approximately sixty per cent of the billet through the die changing the mode of extrusion to indirect by applying an equal pressure to the container to continue the extrusion of the billet by the indirect method, and increasing the pressure on the ram to cause the movement of the container to be relatively slow with respect to the movement of the ram to produce a condition of mixed direct and indirect flow of the billet.

8. The herein described method of extruding metals consisting of placing a billet of the metal to be extruded in a billet container, placing a die at one end of the container and a ram at the other end of said container, applying an increasing pressure on the ram to compress` the billet of metal at one-half the pressure necessary to eiect metal flow through the die, removing the application of increasing pressure and maintaining the billet under a constant pressure of approximately one-half the pressure necessary to effect metal iiow through the die, applying pressure to the container to urge the same towards the die to extrude the billet to produce a condition of pure indirect flow, and subsequently increasing ram pressure on the billet to produce a condition of mixed direct and indirect flow of the billet.

9. Apparatus for effecting extrusion of material in a plastic condition comprising a billet container, a die, and means for simultaneously moving said container and billet at different rates of speed with respect to each other towards the die.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,479,437 Webster Jan. 1, 1924 1,654,109 Born Dec. 27, 1927 1,661,594 Born Mar. 6, 1928 1,670,336 Born May 22, 1928 2,142,704 Sparks Jan. 3, 1939 FOREIGN PATENTS Number Country Date 609,626 Great Britain Oct. 5, 1948

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