US2901104A - Piercing ram arrangement for an extrusion press - Google Patents

Description

Aug. 1959 M. ARENZ 2,901,104

PIERCING RAM ARRANGEMENT FOR AN EXTRUSION PRESS Filed April 11, 1955 I M l l i I I i i 3' I I 3 I 1 'H l i: :l 1{

"1 7 an ii "I. 7 4-- N ii'l 47 INVE/VIUP: (4 od Mk6 H enz PIERCING RAM ARRANGEMENT FOR AN EXTRUSION PRESS Application April 11, 1955, Serial No. 500,504 7 In Germany November 26, 1949 Public Law 619, August 23, 1954 Patent expires November 26, 1969 1 Claim. (Cl. 201-3) The present invention relates to extrusion presses.

More particularly, the present invention relates to an extrusion press for extruding tubular articles.

As is well known, such tubular articles ar extruded from a solid billet which is first pierced by a piercing ram of the extrusion press. After the billet is pierced, the piercing ram remains in its position extending through the billet, and then the hydraulic ram compresses the billet to force it through the extrusion die while the piercing ram acts as a mandrel along which the work material moves. The tension to which such a piercing ram is subject by the extruded material rubbing against the same sometimes becomes so great that the result is a failure of the piercing ram with consequent shutting down of the apparatus and a replacement of the broken piercing ram.

The piercing ram is weakened considerably during the extrusion process by the great heat generated by extrusion of the billet, and although breakdown of the piercing ram has been reduced by making these piercing rams of special alloys, nevertheless complete protection from pulling the piercing ram apart has not beeen obtained up to the present time with conventional presses.

One of the objects of the present invention is to overcome the above drawbacks by providing a piercing ram with a means which will enable it to shift axially together with the extruded material whenever the latter exerts on the piercing ram a pulling force above a given value.

A further object of the present invention is to provide a means which yieldably resists movement of the piercing ram together with the extruded material.

Another object of the present invention is to provide a means for adjusting the force at which a piercing ram will shift together with the extruded material.

With the above objects in view, the present invention mainly consists of an extrusion press which includes a piercing ram and a moving means operatively connected to the piercing ram for moving the same in a piercing 55 direction which causes th piercing ram to pierce a billet.

A connecting means connects the piercing ram to the moving means for yieldable movement in the piercing direction independently of the moving means when the work material exerts on the piercing ram a force above 0 a given value.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claim. The invention itself, however, both as to its construction and its method of operation, to- 5 gether with additional objects and advantages thereof, will be best understood from the following description of a specific embodiment when read in connection with the accompanying drawing.

The drawing shows a partly diagrammatic, fragmentary, 70 elevational view of a press constructed in accordance with the present invention.

nited States Patent 0 In the interest of conciseness the drawing shows only enough structure to afiord a complete understanding of the invention. Many extrusion press parts not shown in the drawing are purely conventional and well known to those skilled in the art.

Referring to the drawing a vertical extrusion press is diagrammatically illustrated therein. This press includes a hydraulic extruding ram 1 fixed to a piston 2 which is slidable within a cylinder 3 supplied with a hydraulic fluid under pressure in any known way. Piston rod 2' of the piston 2 extends slidably through the top of cylinder 3. The cylinder 3 is carried by a part 3' of the press. The palts 1 and 2 are axially bored to accommodate, in a known way, a piercing ram 4, 5 come posed of the elongated piercing element 4 which is fixed at its top end to the remainder of the piercing ram 5. The piercing ram 4, 5 is axially slidable through and with respect to the parts 1 and 2. The piercing ram part 5 has a top free end portion 5' of reduced diameter which extends with a slight clearance through a bore of a cross bar 7. The cross bar 7 bears against a shoulder 8 located between end portion 5' and the remainder of the piercing ram part 5. The cross bar 7 is fixed to a pair of piston rods respectively connected to pistons which are slidable in the cylinders 6, also carried by the frame part 3, and to which fluid under pressure is supplied in any known way for moving cross bar 7 together with the piercing ram downwardly independently of the piston 2 through which part 5 slidably extends. A coil spring 9 is coiled about the end portion 5, bears at one end against the cross bar 7, and bears at its opposite end against an annular member 15 which keeps the spring 9 compressed. 'Ihe annular member 15 may be in the form of a nut threaded on to the end portion 5' to compress spring 9 to a desired degree in accordance with the particular material being extruded, for example.

Th drawing shows diagrammatically the container 16 in which the billet 17 is located, this billet resting on extrusion die 18. In operation, the parts shown above container 16 are lowered until ram 1 engages the billet 17, then hydraulic fluid is applied to the cylinders 6 to move only the piercing ram downwardly through the billet 17 to the position 4 shown in dotted lines. Thereafter, the piercing ram 4, 5 is maintained in this position and hydraulic fluid is supplied to cylinder 3 to lower the hydraulic ram 1 and extrude material through the die 18. Should this material pull downwardly on the piercing ram with a force which otherwise would break the ram, the entire piercing ram will shift downwardly with respect to cross bar 7 compressing the spring 9 which is set to yield only when a force which might break the piercing ram is applied thereto. The piercing ram might then shift down to the position indicated at 4" which is sufficient to avoid the danger of breaking the piercing ram, and then the spring 9 expands to return the piercing ram to its operating position while the extrusion process continues.

The invention obviously is applicable to horizontal as well as vertical presses, and the invention also is applicable to presses where the piercing ram is mounted diiferently from the embodiment shown in the drawing.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of extrusion presses differing from the types described above.

While the invention has been illustrated and described as embodied in piercing ram arrangement for extrusion presses, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the invention.

Without further analysis, the foregoing will 'so fully reveal the gist of th present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpointoffipriorart, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations shouldand are intended'to be comprehended within the meaning and range of equivalence of the following claim.

What is claimed as new and desired to be secured by Letters Patent is:

In an extrusion press, in combination, an elongated piercing ram having an elongated free end portion of a diameter smaller than the next portion of said ram and joined thereto by a shoulder; a cross bar formed with an opening through which said end portion of said ram passes with slight clearance, said cross bar engaging said shoulder; moving means for moving said cross bar toward the end of said ram distant from said free end por- References Cited in the file of this patent UNITED STATES PATENTS 349,015 Thompson Sept; 14, 1886 861,194+v Schwieger, July 23, 1907 1,150,394 Schlenstedt Aug. 17, 1915 1,664,990 Oehmig et a1 Apr. 3, 1928 FOREIGN PATENTS 233,891 Germany Apr. 26, 1911 822,988 Germany Nov. 29, 1951

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