US2778494A

US2778494A - Extrusion apparatus for thin-walled hollow tubing

Info

Publication number: US2778494A
Application number: US326428A
Authority: US
Inventors: Kreidler Alfred
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-12-31
Filing date: 1952-12-17
Publication date: 1957-01-22
Anticipated expiration: 1974-01-22

Description

Jan., 22, i957 A. KREIDLER 778,494

EXTRUSION APPARATUS FOR THIN-WALLED HOLLOW TUBING Filed nec. 17, 1952 United States Patent Fice.

EXTRUSION APPARATUS FOR THIN-WALLED HOLLOW TUBING Alfred Kreidler, Stuttgart, Germany Application December 17, 1952, Serial No. 326,428 Claims priority, application Germany December 31, 1951 1 Claim. (Cl. 207-9) The invention concerns the production of hollow, especially thin-walled bodies by forming. It is also concerned with the production of a sleeve-shaped body, in which the material for the formation of the wall of the sleeve rises round the ram in the ow forming process (Becher-flow pressing) and it can also concern the forming by punching of a hollow body by a ram in the die penetrating into the bar, or a hollow body with stranddike extensions by forming, in which the shell of the bar to be extruded remains as the wall of the hollow body, or finally, any desired combination of two or all three of the above possibilities. The process according to the invention may be considered for hot forming and for cold forming.

ln all these processes there arises a difficulty that the press ram can only be removed from the finished hollow body with diiiiculty. The present invention seeks to overcome these difliculties.

It is, therefore, one object of the present invention to provide a substantially thin disc, projecting over it-s frontal surface, on the press ram which remains in Ithe hollow body as a lost disc after the forming operations; thereby then resulting in a certain play between the inner wall of the hollow body and the ram so that it can be extracted without effort.

The use of pressure discs of 'greater thickness, for example about 60 mm. thickness, is known in itself. These consist of expensive heat resisting tool steel, as they are intended to be used for a large number of pressing operations. For the present case, where the disc remains in the formed part-i. e. is only used once-fairly thin thick-- nesses are sufficient and also the material need not be of such high value.

It is another preferred object of the present invention to provide a cap (sheet metal hood) over-lapping the ram with its edges which can be used as the lost disc. In order to keep the disc or cap central with respect to the bar so that equal thickness of the wall may be obtained around the hollow body, it is expedient to use a blank which is provided on its frontal surface turned towards the ram with a flat central shallow bore for the reception of the disc or cap.

It is still another object of the present invention to provide a disc of sheet metal to be disposed in front of the ram, the edge of this disc projecting beyond the ram being flanged over the frontal edge of the punch at the beginning of the pressing operation, like a cap.

As the thickness of the disc or cap mounted in front is generally comparatively slight, it will be advisable for it to be cooled during the forming operation with a suitable cooling liquid fed and discharged through the ram.

lt is therefore, still another object of the present inven- 2,778,494 Patented*y J'a-n. 22', 1957' tion in which the ram, is expediently provided onl its frontal surface-with coolingA grooves extending spirally or radially, for example, into which longitudinal bores empty for the feeding and discharge of the cooling fluid.

With these and other objects in view which will become apparent in they following detailed description, the present invention Will be clearly understood in connection with the accompanying drawings, in which:

Figure l is a longitudinal section through the relevant parts of a forming press at the beginning of the pressing operation, with the use of `a lost disc;

Fig. 2 is a similar view at a later stage at the same operation;

Fig. 3 is a view similar -to Fig. 2 but showing the use of a sheet metal hood instead of the flat disc; and

Figs. 4 and 5 are similar views showing the use of a round of sheet metal mounted in front of the ram.

A cylindrical holder 1 of a forming press (Fig. l) is sealed oi by a matrix 2, which has a discharge aperture 3. A blank 4, which has a shallow central bore 6 on its frontal surface turned towards the ram 5, is inserted into the holder 1. A pressure disc 7 is inserted into the bore 6 so `as to be mounted in front of the ram 5. The ram has on its frontal surface radially extending cooling grooves 8 which communicate with feeding and discharge channels 9 for the cooling liquid. Although the feeding and passage channels 9 and cooling grooves 8 are shown in the embodiment disclosed in Figs. 1 and 2 only, it is to be understood that such cooling grooves may be provided also in the ram 5 of Figs. 3 to 5, disclosing the other two embodiments, described below.

When the ram 5 is lowered with the disc 7 (Fig. 2) on the one hand a strand-like extension 8 is forced through the aperture 3 of the matrix 2, whilst on the other hand the wall 11 of the hollow body to be produced remains in the holder. As a result of the difference in diameter between the disc 7 and the ram 5, a clearance 12 remains between the latter and the remaining wall 11. This clearance allows lthe ram 5 to be withdrawn immediately after the completion of the forming operation, whilst the disc 7 remains in the pressed piece as a lost disc.

In a variation (Fig. 3) a sheet metal hood 13 is mounted in front of the ram 5 instead of the disc 7. The iiange 14 of this hood overlaps the frontal edge of the punch. The thickness of the flange 14 determines the clearance 12 between the wall 11 and the punch S.

Finally, a deformable sheet metal disc or round plate 15 may be used (Fig. 4). This round plate is disposed in front of the ram 5; and the front edge region 16 of the round plate 15 (Fig. 5) is anged backwards during the pressing to form a hood over the 4front edge of the ram.

While I have disclosed several embodiments of the present invention, it is to be understood that these embodiments :are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claim.

l claim:

In a forming press for producing hollow workpieoes by pres-sing out the core from solid main blanks by means of a relatively thin auxiliary blank disposed on the face of the said main blank which is subjected to pressure, a reciprocating ram having passages extending longitudinally therethrough, grooves disposed in the front face of :the said ram, the said passages terminating into said grooves, the latter bearing against the said auxiliary blank, the said passages and grooves being adapted to pass a cooling medium through the said ram for cooling the ram face and the said auxiliary blank.

References Cited in the le of this patent UNITED STATES PATENTS Born Nov. 14, 1933 Staples Feb. 18, 1936 Singer Mar. 31, 1936 Friden Nov. 21, 1939 Hill Feb. 11, 1941 Poux Oct. 19, 1948