US2932390A - Displaceable guiding mechanism for extrusion mandrel - Google Patents

Description

April 12, 1960 D. A. EDGEcoMBE 2,932,390

DISPLACEABLE GUIDING MECHANISM FOR ExTRusIoN MANDREL 2 Sheets-Sheet 2 Filed April 16, 1954 INVENTORY' Enfca/vaf bmm l l l l l I l r l l z l l l passage.

DISPLACEABLE GUIDING MECHANISM FOR g EXTRUSION MANDREL Application April 16, 1954, Serial No. 423,802v

6 claims. (c1. 207-19) This invention relates to the extrusion of tubular "nited States Pam O metal elements from pierced billets and, more particularly, to novel displaceable lguidingmechanism for the free end of the mandrel of an extrusion press.

In the formation of metal shapes by extrusion, a block lor billet of metal at an elevated temperature is forced under high pressure to ilow through a die having an opening corresponding to the desired cross-sectional shape of the extrusion to be produced. The temperature of the metal may be 2300 F., in the case of steel, byway of example.

To form a tubular extrusion, the billet is usually pierced Y before insertion in the extrusion press and, before ram pressure is applied to the billet, a mandrel is projected coaxially through the billet and die. When pressure is `applied to the billet, the billet metal ows through the die around the mandrel, so that a tube is extruded having dimensions determined by the die and the mandrel. In effect, the die and mandrel cooperate to form an annular die. y In a typical extrusion press, a front and rear platen are held in accurately spaced relation with `each other. Between the platens is mounted a billet container for movement toward and away from the forward platen. The rear platen supports a ram arranged to project into the container and'force a billet therein to ow through the die. The latter is mounted in a die holder releasably j engaged `in a die carrier aligned with the container This carrier is mounted for movement into and out of the forward platen to move the die into and vout of operative relation with the exit or downstream end of the container. The ram hasA a mandrel coaxially ltelescoped therewith for forming tubular extrusions.

When an extrusion is to be made, the container is moved forwardly to seat against the rear face of the forward platen. A die holder and die assembly is meanwhile mounted on the rear face of they carrier and the latter is moved rearwardly into the forward platen to engage the die in a recess in the forward endof the lcontainer and coaxial with the container passage. The

carrier is then locked to lthe forward platen. After a heated billet has been loaded into the container, the

.mandrel is projected through the pierced billet into the `die. yend, is then moved forwardly under very high pressure to force the billet outwardly through the die.

The ram, carrying a dummy block on its outer The extrusion is then severed and conveyed away from the press.

j The formation of metal shapes by extrusion has been successfully applied to non-ferrous metals for some time. However, it is only recently that plain and alloy steels have been extruded using glass as a lubricant. This has been due to the relative diiculties and problems involved in the extrrusion of steels and alloys as compared to the diliculties and problems of extruding non-ferrous metals such as aluminum, brass, and copper. For example, the use of lubricants having ,a carbon base for Vthe extrusion of some alloy `steelsr`nay require an eX'- the billet` internal passage.

'ice

cessive amount of refinishing of the extruded shape due lto the carbon pickup inthe hot metal. These extra finishing operations have prevented the extrusion process from attaining a competitive position with respect to other metal working processes.

This picture has been changed radically by the introduction of a new steel extrusion process in which rela- ,tively refractory materials, such as glass, have been used as lubricants. These refractory materials have the advantageV that they do not contain any significant amounts of carbon as Aa constituent element, coupled with a further advantage that the glass has the property of melting in successive layers or films as it is contacted `layer ofthe glass -is initially melted as the billet moves therealong, and as this lm is destroyed, successive underlying layers or fh'ns are melted sequentially, thus provid-l ing a continuous lubricant iilm between the extrusion `and the die through which the extrusion is being forced under very high pressures.

In the aforementioned typical extrusion press, plugs of glass ber or similar material are placed in the container passage before the billet is loaded into the container. Charging of the billet into the container pushes these plugs up against the upstream or entry surface of the die. In addition, a layer of glass lubricant is applied to the external surface of the hot billet as the latter. is being fed to the extrusion press. This is presently effected by rolling the hot billet over powdered or particle form glass spread on a transfer surface over which the hot .billet moves to the extrusion press. The glass adheres to and form-s a thin layer on the external surface of the billet. Y v

As described Iin the copending application of A. Bv. Capron et al., Serial No. 413,766, filed March 3., 1954, the surface of the internal passage in the pierced billet is lubricated by depositing a measured quantity of powdered glass in such passage for distribution over the surface thereof as a lm or layer as the billet rolls over the transfer surface.

The application of lubricant tothe billet surfaces in the form of powdered glass provides thin glass lms of uniform depth on these surfaces. The resulting thin films permit the clearances between the billet and-con tainer, and between the mandrel and billet, to be greatly reduced as compared to the clearances required .when the glass lubricant is applied in the form of blankets or sleeves ofl glass ber. This, in turn, greatly improves the concentricity of the extrusion.

However, the close clearance between the mandrel and the internal surface of the billet introduces a problem in projecting the mandrel through the billet. Any deflection .of the free or unsupported end of the mandrel causes the mandrelto engage the glass layer and scrape it off This is particularly true in the case of mandrels having a high ratio ofV length to Y diameter.

trusion by the latter as the ram forces the billet through the die around the mandrel. j K t \More specifically, the spider body has circumferentially "spaced radial slots therein' in each of"whih\-"is pivotally mounted a blade or runner. When the mandrel is projected into the billet passage, these runners are swung backwardly and outwardly to project from the spider to ride along the glass layer or surface of the billet to center-the mandrel in its movement through the fbillet and into the die. While the runners may scrape some lglass from the billet internal surface, the amount removed is inconsequential as the guiding surfaces of the runners are narrowed -to attain substantially line-contact with the engaged surface. Backward movement, and thus projection, of the runners is limited to a pre-set value by engagement of surfaces of the runners andslot.

The spider may take either one or twoforms. -In one form, the spider body is xedlysecured to the Vfree end of the mandrel, and the runners are lof suchdimension as to be folded or collapsed within their slots by the extrusion as the latter flows over the mandrel and spider. In the lother form, -the'spider body `is merely set on the end of the lmandrel to guide it through the fbillet. In this form, the runners'do not collapse and the spider is carried out of the vpress in front of the extrusion -as the latter isformed.

For an understanding of the invention-principles, refenence is made to the following description of typical-embodiments thereof as illustrated in the accompanying drawings.

In the drawings:

Fig. l is a longitudinal sectional view through an extrusion press die, loaded container and ram, showing a mandrel equipped with vthe guiding means of the invention;

rFig. 2 isa front elevation view of thespider, taken on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged logitudinal sectional view `of a pierced billet showing a mandrel with a completely collapsible form of spider being projected therethrough;

L'Fig. 4 is a similar view of a die and extrustion, showing thecollapsible spider as an extrusion ows thereover;

Figs. 5 and 6 are views, respectively similar to Figs. 3 and 4, illustrating a modified form of runner;

Fig. 7 is a front elevation -view of a non-collapsible spider; and

Fig. 8 is a view, similar to Figs. 4 and '6, of the spider of Fig. 7 being displaced from a mandrel byan extrusion.

Referring to Fig. 1, an extrusion press 10 is illustrated as including a die assembly 20, a container 15, a ram 17, and a mandrel 18 mounted coaxially of ram 17 and projectabl'e therefrom. Die assembly 20 is held against the exit or downstream end of a passage 16 in a container liner 14 by a suitable die carrier (not shown), and includes a mounting ring 21 in which is mounted a frusto-conical die 25 and a frusto-conical backing ring 22. Mounting ring 21 has a frusta-conical surface 23 engaging a frusto-conical seat 27 in liner 14, and an annular concave upstream surface 24 forming a continuation of the upstream or entry surface 26-of die 25.

Mandrel 18 extends through and supports replace- -able dummy block 11 on ram 17. In accordance with the invention, the free end of mandrel 18 carries a spider 40 described more fully hereinafter.

As described in the copending application of vSidley O. "Evans, Serial No. 328,688, tiled December 30, 1952, now 'Patent No. V2,739,799 billets intended for the extrusion of tubular products are preferably initially heated to a piercing temperature and then pierced with Yan I.D. somewhat larger than that of the extruded tubular products. The initial heating means, the piercing press, and associated conveyors, and handling devices have not been shown as they form no part of the present invention.

The pierced billets are then heated to a high temperature, such' as 2300 F. in the case of steel, in a suitable vheating means. `The billets are charged into the heating means and extractedl therefrom by suitable billet handling device. This device deposits the heated billets 4onto a transfer means which transfers the billets into alignment with passage 16 of container liner 14 and ejects them into this passage.

While being transferred from the heating means for injection into container 15, the pierced billet 30 has thin layers of glass, uniform in depth, applied to its outer surface and to the surface of the pierced passage 35. These layers are indicated at 31 and 36, respectively. Layer 31 is applied by rolling the heated billet over particulate glass spread on a surface of the transfer means. Layer 36 is applied by depositing a measured quantity of particulate glass into vpassage 35. As the hot billet rolls along the transfer surface, the particulate glass is spread over and adheres to the billet cylindrical surfaces forming the thin glass ilms 31 and 36 of a predetermined small depth on these surfaces.

Mandrel 18 with spider 40 is first extended through passage 35 and into die 25. Ram 17 is then projected into passage 16 to engage the billet and force it, under high pressure, to ow through die 25 around mandrel 18, thus forming a tubular extrusion. Mandrel 18 is withdrawn into ram .17 at the end of the extrusion stroke, and ram 17 and mandrel 18 are then conjointly withdrawn and container 15 moved rearwardly a short distance away from the front platen of the press. The extrusion is then severed between the container and front platen, after whichcontainer 15 is moved forwardly and theextrusion withdrawnby a runout table and conveyor. Ram 17 is -then moved into container 15 to eject the severed end, or discard, of the extrusion, this discard moving into the front platen and falling into a suitable receptacle.

Before the billet 30 is charged into the passage 16 of container liner x14, one or more cylindrical plugs of glass fiber (not shown) are placed in the passage 16 so that loading of the billet thereinto will result in the plugs being interposed lbetween the billet and the upstream face of the die assembly. The die assembly is shown and described more particularly in the copending application v vof David A. Edgecombe, Serial No. 334,211, tiled January 30, 1953, for Die Charging Arrangement for Metal Working Apparatus, now Patent No. 2,731,123.

Referring lmore particularly to Figs. 2, 3 and 4, the spider 40 illustrated is completely collapsible by the extrusion, and includes a body 45 carrying radially projectable, circumferentially spaced runners 50. A tapped axial recess 41 at the body rear end receives a threaded axial mounting pin or stud 12 on the free end of mandrel 18. The forward end of body 45 is formed with circumferentially spaced radially and axially extending slots 42 which open through the front of the body and have radial rear walls 43 and parallel at side walls 44. Preferably four (4) slots 42 are provided, although a different number of radial slots may be used.

At equal, pre-set distances from the axis of body 45, the side walls 44 of each slot are formed with coaxial drilled passages 46 extending perpendicularly to the side walls to receive driven pins 47 having a length such as to 'terminate inwardly of the outerl surface 48 of body 45. These pins pivotally support the runners 50, each of which is `mounted in aslot 42.

Runners 50 have-the general shape of an isosceles trapezoid with the base corners rounded. The main body portion 51.has a thickness substantially equal to the width of a slot 42, for guiding contact with slot side walls 44. A transverse aperture 52 adjacent one base corner receives pin 47. The base 53 and outer sloping side 54 of the runner are bevelled o'n each side surface to provide narrow edges 55, 56.

Short, narrow edges 55 engage the glass lm 36, when mandrel 18 is projected into passage 35, to guide and center the mandrel in passage 35 and die 25. When mandrel 18 is thus to be projected, runners 50 are swung backwardly and outwardly luntil runner surfaces 57 engage slot rear'walls 43,V limiting the runner projection to a pre-set .amount just suicient `for guiding contact with assenso glass layer 36. The runners may remove narrow strips of layer 36,' but the amo'unt removed is inconsequential due to the narrowness of edge 55. The spider projects beyond passage 35 before billet 30 is compressed and extruded. When the ram 17 is forced into passage 16 to `compress and extrude billet 30, the extrusion 38 ilows through die 25 overmandrel 18 and spider 40. The extrusion 38 collapses runners 50 into slots 42, as shown in Fig. 4. It should be noted that the configuration of runners 50 is` such that the dimensional spread of the runners, when collapsed, is less than the I.D. of extrusion 38, so as not to obstruct the latter.

The circular rounding of the pivo't corner of each runner assures that the distance of the edge of this corner from its pivot cannot increase as the runner folds, and can, at the most, remain constant. This prevents damage to the inside of the extrusion by the folded runners.

Figs. and 6 illustrate an alternative form of runner which is notcompletely collapsible into the spider body.

Runners 60 are triangular in shape, with rounded corners, and have body portions y61 whose thickness is equal to the width of slots 42 for guiding engagement with slot side walls 44. A transverse aperture at the inner corner of each runner receives a pin 47. Extending lfrom this corner is a rectilinear surface 63 arranged to engage slot rear wall 43 to' limit backward and outward movement of the runner. 'I'he other two edges 64 and 66 are doubly bevelled to provide narrow surfaces 65 and 67, respectively. Surface 65 has guiding engagement with glass lm or layer 36 when runners 60 are extended during projection of mandrel 118 and spider 40 through passage 35.

When ram 17 forces billet 30 through die 25 around mandrel 18 and spider 40 to form extrusion 38, the extrusio'n folds runners 60 forwardly and inwardly until the diametric projection of the runners is less than the internal diameter of the extrusion. The extrusion then Hows over the partially retracted or collapsed runners 60.

In operation of the forms of the invention illustrated in Figs. l through 6, runners 50 or `60 are `first moved outwardly of the slots to their limit of movement, being retained in this position in a suitable manner such as by tight contact between the wall surfaces 44 of the slots and the side surfaces of the runners. Mandrel 18 is then projected through the billet passage and into die 25, runners 50 and 60 remaining fully extended during this movement. Ram 17 is then advanced to extrude the billet, and the extruded tube first folds the runners 50 or 60 inwardly of the slots and then passes over the folded or collapsed runners.

Figs. 7 and 8 shdw a non-collapsible form of spider used in certain instances. Referring to these figures, the spider 40 has a body 45 which is simply a short piece of relatively thick tubing which slips over the smooth or threaded pin 12 of mandrel 18. Welded to the outer surface of tubular body 45 are fins 70, four nsbeing illustrated, although a different number may be used. These tins have a height sucient to provide the necessary guiding function for mandrel 18', the outer edges of the iins having narrow guiding surfaces 75 corresponding to the guiding surfaces 55 and 65 of the other embodiments.

As the ram forces the billet to' ilow around the mandrel to form extrusion G8, this extrusion engages the rear edges 77 of fins or runners 70, forcing spider 40 outwardly through die 25, separating the spider from mandrel .18. The ejected spider is recovered and reused.

on the free end of said mandrel and having a diameter less than the mandrel diameter; said body having peripherally spaced, longitudinally extending, radial slots therein; and runners pivo'tally mounted in said slots for movement into positions projecting from the body surface into substantially knife edged guiding engagement with the billet internal surface as the mandrel is projected through the billet to center the mandrel through the billet; said runners lbeing displaceable out of an extended billet engaging position into a collapsed non-billet-engaging position by force which pivots said runners toward the mandrel axis extending beyond the free vend of said mandrel; outward movement of said runners being limited, by engagement between coacting surfaces on the runners and slots, to positions in which the runners have only guiding contact with the billet internal surface.

2. A guiding mechanism for the free end of an extrusion press mandrel comprising a spider including a body mounted o'n the free end of said mandrel and having lateral dimensions not greater than those of the mandrel; said body having at least one normally vertical, longitudinally extending slot therein; and a runner, having a relatively narrow guiding edge, pivotally mounted in said slot for movement into a position projecting from the body surface into guiding engagement with the internal surface of a tubular billet as the mandrel is projected through the billet to center the mandrel through the billet; said runner being displaceable out of an extended billet engaging position into a collapsed no'n-billet-engaging position by force which pivots said runner toward the mandrel axis extending beyond the free end of said mandrel; outward movement of said runner being limited, by engagement between coacting surfaces on the runner and slot, to a position in which the runner has only guiding contact with the billet internal surface.

3. A guiding mechanism for the free end of a mandrel comprising a spider including a body mounted on the free end of said mandrel and having a diameter not greater than the mandrel diameter; said body-having at least one longitudinally extending radial slot therein; and a runner having a relatively narrow guidingI edge, pivotally mounted in said slot for movement into a position projecting from the body surface into guiding engagement with the internal surface of a tubular billet as the mandrel is projected through the billet to center the mandrel through the billet; said runner being displaceable out of an extended billet engaging position into a collapsed non-billet-engaging position by force which pivots said runner toward the mandrel axis extending beyond the free end of said mandrel; outward movement of said runner being limited, by engagement between coacting surfaceson the runner and slot, to' a position in which 4. A guiding mechanism lfor the free end of a mandrel comprising a spider including a body mounted on the While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventio'n principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A guiding mechanism for the free end of a mandrel comprising a spider including a body detachably mounted free end of said mandrel and having a diameter not greater than the mandrel diameter; said body having peripherally spaced, longitudinally extending, radial slots therein; and runners, having a relatively narrow guiding edge, pivotally mounted in said slots fo'r movement into a position projecting from the body sur-face into guiding engagement with the internal surface of a tubular billet as the mandrel is projected through the billet to center the mandrel through the billet; said runners being displaceable out of an extended billet engaging position into a collapsed non-billet-engaging position by force which pivots said runners toward the mandrel axis extending beyond the free end of said mandrel; outward movement of said runners being limited, by engagement between coacting surfaces on the runners and slots, to a position in which the runners have only guiding contact with the billet internal surface.

5. Mandrel guiding mechanism as claimed in claim 2 in which said guidingedge is convexly curved inthe direc- 180,169 -tion VVof mandrel movement. 294,537 6. Ma-ndrel guiding mechanism as claimed in claim 1 361,569 vin which the vknife edge is coxwezdyl curved in the direc- 1 t' f cl l t. f, 1on`o man re movemen 2,320,071 References'Cited in the le of this patent 21732938 UNITED STATES PATENTS 91,815 Bailey June 29, 1869 1 406,455

8 Tasker July 25, 1876 Waringl Mar. 4,v 1884 Adams Apr. 19, 1887 Thust Oct. v2, 1900 Burlington Dec; V28, 1915 Frothingham -May ,25,v 1943 Albers July '31, `1956 FOREIGN PATENTS .Great Britain Mar. 1, 1934

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