US2967613A - Metal forming apparatus - Google Patents

Description

J. L. ELLIS ETAL METAL FORMING APPARATUS Jan. 10, 1961 4 Sheets-Sheet 1 Filed April 28, 1955 INVENTORS JOHN 1.. ELL/.9

ATTORNEY Ebb! w Jan. 10, 1961 2,967,613

J. L. ELLIS ETAL METAL FORMING APPARATUS Filed April 28, 1955 4 Sheets-Sheet 2 FIG. 3.

/Z //a Z IN VEN TORS l/Ol/N A. ELL/.9

Jan. 10, 1961 J. ELLIS ETAL 2,967,613

METAL FORMING APPARATUS Filed April 28, 1955 4 Sheets-Sheet 3 INVENTORS JOHN L. ELL/5 64/105 6. GOETZEL ATTORNEY 6 J. L. ELLIS EI'AL 2,967,613

METAL FORMING APPARATUS Filed April 28, 1955 4 Sheets-Sheet 4 M \x; m Q m 3 \m R R c5 E E i i 1 sax r METAL FORMING APPARATUS John L. Ellis, White Plains, and Claus G. Goetzel, Hastings-on-Hudson, N.Y., assignors to 134 Woodworth Corporation, a corporation of New York Filed Apr. 28, 1955, Ser. No. 504,474

1 Claim. (Cl. 207-2) The present invention relates to an apparatus for the production of extruded products from diflicult-to-process metals such as titanium and titanium alloys.

Titanium is much more abundant in the earths crust than copper, nickel, lead, tin and zinc combined. Unfortunately, the metallurgy of titanium from the ore to the final product is diflicult and expensive. It has been estimated that the cost of producing ductile titanium from ore is about 200 times the cost of the ore itself.

At present the most widely accepted method of producing titanium is the Kroll process. The metal is produced in the form of a sponge by the reaction of titanium tetrachloride with molten magnesium at an appropriate temperature (e.g. 1475 F. to 1650 F.) under substantially inert conditions in an enc'osed container. Except for the presence of small amounts of residual magnesium and chlorine, the titanium sponge has a fairly high purity and can be used in the production of ductile metal products.

The conversion of the sponge into a usable product by melting presents many metallurgical dffficulties. Titanium has a high melting point (about 3150" P.) which is close to softening points of some refractories. Furthermore, titanium is highly chemically reactive and has a strong affinity for most refractory oxides. The metal has a tendency to attack the crucible in which it is melted. The titanium itself is affected by the crucible and loses its ductile characteristics and consequently cannot be easily worked into wrought shapes. While graphite has been found a more suitable material to contain the molten metal, there is a tendency for the metal to pick up uncontrollable amounts of carbon as titanium carbide which has a deleterious effect on the wrought characteristics of the metal.

To produce cast titanium and alloys thereof requires cumbersome melting and casting equipment. The melting must be carried out under substantially inert conditions, for example under helium or argon or vacuum, as the molten metal has a strong afiinity for oxygen and nitrogen and is affected adversely by these gases.

Because the melting of titanium did not lend itself to conventional economical metallurgical practices, attempts have been made to convert titanium sponge or high purity powder directly to solid ductile metal. Powder metallurgical methods of consolidating and sintering sponge or powder were tried. However, these methods required such high specific pressures and prolonged sintering treatments in high vacuum that their use was greatly limited economically to special situations.

A means has now been discovered which enables the mass production of articles directly from metal power or similar materials by the combined use of hot pressing and hot extrusion in a single apparatus appropriately sealed from the atmosphere to protect the metal from gaseous impurities until it has been converted into the desired solid shape. The expression metal powder as employed herein is meant to include metal sponge, metal fragments,

pieces, etc.

2,967,613 Patented Jan. 10, 1961 It is the object of this invention to provide an apparatus for converting metal powder, particularly titanium and titanium alloy powders, directly into solid shapes.

Other objects will more clearly appear from the following description when taken in conjunction with the drawings in which:

Figs. 1 to 3 depict partially in cross-section an embodiment of an apparatus employed in the invention; and

Figs. 4 to 8 show another embodiment of the apparatus employed in carrying out the invention.

In the two embodiments illustrated by Figs. 1 to 8, only those details are shown to explain the invention. Thus, Figs. 1 to 3 show a partial view of hopper 1 containing metal powder 2, the hopper being slidably mounted on surface 3 and hopper support surface 3a of the compacting and extrusion container 4. Container 4 comprises compacting chamber 5 with heating elements 5a and directly below it extrusion chamber 6 with heating elements 6a, the two chambers being separated by a slidably mounted back-up compacting plate 7 actuated by a hydraulically operated piston 8 through hydraulic cylinder 9 located outside of vacuum bell 21 which houses the compacting and extrusion chambers. Back-up plate 7 has an opening 10 therethrough the same size as the opening in chambers 5 and 6 adapted to place chamber 5 into communicating relation with extrusion chamber 6 when beck-up plate 7 is caused to slide to the left through the hydraulic actuation of piston 8 attached to the end of the plate.

At the bottom of extrusion chamber 6 is a movably mounted split extrusion die 11 made of a wear resistant tool steel or cemented carbide. The die is mounted in two parts in the die holders 12 and 12a slidably supported in the Walls of the extrusion container as shown and connected to hydraulic pistons 13 and 13a actuated by hydraulic cylinders 14 and 14a. suitably supported outside of vacuum bell 21. The compacting and extrusion container assembly is supported by an annular block 15 of cast iron or steel. The opening 11a below the extrusion die into which the product is extruded extends into a receiver 16 in annular block 15, the receiver communicating with chamber 17 of foundation support 18 comprising a heavy iron casting of ribbed construction. Chamber 17, into which the extruded products fall, is sealed against the atmosphere by cover 19 bolted to the bottom openings and maintained air tight by resilient seal 20 as shown.

The vacuum bell 21 has an upper plate 22 bolted to an annular flange 23 which is welded to the bell at 24 as shown, the upper plate being sealed tight against the atmosphere by resilient seal 25. The lower part of the bell is bolted to the top 18a of foundation 18 of ribbed cast iron construction by means of annular flange 26 welded at 27 to the bell, the bell being sealed substantially air tight by means of resilient seal 28 as shown. Annular support block 15 is bolted-to foundation 18 so that receiver 16 communicates with chamber 17 in the foundation.

Above surface 3 of the compacting and extrusion container is located compacting and extrusion ram 29 which passes through upper plate 22 and is supported by an assembly comprising a gland flange 30 and gland box 31 with a seal 32 to seal the bell against the outside atmosphere. The gland box is welded to plate 22 at 33. The ram is actuated by hydraulic means not shown;

As has been stated, powder hopper 1 is slidably mounted on top of surface 3 of the compacting and extrusion container and has means located outside the bell to slide the hopper over chamber 5 and deliver the powder and slide back to surface extension 3a, this being accomplished by a hydraulically operable piston 34 passing through the bell from a cylinder 35 and linked to the hopper at 36. The bell is sealed against the atmosphere where the piston enters by seal 37 in the assembly comprising gland box 38 and gland flange 39 as shown. Pistons 8, 13 and 13a are similarly sealed. Thus, the sealing assembly for piston 8 comprises gland box 40, seal 41 and gland flange 42. The assembly for piston 13 comprises gland box 43, seal 44 and gland flange 45 while the assembly for piston 13a consists of gland box 4311, seal 44a and gland flange 45a. A suitable outlet 46 with a valve not shown is provided in the bell at 46 for attachment to a vacuum pump to effect evacuation.

While supporting means have not been shown for the cylinders, it will be understood that such means are contemplated in the apparatus of the invention. Likewise, it will also be understood that additional supporting means may be employed within the bell for eacn of the pistons in order to reinforce tuem and to minimize vibration, etc.

The foregoing embodiment is particularly applicable to the vacuum step extrusion of powder compacts, for example in the step extrusion of compressor blades from relatively high purity titanium powder. By step extrusion in this case is meant the production of blades in which only part of the material is extruded through the die to form the foil shape, the unextruded part forming the foot section.

In utilizing the foregoing apparatus, metal powder is charged into compacting chamber and upper plate 22 bolted to the bell as shown in Fig. l, the powder being held in place by back-up plate 7. The wall of the chamber which is heated electrically by, for example, electrical heat resistant elements of nickel-chromium alloy of a type comprising about 80% nickel and 20% chromium. After completion of the charging, the hopper 1 is moved to one side by means of the hydraulically operated piston 34. The apparatus within the bell is then evacuated through outlet 46 while the metal powder is brought up to compacting temperature. In the case of titanium powder, the temperature may range from about 1400" F. to 1900 F.

The heated powder is then compacted by ram 29 under a pressure of at least about one ton per square inch, the pressures generally ranging from about one to about six tons per square inch (Fig. 2). After completion of compaction, the back-up plate 7 is caused to slide to the left by means of hydraulic piston 8 bringing plate opening 10 underneath the compacting chamber 5 to connect it to extrusion chamber 6. The downward travel of ram 29 is continued, thereby forcing the compacted metal into the extrusion chamber while under heat and vacuum.

The hot compact is then step extruded (Fig. 3), allowing a portion of the metal to be forced through the extrusion die and taking the shape of the die orifice. The remainder of the metal stays above the extrusion die and is fully worked and condensed by the action of the ram. Depending upon the metal powder being compacted and extruded, extrusion pressure at the commencement of extrusion will range up to about 30 tons per square inch, the extrusion pressure diminishing rapidly as the metal begins to flow.

Upon completion of extrusion, the split extrusion die is separated hydraulically or by other means and the ram caused to force the step extruded product out of the extrusion chamber into chamber or compartment 17 under vacuum. The apparatus is then prepared for another extrusion. After suflicient number of extrusions have been obtained, they can be removed by detaching cover 19 after the vacuum has been released.

While the foregoing apparatus has been described with respect to producing a step extrusion, it is, also adapted for producing complete extrusions such as rods, tubes and other elongated articles of various cross-sectional shapes.

In the other embodiment of the invention illustrated by Figs. 4 to 8, a similar set-up is employed with the exception that the hot compacting chamber and the extrusion chamber are located side by side in the same container and are connected by a transfer chamber through which the hot compacted powder is fed to the extrusion portion of the apparatus. The container is similarly housed in a vacuum bell 65.

Fig. 4 shows a slidably operable hopper 50 through which powder 51 is fed into compacting chamber 52 contained in compacting-extrusion container 53 having an extrusion chamber 54 adjacent and connected to the compacting chamber by transfer chamber or passageway 55.

A plate 56 with an opening 57 the size of the compacting and the extrusion chamber openings is slidably mounted in transfer passage 55 and is actuated by piston 58 hydraulically operated by cylinder 59 outside of vacuum bell 65 by means well known to the art. Associated With tne compacting chamber are electrical heating units 68 similar to tnose described hereinbefore. Similarly, the extrusion chamber has electrical heating units 61. Also associated with compacting chamber 52 are upper and lower compacting rams 62a and b working in opposition to each other to compact the metal powder.

Associated with the extrusion chamber is a movably mounted split die 63 shown better in Fig. 8 which is a top view taken through 88 of Fig. 7. Located at the top of the chamber is an extrusion ram 64 passing through the bell appropriately sealed to protect the hot compactedpowder from atmospheric gases. The opening 66 below the extrusion die into which the product is extruded extends into a chamber or enclosure 67 of foundation support 68 comprising a heavy iron casting of ribbed construction. The chamber receives the finished extrusion, the chamber being sealed against theatmosphere by cover 69 bolted to the bottom opening and maintained air or vacuum tight by resilient seal 70.

The split die arrangement shown in Fig. 8 which simulates the cross-section of a foil section comprises two slidably mounted halves 71a and b connected to pistons 72a and b operable by cylinders outside the bell not shown.

The vacuum bell 65 has an upper plate 73 bolted to annular flange 74 which is welded to the bell at 75, the upper plate being sealed tight against the atmosphere by resilient seal 76. The lower part of the bell is bolted to the top 68a of foundation casting 68 by means of annular flange 77 welded to the bell at 78, the bolted joint being sealed substantially air tight by means of resilient seal 79. The compacting and extrusion container is rigidly bolted to the top of foundation casting 68 and 80a and b.

The opening 81 below the compacting chamber extends into a larger opening 82 containing a bolster ram 83 operated by pusher ram 84 which extends up from the bottom of foundation 68. The ram 84 is sealed air tight by means of seal 85 held in place by flange 86.

Slidably mounted powder hopper 50 is actuated by means located outside of the vacuum bell comprising a suitably supported hydraulic cylinder 87 having a piston 88 projecting into the bell through a gland assembly in the wall of the bell comprising gland flange 89, gland box 98 having a resilient seal 91, said piston being linked to hopper 50 at 92. Thus, hopper 50 containing a charge of powder 51 may be caused to slide over the surface of container 53 to communicate with compacting chamber 52 and to charge said chamber and then be returned to surface extension 93 of said container. Piston 58 is similarly sealed air tight by means of a gland assembly in the wall of the bell comprising gland flange'94, gland box 95 and seal 96.

Rams 62a (compacting ram) and 64 (extrusion ram) enter upper plate 73 of the bell through a similar sealing arrangement as shown comprising gland boxes 97 and 98 with flanges 99 and 100 with seals 101 and 102, respectively, the gland boxes being welded to the upper plate.

A suitable outlet 103 with a valve (not shown) is provided in bell 65 through which evacuation of the bell may be effected.

Like the first embodiment, the foregoing apparatus is applicable to vacuum extrusion of hot compacted metal powder, either in the form of complete extrusions or stepped extrusions such as compressor blades having an extruded air foil section with a worked but unextruded foot section.

In employing the second embodiment of the invention, upper plate 73 is detached and powder is charged into compacting chamber 52 as shown in Fig. 4, the bottom of the chamber being sealed by ram 62b. The upper plate is sealed and the bell evacuated. The hopper is then caused to move to one side by hydraulically operable piston 88 and opposing ram 62a is caused to enter the upper portion of the chamber while the powder is heated to temperature by means of electrical heating units 60. The compacting chamber which is in actuality a hot pressing mold may be made of a heat and wear resistant tool steel or alloy or cemented carbide. The extrusion chamber may be similarly constructed.

After the powder has reached temperature and a protective environment has been ascertained, pistons 62a and b are caused to hot compress the powder into a coherent compact 103 as shown in Fig. 5 fully contained in the opening 57 of transfer plate 56. The pistons are withdrawn and the coherent compact held within opening 57 of transfer plate 56 then transferred to extrusion chamber 54 via transfer chamber 55 by means of piston 58 actuated -by cylinder 59 by means known to the art.

The compact 103 which is now in position for extrusion (Fig. 6) is acted upon by extrusion ram 64 which passes through opening 57 of transfer plate 56 and dislodges the compact and presses it against die 63 to effect the partial extrusion thereof as shown in Fig. 7. The temperatures employed for both the compaction and extrusion and the extrusion pressures are similar to those stated hereinbefore. Upon completion of the extrusion, the pressure is released, the split die separated by means of pistons 72a and b (Fig. 8) and the partially extruded product pushed by the ram through opening 66 into compartment 67 below and the apparatus set for another extrusion. As extruded products accumulate in compartment 67, they are removed through the lower opening by detaching cover 69 after releasing the vacuum.

It is important that the apparatus of the invention be so designed as to insure a seal against the atmosphere from the feeding of powder into the compacting chamber to and through the extrusion chamber. While a vacuum bell has been illustrated as one means of protecting the metal powder during the working operations, it will be understood that other means may be employed to produce the same efiect.

It will be understood that while only those parts of the apparatus have been shown to illustrate the invention, those skilled in the, art will readily appreciate that conventional structural members, such as movable and stationary platens and tie" rods or the like, would be utilized to complete the external portions of the apparatus. For example, the hot compaction and extrusion rams shown in the figures would be actuated by one or more hydraulic rams and cylinders which in turn would be supported by a stationary platen.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claim.

We claim:

An apparatus for making extrusions from metal powder comprising: structure providing at least three bores oriented in fixed alignment one above the other, said bores being spaced from each other; a gate movable in the space between the first and second bores for closing ofi the first bore; means movable across the top of the bore for depositing powder in the closed oiT said first bore; a sectional die having sections movable in the space between the second and third bores for forming an extrusion apparatus in association with the second bore;,a ram movable into said first and second bores to compress the powder in said first bore against said gate, to push the compressed compact from said first bore into said second bore, and to extrude the same through said die; and means for moving said ram, said gate, and said die sections into operative and inoperative positions.

References Cited in the file of this patent UNITED STATES PATENTS 770,471 Moshier Sept. 20, 1904 1,822,939 Stout Sept. 15, 1943 2,325,119 Flowers July 27, 1943 2,389,876 Sequin Nov. 27, 1945 2,439,966 Dinzl Apr. 20, 1948 2,598,016 Richardson May 27, 1952 2,630,623 Chisholm et al Mar. 10, 1953 2,656,743 Levenworth Oct. 27, 1953 2,806,596 Dodds et a1 Sept. 17, 1957 FOREIGN PATENTS 700,461 Germany Dec. 20, 1940 789,411 France Aug. 19, 1935

Images