US2370953A

US2370953A - Centrifugal casting machine

Info

Publication number: US2370953A
Application number: US432223A
Authority: US
Inventors: Greenberg Leon
Original assignee: Ind Steels Ltd
Current assignee: Industrial Steels Ltd
Priority date: 1941-01-10
Filing date: 1942-02-25
Publication date: 1945-03-06
Anticipated expiration: 1962-03-06

Description

March 6,1945. L R 2,370,953

CENTRIFUGAL CASTING MACHINE Filed Feb. 25, 1942 3' Sheets-Sheet 1 March 6, 1945. REE H 2,370,953

CENTRIFUGAL CASTING MACHINE Fileid Feb. 25, 1942 :s Sheets-Sheet 2 March 6, 1945.

L. GREENBERG CENTRIFUGAL CASTING MACHINE s sheets sheet 3 Filed Feb. 25, 1942 Patented Mar. 6, 1945 CENTRIFUGAL CASTING MACHINE Leon Greenberg,

Lidcombe, near Sydney, New

South Wales, Australia, assignor of ninety-five per cent to Industrial Steels Limited, Lidcombe, near Sydney, New South Wales, Australia, a company of New South Wales, Australia Application February 25, 1942, Serial No. 432,223 In Australia January 10, 1941 4 Claims.

' This invention has been devised to provide a machine for casting, with the application of centrifugal force, the shells of bombs and other projectiles and articles of a like shape or of any cylindrical or other shapes capable of being moulded about a common axis.

A feature of the invention is the provision of means whereby the molten metal tov form the casting is caused to rotate at the same or substantially the same velocity as the mould during its entry into the mould. This assures that the metal passes into the mould in a quiet flow thus almost entirely obviating the formation of gas pockets and soenabling clean dense castings to be produced rapidly.

Rotating the metal as it is being poured as aforesaid also obviates the securing action of metal on the mould which has been one of the objections hitherto of centrifugal casting. This scouring action was due to raising, in the mould, the metal from a comparatively static condition to the velocity of the mould.

The aforesaid and other advantages are attained by the machine of this invention which is characterised in that it provides means to rotate a mould on a vertical axis and means to achieve a bottom pour through a hollow core wherein the metal is given the momentum of the mould thereby enabling the metal to fill the mould in a continuously progressing upward flow without splash and without forming gas pockets and without disruptive changes of direction in the flow of the metal.

The machine may be made as a single unit or several of such units may be mounted on a rotatable table adapted to place each unit in a common filling position so that castingcan be carried on in a continuous cycle of operations.

The invention will be described in detail with reference to the annexed drawings as appliedto the casting of shells of bombs: Fig. 1 is 9. diagrammatic view of the lay-out of several ma chines; Fig. 2 is a perspective view of one unit and part of a rotatable table; Fig. 3 is a sectional detail view of the base of a unit on a table; Fig. 4 is a central sectional elevation of a unit; Fig. 5 is an enlarged sectional detail view of the filler end of the machine; Fig. 6 is a sectional plan on lines 6-8 of Fig. 5; Fig. 7 is an enlarged perspective view of the cast removed from a mould; Fig. 8 is a longitudinal section thereof Fig. 9 is a central sectional elevation of part of a machine illustrating how a rod can be cast; Fig. 10 is a sectional plan on line l0- |0 of Fig. 9 and Fig. 11 is a perspective view ofa casting in the shape produced by the machine as illustrated in Fig. 9.

Describing a single unit; it consists of a base It having a cylindrical pedestal H with an annular bearing l2 on the top thereof with a footstep and through bearing l3 positioned axially in the bottom thereof. The pedestal may be slotted as indicated at I4 to provide for the admission of cooling draughts of air; it is mounted on a suitable frame. and like shapes is divided transversely into upper and lower sections IS, IS. The lower section l6 has a flange I! with a bearing |8 to take on the bearing l2. The top face of this flange I1 is stepped as indicated at I9 to take the upper section l5 of the mould and in this face there is a centring groove 20. A cap 2| on the bottom of the lower section held in axial alignment by centring groove 22 has a power shaft 23 thereon. This shaft has a thrust collar 24 to take on the bearings l3 and projecting through said bearings has means for coupling to a power-unit or other actuating device (not shown). Preferably the power unit is a. variable speed motor fixed directly 25 to said shaft 23.

The upper section l5 of the mould has a step 25 complimentary to the step [9 and a centring v ring 26 complimentary to the groove 20. In the top there is a tapered funnel orifice 21 in the wall of which there is a plurality of gas vents 28.

Both sections of the mould may have radiating fins such as 29.

The two sections are held together by lever clamps 30 having a fulcrum pin 3| in bifurcated bearing bracket. 32 on th lower section Hi. In the bottom part of the lever there is one part 33 of a spring box or cage and below it there is a weight 34. The bearing bracket 32 has depending arms 35 incorporating the other part 36 of the spring cage. A spring 31 in the cage is affixed to both parts by bolts 38 and 39. The bolt 38 enables such tension to be placed on the Spring that when the machine is stationary the clamp 30 will swing clear of the top section l5 but when the machine is rotating the weight 33 will overcome the spring and the clamp bearing on the top section l5 will hold it firmly in position. Preferably three of these clamps are incorporated.

In the mould there is a core consisting of a base 40 and a body 4|. The base 40 and body 4| is conveniently made in two longitudinal sections though it may also be made as a single unit. When made in twoparts each body part 4| has an axial groove 43 therein and when'joined together the groove forms a pour hole or runner for A mould for the casting of shells the cast. This runner is in communication with several ports 44 in the base 40. The ports 44 have been specially designed as illustrated to carry the metal from the runner'where it receives its initial rotary movement to the mould face 45 in an even flow with a smooth change of direction so that when the metal reaches the mould face it is rotating at the same velocity as the mould and is travelling in a direction continuous with the entrance to the mould consequently there is no sharp impingement or splashing of metal onto the mould. The flow of the metal onto the mould face at the commencement of the pour is sometimes facilitated by incorporating a runner plate such as 46 at the bottom of the mould. This runner plate may be of such metal as will become embedded in the cast.

The core base 40 holds the bottom of the core centrally in'the mould. At the top the core is held in position by a core funnel 41. funnel 41 has a tapered body 48 to take in the tapered orifice 21 of the upper section l of the mould; it also has a flanged top 49 and a cylindrical base stem 50 is adapted to take in the .top of the runner groove 43 and so hold the top of the core body centrally in the mould. Additionally or alternatively a metal sleeve 5| on the stem 50 takes over the end 52 of the core body 41 to hold it central. The funnel has a pour hole 53 with a flared mouth 54 and it may be reinforced by an inner sleeve such as 55.

There are a series of ports 56 passing through the core funnel 41 from the shoulder 51 at the bottom of the taper 48 to outlets 58 under the These ports constitute gas escape flange 49. vents from the top 59 of the mould cavity and they are additional to the gas vents 28 formed in the upper section l5 of the mould; and said gas vents 28 are in communication with the radial port openings 42.

In operation the mould is rotated at a slow speed say up to 100 R. P. M. while the metal is being poured. The metal flows through the funnel 41 down the runner formed by the grooves 43 and through the ports 44 into the mould cavity and in this journey it attains the momentum of the machine. The metal travels upwardly around the core and gas formed or in the mould is forced ahead of the flowing metal to the vents 28 and the ports 56. Immediately the pouris completed the speed of the mould is increased up to a maximum of 1000 R. P. M. in order to consolidate the molten mass. Alternatively the. speed of rotation may be varied as the pouring operation is carried out.

The mould face may be dusted or coated with various preparations to control chilling and protect the mould surface. For example pulverised ferro-silicon may be used for this purpose either alone or with a pulverised silica sand.

To enable casts to be made in substantially a continuous cycleof operations a battery of machines as described above are mounted on a rotatable table having a series of radial arms such as 60 which are fabricated in any suitable manner and affixed to a bearing cap such as 61 mounted on a pedestal 62. Rollers 53 take the weight of the table or arms 60. Six machines will make an economical battery and means are provided to stop the table as each machine arrives at a pouring position. In such a battery of machines numbered for example as 1" to 6" a cycle of operations could be carried out as follows: Starting at the first or pouring position a cast is made in No. "1 machine and it is then-moved to the This core second position while N0. .6 is filled. At the second position the upper section "15" of the mould is removed and No. "1 machine passes to the third position while No. 5. machine is filled and No. "6 dealt with at the second'position. At the third position the cast is removed from No. 1" machine while Nos. 6 and 5 are worked as previously described. No. 1 machine is then moved on to the fourth position where it is cleaned and No. 4 machine is filled. At the fifth position a new core is inserted and at the sixth position the upper section I5 of the mould is replaced, the funnel fitted and No. 1" machine is then ready for the next cast. While No. "1" machine is at the fifth and sixth positions Nos. 3 and 2 are being filled and passed on for the subsequent operations.

The east 64 (see Figs. 7 and 8) as withdrawn from the mould by removing the upper section IE will have associated therewith a central limb 65 yoke 66 and pips 61 all of which were formed in the pour passages 43, 44 and in the gas vents 28 and 59; these are subsequently removed from the cast in the well known manner.

While the invention has been describedas applied to a machine for casting shells of bombs it will be apparent that it is applicable to the casting of many other articles. For example the invention may be applied to the casting of pipes or as outlined in Figs. 9, 10 and 11 it may be applied to the casting of bars of any sectional configuration In the casting of bars the mould 69 is made into two halves and bolted together as at 10, the core 1| consists of several sections so that it may be readily dismantled when a cast has been made. Such core 11 rests upon a base 12 and is furnished with a centrally disposed pour passage 13 in communication with a pour passage. 14 formed in the top face of the base 12 and is in communication with a cavity 15. This cavity 15 for the cast is made half in the mould 69 and the corresponding half in the core 1| in the form of a helix.

A pour funnel 41 is placed upon the top end of the core 1| so that its pour hole 53 will be in alignment with the pour passage 13.

The cast 16 see Fig. 11 when withdrawn from the mould will have associated therewith a central disposed stem of metal 11 formed in the pour

passages

13 and 14 and which is removed in the well known manner.

Notwithstanding the merits of rotating the mould on a vertical axisas aforesaid it will be apparent to those skilled in the art that the same or substantially the same results may be obtained in a machine where the axis is placed on an angle or even where it is placed horizontal: Indeed forsuch articles as lengthy pipes it may be desirable to have the axis of the mould horizontal or nearly so.

To achieve the objects of the invention with the mould say on a horizontal axis the core fun nel is held stationary and it has an offset stem to take in the core runner groove, a suitable bearing being interposed between the two surfaces; it is also lengthened to provide a head of metal which would be suficient to cause the metal to flow along'the core runner groove and to travel backwardly again in the mould.

I claim;

1. A centrifugal casting machine consisting of a base having a cylindrical pedestal with an annular bearing in the top thereof and a footstep versely into upper and lower sections; said lower section having a flange witha bearing to take on the said annular bearing and a shaft on the bottom thereof mounted in and protruding through said footstep hearing: A centring groove on the top face of said lower section: Said upper section having means whereby it can be aligned with said lower section and having a tapered funnel orifice in the top thereof having gas vents therein: A core held centrally in said mould having a runner positioned axially therein with an inlet at the top and an outlet to ducts at the bottom leading to the base of the mould; means to clamp said sections of the mould together and means to rotate said mould.

2. A centrifugal casting machine comprising a mould mounted for rotation about a vertical axis, means for rotating said mould, a core body in the mould having axially therein a pour runner with an inlet at its top and an outlet at its bottom, a core base in said mould having outwardly and upwardly curving ducts therein leading from the outlet of said core body pour runner to the wall of the mould, said ducts opening to said mould cavity in a direction parallel to the adjacent mould wall surface so that metal flowing from the pour runner through said ducts enters the mould cavity in a direction continuous therewith and free from impingement against the wall of the mould, and a member fitted in the top of said mould to support the upper end of the core. body and having an inlet therein registering with the inlet of the core pour runner, said member also having gas escape ports therein leading outwardly from the top of said mould cavity.

3. A centrifugal castin machine comprising a base, a mould comprising upper and lower mould sections mounted on said base for rotation about its vertical axis, means for locking said upper and lower mould sections together in axial alignment,

\ means for rotating said mould, said upper mould section having an opening in the top thereof, a

core held centrally in said mould and provided axially therein with a pour runner having an with and free from impingement against the wall, of the mould.

4. A centrifugal casting machine comprising a base having a cylindrical pedestal provided with an annular bearing at the top thereof and a footstep and through bearing axially at the bottom, a mould comprising a casing divided transversely into upper and lower sections, said lower section having a flange at its upper end provided with a bearing to take on the annular bearing of said pedestal and having a drive shaft at the bottom thereof journalled through said footstep bearing. and said upper section having an inlet orifice and gas vents in the top thereof, cooperable means on said mould sections for aligning the upper section with the lower section, a core held centrally in said mould provided with a pour runner axially therethrough communicating at the top with said inlet orifice and having an outlet at the bottom. means providing a series of ducts leading from the pour runner outlet to the bottom of the mould cavity between said core and mould, said ducts being constructed and arranged so that metal flowing" therefrom enters the mould cavity in a direction continuous therewith and free from impingement against the mould wall, means for clamping said mould sections together, and means for rotating said mould.

LEON GREENBERG.