US2130726A - Mold for centrifugal casting - Google Patents

Description

Sept. 20, 1938. R. ARDELT MOLD FOR CENTRIFUGAL CASTING Filed Feb. 6, 1936 2 Sheets-Sheet 1 /NVENroH HUBERT AHDELT y /'au 5.

Arron/Vey Sept. 20, 1938. R. ARDELT 2,130,726

Y V MOLD FOR CENTRIFUGAL CASTING Filed Feb. e, 195e 2 sheets-sheet 2 mil /fvvE/va/f HUBERT ABDEL T Patented Sept. 20, 1938 UNITED STATES PATENT vOFFICE Application February 6,

1936, Serial N0. 62,65

In Germany February 6, 1935 f Claims.

the mold for example by preventing the forma- I l0 tion of steam cushions on the outer surface of the mold and other objections to a uniform cooling.

Another object is to obtain a device, which is cheap in manufacture and safe and eiiicient in operation. i f lo Another object is toprevent an early destruction of the mold by cracks and deformations and the like and to obtain castings of high and uniform' quality.

Other objects of my invention will result from the description of the invention which follows.

it is known that molds for centrifugal casting and more particularly metallic molds, such as iron molds, in which tubes and similar castings arecastdirectly (i. e. without sand lining) must tain a predetermined temperature within the mold. As is further known the quality of the castings and the life of the mold depend very much upon a uniformV temperature in all parts of the cooling wall of the mold. The cooling means known heretofore do` not comply with these requirements at all and especially they show two faults.v Firstly differences in temperature occur in the cooling liquid itself as, after entering the cooling space, the cooling liquid is heated at first at one point of the cooling wall and is then transmitted in a heated state to other points in order to have a cooling effect there. A still greater drawback originates from the fact that the centrifugal force, which builds-up when the mold is rotating, ytends to move the cooling liquid away from the cooling wall thus giving rise to the formation of steam cushions which prevent an `efiicient heat transmission. If however `the cooling of the mold is notuniform, strains lwill result within the mold which very often effect the formationof cracks that soon destroy the mold. But already a deformation of the mold, caused by differences in the temperature within the mold, 50 may render this, mold unfit for use. Acooling, which' is not uniform, does not only affect the mold itself but also the castings which, on account of the irregular cooling, show stresses and different hardness.

My invention avoids these drawbacks by disbe provided with cooling means in order to maintributing the cooling liquid uniformly over the whole circumference and the whole length of the mold by way of a'distributing system which introduces a cooling liquid into a cooling space situated between themetallic mold proper and a 5` shell surrounding this mold. This distributing system is provided with inlet ports which are situatedopposite the cooling wall of the mold at such places that the cooling liquid is thrown 0n the cooling wall in the form of jets. By this 10 arrangement it is very easy to raise the kinetic energy of the jets (which can be obtained by changing the pressure or by giving thel inlet portsa certain size or form or by varyingy the distance of the inlet ports from the cooling wall) to such i l5 a point that the force of the jets, beingdirected towards thel interior of the mold, is as much greater than the centrifugal force as is wanted, thus making sure of a good cooling eect and preventing the forming of steam cushions. The cooling liquid is carried away from the cooling space near the hitting points of the jets by a plurality of outlet ports which also extend over the whole circumference and the whole length of the mold, thus assuring the same temperature at all points of the cooling face, as the cooling liquid reaches all points of the cooling surface with the same temperature and is led oif from this surface with a temperature raised for the same amount.

My invention furtherA consists in using for the device mentioned above a cooling liquid, which has a high boiling point` of at least 200 C., the cooling liquid being introduced into the cooling space with a temperature of about 150 C. A cooling liquid which is specially adapted for this purpose is glycerine. The cooling liquid of the kind referred to may be discharged from the cooling space with a temperature which lies below the boiling point of .this liquid under normal pressure. The advantages of using a relatively hot cooling liquid are firstly that the difference 'in the temperatures of the mold are reduced to a small amount, thus increasing the life of the mold very much. A further advantage lies in the 45 fact that the quality of the tubes thus produced is improved. When casting long tubes the mold will be cooled s uiilciently by the hot cooling liquid at that end of the mold-where the casting process is started, while at the other end, at which the casting has not yet been started, a preheating of the m'old by the cooling liquid is obtained.` It was found out that a preheating to C. o f the cooling liquid is quite sufllcient for pre-AA venting 'a substantial hardening of the surface l of cast iron tubes, as the mold, at the place where the liquid iron impinges on it, is further preheated by heat conducted through the mold from the finished part of the tube to this place.

In this way it is possible to avoid the expensive annealing of the casting necessary until now or to replace the intensive annealing by a very short and therefore. cheap annealing process. Besides this advantage the waste is decreased as the annealing process never can close cracks which have been formed already. It was found that when using glycerine introduced at a temperature of about C. and discharged with a temperature of about 230 C. castings will be obtained, the quality of which is equal to the ordinary castings obtained from sandspun molds, except the utmost outer surface which is only Slightly hardened.

The accompanying drawings show several ern-l Varranged within the cooling space over the whole length and the whole circumference of the mold proper. The cooling liquid may be introduced radially to the mold or, in order to get a better efficiency and uniformity, inclined to the radial direction. By introducing the cooling liquid inclined to the radial direction a good circulation of fresh cooling liquid around the mold is obtained even if the mold is not rotating. 'I'he uninterrupted circulation of lfresh cooling liquid around the mold is of greatest importance when the mold is not moving, as in this way the vapours forming at the circumference of the mold are continuously washed away and strains within the material are avoided which otherwise might cause deformations of the mold. The proposed cooling of the molds may be obtained in several different ways according to the different embodiments ofl the inventionshown in the drawings.

Referring now more particularly to Figs. 1 and 2, these figures show the feed pipes I and 2 for the cooling liquid, these pipes being arranged uniformly around the mold l. The feed pipes are held in position by several rings 4, which hold them against the action of the centrifugal force. A i'oed` pipe and a discharge pipe are always arranged one aside of the-other, these pipes containing small holes l over their whole length which lie close to each other. The cooling liquid is led to the mold in the direction of the arrow a by way of the non-rotating annular channel O and the feed pipes I opening into this channel, while the liquid is returned by way of the discharge pipes 2 and the non-rotating annular channel lin the direction of the arrow b. With 8 rolls are designated on which the mold 3 is rotating together with the cooling means, but with exceptinn of the device containing the channels 6 and Y Figs. 3 and 4 show feed pipes 1, which are also uniformly distributed around the mold and are held by rings, in this case all pipes serving as feed pipes. 'I'he cooling liquid is introduced in the direction of the arrow c by way of the non-rotating body containing the channel B, the feed pipes I and the plurality of small holes 9 within these pipes and acts upon the mold II within the annular cooling space I0. From this space the cool--` ing liquid passes through many small holes I2 into the annular space I3 and from there through the holes I4 into the annular channel I5, from which it is discharged in the direction of the arrow d. v

As shown in Figs. 5 and 6 the cooling liquid reaches the cooling space I9 by way of the channels I1 and the small holes I8 provided within the cylindrical body I B. From the cooling space I9 the cooling liquid passes through a plurality of small radial channels 2I, which are uniformly distributed over the whole length and the whole circumference of the mold, into the space 22 and from there through openings 23 into the annular channel 24, from where the liquid is discharged in the direction of the arrow e'.

Figs. 7 and 8 show that the invention also may be embodied by devices in which the outer shell is not rotating while the mold proper rotates. In Figs. '7 and 8 the same example is employed as already shown in Figs. land 2. It goes without saying that the same arrangement may be used for the other examples described before.

In the embodiment of the invention shown in the Figs. 7 and 8 only the mold proper 21 is rotating. The cooling liquid is'distributed by way of the pipes 25 and is discharged by the pipes 28. The different pipes are held by rings 28 and are providedwith openings 29 for the passage of the cooling liquid. The ` pipes 25 and 26 are connected to a common feed pipe 36 and to a common discharge pipe 3i.

What I claim is:

1. An apparatus for centrifugal casting comprising a metallic mold, an outer shell, said mold and said shell forming a cooling space, feeding means and discharge means for carrying a. cooling liquid to and from said cooling space respectively, said feeding means having inlet ports communicating with said cooling space, and being directed onto the outer surface of said metallic mold, said discharge means having outlet ports communicating with said cooling space, said inlet and outlet ports being distributed over the whole circumference and over the whole length of said metallic mold, and two means separate from each other for connecting said feeding means to an external source of lcooling liquid supply, and said discharge means to the outside ona level above said shell respectively.

2. An apparatus for centrifugal casting comprising a metallic mold, an outer shell, said mold and said shell forming a cooling space, a system of pipes fixed within said cooling space, said pipes serving for introducing and discharginga cooling liquid to and from the cooling space, said pipes being provided with a plurality of small ports distributed over the whole circumference and over the whole length of said metallic mold, means for feeding the cooling liquid to every second pipe, and means for discharging the cooling liquid from the rest of the pipes on a level above said shell.

3. An apparatus for centrifugal casting comprising a metallic mold, an outershell, said mold and said shell forming a cooling space, a system of pipes fixed within said cooling space, said pipes being provided with a plurality of small ports over the Whole length and the whole circumference of said metallic mold, a tube between said system of pipes and said outer shell, said tube being also provided with a plurality of small ports cooling liquid from the space between the outer4 shell and the tube on a level above said shell.

' fl. An apparatus -for centrifugal casting comprising a metallic mold, an outer shell, said mold and said shell forming acooling space therebetween, a cylindrical body arranged between said 4metallic mold and said outer shell and being concentric therewith, said cylindrical body being provided on its inner surface only with a plurality of inlet ports and being also provided with a plurality of outlet ports alternatively arranged with respect to the inlet port over substantially the wholelength and the whole circumference of said metallic mold, means for feeding a cooling liquid to said inlet ports and means separate from said feeding means forcarrying away the cooling liqulild 1from said outlet ports on a level above said s el 5. An apparatus for centrifugal casting comprising a metallic mold, an outer shell, said mold and said shell forming a cooling space, a cylindrical body between said metallic mold and said outer shell, said cylindrical body being provided on its inner surface with a plurality of inlet ports and /outlet ports alternately arranged to each other over the whole length and the whole circumference of said metallic mold, first means for feeding a cooling liquid to said inlet ports, and second means for carrying'away the cooling liquid from said outlet ports, said rst means comprising axial channels connecting the inlet ports of the same row with each other and means for feeding the cooling liquid to said axial channels, said second means comprising radial channels connecting said outlet ports with the annular space between said cylindrical body and said outer shell, and means for carrying away the cooling liquid from said annular space between said cylindrical blady and said outer shell on a level above said s ell.

6. An apparatus for centrifugal casting comprising a metallic mold, an outer shell, said mold and said shell forming a cooling space and being rigidly connected with each' other so as to rotate together, feeding means and discharge means for carrying a cooling liquid to and from said cooling space respectively, saidfeeding means having inlet ports communicating with said cooling space and being directed onto the outer surface of said metallic mold, said discharge means having outlet ports communicating with said cooling space,

said inlet and outlet ports being distributed over the whole circumference and over the whole length of said metallic mold, and two means separate from each other for connecting said feeding means to an external source .of cooling liquid supply, and said discharge means to the outside above the level of the shell respectively.

7. An apparatus for centrifugal casting comprising a .metallic mold, a supported outer shell, said mold and said shell forming a cooling space and being so arranged andconstructed, as to permit the metallic mold to rotate whilethe outer shell stays fixed 'on its supports, feeding means and discharge means for carrying a cooling liquid to and away from said cooling space respectively, said-feeding means having inlet ports communicating with said cooling space and being directed onto the outer surface of said metallic mo1d,`said discharge means having outlet ports communicating with said cooling space, said inlet and outlet ports being distributed over the whole circumference and over the whole length of said metallic mold, and two means separate from each other for connecting said feeding means to an external source of cooling liquid supply, and said discharge means to the outside on a level above said shell respectively.

8. An apparatus for centrifugal casting com- A prising a metallic mold, an outer shell, said mold and said shell forming a cooling space, a cylindrical body between said mold and said shell, said cylindrical body having a plurality of axial channels, each with a plurality of inlet ports directed towards said mold, said cylindrical body having also a plurality of radial channels connecting the spaces at the inside and at the outside of the cylindrical body with each other, means for feeding a cooling liquid to said axial channels, and

means for carrying off cooling liquid from the space between said cylindrical body and said shell on a level above said shell.

9. An apparatus for centrifugal casting comprising a metallic mold, anouter shell, said mold and said shell forming a cooling space adapted to be completely filled with a cooling liquid, means for admitting cooling liquid to said cooling space, and means for carrying cooling liquid away from said cooling space, said means including a plurality of inlet and outlet ports respectively, said ports being distributed over the entire circumference and length of the mold and being soarranged as to create, within the cooling space, a plurality of inlet currents directed radially towards the outer surface of said mold, and of outlet currents directed radially towards said shell, means for feeding liquid to said admitting means, and means for collectively discharging the liquid having passed said outlet ports, said discharging means comprising a ring channel surrounding said shell and communicating with the inside thereof, and having an outlet above said shell so as to safeguardcomplete lling of said cooling space with liquid.

space, said pipe-like system comprising feeding channels and discharge channels, and two means separate from each other for connectingsaidfeeding channels to an external source of cooling liquid supply, and said discharge channels to the outside above the level of said .shell respectively, said feeding channels having inlet ports and said discharge channels having outlet ports, said inlet and outlet ports being distributed over the whole length and circumference of said mold, and being so directed as to create a plurality of individual currents within said cooling space towards and away from the outer surface of said mold.

ROBERT ARDELT.-

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