US2841839A - Casting machine for chill casting cylindrical liners - Google Patents

Description

A. ROEBIG July s, 1958 CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS 9 Shets-Sheet 1 Filed Sept. 17, 1952 9 D e O .mR WW wd NA. v G 5 A TTOQ/VE A. ROEBIG July 8, 1958 CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS 9 Sheets-Sheet 2 Filed Sept. 17. 1952 July 8, 1958 ROEBIG K 2,841,839

CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Filed Sept. 17, 1952 9 Sheets-Sheet 3 BY Ado/f'koebl 'g V" SUM-r ATTOQA/EY July 8, 1958 A. ROEBIG 2,841,839

CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Filed Sept. 17, 1952 9 Sheets-Sheet 4 INVEN TOE BY Ado/f Roe/5Z Arron/way July 8, 1958 A. ROEVBIG 2,841,839

CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Filed Sept. 17, 1952 9 Sheets-Sheet 5 log m 0%; [/0 K79 I /09 //.9

l I l i l ILJI I i ///6 fNVEN 7012 BY A Clo/f R0126? ATTORNEY July 8, 1958 A. RQEBIG CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS 9 Sheets-Sheef 6 Filed Sept. 17. 1952 AIIII Z INVENTOR.

& mm W K 0 5 5 e N o p R m NJ o A d w A A July 8, 1958 A. ROEBIG 2,841,839

CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Filed Sept. 17. 1952 9 Sheets-sheaf 7 III/M7117,

INVENT OR.

Ado/f Roe/ 4 V1 5W ATTORNEY July 8, 1958 I A. ROEBIG 4 CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Filed Sept. 17. 1952 9 Sheets-Sheet 8 [Ill/III) WVEA/TOQ BY Ada/f fioebllj July 8, 1958 A. ROEBIG 2,841,839

CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Filed Sept. 17, 1952 9 Sheets-Sheet 9 m/v e/vrkz Ado/f Roe/5Z V. A WMM 5c/kzr AFTOQNEY r 2,841,839 6 Patented July 23,- less CASTING MACHINE FOR CHILL CASTING CYLINDRICAL LINERS Adolf Roebig, Verona, N. J.

Application September 17, 1952, Serial No. 309,978

3 Claims. (Cl. 22-57) ,This invention relates to a casting machine for chill casting cylindrical liners. The invention is concerned, more particularly, with the manufacture of thin walled chill casting cylinder liners. 7

An object of the present invention is to provide a cylinder liner which will satisfy the many requirements made of the operative surfaces thereof, particularly in the case of liners used for internal combustion engines, such requirements including hardness, a good sliding capacity, a high firmness andadhesiveness for the lubricating oil.

Another object is the provision of liners which can be manufactured comparatively inexpensively and in mass production.

Another object is to utilize for cylinder liners the advantages of chilled castings for surfaces subjected to substantial friction, such advantages consisting among others of the fact that a chilled casting may have a hardness up to 65 Rockwell while having the porous structure of pig iron, which produces excellent adhesiveness for the oil filtrate; the excellent sliding capacity is caused in the first place by a diminished graphite precipitation and by the structure produced as the result of quenching.

A still further object is to eliminate prior art methods which make it necessary to cast liners in thick walled iron forms or to place iron plates into the sand forms.

Still another object is the provision of a liner having very thin walls and a completely uniform structure.

Other objects of the present invention will become apparent in the course of the following specification.

In accordance with the present invention, the difliculties of prior art methods are eliminated by the construction of a specific cylinder liner and by the use of special methods and means for manufacturing such cylinder liners. One of the many diificulties encountered in prior art methods, namely, the provision of uniform hardness, is overcome by providing a cylinder liner having a wall thickness of only about one millimeter. The liner is quenched from inside and outside, so that it is uniformly hard. Due to the thin walls of the liner, subsequent treatment is unnecessary with the exception of an inner polish. The liner is then as elastic as hardened steel sheets and fits easily into the bore holes of the motor casing or of a sleeve made of wrought iron. The pressing of the liner into the bore holes is carried out without difficulty. The outer surface of the casting is so smooth that the liner can be easily pressed into the sleeve without further surface treatment. The heat conductivity between the liner and the sleeve will not be affected and will be approximately the same as if the two parts constituted a single piece. This may be explained by the adaptability of the thin elastic liner to the surface of the sleeve. A l

The withdrawal of heat can be increased by providing the sleeve with perforations, so that the cooling water will contact the liner directly. Furthermore, as the result of these perforations, the sleeve presents a larger,

surface which may be contacted by the cooling water.

i In the manufacture of so-called wet liners, the sleeves can be madeof cut up pipe portions, which consist of spirally wound and welded iron bands. These pipes are very firm and, therefore, they can be made thinner than prior art pig iron sleeves, which is quite important from the point of view of heat withdrawal. The inner diam eter of these tubes is set by the usual calibrating process upon a core bar. The mounting in the motor casing is usually carried out by two small pins which are brought to the precise size by the usual forming and grooving methods.

It is a necessary prerequisite that the material for the liner should contain at least 30% of charcoal raw iron. A higher percentage increases the quality. The

following composition was found to be most suitable:

In accordance with the present invention, the casting on the liner takes place entirely automatically in a high frequency casting machine. The melting and the casting take place in a permanent iron mold which is subjected to a high vacuum. All movements of the casting machine take place by means of hydraulically driven cylinders.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings, showing by way of example a. preferred embodiment of the inventive idea. V

Figure 1 is a front view of the melting and casting cylinder constructed in accordance with the principles of the present invention;

Figure 2 is a side view thereof and illustrates a part of the feeding and actuating mechanism;

Figure 3 illustrates, diagrammatically as operating and feeding mechanism;

Figure 4 is a longitudinal section through themelting and casting cylinder;

Figure 5 is a transverse section along the line V- -V of Figure 4;

Figure 6 is a transverse section along the line VI-VI of Figure 4;

Figure 7 is a transverse section along the line VII-VII of Figure 4;

Figure 8 is a transverse section along the VIII-VIII of Figure 4;

Figure 9 illustrates in side elevation another part. of the hydraulic operating mechanism;

Figure. 10 shows in side elevation a liner constructed in accordance with the present invention;

Figure 11 is a section through the liner after it has been inserted into a sleeve;

Figures 12 to 17 are diagrams illustrating the operation of the melting and casting machine, namely:

Figure 12 is a section illustrating the melting mechanism with the mold closed; t

Figure 13 is partly a section and partly aside elevation part of the l llIlC 3 illustrating the filling of the melting pot after the latter has been drawn out;

Figure 14 is partly a section and partly a side elevation illustrating the device with the mold evacuated and subjected to the melting process;

Figure 15 is a section illustrating the position of the mold after it has been turned over for pouring;

Figure 16 is a section illustrating the withdrawal of the core after the casting iscompleted;

Figure 17 is partly a side view and partly a section and illustrates the removal of the cast'liner;

' Figure 18 is a side view of a differently constructed core; a

Figure 19 is a longitudinal section through the core of Figure'18.

Figure 20 is a transverse section through the core of Figure 18..

Figure 21 is similar to Figure 20 and shows the core when it is spread out.

Figure 1 of the drawings illustrates a cylindrical casing consisting of three parts, namely, an iron intermediate portion. 1, an upper part 2 consisting of non-conducting materials and a lower part 3 made of iron. The nonconducting upper part 2 may be made of plastic materials and may be provided with metal bands in order to increase its strength and its resistance to high pressure prevailing within the melting chamber after the melting. These metal bands which will be heated by the high frequency coil may be cooled by water or air.

As shown in Figure 2, the cylinder is mounted upon a shaft 4 by means of a flange 5 which is attached to the cylinder portion 1. The shaft 4 is rotatably mounted in bearings 6, one of which is carried by the front wall 7 of the machine. The rear wall, which is not shown, may be provided with another bearing for the shaft 4. Vertical stands of pipes 8 are joined by transverse brackets 9, one of which is shown in the drawings. Bolts 10 are carried by the brackets 9 and are adapted to engage the stands 8. Sleeves 11 are mounted upon the stands 8 and are firmly connected with angle pieces 12. Similarly, sleeves 13 which are mounted upon the stands 8 are joined by a transverse piece 14.

The upper portion 2 of the cylinder carries .bolts or pivots 16 which carry resilient locks 15. The intermediate portion 1 of the casing carries projections 17 adapted to engage the locks 15.

A connecting pin 18 is mounted upon the top of the cylinder portion 2. A similar connecting pin 19 is mounted upon the core on the mold which will be described in greater detail hereinafter. The pin 19 projects beyond the cylinder portion 3.

As shown in Figure 4, the ceramic melting pot 20 is located within the cylinder portion 2 and is enclosed by a high frequency coil 21. The coil 21 and the container 20 are both embedded in an oxide powder 22' having a high melting point. The cylinder portion 2 is provided with an insert 23 leading to a vacuum pump. An insert 24 is located opposite the insert 23 and is connected to a high pressure conduit.

The intermediate cylinder portion 1 carries flanges 26 which firmly engage sealing rings 25 made of elastic material and carried by the cylinder portion 2. A sleeve 27, which is made of graphite, is located between the melting pot 20 and the mold cavity 33. A ring 28, which is also made of graphite, is used to hold in place the sleeve 27 and funnel like members 29 and 30. A cap 31 is conical in shape and is located in the middle of the casing. The members 29, 30 and 31 are also made of graphite and cooperate with a guide sleeve 32.

The mold cavity 33 has the form of a narrow cylin drical chamber, one side of which is formed by a wall 1a, constituting a part of the intermediate cylinder portion 1. The core of the mold consists of a plurality of conical parts, namely, of a central reduction cone 34 and outer core portions. 35 and '36 provided with conical '4' surfaces. Due to this arrangement, the circumference of the core can be reduced whenever necessary. Springs 37 press against the core members 35 and 36, while a ring 38 is located within the cylinder close to the juncture of the cylinder portions 1 and 3. Projections 39, best shown in Figure 8, are separated by channels 40 for the cooling liquid.

As shown in Figure 4, the cone member 34 is integral with a rod 41 which carries the pin 19 and which extends through a passage 42 formed in the end wall of the cylinder portion 3. This end wall carries a sealing sleeve 43 which is held in place by a threaded cap 44. The members 39 (Fig. 8) are preferably made of heat resistant steel. The channels 40 are joined at the upper and lower ends so as to provide a continuous flow for the cooling liquid, which passes into and out of the intermediate cylinder portion 1, through corresponding bore holes provided in the outer walls of the central portion 1 of the cylinder.

The reduction cone 34 can be also provided with bore holes which may be used for the cooling liquid. The core pieces 35 and 36 are made of metallo-ceramic materials, graphite or petroleum coke in order to avoid the possibility of contraction. These materials can be made porous if desired.

As shown in Figure 2, a gear 45 is keyed upon the shaft 4 and meshes with a rack 46 whichis movable in the guides 47. A universal joint 48 is connected with the upper end of the member 46. As shown in Figure 3, the universal joint 48 is connected with a piston rod which extends into a hydraulic cylinder 50. The piston rod 49 is connected with a piston which is not shown in the drawing. The cylinder 50 is suspended by a universal joint 51 and is provided with openings 52 and 53 for the in and out flow of the hydraulic medium.

A carriage 54 is slidable in the guide rails 55 and is connected with a universal joint 57 which is also connected with a piston rod 58. The piston rod 58 is connected to a piston 'reciprocable within a hydraulic cylinder 56 which is suspended on both sides by universal joints. The cylinder 56 is provided with an opening 59 for the hydraulic fluid.

A slide 60, which is similar in form to the slide 54, is movable upon rails 61 which are preferably attached by screws upon the front wall 7 of the machine at an angle of 45 to the vertical. The slide is actuated by a hydraulic cylinder 62 containing a piston provided with a piston rod 63 which is joined by a universal joint 64 with the slide 60. A universal joint 65 is used to suspend the cylinder 62, which is provided with openings 66 and 67 for the in and out flow of the hydraulic medium.

A chamber 68 is filled with the metal to be melted, the metal being stacked in the chamber 68 in the form of cylindrical rods 69. The rods 69 are transported by a carriage 70 which is held in the guides 71. A shaft 72 is rotatably mounted in brackets 73 and 74, which are best shown in Figure 2, and which constitute a part of the carriage 70. One end of the shaft 72 carries a holder 75 which is adapted to'receive the metal pieces 69. The opposite end'of the shaft 72 carries a lever 76.

The carriage 70 is connected by a universal joint 77 with the piston rod 78, extending into a hydraulic cylinder 79, which is suspendedat the other end by a universal joint (not shown). The cylinder 79 is provided with an opening 80 for the hydraulic fluid.

Another hydraulic cylinder 81 contains a piston which is connected with a piston rod 82. As shown in Figure 3, the cylinder 81 is connected with pipes 83 and 84 for the hydraulic fluid.

Yet another hydraulic cylinder 85, best shown in Fig. 2, contains a piston provided with a piston rod 86. Pipes 87 and 88 lead to the cylinder and are used for the circulation of the hydraulic medium. 7 I

As shown in Figure9, an operating shaft 89 is firmlymounted upon the axis 90 and is provided with members 91 carrying cams 92 which are attached to the member 91 by bolts 93. The shaft 89 may be rotated clockwise (looking in the direction of Fig. 9) to rotate the cams 92.

As shown in Figure 9, two levers 94 are directed toward each other and carry pivots 96 upon which the rollers 95 are rotatably mounted. The. rollers 95 may be engaged by earns 92. The levers 94 are swingably mounted upon shafts or pivots 97 and also carry set screws 98 provided with screw heads 99.

A valve 100 has a casing mounted upon a support 101 and attached to a bracket 102 by a bolt 103. Another valve 104 is located opposite the valve 100 and is similarly connected with a bracket 106, a support 105 and a screw 107. The valve 100 may be connected to the conduits which supply the hydraulic fluid to the operating cylinders while the valve 104 may be connected to conduits which withdraw the hydraulic fluid from the cylinder. Both types of conduits consists preferably of metallic pipes which are disposed to provide the shortest possible connection between the valves and the operating cylinders. When necessary, particularly in the vicinity of the cylinders, the pipes may include elbow portions made of flexible materials, such as reinforced high pressure-resisting tubing.

While Figure 9 shows two valves 100 and 104, actually there are several valves 100 and 104 which are located in a row one behind the other, the number of the valves being determined by the number of the hydraulic cylinders. Similarly, the shafts 97 carry several pairs of levers 94 and the shaft 89 carries several supports 91 for the earns 92, the levers 94 and the supports 91 being located one behind the other above the corresponding valves 100 and 104.

Each of the valves 100 and 104 comprises a valve rod 108, carrying supports 110 and clamps 111 and enclosed by springs 109. The ends of the valve rods 108 engage the set screws 98. l

The valves 100 carry flanges 112 which are connected to conduits, (not shown), extending to the hydraulic cylinders.

A pipe 113 extends in the direction of the valves 100 .and is connected to all of these valves by the conduits 113a. The pipe 113 is connected with a pressure pump 114. A suction pipe 115 is connected to the pump 114 and extends into a container 116 which is filled with oil. A relief valve 117 is also connected to the pipe 113.

Pipe sections 118 which are connected to the valves 104 are also connected to conduits (not shown) which lead to the operating hydraulic cylinders. Flanges 119 are connected to the valves 104 and are also connected with pipes 120, leading to the oil cylinder 116 and used for the return flow of the hydraulic fluid.

The described aggregate is operated as follows:

As already stated, all the movements for the melting and casting are produced by the hydraulic drive. This hydraulic drive is actuated by switching on a motor (not shown) driving through a reduction gear box which is also not illustrated, the axle 90 and the shaft 89 which is firmly connected therewith. The shaft 89 will rotate all the cams 92 carried by their respective supports 89 in such manner that the various devices of the aggregate are actuated in their proper sequence. This sequence of operations is as follows:

The first cam 92 actuates over the corresponding valves the hydraulic cylinder 50 which is shown in Figure 3. The piston shaft 49 of the cylinder will be moved and will shift the bracket 47 which will turn the gear 45, meshing therewith. T hen, the shaft 4 will be rotated. As shown in Figure 2, the shaft 4 is firmly connected with the melting and casting casing 1, 2, 3, and the cam will cause the shaft 42 to turn along with the casing until a 6 the upper portion 2 is located below. This position is illustrated in Fig. 12.

In this position the pin 13 of the container portion 2 will engage the slide 60 shown in Fig. 3.

At that time another hydraulic cylinder is operated to actuate two conical wedges which are not shown in the drawings and which release the locks 15 shown in Figure 1, so that these locks can now slide over the projections 17. Thus, the cylinder portion 2 is unlocked from the rest of the cylinder. Thereupon, a cam operates the hydraulic cylinder 62 (Fig. 3) which will actuate by the piston rod 63 the slide 60 which engages the pin 18 of the cylinder portion 2. Thus, the slide 60 will move the cylinder portion 2 away from the rest of the cylinder. It should be noted that the cylinder portion 2 slides upon rods 8 (Fig. l) by means of sleeves 11 which are firmly connected with the cylinder portion 2. The above mentioned conical wedges which are used to actuate the locks 15 move hack to their positions of rest.

As soon as the withdrawal of the cylinder portion 2 from the rest of the cylinder has been completed, the hydraulic cylinder 79 (Fig. 3) is operated and moves the carriage 70 upon the tracks 71 until the member 75 (shown in Fig. 2), which carries a piece 69 of the material to be molten, is moved directly above the melting pot 20 (Fig. 4). At that time the lever 76 (Fig. 3) is located directly above the piston rod 82 of the hydraulic cylinder 81.

One of the cams now actuates the hydraulic cylinder 81 with the result that the piston rod 82 pushes the lever 76 upwardly. The shaft 72 and the lever 75 turn along with the lever 76 until they assume an inclination amounting to an angle of 45. A resilient gate (not shown) holds the material 69 until this inclined position is reached. When this inclination of 45 is reached, the material is freed, so that it can drop by its own gravity into the melting pot 20. This position is shown diagrammatically in Fig. 13. The member 70 which moves along with thelever of the carriage 75 will be shifted under the container 78 and will prevent other pieces 69,

of the material to be molten fromdropping out of the container.

The hydraulic cylinder 79 (Fig. 3) is operated again by a suitable cam after the melting pot 60 has been filled, and then the carriage 75 is moved by the cylinder 79 to its initial position shown in Figure 2. In this position the member 70 clears the container 68 so that another piece 69 of the material to be molten can drop into the carriage 75.

After the filling of the melting pot 20, the hydraulic cylinder 62 is again actuated by a suitable cam to move by means of the rod 63 the slide 60 back to its original position. The slide 60 will move the cylinder portion 2 into its initial position.

Thereupon, another hydraulic cylinder is actuated to operate the locks 15 and to move them into the locking position shown in Figure 1. Then the mold is closed.

Due to the provision of the annular inserts 26 and the sealing ring 25, the cylinder portion 2 is now closed in an airtight manner.

After the closing of the cylinder portion 2, a suitable hydraulic cylinder is actuated to switch on the high frequency coil 21. This can be accomplished by a flexible high frequency cable which connects a generator with the coil 21 or by slide contacts located upon the wall 7 and the cylinder portion 2, and engaging each other in a predetermined position of the cylinder portion 2 so as to close an electrical circuit. Care should be taken not to subject the contacts to voltage before they are completely in contact so as to avoid arcing and so as to provide high frequency voltage at just the right moment, These devices are not illustrated.

At the same time the hydraulic drive is actuated to open a valvetnot shown) which connects the interior of the container portion 2'with a vacuum pump so that air located in the mold and gases formed in the course of the melting process are evacuate'cl' from the interior of the container 1., 2, 3.

In the course of the melting process an automatically operating regulator provided in the generator switches the device to, a higher voltage while the permeability of the molten mass shrinks.

, The melting process continues for a few seconds only. Upon its completion the hydraulic steering device switches off the high'frequency voltage and then a cam again operates the hydraulic cylinder 70 which turns the shaft 4 by means of the piston rod 49, the rack 47 and the gear 45 (Fig. 3). The shaft 4, along with the container 1, 2, 3, is now turned to an extent of 180", so that the molten material can flow out of the melting pot 20. The cam is so formed that the rotation takes place quickly to make certain that the molten material due to the centrifugal force remains in the melting pot 20 until the end of the rotation. Then, the molten material falls into the chamber enclosed by the sleeve 27 (Fig. 4) and passes through the passages formed between the graphite ring 28 and the graphite core elements 29 and 30 into its permanent iron form 33. This is diagrammatically illustrated in Figure 15 of the drawings.

As soon as the melting pct 20 is emptied, the hydraulic steering device actuates a valve in a high pressure conduit system which is not shown in the drawings. Then high pressure is provided within the container 1, 2, 3, directly above the molten material. This high pressure causes the molten material to flow very quickly into the form 33 which has been evacuated. Due to the quick filling of the form a formation of pores which otherwise might be produced in the course of the solidifying process by the escaping gases is effectively prevented. The gases in the molten material which, as a rule, escape during the solidifying cannot deform the casting due to the thickness of the liquid filling the mold 33, which is being cooled quickly due to the thinness of the casting. Furthermore, the high vacuum in the mold permits the escape of a large portion of gases dissolved in the molten material, such gases being removed through the high vacuum conduits.

The hydraulic system is timed to operate after the molten material has been solidified in the form of a casting.

Hydraulic means, not shown in the drawings, release the locks 15 in the same manner in which the lock of the part 2 has been previously released.

The hydraulic cylinder 56 is now actuated and its piston rod 48 will move the slide 54 with the result that the inner core portion 34 will be withdrawn to the position shown in Figure 16'. This diminishes the operative area of the mold cores with the result that the casting can shrink freely. The adjustment of the cores is assisted by the action of the springs 37.

The core 34 and the rod 41 integral therewith move outwardly in the bore 42 until the position shown in Figure 16 is reached. However, the movement of the slide 54 continues with the result that now the entire container portion 3 is moved away from the container portions 1 and 2. The core and the casting move along with the container portion 3. As shown in Figure 1, the container portion 3 slides upon posts 8 by means of sleeves 13 and the support 14.

The finished casting 122 is removed and held by a holding device 122a which is shown diagrammatically in Figure 17 and which is actuated by a hydraulic cylinder not shown in the drawing. The core is completely withdrawn from the liner 122, so that the latter is held only by the device 122a. Then the cam system actuates the hydraulic cylinder 85, shown in Figure 2, which moves the rod 86., serving as a pusher to shift the liner 122 from 8 the holder 122a upon an endless band, not shown in the drawing, and movable along the aggregate.

The endless band transports the liners 122 to a suitable storage place.

The hydraulic system is now actuated to cause the hydraulic cylinder to withdraw the rod or pusher 86 to its inoperative position shown in Figure 2.

Then the cam system actuates the hydraulic cylinder 56 which by means of the piston rod 58 and the support 55 moves the container portion 3 back to the container portions 1 and 2.

Finally, the hydraulic system (not shown) is operated to close locks 17, so that the container 1, 2, 3 is completely locked.

This completes the cycle of operations which is then repeated.

The completed liner 122 is shown in section in Figure 11. Preferably, the liner is pressed into a sleeve 121 having bottom inwardly projecting flanges 123, as well astop flanges 124 which extend outwardly. The sleeve 121 is provided with perforations 126.

The liner 122 may have a thickness of one-half millimeter to three millimeters. The important feature is that the thickness of the liner 122 is not greater than the highest charge depth of carbonized particles of low carbon-steel.

As already stated, the high frequency coil 21 of the machine is operated by the usual high frequency generator which is used for the inductive heating of electrical conductors.

According to a preferred construction, two of the described devices can be connected to a single generator which will actuate the induction coil of one of the aggregates, while the other aggregate carries out the casting operation. Such an arrangement will make it possible for the generator to operate continuously.

The liners 122 are obviously cut upon a polishing and cutting machine to the desired length before they are inserted into the sleeves 121, preferably made of wrought iron. The sleeves 121 will hold the liners 122 firmly by frictional pressure alone. 7

If the mixture of the material to be molten is always the same and if the temperature and the voltage are the same, one casting liner will be precisely the same as the other with reference to its mass and metallurgical data, since the described process can be reproduced to the finest detail.

- An important advantage of the described process is that the melting and the casting are carried out in the same chamber and that the gases formed during the casting are continuously removed by an effectively operating vacuum pump.

A further advantage is that the melting and the casting are carried out completely automatically in a continuous manner.

Furthermore, the following metallurgical advantages are available:

If cast iron which was molten in vacuum is again exposed to the atmosphere after the casting temperature is reached, which is obviously the case when it is transported to a mold, then a part of the advantages produced by vacuum melting is lost. The reason for this is that as soon as liquid iron is brought in contact with oxygen, even for a fraction of a second, an oxide layer is formed at the point of contact which flows with the molten material into the mold. When castings of a large crosssectional area are produced, this oxide layer is usually reduced again and the reduction gases either escape through the sand form or are divided in small amounts in the casting. On the other hand, if the casting has thin walls which cool very quickly, then the available heat is not sufficient for the reduction process, so that oxidized sections occur which make a thin walled casting unusable. The composition of the material in those places is not the desired one and usually breaks or tears occur in the casting. Other drawbacks also take place, such as porous sections and spherically shaped imperfections. All these drawbacks are completely eliminated by the present process, since the liquid molten material cannot be contacted by air.

The cores can also consist of a large number of thin sheets of heat-resistant material, such as tungsten. The permeability to gases can be increased if the two surfaces ofthe individual sheets are roughened by means of a sand blast.

Figures 18 to 21 show a reduction core 126 and side portions 127 which are composed of thin sheets 128. The sheets 128 are held on opposite sides by cover plates 129 and 130, as well as bolts 131, which may be threaded or riveted. The sheets 128 consist preferably of heat-resisting material, such as tungsten.

The reduction core 126 is conical in form and includes four dovetail-like guides 132. The conical side members 127 have corresponding grooves in which the guides are located. The side members 127 are of such shape that intermediate spaces 133 are located there between. They are provided with sliding surfaces 134 extending at angles of 45 to the vertical and the horizontal. Due to this location of the surfaces 134 the side members 127 can freely slide relatively to each other when the reduction core 126 is withdrawn, thereby diminishing the spaces 133 and providing for the construction of a core in its entirety.

As already stated, the side surfaces of the sheets 128 are preferably roughened, thereby allowing for the passage of gases. Gases liberated while the casting is being solidified, can thus penetrate through the small interstices between the sheets 128 into the intermediate spaces 133, and then can escape through the bore holes 124.

The cover 135 can also consist of thin sheets, for the purpose of facilitating the escape of gases which thus can pass between the sheets into the recesses 136.

These two constructions can be used jointly or each of them can be used separately.

It is apparent that the examples shown above have been given solely by way of illustration and not by way of limitation and that they are subject to many variations and modifications within the scope of the present invention. All such variations and modifications are to be included within the scope of the present invention.

What is claimed is:

1. A high frequency melting and casting machine for chill-casting cylindrical liners, said machine comprising, in combination, a single casing having two aligned end sections, a melting pot within one end section of said casing, a high frequency coil enclosing said melting pot, a casting form within another end section of said casing in alignment with said melting pot, means supporting said casing intermediate its ends, hydraulic means for swinging said casing to move downwardly the end section of the casing containing said melting pot, hydraulic means withdrawing the end section of the casing containing said melting pot from the rest of the casing, hydraulic means filling said melting pot with the metal to be molten, the

second-mentioned hydraulic means being adapted to return the end section of the casing containing the melting pot to the rest of the casing after said melting pot is filled with said metal, the first-mentioned hydraulic means being adapted to swing said casing to move upwardly said end section of the casing after its return, means switching on said high frequency coil when the melting pot is filled with said metal, hydraulic means withdrawing the end section of the casing containing said casting form from the rest of the casing, and means connected with all of said hydraulic means for operating them in the above sequence.

2. A high frequency melting and casting machine for chill-casting cylindrical liners, said machine comprising a casing having an intermediate portion, an upper part and a lower part, said portion and said parts being in en-, gagement with each other and constituting a single unitary casing during the melting and. casting, means con nected with said intermediate portion for swinging the casing as a unit from the casting position in which said upper part constitutes the top of the casing to the charging position in which said lower part constitutes the top of the casing, a pin mounted upon said upper part, means adapted to engage said pin to move said upper part away from said intermediate portion in said charging position, a melting pot, a high frequency coil enclosing said melting pot, means supporting said melting pot and said coil within said upper part, an outer core portion, springs carried by said lower part and supporting said outer core portion within said intermediate portion and said lower part, a central reduction cone fitting within said outer core portion and movable within said intermediate portion and said lower part, a rod integral with said central reduction cone and extending through said lower part, another pin connected with said rod and projecting outside of said lower part, said central reduction cone having a portion located adjacent said rod and adapted to engage said lower part when said central reduction cone is withdrawn from said outer core portion, means adapted to engage said other pin to withdraw said central reduction cone into a position in which it will engage said lower part and then to withdraw said central reduction cone jointly with said lower part from said intermediate portion upon completion of the casting, a wall within said intermediate portion and enclosing said outer core portion, said wall being spaced from said outer core portion, whereby a mold cavity is defined by opposed surfaces of said wall and said outer core portion, a cap covering an end of said central reduction cone, and means supporting said cap within said intermediate portion for guiding the melted contents of said melting pot into said mold cavity.

3. A high frequency melting and casting machine for chill-casting cylindrical liners, said machine comprising a casing having an intermediate portion, an upper part and a lower part, said portion and said parts being in engagement with each other in the casting position, a flange connected with said intermediate portion, a shaft connected with said flange, means connected with said shaft for turning the shaft, whereby the entire casing is swingable along with said shaft, 21. releasable lock carried by said upper part, a projection carried by said intermediate portion and engaging said lock in said casting position, a melting pot within said upper part, a high frequency coil enclosing said melting pot, oxide powder within said upper part, said melting pot and said high frequency coil being embedded in said oxide powder, sealing rings carried by said upper and lower parts, flanges carried by said intermediate portion and engaging said sealing rings in said casting position, an outer core portion within said intermediate portion and extending into said lower part, a wall within said intermediate portion and enclosing said outer core portion, said wall being spaced from said outer core portion, whereby a mold cavity is defined by opposed surfaces of said wall and said outer core portion, a sleeve within said intermediate portion and located between said wall and said pot in said casting position, said outer core portion having an inner conical surface, a central reduction cone adapted to engage said inner conical surface and extending through said intermediate portion in said casting position, a cap covering one end of said central reduction. cone and located opposite said pot in said casting position, a guide sleeve connecting said cap with said outer core portion, said cap being spaced from said sleeve, whereby the interiors of said pot and said sleeve are in communication with said mold cavity, springs carried by said lower part and engaging said outer core portion, a rod integral with said central reduction cone and extending through said lower part, a pin connected with said rod and projecting outside of said lower part, a cap carried by said lower part and engaging said rod, another pin mounted upon said upper part, means adapted to engage said other pin 11 to move said upper part away from said intermediate portion in a charging position of said casing, and means adapted to engage the first-mentioned pin to Withdraw said central reduction'cone'froni said outer core portion upon completion of the casting. 5

References Cited in the file of this patent UNITED STATES PATENTS 428,378 Colby May 20, 1890 10 1,019,905 McKee et a1. Mar. 12, 1912 1,138,443 Bierbaum May 4, 1915 1,449,907 Guyot Mar. 20, 1923 1,734,313 Von Malmborg Nov. 5, 1929 1,897,589 Reeve Feb. 14, 1933 15 Switzerland Aug. 16, 1951

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