Nov. 10, 1959 w. K. BECKWITH 2,911,669
METHOD AND APPARATUS FOR FORMING SPHERES Filed March 50, 1955 2 Sheets-Sheet 1 wan/x1012 VIBRATOR FIG 3 V INVENTOR. WENDELL K; BECKWITH ATTV.
W. K. BECKWITH METHOD AND APPARATUS FOR FORMING SPHERE IS Filed March 30, 1955 2 Sheets-Sheet 2 BALL COOLED llallinl D. A H S L S S L m A m N a a M@ p s a m L F (Q a W w m o u R w i I 5 wm 5 L D 5 &m m UN 0 BALL mops:
cooL EaAl-L DQoP BALL TIMER: T\MER #z T|MER#3 TIMER *4 cuE ON FUEL ON OXYGEN ON FEED nouuuEL-|- Fuse. BALL FUEL ON FUEL ON OXYG EN 0N OXYGEN ON OXYGEN OFF AIR O AIR ON TO ROUNDEL INJECTOR INVENTOR. WENDELL K. BECKWITH VALVEfi O FUEL CONTROL VALVE.
United States Patent O A METHOD AND APPARATUS FOR FORMING SPHERES Wendell K. Beckwith, Whitewater, Wis., assignor to The Parker Pen Company, Janesville, Win, a corporation of Wisconsin Application March 39, 1955, Serial No. 497,980.
8 Claims: (Cl. 18-1) perfectly spherical in order to fit well in the ball seat and to effectively apply a line to a writing surface.
I An object of the invention is to provide a method of forming spheres from fusible material whereby they are perfectly shaped.
.Another object is to provide a method of forming .spheresby fusion in which the pieces from which they are formed aresuspended in space during their formation and thereafter until they are cooled sufiiciently to retain their shape resting on a solid supporting surface.
A further object is to provide a method of and apparatus for fusing spheres or balls in which the flame for fusing them is so shaped and composed that the piece being formed into a sphere is so maintained in the flame that most efficient and perfect fusion is produced.
Still another object is to provide balls that are perfectly spherical and can be pitted without losing their sphericity.
Another object is to provide a method of forming spheres that is unusually economical.
Still another object is to provide apparatus for forming spheres by fusion having construction for maintaining the pieces in the most effective part of the flame.
Other objects and advantages will appear from the following detail description taken in conjunction with the accompanying drawingsin which Figure 1 is a vertical sectional view of a furnace em bodying principles of the invention, and well adapted to carrying out the method of the invention;
Figure 2 is an enlarged partial sectional View of the throat portion of the furnace;
Figure 3 is a view similar to Figure 2, but showing one of the elements in an alternate adjusted position;
Figure 4 is a diagrammatic-schematic representation of the stages of the fusion of a ball;
Figure 5 illustrates various stages of a piece and the ball into which it is formed;
Figure 6 is a diagrammatic representation of a timing arrangement for controlling the furnace; and
Figure 7 is a greatly enlarged sectional detail view of a ball fused according to the present invention and later provided with a pitted surface.
Referringin detail to the drawings, attention is directed first to Figures 1, 2 and 3 in which the furnace 12 includes a body portion having an upper part 14 and a lower part 16 suitably fitted together as in a telescopic ,arrangement and secured by a set screw 18. I Y The lower part 16 includes a central bore or passage 20 extending downwardly, and is fitted with a receptacle 22 for receiving the balls 24.
The halls merely drop into the receptacle 22 from a position in the furnace in which they out portion of the insert. passage 50 in the furnace body which communicates with I, Patented. Nov. 10, 1959.
are formed in the fusion process. Thefurnace is supported on a suitable support 26 upon which vibrators 28 of conventional form are mounted for vibrating the furnace and preventing the balls from adhering to the furnace in the fusion process.
The upper part 14 is provided with a central bore 30 terminating upwardly in a reduced portion 32, the latter opening into a bowl 34 above it which diverges upwardly at a suitable angle for controlling the flame in which the balls are fused, as will be brought out later in detail. The throat of the furnace is where reduced portion 32 joins bowl 34, and this is where the flame is controlled.
Fitted in the central bore 30 is an insert 36 having a flange 38 at its lower end clamped between mating surfaces of the parts 14 and 16 for securing the insert in place. A shim 40 is interposed between the flange 38 and the upper part 14 for adjusting the upper part 14 upwardly and thereby effectively positioning insert 36 relative to the throat of the furnace for controlling the character of the flame at thethroat of the furnace. The shim 40 may be one of a series of shims of different thicknesses. A shim is selected according to the relative position of the upper end of the insert 36 relative to the throat of the furnace. The upper end of the insert 36 has a reduced portion 42 extending into the reduced portion 32 of the bore of the furnace.
The insert 36 has a central passage 44 for receiving air and oxygen, and this passage opens upwardly into the bowl 34 and downwardly for dropping the balls therethrough upon completion of the fusion process. The passage 44 is fed by radial passages 46 which in turn communicate with an annular space 43 formed by a cut- The passage 48 is fed by a a conduit 52 having branches for air and oxygen, the air branch being designated 54 and the oxygen branch, 56.
These conduit branches are provided with suitable control 34. The passage 58 is fed by a passage 64 to which is connected a conduit 62 for providing fuel to the furnace. .The conduit is provided, similarly to the air and oxygen conduits, with suitable control valves :and apparatus for supplying fuel to the furnace.
A chute 64 is disposed above the furnace bowl 34 for introducing pieces into the furnace for forming the balls.
Associated with the chute 64 is suitable apparatus for introducing the pieces in timed relation to the other steps in the fusion process, namely, the supply of combustible gases, cooling air, dropping the fused balls out of the furnace, etc.
A finished ball 24 is shown in each of Figures 2 and 3. The piece or mass from which the ball is formed, to begin with, is non-spherical or irregular as is, of course, understood in accordance with-the purpose of the invention. As explained above, the apparatus and method is particularly adaptable to balls for use in ball point pens.
Sapphire and its equivalents are suitable materials for such balls; these materials are extremely hard, and they lend themselves to forming perfect spheres. As is well known, sapphire, natural or synthetic, is chemically the same or similar to aluminum oxide. Sapphire or the multi-crystal material known as corundum maybe used with equal effectiveness in forming balls according to the invention. It will be understood also that other materials capable of being fused at practical temperatures in such furnaces may also be used, ruby being one of the materials.
As an example, the balls may be formed from roundels cut from a rod; processes for performing this step are known. The rod is of a diameter similar to, or perhaps slightly smaller than, that of the intended sphere (which is in the neighborhood of 1 mm), and the roundel is cut to such length that its mass is that of the intended sphere, plus that small amount lost by the tumbling operation, referred to hereinbelow, when such is utilized. The roundel as thus formed is shown at a in Figure and is of the shape generally of a short cylinder. One of these roundels is deposited from the chute 64 into the furnace, as indicated in Figure 1, by suitable feeding means which will feed one such roundel at the desired time in the cycle of fusion. The roundel is dropped or deposited after establishment of the flame 66 (Figures 2 and 3) which is the product of the fuel and oxygen delivered through the passages 44 and 58. The flame is annular in shape, and it is so shaped and composed that the ball is maintained at that portion of the flame of the desired temperature for proper fusion. Sapphire fuses best at around 4000 F. and the ball is maintained at the portion of the flame of approximately that temperature. The piece or roundel is supported in the upstream of the flame by a well-known phenomenon and is thus suspended in space or suspended in air (as the saying goes, although it is suspended by a mixture of gases, the point being that it is not supported on a solid non-yielding support). As a step preliminary to fusion, the corners or the end edges of the roundel are slightly rounded to a short radius by a tumbling operation preferably in water, over a period of a number of hours. This is desirable so that such sharp corners are not overheated as might otherwise be the case. Phase a of Figure 5 shows a roundel after tumbling but before any fusion effect. Phase b shows the roundel or piece after 'partial fusion; the corners, although they have been slightly rounded by the tumbling operation, are subjected to the greatest heat and thus fuse faster than the other portions. This fused portion at the corners is then drawn in more and more as the fusion operation progrosses, and the piece approaches a spherical shape. A later phase is shown at c in Figure 5 showing the corners more rounded but the piece not yet a sphere. In the last phase d the piece is a perfectly rounded sphere. It might be here noted that the apparatus is so dimensioned relative to the intended dimension of sphere that the passage 44 is only slightly larger than the completed sphere. The passage permits the sphere to drop there- 'through upon completion of the fusion and cooling operations, into the receptacle 22, as was brought out briefly above. Figure 7 shows a portion of a ball that has been made spherical according to the present process, but afterward subjected to a pitting process for providing a pitted surface for carrying ink from the ball seat to the writing surface. The method of providing the pitting is not an essential of the present invention and is referred to here for the purpose of pointing out the sphericity of the balls according to the process. The ball 24 of Figure 7 is formed with a plurality of pits 68, but notwithstanding this, the surface portions 70 between the pits lie in a spherical surface formed and determined by the formation of the sphere according to the process outlined above. It is in connection with a pitted ball that the hardness of the material, such as sapphire or ruby, comes into prominence, in a ball point pen. Sapphire, for example, is extremely hard and a sapphire ball thus will not wear greatly when subjected to an abrading action with a ball seat formed of a softer material such as steel. Even where the seat is formed of glass, which is su than sapphire and does not have a great deleterious effect in abrading the sapphire ball. The same is true of foreign particles that find their way between the ball and the seat. These particles, as is well known, cause a serious abrading effect on a ball of soft material, but since any such particles would be much softer than sapphire, they would not seriously affect sapphire. Hence the pits remain in the surface.
As noted above, the sapphire must reach a substantial temperature to fuse, namely, in the neighborhood of 4000 F. It was found that in a solid flame issuing from a single passage the pieces did not reach the portion of the flame having the temperature necessary for fusion. In such a flame the hottest portion is in or near the center. The piece bounced above the flame or at the upper tip thereof and did not reach down into the center where it was hot enough to fuse the material. The annular type of flame formed by the apparatus of the present invention enables the piece to lower into the flame where it is sufficiently hot to fuse it. The flame issuing from the throat of the furnace is annular in shape, and the roundel or piece is enabled to reach further down into the flame while the flame is in full elfect. Figure 2 shows the portions of the flame of the various temperatures. The portion where the ball rests is at approximately 4000 F. A neighboring portion outwardlyof the first may be 3500 F. Another portion deeper into the flame may be 4500 R, which would be too hot for the fusion operation; and yet a fourth portion may be 2500 F. at the lowermost portion of the flame. The
stream of gases and flame is such as to support the ball as indicated in Figure 2, namely, at approximately 4000' F. The fuel, maintained constant, is delivered through the conduit 62 into the passage 58, and it then passes into the bowl 34 in an annular formation. The flame is supported by oxygen in the fusing operation, rather than by air, so as to produce a greater temperature. The oxygen is delivered through the conduit 56, 52 and into the passage 44 by suitable means, as was explained above.
The oxygen then issues upwardly from the passage 44 and combines with the fuel at the throat in the bowl of the furnace, as indicated. Since the fuel is fed in in an annular pattern, the resulting flame is in annular form.
It is necessary that the pressure of the fuel and oxygen be maintained within very close tolerances in order to flame issuing from the throat of the furnace. Obviously,
the heat would be greatly dissipated from the flame if the bowl were not present. The bowl, on the other hand, diverges upwardly so that the flame is permitted to expand as it rises, and a certain latitude is permitted the piece or sphere to bob or bounce from side to side somewhat and still be supported in the proper portion of the flame. The furnace may be provided with suitable air cooling fins 72. Any tendency for the piece or roundel 24 to stick or adhere to the surface of the bowl 34 is obviated by the vibrators 28.
The upper end of the insert 36, namely, the portion 42 thereof, may be effectively adjusted, as was pointed out above, by interposing a shim 40 of different thick ness so as to position the insert variously with respect to the lower end of the bowl 34. Such an adjustment is indicated at Figure 3 in which the portion 42 terminates would be lowered somewhat in the throat so as to be more confined at the smaller portion of the bowl. Hence by such an adjustment as indicated, an additional control stautially harder than steel, the glass is nevertheless softer of the heat of the flame may be attained. The flow of the gases or flame over the edge of the juncture between the bowl and the bore is also of some importance in the control of the flame.
' It is apparent from the foregoing that the sphere is completely formed while suspended in air, as contrasted with resting on a solid surface in which case a flat side may be formed. Thefusion of the sphere is completed while it is suspended. It is, of course, furthermore important that the sphere so formed be cooled and hardened sufliciently to prevent forming a flat side before the sphere drops. This is accomplished by replacing the oxygen with air, which is done after the fusion is completed and is preferably done gradually so as to stabilize the sphere or ball in the flame. In this step of the operation the air is introduced in the air line shown and gradually increased in pressure until it surpasses the pressure of the oxygen and so backs up the oxygen in its line which is connected with the air line. The oxygen is eflectively cut off, but gradually so. The fuel is continued, however, and with the cessation of flow of oxygen, the. temperature of the flame is greatly reduced. The air which is injected is sufficient to maintain the flame burning, but insufficient to retain the higher fusing temperatures. The stream of air may be of any suitable pressure to cool the ball and even raise it from the flame if desired. A ball need not be cooled greatly in order for it to set or harden sufficiently to maintain its true sphericity when resting on a solid surface. After this is accomplished, the air and oxygen are reduced and actually cut ofl, and thus the pressure of the stream of gases and the upstream force or strength of the flame is materially reduced, and the ball drops by its own weight through the passage 44 and into the receptacle 22. The ball drops through the flame, but the flame is lazy and incapable of supporting the ball or sphere. The flarne is maintained burning for convenience in establishing the proper flame for the next cycle. The cycle of operation is indicated in Figure 4, which is diagrammatic and schematic in nature. The cycle is composed of four stages, in the first stage the fuel and oxygen are on. The flame then quickly attains its desired heat and approximately half through the first period the roundel 24 is injected. The flame and stream of gases is of suflicient upstream force to support the roundel. In the second period the flame cotninues as it was at the end of the first period, and during this period the roundel changes shape and is completely formed into a sphere. In the'third period the air is turned on, While the fuel remains on, and the oxygen replaced as described above, with the result that the temperature of the flame drops materially, but the upstream force is not decreased, and the rapid cooling action referred to takes place. At the end of the third period the air and oxygen are turned olf, and the up stream force of the flame becomes insufficient to support the sphere and the sphere drops as indicated at the end of the schematic diagram. The temperature of the sphere when it drops is substantially below its fusion point, and all danger of its becoming misshaped upon dropping is eliminated.
Figure 6 illustrates a schematic arrangement or device for controlling the apparatus according to the steps or phases of Figure 4. A dial 74 is provided with a hand 76 operated by a suitable clockwork. The dial is provided with a plurality of sets of electrical contacts 78 arranged in pairs, and the hand 76 is provided with contact elements 80 arranged for making contact between the contact strips of each pair when passing over those strips. Leading from the contact strips are electrical wires 82 connected to the respective controls such as roundel injector, fuel control valve, etc. The diagram indicates that the fuel remains on continuously; the roundel injector is actuated approximately mid-way of the first period; the oxygen control valve is opened throughout the first three periods; and the air control valve is open during the third period. The lengths of the various periods are also indicated on the dial, the first being of three seconds, the second of four seconds, the-third of three seconds, and the fourth of two seconds. The complete cycle is thus approximately twelve seconds. It will be understood that the form of control device may be as desired, and it is also desired that the lengths of the various periods may be adjusted without affecting other periods, such as providing that certain periods may overlap somewhat, suitable controls being utilized for that purpose which do not enter into the essence of the present invention.
One of the most important advantages of the invention is the change in crystal structure of the material of the balls. In the case of sapphire or other materials having single-crystal structure, it is virtually impossible to pit the material and maintain its perfect sphericity. For example, in a conventional lapping operation, the effect is to produce an out-of-roundness according to the orientation of the crystal axis. But the fusion process of this invention produces such a change in the crystal structure that a uniform surface hardness is formed, and pitting can be carried on without adversely affecting the sphericity. This phenomenon is also present in the case of pellets formed of aluminum oxide powder, which is of multi-crystal structure. The surface of balls fused of this material is perfectly uniform and lends itself perfectly to a pitting process.
It will be apparent from the foregoing that an unusually inexpensive method has been developed for producing spheres, in addition to having the advantage of forming perfect spheres.
1. The method of forming a sphere from a piece of fusible material, comprising providing an upstream flame of controllably variable temperature and upstream strength, suspending the piece in and by the flame stream until it is fused at least on its surface and the fused material flows to form a sphere of the piece, introducing a stream of air into the flame stream thereby maintaining the strength of the stream but lowering the temperature for cooling the sphere to below its fusion temperature while suspending it in the stream, and thereafter diminishing the strength of the stream to allow the sphere to drop onto a supporting surface.
2. The method of forming a sphere from a piece of fusible material, comprising, providing an upstream flame of annular form having a root portion slightly larger in diameter than the sphere to he formed, said flame being of controllably variable temperature and upstream force, introducing the piece into the flame, and controllably varying said temperature and force to suspend the piece in and by the flame stream until it is fused at least on its surface and the fused material flows to form a sphere of the piece, to cool the piece while suspended, and to thereafter allow itto drop onto a supporting surface.
3. The method of claim 2 in which the piece is of sapphire or chemical equivalent and the flame has portions of various temperatures and is so constituted that the piece is maintained closely adjacent the region of 4000 F. temperature.
4. The method of forming a sphere from a piece of fusible material, comprising providing an upwardly flowing stream of gases including an annular portion of fuel and a central portion of oxygen forming an annular flame at their confluence, suspending the piece in and by the stream until it is fused at least on its surface and the fused material flows to form a sphere of the piece, thereafter replacing the oxygen with air until the sphere is cooled below its fusion point and then diminishing the strength of the stream and allowing the sphere to drop onto a supporting surface.
5. Apparatus of the character disclosed, comprising a body having a central vertical passage which opens at its upper end into a bowl, and which opens at its lower end into a collection receptacle, fuel conduit means leading into the bowl and having an annular opening there- "7 into adjacent and surrounding the open upper end of the central passage, means for introducing acombustionsupporting gas into the bowl through the central passage, and means for controlling the force at which the gas is introduced and for controlling the degree to which the introduced gas supports combustion.
6. The invention of claim 5 in which the bowl of the body has an upwardly diverging conical wall leading upwardly from the upper end of the central passage.
7. Apparatus of the character disclosed, comprising a body having a central vertical bore with an upper portion of reduced diameter and opening at its upper end into a bowl, an insert in the bore and complementally shaped therewith, said insert having a central vertical passage which opens at its upper end into the bowl, and which opens at its lower end intoa collection receptacle, the upper end of said insert having clearance in the bore to form an annular passage between the insert and the wall of the bore, which passage opens upward into the bowl annularly adjacent and surrounding the central vertical passage, means for adjusting the insert vertically to vary the size of the annularpassage between the insert and the wall of the bore, means for supplying fuiel to the annular passage, means for supplying a combustionsupporting gas into the bowl through the centralpassage, and means for controlling the force at which the gas is introduced and for controlling the'degree to which the introduced gas supports combustion. p
8. The invention of claim 7 in which the bowl of the body has an upwardly diverging conical wall leading upwardly from the upper endof the central passage.
References Cited the file of this patent UNITED STATES PATENTS Vogt Apr. ,2l, 1936 Potters Dec. 2, 1952