US1793855A - Rotor mold - Google Patents

Description

Feb. 24, 1931. 1 c. E JQHNSON 1,793,855

ROTOR MOLD Filed Feb. 18, 1929 flTToen/Ey Patented Feb. 24, 1931 UNlTED STATES PATENT OFF-WE CARL E. JOHNSON, OF PASADENA, CALIFORNIA, ASSIGNOR'TO STERLING ELECTRIC MOTORS, INCL, OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALIFORNIA ROTOR MOLD Application filed February 18, 1929. Serial No. 340,991.

' lar utility in casting rotors, for instance, or

other devices.

Such devices are ordinarily singly cast 1n a mold from which they are subsequently removed. Machining is invariably necessary.

I have invented a mold whereby a plurality of rotors or other elements may be simultaneously cast, thus effecting a great saving in time as well as making possible a continuous process whereby a mold may be utilized time after time without preheating or supplying thereto any external heat other than that received from the molten metal. I

It'is an object of this invention to provide a mold. whereby a plurality of elements may be cast at the same time.

Still. a further object of this invention is to provide a mold having a casting chamber and a pouring chamber whereby the molten substance maybe poured into the pouring chamber and may pass into the casting chamber at the lower end thereof. This metal then rises to fill a casting chamber to form the element so that no subsequent machining is necessary.

A further object of this invention is to provide a mold whereby the contraction of the cooling metal is compensated for so that this contraction will not cause undue strains in the cast element.

A further object of this invention is to provide a novel method of casting rotors or other elements.

Still further objects and advantages of this invention will be made evident hereinafter.

Referring to the drawing,

Fig. 1 is a vertical cross-sectional view of my invention showing the form thereof utilized for casting rotors, one .of these rotors being shown as cast, and the other being shown as it a pears after the protruding tongues are file 05.

Fig.- 2 is a plan view, partly in'section, of my invention shown in section Fig. 1.

Referring particularly to Fig. 1, my in vention comprises a confining member 10 having a base 11 and side walls 12. This member is preferably formed in the shape of a cloverleaf, as shown in Fig. 2, and provides a plurality of chambers 13 positioned therearound. It is ordinarily preferable to form these chambers so that the walls thereof diverge very slightly in an upward direction. The construction of the confining member 10 is best shown in Fig. 2, which clearly indicates both the shape and position of the chambers 13 in the confining member 10.

The walls 12 provide webs 14 separating adjacent chambers 13, these webs terminating in arcuate walls 15, each of which is formed on an equal radius of the vertical axis of the confining member 10 indicated by the numeral 16.

Adaptedto engage the arcuate walls 15. and to be centrally disposed relative to the confining member 10, is a core member 18 which cooperates with the confining member 10 in defining the chambers 13. the outer pcripliery of the core member having out therein channels 19, the radius of curvature of which is the same as the radius of curvature of the chamber 13, these channels being positioned so as to lie between the points of the webs 14 in a manner to form the chambers Adapted to fit in each of the chambers 13 IS a core element 20. In the particular form shown this core element comprises a base plate 21 which rests on the base 11 ot the confining mcmber and has an arbor 22 extend ing upward and around which rotor laminations 23 are placed. A cap2l isthen placed over the arbor 22 and forced downward by means of an eyebolt 25 having a head 26 hearing against the cap 24-, and a screw 27 threaded into the arbor 22, so as to clamp the laminations between the base plate and this cap. It should be understood that the core elements 20 are assembled before being inserted in the chambers 13.

The walls of the chambers 13 provide shelves 35 which cooperate with the base plate 21 in forming a s ace for a lower end ring 36 of the rotor. imilary, the cap 2-1 provides an annular channel 37 wherein is formed an upper end ring 38. The laminations 23 have notches 39 cut therein which are brought into alignment when these laminations are assembled on the arbor 22, these notches providing spaces for forming conductor bars 40. These conductors bars,

and the end rings 36 and 38 are cast integrally in place by molten metal which is poured into a pouring chamber 43' formed in the core member 18, this metal passing through passages 44, one of which communicates with the lower end of each chamber 13. lhe space in the chamber 13 which is filled by the molten metal entering the lower end thereof has been termed a casting chamber and is indicated by the numeral 45, this chamber being defined below the cap 24 and inside the walls 12.

'lhis methodof casting rotors by pouring a molten metal into the lower end of a casting chamber is a very important part of this invention. There is, of course, a tendency for the molten liquid to maintain the same level in the pouring chamber 43 as it does in the casting chamber 45 so that as the level of the molten metal in the pouring chamber builds up, this molten metal passes through the passages 44 and simultaneously fills each of the casting chambers to substantially the same level.

Molten metal is poured into the pouring chamber 43 until it reaches a level 48 above the uppermost portion of the casting chamber 45. The molten liquid in the casting chamber is thus subjected to a pressure, and any contraction of the molten metal in the casting chamber will be compensated for by a renewed supply of molten metal through the passages 44. The amount of metal passing through the passages 44 after the casting chamber has been filled is, of course, small due to the fact that the shrinkage is not large. As soon as the metal in the casting chamber sets no further flow can, of course, take place. but I have found that this method of casting produces rotors which show little or no shrinkage effects. It should be understood that the metal in the pouring chamber 43 remains molten after the metal of the casting chamber has been set, due to the central placing of this pouring chamber. This insures a supply of molten metal to the passages 44 which may enter the casting chamber 45 and compensate for contraction of the cooling metal therein.

As the level of the molten liquid in the casting chambers rises, the air entrapped thereabove, is vented to the atmosphere through a vent means in the form of three small openings 47 formed through the cap 24 and communicatingwith the casting chamber 45. Any molten metal which rises in these openings may be easily chipped off. but I have found by making these openings sufiiciently small that there is little tendency for the molten metal to rise therein.

When the metal in the casting chamber has greases hardened, a suitable'means is utilized for $11- gaging each of the eye-bolts 25 in such a manner-that the filled mold and its associated rotors is suspended therefrom. The confining member 10 is then tapped, and this member drops, leaving the core member secured to the rotor by means of the metal filling the passages 44. The core member 18 is then tapped at the bottom in a manner to remove this core member from engagement with the rotors which are still secured together and v to the metal previously in the pouring chamber 43 by means of the metal previously filling the passage 44. These latter portions of metal are then suitably cut, and the rotor removed from between the base plate 21 and cap 24 after the eyebolt 25 has been unscrewed. The rotor is completed in this form with the exception that itis, of course, necessary to remove the metal previously occupying the passages 44 and the o enings 47 this being conveniently done by filing or grindmg.

In the right-hand side of Fig. 1 I have shown the completed rotor in the casting chamber 45, while on the left-hand side of this figure is shown a rotor in the process of being formed and having attached thereto the material in the passage 44: It should thus be apparent that no expensive machine operations are necessary on the completed rotor, the only work necessary being that of filing oil the metal protrusions, as previously explained. v

urthermore, it is not necessary to preheat the mold except when the first batch of rotors is being cast. Subsequently, the rotors are removed before the confining member 10 and core member 18 are cold, thus permitting additional rotors to be poured without preheating these members. -T his continuous process is a saving not only in the heat units previously required in preheating the mold, but also permits one mold to be used continuously, thus performing the work previously done by a large number of molds.

it should further be understood that my invention is not limited to a confining member of the clover-leaf shape shown. Such a shape is used on small rotors, but on larger sized rotors it is preferable to decrease the number ofcasting chambers formed around the pouring chamber 43, and with rotors of very large size it is desirable to utilize a single casting chamber in conjunction with the pouring chamber 43. All of these forms fall within the scope of this invention.

Furthermore, while I have shown and described my invention as being applied to motors for induction machinery, such a use is not essential to the utility thereof. It is possible to cast various other articles in my mold, including pistons or other metallic or non-metallic bodies.

A very important feature of this invention end thereof; and vent means in is the method of introducing a molten substance into the lower end of a casting chamber, and venting the upper end of this chamber to permit the escape of gases therefrom. This system finds its maximum utility when the walls of the pouring chamber extend above the walls of the casting chamber whereby a pressure-head may be maintained on the molten material in the casting chamber.

I claim as my invention:

1. A mold comprising: walls defining a plurality of casting chambers; walls forming a pouring chamber around which said casting chambers are placed, said casting chambers and said pouring chamber being separated by but a single wall; and means communicating between said pouring chamber and the lower portion of each of said casting chambers.

2. A mold comprising: a confining member; a core member removably positioned in said confining member and having a pouring chamber therein, said core member cooperating with said confining member to define a chamber; and means communicating between said chamber and said pouring chamber in a manner to conduct a molten substance thereto.

3. A rotor mold comprising: walls defining a casting chamber; means for supporting a group of laminations in said casting chamber, said means extending substantially across said casting chambers; walls defining as a unit together with the casting material. 70 In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 13th day of February, 1929.

CARL E. JOHNSON.

a pouring chamber adjacent said casting I chamber and communicating with the lower said means for venting said casting chamber.

4. A mold comprising: a confining member providing a plurality of webs extending inward; and a core member removably positioned in said confining member and defining a central pouring chamber, said core member cooperating with said webs in defining a plurality of chambers grouped around said pouring chamber and communicating therewith.

5. A combination as defined in claim 4 in which the ends of said webs are in the form of arcuate walls, and in which said core member provides an outer face corresponding in curvature to said arcuate walls and engaging therewith.

6. A combination as defined in claim 4 in which said core member provides channels corresponding in curvature to said chambers and forming a continuation of the walls of said chambers.

7. A mold comprising: a confining member; a core member removably positioned in said confining member and having a pouring chamber therein, said core member cooperating with said confining member to define a plurality of chambers around sald pourmg chamber and in communication therewith; a core element positioned 1 each of said cham-

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