US2065287A

US2065287A - Piston molding apparatus

Info

Publication number: US2065287A
Application number: US350296A
Authority: US
Inventors: Frank N Nutt
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1929-03-27
Filing date: 1929-03-27
Publication date: 1936-12-22
Anticipated expiration: 1953-12-22

Description

Dec. 22, 1936 F. N, NUTT 2,065,287

P I STON MOLD ING APPARATUS Dec. 22, 1936.

F. N. NUTT 2,065,287

PISTON MOLDING APPARATUS Filed March 27, 1929 'I Sheets-Sheet 2 Patented Dee. 22, 1936 rls'roN Monouso Arranaros y Frank N. Nutt, Flint, Mich., assignor, by menne assignments, to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 27, 1929, serial No. 350,296 zo claims. (Ci. 2er-12s) For well` known reasons, it is desirable to use `what are commonly known as permanent molds.i. e. molds which consist of `a metal body anda metal core-in casting pistons of light metalsor alloys. And sincepistons of light metals or alloys, as well, in tact, as pistons oi heavy metals or alloys, are commonly provided with a 'plurality o't internal projections, it has heretofore been considered necessary to provide such molds with complicated, multipart cores in order that the castings may be separated'irom the coresatter the'molten metal has congealed. A `core oi this type is objectionable for the reason. among others, that, due to the irregular shape 154 oifthe several parts, they become warped and,

, consequently, difiicult to manipulate after being subjected to the. temperatures encountered during the casting operation. My invention resides in the provision of cer- `tain new and useful improvements in molding apparatus for use" in casting pistons, particularly pistons made of light metals or alloys, and particularly, in apparatus of the type described, in the provision of a mold which includes a mold body made of an inirangible material, suchV as iron or steel, and a core of which the portions which can be withdrawn as a unit from the casting alter the molten metal has congealed,"without iracturing the casting. are made of an ,ini'rangible material, such as iron or steel, and the portions which cannot be withdrawn from the casting. without iracturing `it for them or without'being moved with respect to the ilrst-mentioned portions. are madeof a suitable `frangible material, such as molding sand, plaster of Paris, A or suitable graphite compositions. 1

V `In the accompanying drawings there are illustratedpreierred embodiments of my invention,

for a 4detailed description oi4 which reference made to the following speciiication.

In thedrawings; Figure 1 A-is a view showing,mainly in vertical cross section, piston molding apparatus, in which is embodied my invention; with the parts in positionto receive the moltenmetal oi which the pisi toncasting is to be made. i Figure 2 is a view, similar to Figure 1. but showing'the parts of the molding apparatus `in the positions which they occupyafter thecore has been lowered and thehalves of the mold body have been'moved to an intermediate position preparatory to removing a casting therefrom. -Figure 3 is an end elevation of the molding apparatus shown in the preceding figures with the' with, there extends a cylindrical opening 22. On

parts in the same positions in which they are shown in Figure 1.

" Figure 4 is an enlarged fragmentary view showing the coreand one side of the mold body of the molding apparatus shown in the preceding 5 gures in section on-the line 4 4 of Figure 6.

. Figure 5 is an exploded side elevation of the Vcore o! the molding apparatus shown in the preceding ilgures.

Figure 6 is a top planview of thecore o! the 10 molding apparatus shown in the precedi gures. I

`Figure '1 is a fragmentary side elevation, with parts broken away and in section, of aslightly modiiied form oi core. 15

Figure 8 is a top plan-view of the core shown in Figure '1.v

, Figure 9 is a fragmentary section taken on the line 9-9 oi Figure` 8.

Figure 10 is a view, partly in side elevation and partly in longitudinal `cross section through the axis of the wrist pin bosses, of a completed piston oi the type which` the apparatus shown in the precedingilgures isdesigned to produce.

' Figure 11 is aV section taken on line Ii-Ii of u Figure 10.

The i piston, which the i molding" apparatus shown in the drawings is designed to produce is shown, as it appears after having been machined and ilnished. in vFigures 10 and 11 of the draw- 30 ings. The lpiston is made of a light aluminum alloy and consists of a head a and a skirt b. In the upper end oi the skirt is embedded a ring c of a `metal or alloy, such as iron, steel, or invar metal, which has a lower temperature coefficient 35 of expansion than the aluminum alloy of which the piston is made. From diametrically opposite webs d formed integrally with the skirt and partially separated thereirom by upper and lower arcuate slots e and f extend inwardly projecting 4o wrist pin bosses y'. Columns h, integral with the wrist pin bosses and the head oi' the piston, extend vertically upward from the inner ends of the wrist pin bosses to the end wall oi the head and are separated `from the side walls of the 45 head and the skirt by spaces i.

'The molding apparatus shown in the drawings includes 4a support 2l through which.and a depending guide member 2| formed integral there- 50 the upper surface of the support and on opposite sides of the opening 22 are provided guideways 2 3. In each of the guideways' 23. there is mounted to slide toward" and away from the opening n 22 a frame 24 which carries a half of the mold body.

Each half of the mold body is made of a suitable infrangible material, such as iron or steel, and consists of a wall 28 in which is provided a substantially semi-cylindrical recess whose upper end is closed by a wall 21 in the diametral edge of which is formed half oi the pouring gate 2l. The interior surfaces of the walls 23 and 21 are so shaped that, when the halv of the mold body are in their innermost positions, in which the side and top walls of one abut against the side and top walls, respectively, of the other, as shown in Figure 1, there is formed therebetween a cavity which is coaxial with the opening 22 and whose walls are so shaped as to give the desired form to the outer side and end walls of the piston casting and to provide cores 29 for the wrist pin boss cavities.

To give the desired shape to the interior of the piston casting. there is provided, as shown in Figures 1 to 6 of the drawings, a core 30 on which is provided a cylindrical guide extension 3| which is slidably mounted in the guide member 2|. The core is of such shape as to give the desired form to the interior of the piston casting and, with the exception of the portions 32 which are adapted to core the spaces i between the columns h and the adjacent portions of the inner side wall of the casting, is formed of av suitable infrangible material, such as iron or steel. The portions 32, which may be made of any suitable frangible material, such as molding sand, plaster of Paris, or a suitable graphite composition, are generally arcuate in shape, are adapted to fit into recesses 33 formed in the sides of the infrangible portion of the core by removing the portions thereof directly above the wrist pin boss cavities, and are provided with lateral extensions 34 adapted to ilt into the undercut portions of the recesses 33 to interlock the portions 32 with the infrangible portion of the core.

In the event that it is desired to incorporate in the skirt of the piston a ring, such as c to control the expansion and contraction thereof, there are provided on the infrangible portion of the core projections 35, each spaced 90 from the axis of the wrist pin boss cavities and diametrically opposite each other, on which the ring is adapted to be supported during the casting operation. In this event it may also be advisable, as shown in the drawings, to form each of the frangible portions of the core in two parts, 33 and 31, whose plane of separation is perpendicular to the longitudinal axisof the casting and at the level of the center of the ring c, to form on the parts 36 projections 33 having in their upper surfaces substantially semi-cylindrical recesses 39 in which diametrically opposite portions of the ring c are adapted to be seated and which are adapted to provide additional support for the ring during the casting operation, and to form on the parts 31 projections 40, adapted to be seated on the upper surfaces of the projections 38 and having therein substantially semi-cylindrical recesses 4| adapted to receive diametrically opposite portions of the upper half of the ring.

There may be formed, as shown in the drawings, on the parts 38 of the frangible portions of the core, arcuate ribs 43 to core the arcuate slots e which partially separate the webs d from the skirt b oi the piston. If, for any reason, it is undesirable to provide these core portions on the frangible portions of the core, they may be formed on the interior surface of the mold body.

In Figure 1, the parts of the molding apparatus are shown in the positions which they occupy when the mold is ready to receive the molten metal from which the casting is to be made. The molten metal is introduced into the interior of the mold through the gate 28 and flows into and 1111s all of the space between the mold body and the core and thus produces a casting of the desired shape. It will be noted that during this operation, molten metal is introduced directly into the wrist pin boss cavities from the gate 23 through the portions of the recesses 33 which are located between the infrangible and frangible DOrtions of the core.

To separate the halves of the mold body, after the molten metal has congealed, so that the casting may be removed therefrom, there is provided on the support 20, adjacent the outer end of each of the guideways 23, a bracket 44 in which is journalled a shaft 45. To each of the shafts 45 is secured an operating arm 46 and a pair of cranks 41. Between each pair of the cranks 41 is pivotally secured one end of a link 48 which is bifurcated at its opposite end and carries adjacent the latter end a pin 49 which extends between its legs and is adapted to be seated in any one of a plurality of notches 50 which are provided in the upper surface of the frame 24.

To separate the halves of the mold body, the pins 49 are each seated in one of the outer notches 50 (as shown in Figure l) and the upper ends of the levers 46 then swung outwardly to the positions in which they are shown in Figure 2. After this, the upper ends of the levers 45 may be swung inwardly until the pins 49 engage in the inner notches 50 and then again swung outwardly until the halves of the mold body are entirely clear of the casting. It is obvious that, under ordinary conditions, the preliminary separating operation may be dispensed with and the halves of the body moved to positions in which they are entirely clear of the casting by a single operation.

To maintain the core 30 in its uppermost position, in which it is shown in Figure 1, there is provided a spring catch 5| which is secured to the guide member 2| and is adapted to engage a boss 52 formed on the lower extremity of the guide extension 3| of' the core. To move the core from its uppermost to its lowermost position and vice versa, there is provided on each side of the guide member 2| a toggle linkage which consists of pivotally connected

links

53 and 54 which are pivoted, respectively, to the guide member 2| and the guide extension 3|. The links 53 are provided with extensions 55 which serve as operating arms for the toggle linkages and which are secured together adjacent their free ends so that the two toggle linkages may be operated as one.

After the halves of the mold body have been moved to positions in which they are entirely clear of the casting, the arm 55 is operated to move the core 30 downwardly from the position in which it is shown in Figure 1 to that in which it is shown in Figure 2. Since the casting cannot move downwardly with the core and the frangible portions 32 of the core are interlocked with the casting, the downward movement of the core will free the infrangible portion thereof from the casting and separate it from the frangible portions 32. The casting may then be removed from the molding apparatus by lifting it vertically. The separation of the frangible and infrangible parts of Vthe core may fracture and free the former from the casting but if it does not this may be done by u acostar core in the recesses 33 in an infrangible portion of the core. (3) to seat the ring c on the projections 35 and in the recesses 3d in the projections 38. (4) to insert the upper parts 3l or the frangible portion o1' the core in the recesses 33 in the infrangibleportion oi. the core, and (5) to move the halves of the mold body back to the positions in which they are shown in Figure 1.

The modified `form of `core which is shown in Figures 'l to 9 of the drawings differs from that shown in the preceding figures only (1) in that, instead of two arcuate lower frangible core parts there is provided a single annular frangible core part 56, which may be described as consisting of two parts, similar to those which are designated by the reference characters 36 in the preceding gures, arranged diametrically opposite each other and integrally joined by two arcuate sections, on each of which is formed at 90 to either of the projections 5l, which are similar to and correspond to the projections 38 shown in the preceding flgures,`projections 58 which replace and perform the same functions as the parts 35 shown in the preceding figures; (2) in that, instead of two arcuate upper frangible core parts, there is provided a single annular frangible core part 59, which may be described as consisting 'of two parts, similar to those which are designated by the reference characters 3l in the preceding gures, arrangedy diametrically opposite `each other and integrally joined by two arcuate sections; and (3) in that the infrangible portion Gil of the core is cut away to provide arcuate rabbets 6i, which communicate with the recesses 62, which correspond to the recesses'which are designatedby the reference characters 33 in the preceding figures, and which are provided to receive the additional sections, hereinbefore mentioned, of the frangible core parts 56 and 59. The method of assembling the frangible core parts 56 and 59 and the ring `c on the infrangible core part previous to each casting operation will be obvious from what has previously been said regarding the corresponding parts shown in the preceding iigures. `'Ihe advantage of the structure shown in Figures 'l to 9 over that shown in the preceding figures is that there are only half the numberof frangible core parts to be assembled on the infrangible core part previous to each casting operation.

It will be understood that, although I have described `the molding apparatus in which is embodied my invention as adapted for use in casting pistons of light metals or alloys, it may be used in casting pistons of the heavier metals or alloys; that the upper and lower frangible core parts, which have been shown and described as separate pieces, may be made integral; and that many the type in which the skirt is connected to the head by columns spaced inwardly from portions of the side walls of the piston, a mold body, and a core having therein column cavities the walls of which are formed in part by a irangible material and in part by an infrangible material.

2. In apparatus for use in molding pistons of the type in which there are provided on the shirt i inwardly projecting wrist pin bosses and in which the head is connected to the shirt hy columns which extend from the inner ends or the wrist pin bosses to the end wall of the head and which are disconnected from the side walls of the skirt and head intermediate the wrist pin bosses and the end wall of the head, a mold body, and a core having therein wrist pin boss cavities, and column cavities. the inner walls of which are formed of an infrangible material and the outer walls of which are formed of a frangible material, and each of which extends from the upper end of the core and communicates at its lower end with one of the wrist pin boss cavities.

3. In apparatus for use in molding pistons, a

`mold body formed of an infrangible material, and

a core on which there is provided a casting engaging surface of which a portion is formed of an infrangible material and a portion of a frangible material.

4. Apparatus for use in molding pistons which includes, a mold body onwhich there is provided a casting engaging surface, and a core on which there is provided a casting engaging surface, one of said surfaces being formed in part of an infrangible material and in part of a frangible material, and the other of said surfaces being formed in whole of an infrangible material.

5. In apparatus for use in molding pistons, a mold body, a core of which a portion is formed of an infrangible material and a portion of a frangible material, and means to move the infrangible portion of theu core with respect to the casting in order to fracture the irangible portion of the core and free the casting from the core.

6. In apparatus for use in molding pistons, a mold body which consists of a plurality of relatively movable parts which are made of an infrangible material, a core of which a portion is formed of an infrangible material and a portion of a frangible material, means to move the several parts of the mold body with respect to each other and the casting to free said parts from the casting, and means to move the inirangible portion of the core with respect to thecasting in order to fracture the frangible portion ofthe core and free the casting from the core.

'7. In apparatus for use in molding pistons, a

mold bodyyand a core which includes portions which are adapted to be interlocked with the casting so that they cannot be withdrawn therefrom by simply moving them axially of the casting, and other portions which can be withdrawn from the casting by simply moving them axially thereof-the iirst mentioned portions being made of frangible material and the last mentioned portions being made oi.' lnfrangible material.

8. In apparatus `for use in molding pistons, a mold body, and a core in which there are provided wrist pin boss cavities-portions of the core above the wrist pin boss cavities being made of a frangible material, and the remaining portions of the core being made of an infrangible'material.

9. In a core for use in molding pistons, a body made oi an inirangible material having therein wrist pin boss cavities, and recesses extending from the wrist pin boss cavities to the head end therecesses.

10. In a core for use in molding pistons, a body in which there is provided a projection cavitythe portions of the body below the projection cavity being made of an infrangible material and portions above the projection cavity being made of a frangible material.

11. In a core for use in molding pistons, a body made of an infrangible material and having in the side walls thereof wrist pin boss cavities and recesses having undercut portions extending from the wrist pin boss cavities to the head end thereof. and inserts of a frangible material in the recesses and having portions engaged in the undercut portions thereof to interlock the inserts with the body of the core.

12. In apparatus for use in molding pistons of the type in which there is embedded in the side wall thereof a metallic ring, a mold body, and a core on which there are provided projections on which the ring is adapted to be supported during the casting process.

13. In apparatus for Vuse in molding pistons of the type in which there is embedded in the side wall thereof a metallic ring, a mold body, and a core of which portions are made of an infranglble material and portions of a frangible material, and projections on which the ring is adapted to be supported during the casting process, of which projections one is formed on an infrangible portion and another on a frangible portion of the core.

14. In apparatus for use in molding pistons, a core made of an infrangible material and in the outer side wall of which is provided a vertically extending recess having undercut portions, and upper and lower segment-like inserts in said recess and having portions engaged in the undercut portions of the recess to lock the inserts in the recesses.

15. In apparatus for use in molding pistons, a

' core made of an infrangible material and having in the outer side wall thereof an annular recess and a ring-like element of frangible ma' terial seated in the recess.

16. In apparatus for use in molding pistons of the type in which there is embedded in the side wall thereof a metallic ring, a mold body, a core made of an infrangible material and having in the outer side wall thereof 'an annular recess and a ring-like element of frangible material seated in the recess and having thereon projections on which the ring is adapted to be supported during the casting process.

17. A core for cup-shape articles having an internal undercut comprising a permanent centrai section and two disintegrable side sections, the central section comprising the entire core outside the undercut portions of the casting and the central part of the core at the undercut portions of the casting.

18. A core for cup-shape articles having an internal undercut comprising a permanent section forming the entire core outside the undercut portion of the article and having a reduced axial extension forming the central part of the core at the undercut portion of the article and two disintegrable core sections having a shape complemental to the undercut portion of the article and detachably'secured to the axial extension on said ilrst section.

19. A core for cup-shape articles having an internal undercut comprising a permanent section forming the entire core below the undercut 2,065,987 of the core, and inserts of frangible material in.

portion of the article and having a longitudinal extension forming the central part of the remainder of the core, and two disintegrable sections for forming the undercut recesses in thev article detachably secured to the extension on said permanent section. the contiguous faces of the sections having dove-tail interlocking relation.

20. Molding apparatus comprising a permanent mold having a casting cavity therein shaped to form the outer walls of a piston, a permanent corevconstruction removably positioned within said casting cavity and spaced from the walls thereof to define the inner surface of the piston skirt and a pair of oppositely disposed piston pin bosses, said permanent core construction extending toward said mold to form a portion of the under surface of the piston head and being widely spaced from the side walls of said casting cavity between the piston pin bosses and the head to form the inner surfaceseof a pair of webs extending from the head to the bosses, and a pair of oppositely disposed cores spaced from said mold and from said permanent core construction to define portions of the inner surface of the piston and the outer walls of the webs.

2i. Molding apparatus comprising a permanent mold having a substantially cylindrical casting cavity therein to form the outer walls of a piston, positioned within said casting cavity and having a substantially cylindrical portion spaced from said mold to define the inner surface of a portion of the piston skirt, said permanent core construction being offset inwardly on opposite sides to define the inner surfaces of a pair of piston pin bosses and a web integral with one of said piston pin bosses, and a sand core spaced from said mold to deiine the inner surface of a portion oi' the cylindrical wall of the piston and spaced from said permanent core construction to define the outer wall of the web.

22. Molding apparatus comprising a permanent mold having a casting cavity therein shaped to form the outer walls of a piston, a permanent core construction removably positioned within said casting cavity and spaced from the walls thereof to define the inner surface of the piston skirt and a pair of oppositely disposed piston pin bosses, said permanent core construction extending toward said mold to form a portion of the under surface of the piston head and being widely spaced from the sidewalls of said casting cavity between the piston pin bosses and the head to form the inner surfaces of a pair of webs extending from the head to the bosses, and a pair of oppositely disposed sand cores spaced from said mold to denne portions of the inner surface of the piston and spaced from said permanent core construction to define the outer walls of the Webs.

23. Molding apparatus comprising a permanent a permanent core construction removably mold having a substantially cylindrical castingv I cavity therein to form the outer walls of a piston, a permanent core construction removably positioned within said casting cavity and having a substantially cylindrical portion spaced from said mold to denne the inner surface of a portion of the piston skirt, said permanent core construction being on'set inwardly on opposite sides to define the inner surfaces of a pair of piston pin bosses and a pair of webs integral with said bosses, and a pair of sand cores spaced from said mold to deiine the inner surfaces of portions of the cylindrical wall oi the piston and spaced fromA said permanent core construction to define the outer walls of the Webs.

2li. A piston mold comprising a permanent mold having a substantially cylindrical casting cavity, a permanent core member supported within said casting cavity and spaced from said mold to define the inner surface of the piston skirt, oppositeiy disposed inwardly projecting piston pin bosses and webs extending from the bosses to the head of the piston, and a pair of sand cores spaced from said permanent core to dene the outer surfaces of the webs between the bosses and the head, and spaced from said mold to define a portion of the inner surface of the wall of the piston.

25. A piston mold comprising -a permanent mold having a substantially cylindrical casting cavity therein shaped to form the 'outer Walls of the head and skirt of a piston, a permanent core construction removably supported in said casting cavity and h-aving a substantially cylindrical portion spaced from said mold to define the inner surface of the piston skirt and a reduced extension for defining the inner surfaces of a pair of piston pin bosses, said reduced extension being continued to form the central portion of the inner surface of the head, and a pair of nonp-ermanent cores arranged between the bosses and the head on opposite sides of said reduced extension.

26. Molding apparatus comprising a permanent mold having a casting cavity therein shaped to form the outer walls of a piston, a permanent core construction removably positioned within said casting cavity and spaced from the walls thereof to defme the inner surfaces of the piston skirt at the open end thereof, the sides of said core construction being offset inwardly to form the inner surfaces of a. pair of piston pin bosses and the inner surfaces of `webs extending from said piston pin bosses to the skirt, the offset portion of said core construction being extended to form a portion of the inner surface of the piston head and to form the inner walls of a pair of hangers extending from said piston pin bosses to the head and a pair of sand cores arranged to provide re-entrant recesses between each of the sand cores and the permanent core to form the outer side surfaces of the hangers and the adjacent inner surfaces of the piston skirt and head. l

27. Molding apparatus comprising a permanent mold having a casting cavity therein shaped to form the outer walls of a piston, a permanent core construction removably positioned within said casting cavity and spaced from the walls thereof to define the inner surfaces of the piston skirt at the open end thereof, the sides of said core construction being offset inwardly to form the inner surfaces of a pair of piston pin bosses and the inner surfaces of webs extending from said piston pin bosses to the skirt, the offset portion of said core construction being extended to form a portion of the inner surface of the piston head and to form the inner walls of a pair of hangers extending from said piston pin bosses to the head and a pair of sand cores arranged to provide re-entrant recesses between each sand core and the permanent core so as to form the outer side surfaces of the hangers and the adjacent inner surfaces of the piston skirt and head, said sand cores being supported by said permanent core construction.

28. An internal mold for use in casting a piston with integral wrist pin bosses, consisting of a metallic core conforming to a portion of the interior of the piston with a plastic mold material associated with said core to form portions of the interior of the head of the piston and the wrist pin bosses.

29. A combination core for a piston for internal combustion engines, consisting of a metal core substantially conforming to the interior of the body element and a portion of the head element of the piston, and a plastic mold insert associated with said metal core to complete the formation of said combination core.

FRANK' N. NUTT.