US2139734A - Piston mold mechanism - Google Patents

Description

Dec. 13, 1938. P. s. DIAMOND PISTON MOLD MECHANISM 3 Sheets-Sheet 1 Filed Jan. 22, 1956 INVENTOR.

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Dec. 13, 1938. P. s. DIAMOND I ,7 4

PISTON MOLD MECHANISM Filed Jan. 22, 1936 5 Sheets-Sheet 3 I INVENTORL 6' Paul 5. fli'amo 27d L L EB I ATTORNEYS.

Patented Dec. 13, 1938 UNITED STATES PATENT OFFICE and-:34 PISTON MOLD MncmmsM Application January 22, 1936, Serial No. 60,302

5 Claim.

This invention relates to piston mold mechanism and more particularly to a mold for die casting cup-shaped articles, such as pistons, in which a sectional steel or metal core is provided.

In the art of die casting and particularly in the casting of cup-shaped articles great difilculties have been experienced in providing an easily removable core, since in many instances such cup-shaped articles have various flanges, bosses and the likeprojecting inwardly from the walls of the article, which make it impossible to remove a one-piece core after the article is cast. One instance in which the above difliculty has been particularly serious is in the case of pistons for internal combustion engines. In many cases, particularly with the old type trunk pistons, it was found possible to solve the above difliculties by making the core of three sections, the middle section being'adapted to be removed first by a longitudinal pull, whereupon the side sections or segments could be moved together radially of the piston and removed by a longitudinal pull. However, with the advent of pistons of more intricate shapes, and particularly of diagonal strut pistons in which the inwardly projecting .parts measured a considerable distance radially oi the piston, the radial dimensions of the inner section, in order to enable the side sections when brought together to clear said parts, had to be more than double the radial measurement of the longest inward extension. This resulted in objectionably thin side sections which would warp or break at the thin neclm when heated in operation. The above objection being particularly serious. with the use of metals having high melting points resulted in the necessity of using, in connection with certain types of pistons, either sand cores or complicated sectional metal cores composed of as many as seven sections. Such disadvantages, however, are overcome by virtue of the present invention wherein a more emcient and simplified mechanism is provided.

An object of the invention is to provide an improved permanent mold for casting pistons wherein a three section metal core mechanism, together with outer mold members, is utilized, and improved means is provided for mechanically separating and removing the core sections after the mold is opened and also for assembling the core sections preparatory to the casting operation.

A further object of the invention is to provide a piston mold having a three section metal core wherein the piston, after casting, may be removed from the mold by withdrawing one of the core sections with the piston casting after the center core section and one of the outer core sections have been moved into positions to free the castcasting pistons having internal webs or struts in which the skirt or slipper section or sections are carried or supported by the piston head through the medium of webs or strut members which extend diagonally from opposite sides of the piston pin bosses to points on the interior of the skirt or slipper sections located at opposite sides of the piston pin bosses.

Other objects and advantages of the invention will appear from the following description and appended claims when considered in connection with the accompanying drawings forming a part of this specification.

' In said drawings:

Fig. 1 is a side elevation, partly in sectionand partly broken away, of the piston mold mechanism of my invention, showing the mold in closed position.

Fig. 2 is a vertical section taken substantially along the line 2--2 of Fig. 1, looking in the direction of the arrows.

Fig. 3 is a detail side elevation, partly broken away, taken substantially along the line 33 of Fig. 2, looking in the direction of the arrows.

Fig. 4 is a top plan view, partly broken away, of the mechanism shown in Figs. 1' and 2.

Fig. 5 is a transverse vertical section, partly in elevation, showing the core members in pistonreleasing position; and

Fig. 6 is a horizontal section on an enlarged scale, taken substantially along the line' 56 of Fig. 1, looking in the direction of the arrows.

Before explaining in detail the present invention, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In accordance with one of the important features of the invention the sectional core is so constructed and operated as to permit utilization thereof in casting pistons having internal obstructions, particularly wrist pin bosses, which limit lateral movements of the core sections in order to free the piston casting and permit removal thereof. On embodiment of the invention is illustrated in the drawings, by way of example, in which the central core section is carried by a hydraulically operated piston or plunger capable of withdrawing the section by a downward vertical movement. Thereafter, one of the outer core sections is shiftable inwardly toward the opposite outer core section to clear the wrist pin boss, this being accomplished by suitable mechanism, and then the piston casting is withdrawn vertically from the mold, carrying with it during this operation the said opposite core section until clear of the mold whereupon the casting is dislodged or freed from the vertically movable core section.

The mold is preferably supported upon a vertical standard or upright I4 which carries at its upper end a rigid offset extension or arm II drilled adjacent its inner or free end to receive a pin I2 which also extends through alined holes formed in a series of lugs or extensions I4 on the mold members or sections I3 and I3a. A pair of these lugs I4, one for each half of the mold, is located above the member II, and a similar pair is located below it. The pin I2 thus provides a support for the mold and also a pivot or hinge connection for the halves I 3 and I3a. The mold sections are clamped together in any suitable manner, as by means of a clamping device 9 such as that shown in the application of Ray E. Day, Serial No, 49,495, filed November 13, 1935. The mold sections when closed together provide a cavity to receive the steel piston core hereinafter described.

The standard III also provides means for supporting the core and core operating mechanism of my invention. As shown, the core and mechanism are supported by a preferably horizontally disposed platform or bracket I6, the outer end I 6a of which is semi-cylindrical to form a hearing engaging the standard Ill and is held in position upon, the standard by means of a cooperating semi-cylindrical portion or hearing I6b. The two bearing portions are releasably and adjustably secured together by means of bolts or the like IT. The lower end of the pivot pin or shaft I2 is fitted within a vertical hole I6c formed in the bracket. Thus the platform l6 and the twopart mold are supported adjacent one another and in superimposed relationship by the standard III. The bracket I6 adjacent its inner or free end is provided with an opening I6d through which the piston core members extend. At opposite longitudinal sides of the opening I6d hanger studs I9 are supported in depending relation to the bracket and carry at their lower ends a cylinder hanger plate 20, the plate being spaced from the bracket I6 by means of spacer tubes or members 2| through which the studs extend. Secured to the hanger plate 20 by means of a bolt or bolts 22, and located beneath said plate, is the upper portion 23 of an air cylinder or the like 24. Preferably four hanger studs I9 and spacer members 2I are provided. The air cylinder 24 is provided with the usual piston 24a having a rod or ram 25 which extends upwardly through a conventional guide 26. The escape of air pressure around the ram is prevented by the usual packing gland and nut construction 21. The upper end of the plunger or ram 25 is provided with a cross head 29 which is adapted to be secured to one of the core members, preferably the central one, in any sui able manner, as by means of bolts 30, for a purpose to be hereinafter described. At opposite lateral sides of the opening I6d the bracket or platform is provided with additional openings through which the outer core members extend.

The central metal core member 35 is insulated from the ram or plunger 25 by means of an interposed disc or pad 38 of any suitable heat insulation material such, for example, as a composition of hard asbestos and Bakelite. when the plunger of ram 25 is projected outwardly orupwardlyfrom within the cylinder 24, the central core member 35 is moved vertically from its position of Fig. 5 to that shown in Figs. 1 and 2. When the ram is retracted into the cylinder, the central core member 36 is drawn inwardly or downwardly into its position of Fig. 5. The two outer metal core members 36 and TI are shaped to interfit with and engage the major portion of the inner core member 36, see Fig. 6. Thus the three core members, which are preferably formed of steel, when nested as in Figs. 1, 2 and 6, have a combined outer .contour which in shape and conformation corresponds to the inner-contour of the piston to be cast, the exterior walls of these core members being spaced a predetermined distance from the inner walls of the mold sections I3 and I30 so as to provide the necessary space into which the metal flows when poured into the mold through the filler passage I5. The mold sections are provided with a pair of oppositely disposed tapered openings to receive the usual removable core locating pins I8, these pins, as is usual in piston molds of this character, also provide the piston pin openings in the piston casting.

As previously explained, the central core member is connected to and adapted to move with the ram 25. The outer core members 36 and 31 are supported independently of the ram, the member 36 being secured as by means of bolts or the like H to a core holder 40 having a head portion 46a and a depending portion or stem 4017, the stem being located in and projecting through the opening 42. The core member 31 is connected in, any suitable manner, as by means of a bolt or bolts 44, to a core holder 43 having a head portion 43a and a depending stem or shank 43b which extends through the opening 45 formed in the supporting member or bracket I6. The stem 43b is elongated and extends downwardly at 43c beside the ram support 26 and is slotted at 43d to receive a guide pin 46 carried by the platform or bracket I6. Thus the core holder 43 may move upwardly and downwardly with the core member 31 for a distance corresponding to the length of the slot 43d. The core holders 46 and 43 are insulated from the core members 36 and 31 by interposing between their adjacent surfaces a shim 49 formed of some suitable insulating material such, for example, as a composition V of hard asbestos and Bakelite, this for the purpose of reducing the conduction of heat from the core members and other parts of the mold to the core holders and operating mechanism.

Extending laterally from one side of the bracket is a rack cylinder or housing 50 having a screw threaded cap 5| engaging one end of a compression spring 52, the other end of which is seated .in a recess 53a formed in the rack member or plunger 53. A gear 55 is mounted upon a shaft 54 journalled in an enlargement formed in the housing, the gear being adapted to be oscillated through the medium of an operating handle 56 secured to one end of the shaft 54, see Fig. 3. The rack member 53 is connected to the core holder 40 by means of a pin 66. There is a slight -clearance provided at 51 between the inner end of the rack member or plunger 53 and the adjacent face of the core holder 40 to permit the core holder to have a slight tilting movement out of its vertical plane relative to the housing 50. By moving the handle 56 in a clockwise direction, the core holder 40 and core member 36 are moved in the direction toward the central core Kali member 35. By moving the handle in a counterclockwise direction, the core holder 40 and core member 36 are moved outwardly toward the housing 50. The tension spring 52 may be adjusted by means of the screw cap 5! to vary the tension on the rack member or plunger 53, 'if desired.

In operation, with the parts in the positions as shown in Fig. 2, after the molten metal has been poured into the filler opening or passage l5 and the piston P formed, the locating pins l8 are removed, the halves or sections it! and Ba of the mold opened, and the air cylinder 2ioperated to withdraw the ram 25 downwardly, which in turn, moves the central core member 35 downwardly with it. After withdrawing the central core member from its normal position within the mold, the handle 56 is moved in a clockwise direction to shift the core holder 39 and its attached core member 38 laterally until the core member 36 is in engagement with the core member 37, (full lines Fig. 5). The piston P is then withdrawn or moved upwardly during which operation the core member 3i and its support or holder 43 travel with it a distance corresponding to the length of the slot l-Sd or until they reach their dotted line positions of Fig. 5. With the parts in this position a slight tap on the outer wall of the piston will release it completely from the core member It? whereupon the core member and its holder may return by gravity to their normal positions as shown in full lines, Fig. 5. To reset the mold and core, the air cylinder 2% is operated to project the ram 25 and its attached central core member 35 upwardly either before or after the handle 5%- has been operated in a counter-clockwise direction to return the core holder M3 and its attached core member 36 to their normal or operative positions, as shown in Fig. 2. The inner adjacent faces of the head portions Mia and 53a of the core holders are bevelled or tapered so that upon projecting the ram and central core member 35 upwardly, the core members 36 and 37' and their respective holders will be moved into their normal or casting positions. It will be noted that there is a slight clearance provided for each of the core holders, allowing them a limited amount of play to facilitate the positioning and releasing of them.

I claim:

1. An apparatus for casting pistons including a mold comprising three cooperating metal core sections, the central section being movable axially of the piston casting to withdraw it from the mold, a second section being movable transversely of the piston into the space normally occupied by the central section, and the third sections being movable axially with the piston for a limited distance when the latter is removed and in a direction opposite to the movement of the central section.

2. An apparatus for casting pistons including a mold, a plurality of movable core members associated with said mold and comprising an inner core member and a pair of opposed cooperating outside core members, means for shifting the inner core member longitudinally in a predetermined path into and out of cooperative relation with the mold, means permitting longitudinal movement of one of the outside core members into and out of co perative relation with said mold in a path substantially paralleling the path of movement of said inner core member, and means for moving the other outside core member in a direction transverse to the paths of movement of said remaining core members and into and out of engagement with the piston casting after said inner core member is withdrawn from the mold, said first named outside core member being free to move with the piston casting at a predetermined time.

3. An apparatus for casting pistons, comprising a separable mold, a support, a plurality of movable metal core members including a central and a pair of opposed side members mounted on said support, means for guiding said members, means for shifting said central member substantially vertically intoand out of assembled relation with the side members, means for shifting one of said side members substantially horizontally toward and away from said other side member when the central member is out of assembled relation with the side members, and separate means permitting substantially vertical movement of the other side core member with the piston casting when said casting is removed from the mold.

4. An apparatus for casting pistons, comprising a separable mold, a support, a plurality or movable metal core members including a central and a pair of opposed side members mounted on said support, means for guiding said members, said central core member being capable of movement substantially vertically into and out of assembled relation with the side members, a rack and pinion for shifting one of the side core members relative to the other side core member after the central member is disassembled from said side members to release the piston casting, said other side core member having an independent connection with said support whereby it can be elevated with the piston casting in a substantially vertical path to a position above and out of contact with said mold, and independent means for actuating said central core member and said rack andpinion.

5. An apparatus for casting pistons, comprising a separable mold, a support for said mold, three interfitting and independently movable metal core members disposed in substantially the same plane, a separate and independently movable core holder for each of the core members, a platform carried by the mold support and located adjacent said mold for supporting said core holders, means for moving the inner core member into and out of assembled relation with the outer pair of core members in a path substantiallyparallel to the adjacent faces of said outer core members, and separate means for moving one of said outer core members toward and away from the other outer core member in a path disposed substantially at a right angle to the path of movement of said inner core member after the inner member is disassembled from said outer members whereby to release the piston casting, the core holder for said other outer core member being slotted to permit the latter to move with the piston casting upon release from the mold longitudinally in a. path substantially paralleling the path of movement of the inner core member but being held against movement in a transverse direction.

PAUL B. DIAMOND.

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