US2818618A - Four-part core pin - Google Patents

Description

Jan. 7, 1958 J. w. WlNSHlP ETAL FOUR-PART com: PIN

Filed Sept. 7. 1955 INVENTORS y mm/o/m GSCI/UMACHER JAMES H. Wl/VSf/IP THE/Q Arron/5V5 United States atent FOUR-PART CORE PIN James W. Winship, Lake Orion, and Raymond C. Schumacher, Detroit, Mich., assignors to Bolin Aluminum & Brass Corporation, a corporation of Michigan Application September 7, 1955, Serial No. 532,998

4 Claims. (Cl. 22173) This invention relates to a collapsible core pin useful in connection with permanent metal molds used for molding articles which have a circular bore. An example of such an article is an aluminum piston having bore for the wrist pin in the wrist-pin bosses.

The invention provides a collapsible metal core formed in four pieces, and arranged so that when the core is withdrawn from the mold after the piston has been cast, the core collapses inwardly on two axes, at right angles to each other.

This is arranged by providing a main core piece that is tapered on three sides, and providing three sliding core pieces, one of which slides down each of the tapered sides of the main core piece. The parts are so arranged that the sliding movement of two of the sliding core pieces is permitted to carry farther than the movement of the third sliding core piece. This arrangement permits the two core pieces to collapse toward each other, thereby providing for collapse on two axes at right angles to each other.

These, and other objects and advantages of the invention will become apparent as the description proceeds.

In the drawings:

Fig. 1 is an exploded view of the parts of the device in perspective.

Fig. 2 is perspective view of the parts in the assembled position which they assume Where the core is ready for a molding operation.

Fig. 3 is a view similar to Fig. 2 but showing the parts in position after the first part of the withdrawing action.

Fig. 4 is a view similar to Fig. 2 but showing the parts after the completion of the withdrawing action.

Referring first to Fig. 2 of the drawing, it should be understood that the core pin as a whole consists in general of a central cylindrical part indicated at A, which extends through the metal mold half. The part indicated at B is the tapered end which projects into the mold cavity and forms the opening in a wrist pin boss of the piston being cast. The part marked C is the operating end of the core, and is provided with a hole through which may be passed a pin or other device to connect the core to a suitable operating device.

Construction As shown in the exploded view, Fig. 1, the collapsible core pin consists of 4 separate parts, the main core piece 11, the two side core pieces 12 and 13, and the top core piece 14.

The main core piece 11 has a rounded lower surface 15, which forms part of the outer rounded periphery of the assembled core pin; a fiat upper side 16, and two fiat lateral sides 17 and 18. The sides 16, 17 and 18 all taper inwardly toward each other as they go toward the free end of the core pin.

The main core piece 11 is also formed with a shoulder 19 at the large end of the tapered part.

The top core piece 14 has a rounded upper surface 20, which forms part of the outer rounded periphery of the "ice 2 assembled core pin; a flat lower side 21 which rides on the flat upper side 16 of the main core piece 11; and flat lateral sides 22 and 23.

The top core piece 14 is tapered in thickness, getting thicker toward the free end of the core. That is, the upper rounded surface 20 diverges from the flat lower side 21 going toward the free end of the core. This taper permits the top core piece 14 to fit on the upper side 11 of the main core piece 11 and to fill out the required dimension for the rounded periphery of the core pin when in its assembled position of Fig. 2.

The top core piece 14 is also tapered in its lateral dimension. That is, the two lateral sides 22 and 23 converge toward each other going toward the free end of the core. This taper of the core piece 14 corresponds with the taper between the sides 17 and 18 of the main core piece 11, so that when the core is assembled, the side 22 lies in substantially the same plane as the side 17, and the side 23 lies in substantially the same plane as the side 18.

The side core piece 12 is formed with a flat inner face 24, which is adapted to ride on the surface formed by faces 23 and 18; and with a rounded outer side 25.

Similarly, side core piece 13 is formed with a fiat inner face 26, which is adapted to ride on the surface formed by faces 22 and 17; and with a rounded outer side 27.

A pin 28 anchored in the main core piece 11 cooperates with a short slot 29 formed in the top core piece 14, to limit the extent to which the top core piece 14 can slide down the tapered face 16.

Similarly, a pin 30, which passes laterally through the main corepiece 11, cooperates with longer slots 31 formed in the two side core pieces 12 and 13, to limit the movement of the side core pieces.

Operation Before a molding operation is started, the core pin is assembled as shown in Fig. 2. The part A extends through a bore in a mold half, not shown, and the part B projects into the mold cavity. All of the slidable core pieces are in their extreme right-hand positions, that is, they are all in contact with shoulder 19.

When the metal, which may be an alloy of aluminum, is poured into the mold cavity, it surrounds the part B. After the metal has congealed (set) sufliciently, the core pin is withdrawn by pulling outwardly (toward the right as viewed in the drawings) on end C. The contraction of the metal around the end 13 causes a tendency of this end of the sliding parts 12, 13 and 14 to resist movement toward the right.

During the first part of this withdrawing action the parts move from the position of Fig. 2 to the position of Fig. 3.

During this part of the action the top core piece 14 slides down on the tapered surface 16 of the main core piece, thus collapsing the core on the axis ab of Fig. 2.

Simultaneously, the two side core pieces 12 and 13 move along the faces 23-48 and 2217. If the top core piece 14 were not present, the two side core pieces 12 and 13 would, during this part of the action, move toward each other as they slide down the tapered faces 23-18 and 2217. However, since the three sliding pieces 12, 13 and 14 have moved together, the wedgeshaped top piece 14 still holds the two side pieces 12 and 13 apart at their upper edges, the same distance apart as they were in the position of Fig. 2. This interferes with the collapsing of the core on the axis c-d of Fig. 2.

During the next part of the Withdrawing action the parts move from the position of Fig. 3 to the position of Fig. 4.

During this part of the action there is no further movemerit of the top core piece 14 relative to the main core piece 11. This is because the pin 28 engaged the end of slot 29 when the parts reached the position of Fig. 3.

But since the slots 31 are longer than the slot 29, further movement of the side pieces 12 and 13 relative to core piece 11 has taken place. During this movement the side pieces 12 and 13 slide down the tapered sides of the top core piece 14, thus permitting the core to collapse on axis cd of Fig. 2.

It will be clear from the above explanation that this invention provides a simple core structure which collapses on two axis at right angles to each other during the action of withdrawing the core.

While the parts have been described as upper, lower, etc. With reference to the position of the parts as illustrated in the drawings, it will be understood that this is done merely for convenience, and not by way of limitation.

According to the provisions of the patent statutes, We have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. A collapsible core pin which consists of only four individual parts as follows: a main core piece composed of a rounded lower face, a fiat upper face, and two flat lateral faces, all of said flat faces tapering toward each other going toward the free end of the core, a top core piece slidable on the flat upper face of the main core piece, the top core piece having its lateral sides tapered inwardly corresponding with the taper of the lateral faces of the main core piece, and having 'an upper rounded face which .4. tapers conversely to the taper of the flat upper face of the main core piece, the top core piece being formed with a slot, the main core piece carrying a pin which engages in the slot of the top core piece to provide for limited move ment of the top core piece relative to the main core piece, a pair of side core pieces, each of the side core pieces being formed with a slot which is longer than the slot in the top core piece, the main core piece carrying a pin which passes through the main core piece and projects on both sides of the main core piece and engages in the slots of the side core pieces to permit the side core pieces a greater travel than the top core piece relative to the main core piece, whereby the core is permitted to collapse on two axis which are at right angles to each other.

2. A device as specified in claim 1 in which the main core piece is provided with a shoulder at its operating end, the three sliding core pieces being in engagement with the shoulder to form a cylindrical outer surface when the parts are in molding position.

3. A device as specified in claim 1 in which the main core piece, and the three sliding core pieces are all formed at their outer ends with curved peripheral walls which cooperate to form a circular hole in a casting when the parts are in molding position.

4. A device as specified in claim 1 in which the slot in the top core piece and the slots in the side core pieces extend entirely through their respective pieces.

References Cited in the file of this patent UNITED STATES PATENTS 744,970 Miller Nov. 24, 1903 1,018,669 Leuthner et al Feb. 27, 1912 1,019,905 McKee et 'al Mar. 12, 1912 1,783,805 Leuthner Dec. 2, 1930

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