US2161521A - Mold and core structure - Google Patents

Description

June 6, 1939.

H. E. McwANE MOLD AND CORE STRUCTURE Original Filed Oct. 16, 193f1 Patented June 6, 1939 UNITED STATES PATENT oFFlcE Application October 15, 1934, Serial No. '748,540

Renewed January Il, 1939 8 Claims.`

This invention relates to casting, and more particularly has reference to a mold and core structure.

Due to the fact that the casting during the period of cooling from the molten state undergoes appreciable shrinkage, considerable diiculties have been experienced in the past with reference to the cores that are employed. Remedial measures have been attempted but in general they have not proved satisfactory, principally because of the labor involved in the construction and operation of the core with its attendant expenses.

To overcome they above diiculties is one of the objects of my invention.

Another object of my invention is to provide a permanent core that is movable to compensate for shrinkage of the casting.

Yet another object of my invention is to provide a core capable of movement but which is self-positioning upon removal of the casting.

To accomplish the above and other objects, as will appear herein, my invention in general embraces the concept of using a core that is ireely movable in all directions in association with means whereby the core is self-centered or selfpositioned upon completion of the casting operation and removal of the casting.

To insure an adequate comprehension of my invention there is depicted in the accompanying drawing one specific embodiment, but it will, of course, be appreciated that my invention is capable of other embodiments and modications.

In the drawing, in which similar numerals indicate the same part:

Figure 1 is a top plan view of a section of a mold provided with cores built in accordance with my invention;

Figure 2 is a vertical sectional View along the line 2-2 of Figure l, showing the arrangement of the core in the assembled mold;

Figure 3 is a plan view along the line 3-3 of Figure 2, looking in the direction of the arrows;

Figure 4 is a sectional View along line 4 4 of Figure 2, looking in the direction of the arrows;

Figure 5 is a sectional view along line 5-5 of Figure 2, looking in the direction of the arrows.

While I have shown in the drawing, and shall describe my invention as applied to a mold for casting a relatively flat plate, it will of course be appreciated that it will find application for various types of castings.

Also, I shall describe my invention with reference to a mold made up of two sections, but the whole structure may be embodied in other forms of molds.

For the purpose'of illustration I have shown in Figure l a section of a mold I, which, as shown in Figure 2, may be the lower half of the mold. A mold cavity 2 is provided, to which the metal may be supplied by means of gates 3. At the desired places in the cavity, there are situated cores 4 for the purpose of forming recesses or apertures in the casting.

Referring particularly to Figures 2 and 3, it will be observed that each core 4 is composed of a body portion 5. While I have shown this body portion as frusto-conical in shape, it will of course be appreciated that it may assume various shapes, depending upon the type of recess or aperture desired in the finished casting. t will also be noted that by a core such as depicted herein, an aperture extending through the entire thickness of the casting is formed, but it is of course obvious that recesses may be formed in the casting by decreasing the height of the body portion 5.

As clearly shown in Figure 2, the body portion rests over a channel 6 which extends from the mold'cavity. The lower portion of the channel E is enlarged as at 'I in order to form a shoulder 8. The lower half or the enlarged portion 1 is threaded and is adapted to receive interiorly a nut 9. The nut 9 may be slotted as at II in order to receive a screw driver or some other suitable instrument for enthreading the nut within the channel.

The body portion 5 of the core is provided with a stem I2 which extends into the channel 6. A nut I3 is threaded on the lower end of stem I2 and is adapted to bear against the shoulder 8 formed in the channel. The nut is screwed onto the stem a sufficient distance to secure the under surface of body portion 5 against the wall of the mold cavity, but at the same time it is not screwed sufficiently tight to prevent sliding movement of the core in the cavity. Radially spaced holes I4 may be drilled in the nut I3 to receive a suitable instrument for tightening or loosening the nut I3.

A channel I5 is drilled centrally of the stem I2, and is adapted to receive a helical spring I6. One end of the spring I3 bears against the top of channel I5 while the lower end of the spring bears against a plunger I1. The plunger I'I is provided with a rounded head I8 which, in the normal position of the core, is adapted to rest in a seat I5 on the inner surface of nut 9. It will therefore be seen that the plunger arrangement provides for the seating of the core at a predetermined place in the mold caviy, but at the same time permits of limited displacement of the core. It will be further noted that upon limited displacement of the core I and up to the time that the head I8 is entirely removed from the seat, the plunger arrangement will serve to return the core to its normal position upon removal of the casting from the mold.

In addition to the plunger, I provide further means to resist displacement of the core and its return to its normal position. As best shown in Figures 2 and 4, I provide a plurality of leaf springs 2l, preferably four in number, and preferably spaced quarterly around channel 6. One end of each leaf spring is secured to the Wall of the channel 6 by means o-f nut 22, and. to facilitate assembly it is the upper end adjacent the Wall cavity that is so secured. The lower and free end of each leaf spring is adapted to bear against stem I2. Inasmuch as these springs are spaced at quadrants around the periphery of stem I2, it will be obvious that upon displacement of the core in any direction, the core will be returned to its initial and normal position. Of course, three springs might be used instead of four, or any greater number than four, if desired.

From the foregoing it is believed that the operation of the device is apparent. As stated, the punger arrangement serves to initially position the core at its desired location in the mold cavity, and it is resiliently held in this position by virtue of the plunger and the leaf springs 2i. In such position the upper half of the mold 23 is secured to the lower half 2, and molten metal is poured in the cavity through gate 3. The metal flows around the cody portion e of the core and completely iills the cavity. It is to be noted that the body portion ts sufciently tight upon the cavity Wall to prevent the escape of molten metal from the cavity into Channel 6.

As the casting cools there is a concomitant shrinking which of course means displacement of the casting. The core body is free to move with the surrounding part of the casting, such movement however being slightly resisted by the resiliency of leaf springs 2| and helical spring I5 in association with the plunger head I8.

When the casting has cooled sufficiently, the mold is opened and the casting is removed from the cavity. The particular spring, or springs, 2l which have been compressed by the displacement of the mold during the shrinkage then urge the core and return it to its normal position. In View of the fact that each of the springs 2l has the same resiliency, they alone would sufice to return the core to its normal position. Additional means for determining this normal position, however, are the helical spring It, plunger head I3 and seat I9.

Although usually shrinkage of the casting takes place along a predetermined line, it will be noted that the core I is free to move in any direction, and therefore, in the event of an abnormal shrinkage of the casting, the core may follow the movement of the casting.

The advantages of my invention are believed to be obvious. In the rst place, it is simple and economical to construct. Furthermore, the mobility of the core relieves it of the strain and Wear which is normally imposed on cores of the prior art, by virtue of the shrinkage of the casting.

Its principal advantage resides in the fact that a permanent core may be employed which need not be positioned manually prior to each casting operation. As soon as the casting is removed from the mold cavity, the core is automatically returned to the desired position for the next casting operation.

As pointed out above, the core shown herein is adapte-d to move in all directions in the cavity.

Vlhile I have shown and described the preferred embodiment of my invention, I Wish it to be understood that I do not conne myself to the precise details of construction herein set forth by Way of illustration, as it is apparent that many changes and variations may be. made therein, by those skilled in the art, Without departing from the spirit of the invention or exceeding the scope of the appended claims.

I claim:

l. A casting apparatus comprising a mold having a cavity therein, a core positioned against one Wall of the mold cavity and capable of` movement in all directions of a single plane, and means to return the core to its initial position.

2. A casting apparatus comprising a mold having a cavity therein, a core positioned against one Wall of the mold cavity and capable of movement in all directions of a single plane, and resilient means tending to prevent such movement and to return the core to its initial position.

3. A casting apparatus comprising a mold having a cavity therein, a core positioned in the mold cavity and capable of movement in all directions of a single plane, means to return the core to its initial position, and means other than the returning means to determine such initial position.

4. A casting apparatus comprising a mold having a cavity therein, a channel extending from the mold cavity, a core positioned in the Cavity and adapted to rest against one Wall thereof, a stein extending from the core into said channel, a seat at the base of the channel, and means carried by the stem adapted to cooperate with the seat to determine the normal position of the core and stem.

5. A casting apparatus comprising a mold having a cavity therein, a channel extending from one wall of the mold cavity, a core extending over the entrance of the channel to the cavity and adapted to slide on said wall, a. shouldered recess in the channel at the end opposite the cavity, a stem extending from the core through said channel and into said recess, means extending from the stem and adapted to engage the shoulder of the recess, and resilient means mounted in the channel and adapted to position the stem in the channel.

6. A casting apparatus comprising a mold having a cavity therein, a core positioned against one wall of the mold cavity and capable of movement in all directions of a single plane, and spring means tending to prevent such movement and to return the core to its initial position.

7. A casting apparatus comprising a mold having a cavity therein, a channel extending from the mold cavity, a core positioned in the cavity and adapted to rest against one Wall thereof, said core being capable of movement in all directions of a single plane, a stem extending from the core into said channel, and spring means Within said channel and bearing against the stem to prevent movement of the core and to return the core to its initial position.

8. A casting apparatus comprising a mold having a cavity therein, a channel extending from the mold cavity, a core positioned in the cavity and adapted to rest against one Wall thereof, said core being capable of movement in all directionsl of a single plane, a stem extending from the core into said channel, spring arms having one of their ends attached to the Wall of the channel and having the other end bear against said stem to prevent movement of the core and to return the core to its initial position.

HENRY E. MCWANE.

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