WO2004050276A2

WO2004050276A2 - Die cast formation of beryllium copper plunger tips

Info

Publication number: WO2004050276A2
Application number: PCT/US2003/038418
Authority: WO
Inventors: Leonard Furman
Original assignee: Semco, Inc.
Priority date: 2002-12-03
Filing date: 2003-12-03
Publication date: 2004-06-17
Also published as: WO2004050276A3; AU2003298840A1; AU2003298840A8

Abstract

A method for producing a plunger tip suitable for use in metal die casting operations, commences with a metal mold comprising at least two mold portions (16a, 18b), which mold portions (16a, 18b) mate for forming a casting mold. A core (40) is extended into spaced-apart relationship with at least one of the mold portions (16a, 18b) and the mold portions (16a, 18b) are moved into mating relationship with the core (40) disposed therewithin. The mated mold portions (16a, 18b) are rotated from a vertical position into a horizontal position. A trough (46) is disposed in fluid communication with the mated mold portions (16a, 18b). Molten metal is poured into the trough (46). The mated mold portions (16a, 18b) and trough (46) are rotated into a position between horizontal and vertical for any molten metal in the trough (46) to flow into the mated mold portions (16a, 18b) and then back into a vertical position. Finally, the plunger tip is removed from the parted mold portions (16a, 18b).

Description

DIE CAST FORMATION OF BERYLLIUM COPPER PLUNGER TIPS

CROSS-REFERENCE TO RELATED APPLICATIONS None

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH Not applicable.

BACKGROUND OF THE INVENTION

The present invention generally relates to plunger tips such as are disclosed in U.S. Patent No. 4,732,206 and more particularly to an improved method for casting such plunger tips.

The desired plunger tips are cast from a beryllium-copper alloy. These plunger tips are useful in the die casting of aluminum, zinc, magnesium, and other metals and alloys, which can be injected into a mold cavity with the aid of the plunger tips. A variety of plunger tip designs are known in the art, such as shown in, for example, U.S. Patents Nos. 4,667,729, 4,623,015, 4,886,107, 6,311 ,761 , 4,311 ,185, 4,334,575). Most of these plunger tips consist of a circular annular body mounted onto a reduced area, annular rectangular (square) body. The plunger tip is internally threaded up to the circular annular body for insertion of an externally threaded plunger rod. The rectangular (square) body enables the plunger rod to be screwed into the plunger tip.

It is to the manufacture of such plunger tips that the present invention is addressed.

BRIEF SUMMARY OF THE INVENTION

A method for producing a plunger tip suitable for use in metal die casting operations, commences with a metal mold comprising at least two mold portions, which mold portions mate for forming a casting mold. A core is extended into spaced-apart relationship with at least one of the mold portions and the mold portions are moved into mating relationship with the core disposed therewithin. The mated mold portions are rotated from a vertical position into a horizontal position. A trough is disposed in fluid communication with the mated mold portions. Molten metal is poured into the trough. The mated mold portions and trough are rotated into a position between horizontal and vertical for any molten metal in the trough to flow into the mated mold portions and then back into a vertical position. Finally, the plunger tip is removed from the parted mold portions.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the nature and advantages of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a side elevational view of one embodiment of the plunger tip casting apparatus with the mold in an open position; Fig. 1A is a side elevational view of a second embodiment of the plunger tip casting apparatus with the mold in an open position;

Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1 ; Fig. 2A is a cross-sectional view taken along line 2A-2A of Fig. 1A; Fig. 3 is a side elevational view of the plunger tip casting apparatus with the mold in a closed position;

Fig. 4 is a side elevational view of the plunger tip casting apparatus of Fig. 3, which has been rotated on its side for pouring of the molten copper-beryllium alloy into the mold;

Fig. 5 a side elevational view of the plunger tip casting apparatus of Fig. 4, which has been raised to an intermediate position for residual metal in an accumulation trough to be fed into the mold by gravity;

Fig. 6 is an exploded view of the closed mold showing the cooling jacket piping;

Fig. 7 is a side elevational view of the plunger tip casting apparatus of Fig. 5, wherein the mold has been opened to reveal the cast plunger tip;

Fig. 8 is a side elevational view of the plunger tip casting apparatus of Fig. 7 with an overhead line being used to lift the plunger tip casting from the mold; Fig. 9 is a sectional view taken along line 9-9 of Fig. 7; Fig. 10 is a side elevational view of one embodiment of a plunger tip cast in accordance with the present invention;

Fig. 11 a side elevational view of the plunger tip of Fig. 10, which has been machined;

Fig. 12 a cross-sectional view of the plunger tip of Fig 11 ; Fig. 13 is a side elevational view of a second embodiment of a plunger tip cast in accordance with the present invention;

Fig. 14 a cross-sectional view of the plunger tip of Fig 13; Fig. 15 is a magnified view of the edge of a plunger tip manufactured in accordance with the present invention; and

Fig. 16 is a magnified view of the edge of a plunger tip manufactured in accordance with the prior art. The drawings will be described in further detail below.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to Figs. 1 and 1A, the only difference therebetween relates to the mold and plunger tip molded, which are different in construction. The casting or molding apparatus is the same in both cases. Thus, the following description will be for Fig. 1 , with only the differences in Fig. 2 being described in detail. In particular, a casting apparatus, 10, (casting apparatus 11 in Fig. 1A) rests on a floor, 12, supported from a frame or superstructure, 14. The mold is formed from two mold halves or portions, a stationary mold portion, 16a, and a movable mold portion, 18a, for Fig. 1 and 16b and 18b, respectively for Fig. 2. A framework, 20, supports both mold portions 16a and 18b, and is carried by frame 14.

Frame 20 includes an upstanding stanchion, 22, that carries a pair of horizontal bars, 24 (the other not shown in the drawings), and a piston assembly (e.g., rod and cylinder), 26, which translates movable mold portion 18 to and away from stationary mold portion 16. A fluid (e.g., water) piping system, 28, carries cooling fluid to mold portions 16a and 18a, which are jacketed (see Figs. 2 and 2A). Use of water (or other cooling fluid) during the casting of the plunger tips is optional. Frame 20 is pivotally mounted to frame 14 at a plate, 30. Another piston assembly, 32, is mounted stationarily at a pivot point, 34, and at its free end to frame assembly 20 at something, 36. Piston assembly 32, then, can rotate frame 20 to positions as shown in Figs. 4 and 5 for casting of the plunger tip.

A plunger tip platform, 38, is seen supported by a column, 40. The plunger tip, when cast and the mold portions parted, rests atop platform 38. By raising and lowering platform 38, the operator can fit casting apparatus 10 with molds of different sizes to make different size plunger tips. To that end, column 40 is vertically moveable by a variety of means including, for example, electric motor, hand actuated screw, hydraulic/pneumatic piston, or the like. A core, 40, also can be located atop platform 38 for creating the cavity for the plunger tips. The core, 44, in Fig. 2 provides for a different interior cavity for plunger tips cast with core 44. Finally, resting atop mold fixed mold portion 16a is accumulation trough, 46, into which the molten beryllium copper alloy will be poured. Such molten metal accumulates in trough 46 as it runs into the mold. This will be elaborate on in connection with Fig. 5. Referring now to Figs. 2 and 2A, two different mold configurations for casting two different shaped plunger tips are displayed for mold portions 16a and 18a (Fig. 1 ) and 16b and 18b (Fig. 1A). In particular, mold portion 16a is seen to have water (fluid) lines for providing cooling capacity. The shape of the plunger tip to be molded is seen along with core 40 in proper position as determined by column 42 for creating the interior cavity in the plunger tip to be cast. The same is true for mold portion 16b in Fig. 2A, wherein core 44 is seen to be in proper position for casting to proceed.

The first step of the casting operation is seen in Fig. 3, wherein mold portion 18a (18b) is seen pushed into intimate contact with mold portion 16a (16b) by plunger assembly 26 for form a mold assembly, 52. Mold portions 16a (16b) and 18a (18b) have been precisely located by their attachment to frame 20. Core 40 (44) is in proper position also. Thus, casting operations are set to commence upon the closing of the mold.

In Fig. 4, it will be observed that piston assembly 32 has been actuated for rotating frame 20, and concomitantly mold portions 16a (16b) and 18a (18b), about 90° from the starting position illustrated in Fig. 3. It will be observed that a ladle, 48, has been brought into position so that molten metal, 50, such as molten beryllium copper, can be poured (e.g., by hand or remotely with the aid of a machine) into accumulation trough 46. The amount of molten metal 50 calculated to fill mold assembly 52 is poured into accumulation trough 46. What molten metal 50 that can run by gravity into mold assembly 52 does so. It will be appreciated that rotation 90° to a horizontal position is not necessary as rotation of mold portions 16a (16b) and 18a (18b) to a position of between about 45° and 90^° from the vertical is possible. Thus, "horizontal" for present purposes means generally is a horizontal position. The same is true for "vertical" for present purposes.

In order to completely fill mold assembly 52 with molten metal 50, piston assembly 32 is slightly retracted to the position shown in Fig. 5. While a 45° angle is illustrated, any convenient angle of mold assembly 52 can be reached by piston assembly 32 in order for the remainder of molten metal 50 in trough 46 to flow by gravity into mold assembly 52. Of course, a slight excess or shortage of molten metal 50 for completely filling mold assembly 52 can be used as is necessary, desirable, or convenient. The rate at which molten metal 50 is poured into mold assembly and the rate at which frame 20 is rotated to the intermediate position in Fig. 5 can be readily determined by those skilled in the art. Clearly, the rate of molten metal 50 entering into mold assembly 52 is controlled so that air voids or pockets are not created and so that the neck into which molten metal 50 flows is not overfilled causing molten metal 50 to splash back.

The cast plunger tip, 54, resting atop core 40 in mold portion 18a can be seen in Figs. 6 and 7. It will be observed that plunger tip 54 remains seated in mold portion 18a, although this is not critical to the invention. In Fig. 7, it also will be observed that mold assembly 52 has been lowered to the starting position by piston assembly 32. Prior to opening the mold, additional molten metal 50 can be poured into the mold, if needed. Cast plunger tip 54 ordinarily is sufficiently solidified so that the mold can be parted with the aid of piston assembly 26 in just a few minutes.

Cast plunger tip 54 still is quite hot in Fig. 7 and cannot be manually handled. Thus, an overhead crane line, 56, can be used to hook onto plunger tip 54, such as is shown in Fig. 8. As can be seen in Fig. 9, a plate assembly, 58, can be displaced laterally slightly to move plunger tip 54 from being seated within mold portion 18b to that position shown in phantom. This slight displacement or movement of plunger tip 54 enables it to be lifted by crane line 56. It will be observed that plate assembly 58 is composed of a plate, 60, having its back side connected to a pair of pushing rods, 62 and 64, and its front side connected to push rods, 66, 68, and 70, which in turn penetrate through mold portion 18b. By merely pushing slightly on pushing rods 62 and 64, push rods 66-70 push plunger tip 54 slightly to the side for removal from mold portion 18b. It will be appreciated that other push assemblies could be used in place of plate assembly 58. For that matter, the number of push rods can be more of less that the number shown in Fig. 9.

Plunger tip 54 can be seen in its as removed from the mold state in Fig. 10. Plunger tip 54 is made by casting apparatus 10 in Figs 1 and 2. After machining plunger tip 54, a plunger tip, 72, as shown in Fig. 11 is produced. Machining includes not only the removal of extra material from the outside of plunger tip 54, but also any cleaning of a cavity, 74 (Fig. 12), and adding threads, 76, for attaching of a plunger rod. Cavity 74 has the shape of core 40. The nut-like portion, 78, has been created with flats to assist in screwing plunger tip 72 onto the plunger rod.

Plunger tip 80 in Fig. 13 is produced using core 44 (Fig. 2A). Plunger tip 80 also can machined to its final configuration, as shown in Fig. 14. Again, a cavity, 82, in plunger tip 80 can be machined out and threads, 84, machined into the entry for attachment to a plunger rod. Again, a nut-like area also is machined into plunger tip 80 to facilitate attachment it attachment to the plunger rod.

By casting the plunger road in a metal mold, rather than sand casting it, favorable properties are imparted, such as, a finer grain structure, which contributes to a harder plunger tip surface and extended life in use. This can be seen by reference to Figs. 15 and 16. Fig. 16 shows the grain structure of the outside surface of a beryllium copper plunger tip cast in a sand mold. Fig. 15 shows the grain structure of the outside surface of a beryllium copper plunger tip cast in a metal mold in accordance with the present invention. The higher heat conductivity of the metal mold cools the outer surface of the plunger tip in contact with the metal mold, resulting in a finer grain structure at such outer surface.

While the invention has been described with reference to a preferred embodiment, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In this application all units are in the metric system and all amounts and percentages are by weight, unless otherwise expressly indicated. Also, all citations referred herein are expressly incorporated herein by reference.

Claims

We claim:

1. A method for producing a plunger tip suitable for use in metal die casting operations, which comprises the steps of:

(a) providing a metal mold comprising at least two mold portions, which mold portions mate for forming a casting mold; (b) extending a core into spaced-apart relationship with at least one of said mold portions;

(c) moving said mold portions into mating relationship with said core disposed therewithin;

(d) rotating said mated mold portions from about a vertical position into about a horizontal position;

(d) disposing a trough in fluid communication with said mated mold portions;

(d) pouring molten metal into said trough;

(e) rotating said mated mold portions and trough into a position between horizontal and vertical for any molten metal in said trough to flow into said mated mold portions;

(f) rotating said mated mold portions and trough into about a vertical position and parting said mold portions; and

(g) removing said plunger tip from said parted mold portions.

2. The method of claim 1 , wherein said molten metal poured into said trough comprises a beryllium copper alloy.

3. The method of claim 1 , wherein at least one of said mold portions is jacketed.

4. The method of claim 1 , wherein said core sits atop a platform that is vertically moveable.

5. The method of claim 1 , wherein said removed plunger tip is machined after removal from said parted mold portions.

6. The method of claim 1 , wherein said rotating in steps (d), (e), and (f) is aided with a piston assembly.

7. The method of claim 1 , wherein additional molten metal optionally is poured into said trough after rotation of said mated mold portions in step (e).

8. A casting apparatus for producing plunger tips suitable for use in metal die casting operations, which comprises:

(a) a metal mold comprising at least two mold portions, which mold portions mate for forming a casting mold;

(b) a core extendable into said mold;

(c) an assembly for reversibly rotating said mold from a vertical position into a horizontal position;

(d) a trough for receiving molten metal, which trough is in fluid communication with said mold; and

(d) an assembly for reversibly moving said mold portions into mating relationship and for parting said molds.

9. The casting apparatus of claim 8, which is adapted for casting a beryllium copper alloy.

10. The casting apparatus of claim 8, wherein at least one of said mold portions is jacketed.

11. The casting apparatus of claim 8, wherein said core sits atop a platform that is vertically moveable.

12. The casting apparatus of claim 8, wherein said rotating in steps (d), (e), and (f) is aided with a piston assembly.