Split dies provided with cooling means

Nov. 5, 1957 A. F. BAUER 2,811,761

SPLIT DIES PROVIDED WITH COOLING MEANS

Filed Nov. 4, 1954

<img file="US2811761A_D0001.tif" />

of Cooling or Heating Medium

<img file="US2811761A_D0002.tif" />

AGENT

2,811,761

Patented Nov. 5, 1957

United States Patent Office

2,811,761

SPLIT DIES PROVIDED WITH COOLING MEANS

Alfred F. Bauer, Toledo, Ohio, assignor to National Lead Company, New York, N. Y., a corporation of New Jersey

Application November 4, 1954, Serial No. 466,901

Claims. (CI. 22—203)

This invention relates to means for cooling dies. More specifically, it relates to a novel construction for the indirect cooling of large die surfaces.

In the die casting art it is recognized that difficulties are likely to be encountered in removing heat from the dies used in the casting operation. In order to obtain efficient and economical operation of die casting apparatus it is necessary that the heat derived from the molten metal be carried away from the cast piece and also away from the die itself at a rapid rate. It is known to provide passages in the die bodies and to directly pass cooling fluids through said passages. The die steel, however, has been subject to shock caused by the direct contact of cooling fluids such as water. The effect of such shock is to create fatigue cracks and spalling which obviously greatly reduce the useful life of the die steel. Moreover, when a crack occurs which extends to the inside or casting surface of the die member, the die must be discarded since leakage of the cooling fluid into the interior of the die section obviously would make the casting operation impossible.

An object of the instant invention, therefore, is to provide a novel die construction which provides for indirect cooling of the die steel. Another object is to provide a die construction having means for conducting cooling fluids therethrough. Another object is to provide a die construction which will give long life and which will permit utilization of the die even though cracks do occur in the casting surface of the die itself. These and other objects will become apparent from the following more complete description of the invention and from the drawings.

Broadly, this invention is directed to a die construction comprising a die member having an inner face which possesses configuration of the article to be cast, and an outer surface, a passage cut through said outer surface, a conducting member positioned in said passage, at least part of the external shape of said conducting member possessing similar configuration to said passage and being directly bonded thereto, and a filler member portion present in that part of the passage not occupied by said conducting member.

Fig. 1, Fig. 2 and Fig. 3 are presented in order to more clearly show the details of construction of the instant invention. Fig. 1 is a schematic representation of a typical die construction according to this invention.

Fig. 2 is a cut-away portion of the upper section of a typical split die construction along line 2—2 of Fig. 1, and shows in greater detail the central elements of the conducting portion of the die construction.

Fig. 3 shows that section along lines 3—3 of Fig. 2. .

Considering now Fig. 1, there is shown a typical die construction 10. According to this invention the die itself is split into two sections 12 and 14 and is generally split along line 16. The face 13 of the die 10 possesses at least part of the configuration of the article to be cast. Obviously at least one other die would be necessary to form the complete die. A passage 18 is provided in section 12 and opens generally along the splitting line 16. A conducting member 20 is positioned in passage 18 and generally makes contact with the wall surface of the passage. This construction is shown in more detail in Fig. 2. Outlet passage 22 is provided in the other section of the split die so as to permit an extension of the conducting member 20 to pass therethrough and permit inlet and outlet means such as shown generally at 24.

In Fig. 3 the conducting member 20 is shown having an inner face 26 and an outer surface 28. The generally hollow construction of the conducting member permits the transfer and flow of fluid media whereby cooling of the die member may be accomplished. Obviously the instant construction could also be employed to heat the die construction if such were desirable. The outer surface 28 of the conducting tube at least partially conforms to the contour 30 of the passage 18 and is positioned closely thereto. That portion of the passage which is not occupied by the conducting tube 20 is filled with appropriate filler metal 32.

According to the instant invention a passage is cut into the die steel at the selected distance from the die surface. This groove can be regular or irregular in its plane view, but would by necessity have to approximate the shape of at least part of the cooling tube. The tube material may be of any suitable material of construction as commonly employed for conducting heat. Copper or various alloys could be used for this purpose.

The method of applying the tube is as follows: First, the groove is definitely patterned so that a channel can be milled or cut into the one die portion. This channel would be accurate in its cross section contour to accommodate the prescribed tube. After milling and polishing the channel, so cut in the steel die outer surface, the interior of the channel is tinned. This tinning can be done with any suitable alloy that will wet the surface. In the instant case a soft solder medium was suitably employed. Likewise, the external surface of the tube after it has been formed to fit into the cut channel is tinned with the same tinning medium as the steel. The tube is then positioned into the channel. This may conveniently be done with a hammer using a wood block to be sure that the contact between the two tinned surfaces is as complete as possible. Next the entire unit, both the die steel and the copper tube in its position, is heated. This heating actually melts the two tinned media and by capillary action the parts solder together. This bond is not considered complete. An alloy is poured into the void area around the tube so that the dies’ channel is completely filled. The excess is machined off flush with the mating surfaces of the two die casting die portions. In one instance the filler used was a zinc alloy; however, it is conceivable that any heat conducting alloy could be used for this purpose.

Substantially any fluid having heat transfer properties may be employed as a cooling medium. Because it is readily available and easily handled, it is preferred to use water for this job. However, it is to be recognized that many other fluids could be satisfactorily employed.

There are likewise many bonding and filler materials which could be employed, according to the instant invention. It is necessary that the bonding material be compatible with the material of which the die is constructed and also the material of which the cooling tube is constructed. Obviously materials of construction should be employed which do not melt at the temperatures which the die members normally reach when in use.

By the foregoing description and drawings there has been described a novel die construction which can be successfully employed particularly in the production of large size castings. The life of dies constructed accord2,811,761 ing to the invention is substantially greater than those previously employed in the past and it has been found possible to continue using dies of this type for substantial periods of time even after cracks may have formed which extend to the casting surface itself.

While this invention has been described and illustrated by the foregoing description and drawings, it is not intended to be strictly limited thereto and other modifications and variations may be employed within the scope of the following claims.