US2994297A - Apparatus for making molds by gas plating - Google Patents

Description

2 Sheets-Sheet 1 INVENTO'R HARRY A. TOULM/N, JR.

ATTORNEYS Aug. 1, 1961 H. A. TouLMlN, JR

APPARATUS FOR MAKING MoLDs BY GAS PLATIN@ Filed Aug. 18, 1958 BY mm'n/ ggf/min,

Aug. l, 1961 H. A. TOULMIN, JR

APPARATUS FOR MAKING Moms BY GAS PLATIN@ Filed Aug. 18, 1958 2 Sheets-Shed'l 2 INVENTOR HARRY/1. TOUL/WN, JR.

ATTORNEYS United States Patent O 2,994,297 APPARATUS FOR MAKING MOLDS BY GAS PLATING Harry7 A. Toulmin, Ir., Dayton, Ghia, assignor, by mesne assignments, to Union Carbide Corporation, New York, N.Y., a corporation of New York Filed Aug. 18, 1958, Ser. No. 755,603 4 Claims. (Cl. 118-48) This invention relates to apparatus and methods for gas plating. More particularly, the invention is concerned with gas plating forming dies, and especially the plating of metal onto a die forming surface.

Present methods for producing forming dies are costly dueto the large amount of hand labor and machining involved. It has been proposed to use plastic dies but their wear resistance is low. Metal sprayed dies are subject to distortion under shock forces and are relatively fragile. Attempts to electrofonn dies free from stress and resulting distortion have not been achieved with any degree of success.

This invention overcomes these difiiculties for all practical purposes and provides an apparatus and method for making forming dies by gas plating.

After carrying out a large number of experimental tests it has been found that in the making of such forming dies, the same may be made by gas plating metal onto a mold having the contour of the desired die shape. A suitable mold is made of gypsum admixed with powdered metal, such as aluminum. Molds also may be made of resins, particularly epoxy resins, and which have been cured to form a thermoset resin body. The pre-shaped mold surfaces are then gas plated to produce forming dies of any desired shape. Dies of very large area and never before attempted by conventional methods have been successfully produced in accordance with this invention.

The gas plating of the mold surface to produce the die may be carried out using various type molds but that found to be very satisfactory was composed of gypsum having powdered aluminum admixed therein in proportions of approximately 50 parts metal to 50 parts gypsum.

In the instant application, the invention will be described with more particularity with respect to the production of forming dies using nickel carbonyl as a gas plating agent. Other suitable gaseous metal bearing compounds may be used where desired, such Aas chromium carbonyl, molybdenum carbonyl, and the like.

These and other objects and advantages will become apparent from the following description taken in conjunction with the drawings, and wherein- FIGURE l shows in cross section a broken away portion of a mold for forming the die and which mold comprises `a series of spaced coils for heating the inner surface of the mold;

FIGURE 2 is a view in elevation of the die portion shown in FIGURE 1;

FIGURE 3 is a View partly in cross section and illustrating the use of the mold structure shown in FIGURE l;

FIGURE 4 is a fragmentary detailed cross section illustrating a heating element and wherein the same comprises a solid rod or core heated with a coil;

FIGURE 5 is a similar fragmentary cross sectional view as in FIGURE 4 and illustrating a closed top tube through which heated iiuid is circulated for heating the mold surface to be gas plated;

FIGURE 6 is a similar fragmentary View as in FIG- URE 4, and wherein the rod or solid heating coil element comprises a hammer head portion for extending the Iheat along the surface portion of the mold which is to be gas plated;

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FIGURE 7 is a similar cross sectional view of the fragmentary section of the mold and wherein an open tube is used through which heated air is circulated and wherein the upper ends of the tubes are connected with a common channel beneath the surface portion of the mold to be gas plated;

FIGURE 8 is a fragmentary portion of a mol-d shown in section, and wherein spaced heater coils are arranged in a plane closely adjacent the surface of the mold surface to be gas plated for heating the mold surface for effecting uniform gas plating of metal thereon;

FIGURE 9 is a View in elevation of FIGURE 8, and illustrating the arrangement of heating coils in the mold; and

FIGURE l() is a fragmentary sectional View of a mold illustrating the use of a tubular structure which is arranged to be heated by a surrounding hollow coil which is in the form of a tube through which heated fluid is circulated for heating the surface portion of the mold to be gas plated.

In the drawings, in FIGURE l a plastic mold 11 is shown and which may be composed of gypsum and powdered metal as aforementioned. The surface portion of the mold 12 is of a contour shape to form the die plate 13 and which is produced upon deposition of metal thereon by gas plating.

To heat the die surface portion 13 there is arranged within the body of the mold 11 spaced heating coils 14, which coils are disposed about the tubular opening 15. The tubes 15 extend upwardly and terminate adjacent the die forming surface as at 16. Electrical heating coils 14 are made of the usual resistant material, such as Nichrome, and when electrically connected heat the air in the tubes 14 so that they, in turn, heat the mold surface portion 18 at the top of the tubes. In this manner the die forming surface 13 is uniformly heated to the proper temperature whereby gas plating may be eflicaciously carried out.

In FIGURE 3, a gas plating chamber 20 is illustrated, and which is arranged over the mold surface 11. The gas plating chamber 20 is provided with an inlet opening 21 and an outlet opening 22 for receiving and discharging gaseous metal bearing compound which is circulated through the gas plating chamber. Heated air is forced upward through the tubes as illustrated by the arrows in FIGURE 3, while the heating coils are connected so that the mold surface portion 18 is heated uniformly to a temperature high enough to thermally decompose the gaseous meta-l compound, e.g., nickel carbonyl or other metal bearing compound or mixture thereof, which is circulated or conducted into the chamber 20 `and in contact with the heated surface 18 and produce the forming die of metal deposited thereby as at 23.

In the modified structure illustrated in FIGURE 4, the mold 25 is equipped with solid rod 26 such as may be made of copper, steel, or the like, and which rods are heated by electrical resistance coils 27 arranged thereabout and connected to a suitable source of electricity. The rods when thus heated convey heat to the surface portion 28 of the mold so as to uniformly heat the area during the gas plating of the metal onto this surface portion to thus form the die of gas plated metal.

In FIGURE 5 the modification illustrated shows a mold 30 having tubes 31 through which heated fluid such as air or liquid is pumped by means of smaller tubes 32 which extend into the larger tube 31. The hot fluid is conveyed to the die-forming surface portion of the mold 34 which is to be uniformly heated and receives the gas plated metal deposit for `forming the die.

In FIGURE 6 a similar mold portion is shown at 35 and in which the heat is supplied to the mold surface portion 36 by hammer-headed solid rods 37. The rods which are made of copper, iron, steel or the like, are heated by the surrounding electrical resistance coils 38.

ing plate to make a completed die. This procedure is repeated to form the complementary die or lower die.

The gas plating is carried out in the conventional manner at ordinary atmospheric pressure, and using a carrier Similarly in FIGURE 7, a mold 40 comprises hollow 5 gas such as carbon dioxide. The gas plating rate is prointerconnected tubes 41 which extend upward through portional to the rate of evolution of carbon monoxide the body of the mold and communicate with a common employing metal carbonyls. A satisfactory plating rate channel 42 disposed immediately beneath the mold surresults when using nickel carbonyl at temperatures beface portion 43 which is uniformly heated and subjected tween 375 F. and 400 F. Gas plating of the mold to gas plating. The fluid is circulated through the tubes surfaces to form the dies is preferably carried out as a as illustrated by the arrows in FIGURE 7, and the tubes continuous gas plating operation until the desired thickare heated by resistance coils 44. ness of die plate is obtained to avoid the formation of FIGURE 8 illustrates a similar mold 45 and wherein laminations in the die plate structure. The heating elethe surface portion of the mold 46 which is to be heated ments of the mold are controlled so as to heat the mold to eiect the gas plating comprises spaced electrical heatsurface portion which is to receive the metal deposit to ing resistance coils, the same being disposed immediately a temperature high enough to cause thermal decombeneath the mold surface 46, as illustrated in FIGURE 9. position of the gaseous metal compound, e.g., nickel car- In FIGURE l0, a mold 5() is shown and wherein the bonyl, and deposition of the nickel metal to produce the mold die-forming surface portion 51, and which is to be die. gas plated in the production of the forming die, is heated In carrying out the gas plating it was found that an by an open tube 52 extending upwardly and adjacent the important factor in the attainment of proper plating tem-` surface 51. The tubes 52 are heated by means of surperatures and high gas plating eiciency was effected by rounding uid heated coils 53 and through which heated providing the heating coil arrangement and pattern withfluid such as water, mercury or the like is circulated. in the mold in accordance with this invention. The

In the making of the dies use may be made of dilerthermal conductivity of the mold substrate is relatively ent mold shapes, the composition of which must be such P001', hOWeVeT, by Providing internal mOld heating means as to provide a stable mold at the temperature of gas closely adjacent the mold surface portion which is to replating. ceive the metal deposit as illustrated and described, an

A suitable mold composition from which a shaped excellent detail production of the die contour shape is mold may be made comprises the following constituents Obtainedby weight: In practicing the gas plating method to form dies of Parts by Weight nickel metal, for example, nickel carbonyl and carbon Hydrated calcium sulfate (gypsum) 2 dioxide carrier gas is introduced on a parallel ow from Aluminum metal powder (325 mesh or ner) 2 separate vaporizers which is connected to a common Water 1 35 manifold communicating with the gas plating chamber.

h l Liquid nickel carbonyl is connected to a separate vapor- A'hnnlnum Ine-tel Pnl'neles pmvlde the desn'ed C0' izer from which the gaseous nickel carbonyl flows and is eelen'f 0f enpenslen 0f the mold This Prevents dis* admixed with carbon dioxide carrier in the manifold. tomon end d1mens10na1-chan$es duflng gas Plating and This arrangement minimizes possible interruptions of the Production 0f the forming dle- The gYPsnIn enhances 40 gas flow to the gas plating chamber which is desirable t0 the thermal stability of the mold and provides a strong permit Continuous gas plating.

Shock feslstant moldh A die face area of approximately 656 square inches In Paee 0f a gypsum-aluminum metal mold the same was gas plated with nickel metal as described to a thickmeld shape may be made 0f gypsum and ndInXed With ness of about 1A inch to 1/2 inch. The average consumpglass bers for a portion or all of the metal. In place tion of nickel carbonyl was 12% pounds per homof aluminum, iron metal powder or the like metal may The following table shows the results of gas plating runs be substituted. made using both epoxy resin and aluminum-gypsum mold A suitable resin mold is made using epoxy resin with compositions.

Table I Mold Nickel CO2 now Run Mold Temp., Carrier Plating Gas Carbonyl rate(cu Plating Remarks F. Gas now rate, ftJhr. at Time,

cc./1nm. 160 F hrs.

1 Aluminum Gyp- 385 C03 Nickel Carbonyl.. 7.2 12 21% Excellentdetalland ductle sum. metal die.

2-.-. Epoxy Resin 405 C02 do 7.1 12 17% Similar to gypsum mold but darker shade of metal deposit.

or without the addition of fillers such as metal or glass Dies formed in accordance with the invention are conipowders. An example of an epoxy resin for forming posed of substantially pure metal and exhibit high tensile the mold shape, and which will withstand gas plating strength, excellent dnefiliy, high degree 0f hardness, and with nickel carbonyl is made by admxing (in parts by are dense metal structures free of internal stresses.

Weight) 57 parts of biSphenO1 A with 195 parts diglycd 65 One ofthe great advantages o f the mventlon 1s that ether, 46.5 parts aniline and l5 parts of sodium hydroxide, the mold 1S remforced by the heatmg tubes 91' mii means at F- an holr cnvrt .thi mfastshm? an 11 ntflslle nsm Odult' the mold While -being subject to gas plating. The spaced n e pro ucm o e eas p a e Ormmg les t e heating means also evenly distributes the heat boththrough following steps are carried out (l) shape the mold surface to the desired die contour; (2) gas plate the mold contour surface to deposit a uniform thickness of metal, eg., nickel, to produce the die structure; (3) strip the the convection of the heated air or uid as well as by radiation. In this manner by regulating the heat applied to the spaced heating elements, accurate control of the temperature of the mold can be obtained. This is immetal plate from the mold surface; and (4) add a back- 75 portant to prevent a ire hazard where the mold comprises nely divided metal particles dispersed throughout the mold and which particles are pyrotic. Metal panticles such as the non-ferrous as well as ferrous, e.g. stainless steel may be used to vary the heat conductivity and heat conditions of this mold whereby different heat requirements for gas plating with different metal bearing compounds can be readily satisfied.

Gas plating production of dies permits the making of die working surfaces of accurate and iine detail contour shapes. Moreover, complex areas and contours can be uniformly gas plated with metal at high rates not possible by conventional methods.

It will be understood that while there have been described and illustrated certain specific embodiments of the invention, it is not intended thereby to limit the same thereto inasmuch as the invention is readily susceptible to various modifications, and the use of different metal bearing gas plating compounds, and substitutions of materials, as rnay be made by those skilled in the art all of which come within the scope of the invention, and as set out in the appended claims.

What is claimed is:

1. An apparatus for making metal forming dies by gas plating, said apparatus comprising a mold composed of gypsum and aluminum metal particles and having a surface portion shaped in conformity With the contour shape of the metal forming die to be made, said mold including hollow fluid heated tubes spacedly disposed in the body of said mold and terminating at one end closely adjacent said mold surface for heating said mold surface portion to a temperature high enough to effect fthe gas plating of metal on said mold surface portion to produce the metal forming die.

2. An apparatus for making metal forming dies by gas plating, said apparatus comprising a mold composed of gypsum and aluminum metal panticles and having a surface portion shaped in conformity with the contour shape of the metal forming die to be made, said mold including heated solid rods spacedly disposed in the body of said mold and terminating at one end closely adjacent said mold surface for heating said mold surface portion to a temperature high enough to effect the gas plating of metal on said mold surface portion to produce the metal forming die.

3. An apparatus for making metal forming dies by gas plating, said apparatus comprising a mold composed of gypsum and aluminum metal particles and having a surface portion shaped in conformity with the contour shape of the metal forming die to be made, said mold including hollow tubes disposed in the body of said mold through which heated uid is circulated, said tubes being arranged for heating said mold surface portion to a temperature high enough to effect the gas plating of metal on said mold surface portion to produce the metal forming die.

4. An apparatus for making metal forming dies by gas plating, said apparatus comprising a mold composed of gypsum and aluminum metal particles having a surface portion shaped in conformity with the contour shape of the metal forming die to be made, said mold comprising electrical heating coils disposed in the body of said mold and beneath the mold surface for heating said mold surface portion to a temperature high enough to effect the gas plating of metal on said mold surface portion to produce the metal forming die.

References Cited in the file of this patent UNITED STATES PATENTS 1,950,605 Fitzgerald Mar. 13, 1934 2,256,247 Groehn Sept. 16, 1941 2,333,534 Lang NOV. 2, 1943 2,602,033 Lander July 1, 1952 FOREIGN PATENTS 21,025 Great Britain 1890

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