US2870709A - Electroformed articles and process for their manufacture - Google Patents

Description

Jan. 27, 1959 E. D. BOELTER, JR

ELECTROFORMED ARTICLES, AND PROCESS FOR THEIR MANUFACTURE Filed 001;. 28, 1955 m w m um mm- .H 2 Ni P A .1 2 W l lfi HM h A mmm 1 .I/Hx I 1H E Mi an Mn; \JWJW M I w i m M MD w w H H H m I E t I 11 g m ATTORN Y United States Patent cc 2,870,709 ELECTROFORMED ARTICLES AND PROCESS F0 THEIR MANUFACTURE Edwin D. Boelter, Jr., Niagara Falls, N. Y., assignor to E. I. du Pont de Nemours and Company, Wilmington,

Del., a corporation of Delaware Application October 28, 1955, Serial No. 543,496 2 Claims. (Cl. 102-24) This application, a continuation-in-part of my copendmg application Serial Number 426,950, filed May 3, 1954, and now abandoned, relates to electroformed copper articles and to a process for preparing the same.

In the above-mentioned application there is claimed a process for electrodepositing copper at unusually high current densities from a substantially conventional aqueous copper cyanide bath modified by the inclusion therein of an inorganic selenide such'as sodium or copper selenide. The quantity of additive used is not sharply critical but should comprise between about 50 and 1000 p. p. In. of the bath.

selenide bath at very high rates of speed, i. e., one mil 'per minute or greater, in an extremely ductile form. This copper is free of internal strain and can readily be deposited to any predetermined thickness on surfaces having a low radius of curvature. If the surface is one to which copper will adhere, such as carbon steel, the electrodeposit will be held tenaciously. If, on the other hand, the surface is one to which copper will not adhere, such as polished chromium or stainless steel, the copper can easily be stripped therefrom retaining the shape of the base.

Copper can thus be plated at high speeds from the novel baths onto a mandrel and easily removed from the latter. Articles terminating in a point or other closed base can, in particular, be formed as described. Such articles, which may be termed concave, include cones, cups, bowls, fountain-pen caps and the like.

i The cones of this invention have an entirely unexpected property which makes them of great value: they are extremely eifective as liners for small shaped charges.

When so adapted, they surprisingly increase the penetrating power of the charges to a value about 12-15% greater than that obtained with liners made by conventional methods such as deep-drawing or forming the copper.

These shaped charges are particularly valuable in devices such as jet perforators. Jet perforators are described in many publications as, for example, the Muskat et a1. U. S. Patent 2,494,256. Used for piercing oil well casings, they consist primarily of a small shaped charge of high explosives held within a container, a mean for detonating the charge from one end and an internal metallic liner in the end opposite the point of detonation. When the charge is set off the conical liner collapses from apex to base and ejects a metallic stream of such high velocity and small cross section that it readily penetrates anything before it. The initiating means is usually a detonating fuse, but a detonator may be employed if desired.

A specific object of the invention is, therefore, provision of a method for making copper cones adapted for use in producing jet perforators.

Other objects will be apparent from the remainder of the specification and from the drawings, in which:

Figure 1 shows an electroplating bath and apparatus for producing the cones of the invention; 7

. Figure 2 is a section of a jet perforator, positioned for use, showing the electrodeposited conical liner; and

Figure 3 is an elevation of a jet perforator mounted on a pile of steel plates for testing perforation.

Figure 1 discloses tank 10 containing bath 12, shield It has now been found that copper will deposit from the 2,870,709 Patented Jan. 27, 1959 14, and anode 16. Rotating mandrel 18, partly insulated,- serves as the cathode. Pump 20 is provided to remove part of the bath from the lower portion of the tank, pass it through filter 17, and impinge a spray 21 onto the tip of the mandrel and the cone 30 being formed. Use of such a spray is almost essential to insure strength and uniformity of the deposit at the closure when articles terminating in a point or rounded apex, as the preferred cones of the invention, are made.

The composition of andconditions for operating the bath of Figure 1 are essentially those of the copending application except for use of the liquid spray. The spray is maintained by the pump operated at a rate proportional to the desired plating speed. A spray velocity of about 500-1000 ft./ minute is satisfactory for a plating speed of 1 mil/ minute.

Usable bath compositions and conditions include:

Preferred conditions permitting use of current densities of about 850 amperes per square foot or a plating speed of up to about one mil/ minute are: Y

CuCN About 10 oz./gal.' Free KCN About 1 oz./ gal.

KOH About 1 oz./gal. Na Se About 200 p. p. 111. Temperature About -90 C.

Since the selenium is deposited with the copper to the extent of about 2-300 p. p. m. the desired concentrations must be maintained by occasional additions to the bath. These additions may be made, as may the original, in the form of Cu Se if it is so desired. An organic anti-pitting agent such as methylene-bis(naphthalene sulfonic acid) in the aor [3- form, C-decyl betaine or the like should also be used to improve the copper deposits. The concentration of this agent may vary in the bath from about to 500 p. p. m., about 200 p. p. 111. being preferred.

Other plating techniques may be used in operating the process of the invention including current reversal and current interruption. Neither of these current manipulations appreciably affects the properties of the preferred cones of the invention.

As noted above, when cones prepared from a copper cyanide bath containing a selenide are utilized as the liner for the small shaped charge of a jet perforator, they increase the penetrating power of the latter about 12- 15%. This increase in penetrating power renders the perforators especially valuable for use in oil wells. Figure 2 shows a jet perforator 22 positioned :for use against oil well casing 23. The perforator consists of container 24, initiating means 26, and shaped charge 28. In the broad end of the shaped charge is inserted liner 30, preferably formed on the apparatus of Figure l.

Electrodeposited cones are of primary value at small sizes, i. e., up to two inches in both diameter and height, and with small charges of 10-25 g. of explosive. Both larger cones and larger charges can be used although in such cases the improvement due to electrodeposition from the selenium-containing bath becomes more diificult to assess.

The reason for the enhanced penetrating power of shaped charges lined with electroformed copper cones is not precisely known but is believed due to the exact uniformity of the cone structure. The uniformity of the cone in thickness and around the center axis prevents collapse from a number of centers and thus yields a reproeliminated only by polishing the workpiece during interruption in the deposition. The mandrel employed must be-adherent to the copper to retain the latter during polishing operations but also fusible so that it can eventually 'be separated from the article produced. Copper prepared in this manner is non-uniform and possessed of no unusual properties in regard to lining shaped charges. Conventional cyanide baths heretofore utilized employ current densities which are too low for electroforming.

There follow some examples serving to illustrate the practice of the invention:

EXAMPLE 1 This example shows the penetrating power of jet perforators lined with copper cones prepared on the apparatus of Figure 1.

Copper cones were electrodeposited from an aqueous cyanide bath upon a polished chromium mandrel under the following conditions:

CuCN "oz/gal-.. 15 Free KCN oz./gal- 1-2 KOH oz./gal 2 Na Se p. p. in... 50200 Temperature 86 Rate of revolution of the mandrel R. P. M 600-2000 Spray velocity ft./min 850-1000 Distance between jet outlet and tip of mandrel inch 2, Current (D. C.) A./S. F 200-340 The cones were subsequently directly stripped from the mandrel in a single operation. Each cone was 1 inch high externally, 1.31 inches in diameter at its base and possessed an angle of 60. The copper was electrodeposited to a thickness of about 17-20 mils.

Into each cone was forced, at a pressure of 20,000

p. s. i., an 18 gram charge of cyclonite and wax having a weight ratio of 95:5. The resultant assembly was tested as shown in Figure 3, which displays the jet perforator 22 positioned on a stack of steel plates 32 each one inch in thickness. The perforator was detonated and the depth of penetration into the plates and the diameter of the hole formed were measured. Results are given in Table I.

Table l.--Penetration with electroformed cones Depth of Diameter Cone Penetration, of Hole in inches 1st Plate,

inches were. rmmeorm 9999. UlOlkOUF A The tests recorded in Table I were repeated with cones made utilizing both current reversal and current interruption. Results were the same with this second group of cones.

' 1 EXAMPLE 2 I example .shows the results of penetration tests with cones made from sheet copper and is included solely as a control,

The testsof Example'l were substantially. repeatedexr cept that the lining utilized were prepared by deep-drawing sheet copper. The. dimensions of the cones and the weights of the charges were substantially the same as in that example. Results are given in Table II.

Table II.-Penetratidn with drawn co nes Depth of Diameter of 1 Cone Penetration, Hole in 1st inches Plate, inches Average 3. 91 0.

EXAMPLE 3 This example, also included as a control, shows the results of penetration tests with electroformed cones pre- 1 pared by prior, art electroforming processes.

The tests of Example 1 were substantially repeated except that the linings utilized were prepared by electroforming copper from a conventional bathcontaining no selenium. The dimensions of the cones and the weights Having described my invention, I claim: 1. In a jet perforator comprising a shapcdcharge means for detonating said shaped charge, a container sub stantially surrounding the shaped charge-and "a cavity in the base of the same, a lining in said cavity comprising a substantially strain-free copper cone producedby'eiectrodepositing copper from an alkaline copper cyanide bath ing 50-1000 p. p. m. of an inorganic shelenide.

2. A liner for a shaped charge comprising a substantially strain-free copper cone produced by electrodepositing copper from an alkaline copper cyanide bath eontaining 50 1000 p. p. m. of an inorganic selenide.

References Cited in the .file of this patent UNITED STATES PATENTS 2,549,678 'Fiandt Apr. 17, 1951 2,605,703 Lawson Aug. 5, 1952 2,684,030 Muskat et al July 20, 1.954 2,692,850 Safranek et a1. Oct. .26, 1954 Q 2,694,677 Ostrow Nov. 16, 1954 2,701,234 Wernlund Feb. 1, 1955 2,706,170 Marchese Apr. 12, 1 955 2,708,408 Sweetman May 17, 1955 2,732,336 Ostrow Jan. 24, 1956 2,770,587 Ostrow Nov. 13., 1956 OTHER REFERENCES Article of Sanrranck et aL, in Platingj January 1948, 91 13919 wincnueacncn'enenencn

Claims (1)

1. IN A JET PERFORATOR COMPRISING A SHAPED CHARGE MEANS FOR DETONATING SAID SHAPED CHARGE, A CONTAINER SUBSTANTIALLY SURROUNDING THE SHAPED CHARGE AND A CAVITY IN THE BASE OF THE SAME, A LINING IN SAID CAVITY COMPRISING A SUBSTANTIALLY STRAIN-FREE COPPER CONE PRODUCED BY ELEC-

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