US3051632A - Method of electroplating copper elbows - Google Patents

Description

1962 M. A. DIKE 3,051,632

METHOD OF ELECTROPLATING COPPER ELBOWS Filed July 27, 1959 INVENTOR .lZszr/zzf Xena ye .D/KE

ATTORNEYS iQEEE 3,5l.,fi32 Patented Aug. 28, 1962' This invention relates generally to electroplating and more particularly to an electroplating process for rebuilding the stretched area of mechanically bent tubes to a minimum thickness.

In forming a pipe fitting, such as an elbow, a length of thin-walled initially straight copper tubing is bent into curved form by standard mechanical bending processes. Under such conditions, it is impossible to maintain uniformity of tube wall thickness because the metal of the outer wall or convex surface of the tubing is stretched and thus thinned to an unsafe or unsatisfactory extent. This thinning results in a gradual reduction of the convex wall thickness that gradually thins downwardly from a plane substantially coinciding with the lower edge of the inner concave surface.

It is a main object of this invention to provide an electroplating process for rebuilding such thinned curved surface to a desired minimum thickness.

Another object of this invention is to provide an electroplating method for rebuilding the stretched surfaces of mechanically bent elbows so that such elbows may be formed of straight tubes of minimum original thickness.

Still another object of this invention resides in the manner of controlling the immersion of the copper elbows in the electrolyte so that uniformity of the re-built Wall surface is maintained.

A further object of this invention is to provide a controlled electroplating process particularly designed to rebuild and reinforce reduced or stretched metal areas to at least minimum original tube wall thickness.

A still further object of the invention is to provide a controlled withdrawal of the stretched copper elbows from the electrolyte so that the deposit or plating material will be gradually increased to regain at least minimum original straight tube thickness.

A further object is to form an elbow from a metal tube having a minimum wall thickness by first bending said tube into the shape of said elbow and then electroplating the portion of said tube that is thinned by such bending so as to rebuild said portion to said minimum wall thickv ness.

An additional object of the present invention is to provide an elbow mechanically bent from a tube of minimum wall thickness wherein the portion of said tube that is thinned by such bending is covered by a layer of electroplated material whereby said elbow will have a minimum wall thickness throughout its length.

With the foregoing objects in view, and such other objects and advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawing in which:

FIGURE 1 is a perspective view of a thin-walled copper tube before it is mechanically bent into the shape of an elbow;

FIGURE 2 is a perspective view of the tube of FIG- URE 1 after it has been bent into an elbow shape;

FIGURE 3 is a vertical sectional view taken on the line 3-3;

FIGURE 4 is a sectional View similar to FIGURE 3 showing the same elbow following the rebuilding process of the present invention;

FIGURE 5 is a side elevational 'view taken partly in vertical section and showing an elbow-plating mechanism useful in carrying out the process of the present invention;

FIGURE 6 is a sectional view taken on the line 66 of FIGURE 3; and

.FIGURE 7 is a sectional view taken on the line 7-7 of FIGURE 4.

Referring to the drawing, a thin-walled straight copper It is standard practice that the tube tube is shown at 10. 10 be mechanically bent to form an elbow E. Any conventional mechanical bending process may be used to bend the elbow E to any desired degree of curvature.

Irrespective of the degree of elbow curvature, the mechanical bending operation will always stretch and thin the metal of the outer wall or convex surface 11, as shown in FIGURES 3 and 6. The stretching of the elbow outer wall surface results in a gradual reduction or feathering of metal from substantially the beginning of the convex area at 12 to the extreme outer point indicated at 11, as shown in FIGURE 3. This reduction of wall thickness results in a corresponding reduction of strength and useful service life.

Previously it has been necessary to process elbows from straight tubing of considerable thickness and weight in order to provide a sufficiently safe and durable stretched convex surface area. The added material cost did not change the fact that the processed elbows were only as strong as their stretched and thinned outer walls. It is highly desirable that the considerable expense of the above process be materially reduced.

The present invention permits the use of straight tubing of minimum wall thickness and provides an entirely satisfactory copper electroplating process for rebuilding the stretched and thinned outer elbow surface to substantially uniform tube wall thickness. Referring now to FIGURE 5, this process utilizes a standard electroplating tank 16 containing the desired copper plating electrolyte B. It is preferable that the electrolyte B be composed of an acid copper solution or a cyanide copper solution; however, other conventional electroplating solutions may also be. utilized. A conventional copper anode preferably of electrolytic copper is shown at A disposed in the tank 16. Plural copper elbows E are releasably secured to an immersion bar 18 as by conventional clips 19. The bar 18 has a standard electrical connection 20 and complete the electroplating circuit with the elbows E forming the cathode C. The immersion bar 18 is threaded at 21 and 21 on duel feed screws 22 and 23, respectively. The feed screws 22 and 23 are supported at their lower ends in dual brackets 24 and 25, respectively, and dual frames 26 and 27 rising from said brackets support the upper ends of the feed screws 22 and 23. The frames 26 and 27 also provide bearing support for a horizontally disposed feed screw drive shaft 28. The drive shaft 28 carries beveled gears 29 and 30 that mesh with similar beveled gears 31 and 32 on the upper end of the feed screws 22 and 23, respectively.

Means for actuating the drive shaft 28 and feed screws 22 and 23 to raise and lower the immersion bar 18 is provided in a standard variable speed reversible electric motor M drivingly connected to a conventional speed changing mechanism T having a driven shaft 34 coupled with the drive shaft 28. This speed changing mechanism T includes a control wheel 36 which is manipulated so as to vary the ratio of the speed of the shaft of electric motor M relative to the speed of the driven shaft 34 and hence shaft 28. The exact details of construction of the electric motor M and the speed changing mechanism T are not important to the scope of the present invention.

Moreover, other means; accomplishing the same results may be used without departing from the scope of. the.

present invention. a a H In conducting the present process, after'mechanical bending of the copperelbows has been accomplished, the elbows E are clipped to the bar 18 and lowered into the electrolyte B so that preferably only the stretched sur- .fac'e areas to be rebuilt are immersed. An electric circuit is then completed between the anode and the cathode through the electrolyte; Inorder that the plating of the thinned tubular wall surface is uniform, the speed changing mechanism T is set to slowly withdraw the elbows E from the electrolyte B during the plating operation so that the plating material will be deposited in increasing thickness from the point 12 to the point 11 of 7 FIGURE 3. The gradual depositing of the plating material rebuilds and reinforces the initially bent elbow of FIGURES 3 and 6 to the thicknessof the completed elbow of FIGURES ,4 and 7. Control of the electric current during the aforedescribed electroplating process may follow conventional electroplating practice.

Since variou modifications can be made in the invention as hereinabove' described, and many apparently widely difiierent embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter con-' tained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

I claim:

1. A method of forming an elbow having uniform wall thickness out of copper tubing comprising the steps of,

bending the copper tubing into theshape of an elbow, locating the wall portions of said elbow which meet reduced thickness due to such bending, and electroplating onto said wall portions suflicient copper to overcome said reduced thickness to thereby provide an elbow of uniform wall thickness. V I

2. A method of forming an elbow having uniform wall thickness out of copper tubing comprising the steps of,

bending the copper tubing into the shape of an elbow,

locating the wall portions of said elbow which are 'ofreduced'thickness due to such bending, immersing said wall age-51532 duced thickness due to such bending, immersing said Wall portions in an electrolytic solution, activating said solu- 1 tion to effect electroplating, and withdrawing said wall portion -from said electrolytic solution at a predetermined rate to provide an elbow of uniform thickness.

4. A method of forming an elbow having uniform wall thickness out of copper tubing comprising the steps of, bending the copper tubing into the shape of an elbow, locating the wall portions of said elbow which are of reduced thickness due to such bending, immersing said Wall portions in an electrolytic solution, activating said solution to effect copper electroplating on said elbow, and

withdrawing said wall portions from said solution at a rate inversely proportional to the extent of reduction in wall thickness, whereby said wall portions of greater reduction receive increased electroplating to provide an elbow of uniform thickness.

7 ing reduced thickness due to such bending, immersing said wall portion in an electroyltic solution, activating said solution to efiect electroplating of said wall portion, and graduaIIy'WithdraWing said wall portion from said solution so that the areas thereof are immersed therein 7 for a period of time corresponding to the extent of reduction, whereby an elbow of uniform wall thickness is provided 6. A method of forming an elbow having uniform wall thickness out of substantiallystraight copper tubing comprising the steps of, bending the copper tubing into the shape of an .elbow, locating the wall portions of said elbow which are of reduced thickness due to such bending; immersing said wall portions in an electrolytic solution, activating said solution to efiectelectroplating of said wall portions, and controlling the immersion time of said wall portions so that areas of greater reduction in wall. thickness spend a greater amount of time in said activated solution, to thereby 'provide an elbow having uniform Wall thickness.

References Cited in the file of this patent UNITED STATES PATENTS 2,181,257 Arbogastt Nov. 28, 1939 2,229,077 Hammond et al. Ian. 21, 1941 2,358,104 Scavullo Sept. 12, 1944 2,780,019 Sullivan Feb. 5, 1957 2,879,209 Fialkolt Mar. 24, 1959

Claims (1)

1. A METHOD OF FORMING AN ELBOW HAVING UNIFORM WALL THICKNESS OUT OF COPPER TUBING COMPRISING THE STEPS OF, BENDING THE COPPER TUBING INTO THE SHAPE OF AN ELBOW, LOCATING THE WALL PORTIONS OF SAID ELBOW WHICH ARE OF REDUCED THICKNESS DUE TO SUCH BENDING, AND ELECTROPLATING ONOT SAID WALL PORTIONS SUFFICIENT COPPER TO OVERCOME SAID REDUCED THICKNESS TO THEREBY PROVIDE AN ELBOW OF UNIFORM WALL THICKNESS.

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