US1530614A - Method for metal coating - Google Patents

Description

March 24. 1925.

H. W. PLEISTER METHOD For: METAL comme Filed Dec. 29. 1923 Patented Mar. 24, 1925.

UNITED STATES PATENT OFFICE.

HENRY W. PLEISTER, F WESTFIELD, NEW JERSEY, ASSIGNORQBY MESNE ASSIGN- llflENTS,v TO DIAMOND EXPANSION BOLT COMPANY, 0F NEW' YORK, N. Y., A COR- PORATION 0F NEW YORK.

METHOD ron METAL coATING.

Application filed December 29, 1923. v Serial No. 683,424.

T0 all 'whom it may concern vBe it known that I, HENRY IN. PLEISTER, a citizen of the United States, and resident of Westfield, in the county of Union and State-of New Jersey, have invented certain new and useful Improvements in Methods for Metal Coating, of which the following is a specification.

This invention relates to the method of coating iron or steel articles with zinc applied in a molten state and allowed to cool and harden thereon, the process commonly known as galvanizing. Y

This invention relates more particularly to the process of distributing the liquid or semi-liquid coating of zinc while still in a molten state on the surface of the articles so as to form a smooth and even coating of equal density on all surfaces of an irregularly shaped article.

Another object of this invention is to prevent the articles remaining in close contact one with the other when handled in a mass in order to prevent their sticking or freezing one to the other.

It is customary in the process of galvanizing after an article or a mass of articles have been properly pickled to immerse the article separately or a mass of articles in perforated baskets into a bath of molten zinc approximately 50 degrees to 100 degrees Fahrenheit above the melting point of the zinc and to allow the articles to remain until raised to a temperature equal approximately `to the heat of the molten zinc; the articles are then subjected to various treatments after they are taken out of the bath according to the different processes employed by various galvanizers such for instance `as shaking the basket vigorously by hand and throwing the contents on 'the door to spread the articles and to prevent stickers, wiping the surface to spread the coating smoothly and to remove excess spelter or subjecting the mass to rotation so thatthe excess spelter is thrown olf by centrifugal force.

The objectionable features to al] of'these n processes are numerous, the cost of wiping threads on bolts is excessive and the result does not brin about a smooth and uniform `ob.- 4'Such bo ts often require the threads to ere-cut with a die in order to permit the nuts being turned onthe bolts The shaking in perforated baskets by hand is excessively laborious and the production per man is very low. Submitting the articles to simple centrifugal motion has its disadvantages in that the mass thus rotated retains its original relative position one article to thc other in the centrifugal chamber. Thus articles for instance which happen to be at the center of the centrifuge will continuev there to remain and to cast excess spelter on the articles nearer the periphery which excess spelter often freezes on the articles at the outside or periphery causing blisters, icicles, roughness and excess spelter. Articles treated in this manner retaining their same relative position one to the other will in many cases freeze or stick together when'the zinc cools and hardens and when broken apart will leave bare or exposed spots'on one or the other. When a simple centrifuge is used the articles will be coated more thickly on the side further removed from the center than on the side nearer'to the center. This is for the reason that the article retains its original position and the centrifugal force will draw the fluid spelter outwardly taking it from the side nearer the center and drawing it to the side further away causing an uneven distribution of the zinc when hardened. Another objection to the simple centrifuge is that in a mass of articles the articles nearer or at the periphery are subject to more violent action than those nearer to .or at the center where practically no action occurs. This it will be readily seen causes differentv densities of coating to be left on the articles. With sufficient speed it is possible practically to cast olf all the spelter from the outer articles while those at the center 0f rotation still retain a very thick coating.

In my process of galvanizing I employ a primary horizontal rotary platform upon which is mounted between its center and circumference a secondary rotating platform. Upon this is mounted suitable supports for retaining a perforated basket. A planetary 'rotation of the secondary rotating platform is obtained by means of a xed pinion at the center of the primary rotating platform which pinion meshes in the teeth of a gear mounted underneath the secondary platform on its center. Thus when the primary platform S IOtated' the pinion being fixed I against rotation the secondary platform will scribed and claimed as new hereafter. In

` ary rotatable.

order to make this application entirely clear I will describe it in connection with the particular preferred apparatus thatis shown in the drawings.

-It is further understood that the speed of revolution of the secondary centrifuge 'may be varied in relation to the primary to any degree that is found more eiiicient for certain classes of work. While in the majority of cases the relation of threerevolutions to the primary rotating platform to one revolution of the secondary rotating platform is found to be most satisfactory this relation may easily be changed by the substitution of different sizes of gears-and pinions. For ease of description I will in Vthe accompanying drawings and following description illustrate and describe theaction of the apparatus so constructed as to give one revolution on the primary to one revolution on the secondary rotating platform.

Figure 1 is a cross sectional elevation of the preferred form of my apparatus; and

Flgure 2 is a horizontal view of same,

looking down upon the rotatable platforms;

Figures 3, 4, 5, and 6 are diagrammatic plan views of the rotatable platforms in different positions takenv at each quarter turn, each platform rotating clockwise; and

Figs. 7 and 8 are diagrammatic plans showing orbits of an article; with different ratios between rthe rotation of the primary and secondarytables. y

In Figures land 2 ais a stationary pinion mounted rigidly on a fixed shaft. b supported on a base c; the primary rotatable platform alv is loosely fitted to the shaft or column b. Thisv rotatable table may be actuated by a belt about the pulley e or by shaft and gear or in any other suitable manner. A secondlatfo'rm f is mounted on a shaft g spaced etween' the center of the primary table and its circumference and fixed rigidly agearwheel la." which meshes with thev p1n1on a. On they secondary rotatable platform f is suitably mounted a perforated basket jsupported by upright c'. AWhen the primary platform d is rotated the secondary platform will travel with it about the center of the column Z at the same .time rotating about' its own cente This apparatus is preferably enclosed in a steel or other'suit-y able shield Z to vrevent'the spelterwhich is as it is placed in the basket cast ofiI the coated article from ying about the room andV to allow it to fall to the bottom of the enclosure where it may be removed and replaced in the molten bath for repeated use.

In my process of galvanizing articles to be coated are first cleaned or pickled in the usual manner in diluted sulphuric, hydroiiuoric or muriatic acid, according tothe class of work,^diferent acids being used for bright cold rolled steel, rough hot rolledu steel, cast iron, etc. After being pickled they are immersed in a bath of molten zinc at approximately 850 to 900 degrees Fahrenheit larger articles being limmersed separately or strung on wires, smaller. articles being immersed in a mass in aA perforated steel basket. The articles are allowed topremain in the zinc bath until they have attained approximately the temperature of the bath throughout. They are then taken from the bath and placed upon the secondary rotary table f of my apparatus and subjected while the zinc coating is still in a liquid or semiliquid state on the surface of the articles to a' compound rotary motion suiiciently long to expel all surplus zinc and evenly to distribute the coating of molten zinc smoothly and of equal density over'the entire surface of the articles. Very few revolutions of the apparatus are necessary to accomplish this and the material is then removed from the apparatus. If small articles are-treated in bulk in a perforated basket the basket is taken from the machine and dumped upon an inclined chute, while sliding 'down this chute they are sprinkled with salammoniac and allowed .to fall into a tank of clear cold water. This process results in a smooth 'bright coating of zinc upon the steel or iron articles with uniform thicknesson all surfaces free from lumps, projections, blisters or any kind of roughness. `Where threaded articles are so coated the threads of a4 bolt `are clear and free in the 'threads and in thev slot vof thehead so that no'further cleaning or machine work is necessary on the-m and a uut may be run freely over the threads of the bolts.

The even distribution of the metal on 'the llO articles is accomplished bythe particular' rotary motion which is applied in my appaures 34, 5, 6 and 7. In Figure 3, Ihave shown as exemplary of many other shapes an article M having at leastA four O, P, placed in a perforatedl basket upon the secondary rotating platform f. .Its position in `the basket is one of any number of positions that it may have when the basket is removed from the molten zinc and is o ne of many similar articles with which the basket lis filled though not shown in the drawing.

approximately I Its position will be retained due -to its con sides' N, R,

ratus and which motion is illustrated in Figtact with the surrounding articles which lill the basket. In Figure 3 and each of the succeeding Figuresft, 5, and 6, the lines of centrifugal force radiate from the center X of the primary rotatable table and are marked LCF. When the primary rotatable table is turned clockwise the secondary table will also turn clockwise and in an orbit around the center'X. When in the position shown in Figure 3 the-lines of centrifugal force will draw the liquid metal from the side P to the side R. When the primary rotatable table has made a quarter turn on its center Figure 4, the secondary rotatable-table will have made a quarter turn on its center also, and the article M will take the position shown in Figure 4 and the lines of centrifugal yforce are from the sides O and P toward the sides R and N. When the next quarter turn has' been made Figure 5, the article M has taken the position shown in the drawing and the lines of centrifugal force are from the side R toward the side P. When the next quarter turn has been taken the article M is in the position shown -in Figure 6 and the lines of centrifugal force are from the sides N and P toward the sides R and O.. IVhen the next ,quarter turn has been taken the article M will have again taken the positionA shown in Figure 3, the original position at which it started, andthe lines of centrifugal force will be from the side P to the side R. Thus it willbe seen that the centrifugal action upon the article M is constantly changing in its direction causing the metal to be drawn on its surf faces in ever changing directions assuring the casting off of surplus metal from every angle on the surface and assuring a smooth and uniform distribution of the fluid metal over the entire surface of the article.

From the above description it can readily be seen that the ever changing direction of the lines of centrifugal force upon the article treated produces an entirely different action from that obtained in the simple centrifuge where the direction of the lines of centrifugal force remain constant at all times on each article and where kthe articles at the inner portion of the centrifuge are continually expelling metal upon those located at the outer portion or nearer to the periphery of the centrifuge. In my process the article treated is not allowed to remain at the same distance from the center at any time but is constantly changing its location from the center of the primary rotatable table. In Figure 3, the article M is shown at its extreme distance from the center X.v In Figure 4 it is Shown at a pointbetween the extreme and the minidistance from the center X. In Fig ure 5 it is shownat its minimum distance from the center X. In Figure 6 it is again shown at a. point between the extreme and the minimum distance from the center Xand 'trifugal action while those at or adjacent 'Figure 8, I have shown the orbit of the article M about the center X where the primary table makes three revolutions to one revolution of the secondary table. As stated before in this description where a` simple centrifuge/.is used certain articles at or adjacent to the center receive little or no cento the circumference are more forcibly affected by the centrifugal action; With my process all articles receive practically equal cen-A trifugal treatment in their passage from maximum to minimum ydistance from the center.

While I have stated above the articles will be held7 in the same relative position one to the other during the process of expelling the excess spelter during their treatment in my apparatus, there is still suiicient agitation among the articles caused by the changes in linesV of centrifugal force exerted upon them to prevent their adhering one to the other so that when the rotation has been completed and the articles are dumped from the basket down the inclined chute into the water they will be comparatively free from stickers, the term usually applied to galvanized articles which adhere one to the other.

Articles M disposed over the teeth the Wheel h. will vary in speed substantially from zero speed to high speed. JArticles nearer the axis ofthe wheel l1. will vary in speed less.

It is further be understood that While l have shown boththeprimary and secondary rotatable tables operated in a clockwise direction I In. y obtain a similar result by rotating onein a clockwise and the otherin u counterclockwise direction by the insertion of another gear wheel or in other Ways. It is particularly noted that the invention is not limited to the details and metal described. as these may be greatly varied without '.departing from the yscope of the invention as claimed.

I claim as my invention:

1. A process comprising applying molten metal to an article; lthen subjecting the article to motion in 'an endless deeply 120 curved path; and at the same time varying the relation of the article with respect to the path. l

2. A process comprising applying molten metal to articles; then subjecting the articles ,to motion in an endless deeply curved path;

and at the same time Varying the speed of the articles.

3. A process comprising applying molten metal to articles; then subjecting the articles l less deeply to motion in an endless deeply curved path at sufficient speed to throw metal from the articles; and at the same time varying the speed of the articles. v

4. A process comprising applying molten metal to articles; then subjecting the articles to motion in an endless deeply curved path; and at the Sametime varying the'curvature of the path. j

5. A process comprising applying molten metal to articles; then subjecting the articles to cyclic motion in a curved path; and at the same time varying the relation 'of the articles with respect to the path.

6. A process comprising applying molten metal to articles; then subjecting the articles to cyclic motion -in a curved path; and at the same time varying the speed of the articles.

7. A. process comprising applying molten metal to articles; then subjecting the articles to cyclic motion in a curved path; and at the hsame timevarying'the curvature of the pat v 8. A process comprising applying molten metal to articles; then subjecting the articles to cyclic motion in a curvedl path; and at the same time varying the angle of the articles with respect' to the path.

9. A process comprlsmg applying molten` metal to an article; then subjecting the article to planetary motion.

10. A process comprising applying molten subjecting the article to centrifugal force; and at the same time varying the relation of the force with v respect to the article. Y

11. A process comprising applying molten metal to articles; then subjecting the articles tocentrifugal force; and at thevsame. time varying the angle of the force with respect to the articles.

l2. A process comprisingapplying molten metal to articles; then subjecting the articles to cyclic centrifugal force; and at the same time varying the angle .of the force with respect to the articles.

' 13. A process comprising applying molten meta-l to articles then 'subjecting the article/s to cyclic centrifugal force; and at the same time varying the relation of the force with respect to'the articles. i

14.- A processcomprising applying molten metal to an article; then subjecting a carrier with the arti-cle therein to motion i`n .an endcurved path; and at the same time varying the angle of the carrierl with respect to the path. j .l

15. A process comprisin applying molten metal to a-rticles; hen sujecting a carrier with articles therein to motion in an -endless ldeeply curved path; andat the. same time positively varyingthe angle of thecarrier with respect to thel path.

16. The process of galvanizing which constate on the surface of the articles to sists inA 'immersing the articlesin molten zinc, then removi them to a rotary motion while theA zinc is stillin afliquid or semi-liquid state on the surface of the articles inl which motion the articles are rotated centrifugally in constantly chan 'ng distances fromthe center of the centriiige A 17. The process of galvanizing 'which consists in' immersing the articles in molten zinc, `then removing them and subjecting them to a rotary motion while the zinc is still in a liquid or semi-liquid state on the surface of the articles in which motion the articles are rotated centrifugallly in constantly changing distances from the center of the centrifuge whereby each article is' subjected to the-same amount of centrifugal force as the others.

18. The process of galvanizing which consists in zinc, then removing them and subjecting them to a rotary motion while the zinc is still in a li uid or semi-liquid state on the surface of t e articles in which motion the articles are constantly and alternately drawn toward the center and away from the center of the centrifuge.

19. Thev process of galvanizing metal articles consisting of immersing them. in a bath of molten zinc until the temperature of the articles has been brought up to approximately the temperature of the Yzinc, then subjecting the articles in a mass while the zinc is still in a liquid orvsemi-liquid wa compound rotary motion in which motion the position of the articles in relation to the lines of centrifugal force is continuously changed.

20.' The process of galvanizing'metal articles consisting of immersing them in a bath of molten zinc until the temperature of the articles has been brought up to approxi; mately the temperature of the lzinc, then subjecting the articles in a mass while the zinc is still in a liquid or semi-liquid state on the. surface of the articles to a compound rotary motion in which motion the'position of the'articles in relation to the lines of centrifugal force is whereby thev liquid coating will be caused to flow in ever changing directions on the surface of the article. A

21. The process ofA galvanizing metal arlticls consisting of immersing them vin aat the articles has been brought up to approximately the temperature of the zinc, then subjecting the articles in. a mass While the zinc surface ofthearticles to a compound rotary motion in which motion-the position ofthe articlesin relation to fthe lines of 'centrifu- -continuously lchanged g'them .and subjecting immersing the articles in molten of molten zinc until the temperature of v.is still in a liquid or semi-liquid state on the CTI the excess spelter Will be cast otll in ever changing directions relative to the position of the article.

22. The process of galvanizing metal articles consisting of immersing them in a bath of molten zinc until the temperature of the articles has been brought up to approximately the temperature of the zinc, then subjecting the articles in a mass While still at approximately thesame temperature and While the zinc is still in a liquid or semiliquid state on the surface of the articles to a compound rotary motion in which motion the radial position of the articles in relation each to the other is continually changed.

23. The process of galvanizing metal articles consisting of immersing them in a bath of molten zinc until the temperature of the articles has been brought up to approximately the temperature of the zinc, then subjecting the articles in a mass While still at approximately the same temperature and While the zinc is still in a liquid or semiliquid state on the surface of the articles to a compound rotary motion in which motion the distance of each article from the center from periphery to centerand from center ato periphery passing through all points inrermediate thereto.

24. The process of galvanizing metal articles consisting of immersing them in a bath of molten zinc until the temperature of the articles Ahas been brought up to approximately the temperature of the zinc, then subjecting the articles in a mass While still at approximately the same temperature and while the zinc is still in a liquid or semiliquid state on the surface of the articles to a compound rotary motion in Which motion the distance of each article from the center of the centrifuge is continually changed from `periphery to center and from center to periphery passing through all points intermediate thereto, Whereby no article Will be allowed to remain at the circumference to receive the cast olf Spelter from articles nearer the center thereby insuring articles which are initially placed at the circumference-receiving the same treatment as those initially placed at or nearer the center.

Signed at New York, in the county of New York and State of New Yorlc, this 26th day of Dec., A. D. 1923.

HENRY W. PLEISTER.

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