USRE17048E - Method ob making ventilatrnxx stbips fob tbansfobmebs - Google Patents

Description

July 24, 1928.

F. H. TUPPER METHOD OFIMAKING VENTILATING STRIPS-FOR THANSFORMERS Original Filed April 18. 1922 l WJ.

WKIIHVIIIVIllilllflll U f /H/ f 4 O# i. i /H/ INVENTOR Frank f7. Tapper TTORNEY l. beinexpen'siveand'whic rodice uniform results in` quantityl manucharacters designate like parts,

July 24, 1.928. l. UNITED, STATES PATENT oFFiCl-i.

lFRANK rH. TUPPEB, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOB 1 0 WESTDTGHOUSI ELEC'IBIC MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA.-

METHOD-0F IAIING-IVENTII4ATING STRIPS FOB 'IBANSI'OBCMCIIZ'.ES.v

Manlio; 1,565,533, 'dated December 15K, 1926, Serial No, 555,181, med April 1B, 1928. Application for relslue led December 7, 1927. Serial No. 238,446.

My invention relates to composite articles, more especially to a method of joining articles of molded composition embod ing a heat-hardened binder, such as a p enolic l, condensation product.

It is among the objects of this invention to.

-provide a bond between two or. 'more of molded articles which shall be mechanically strong 4and Adurable and electrically vellicient' a and which shall be "of the saine general physical characteristics as the' articles joined.

Another object of this invention is to provide a method of joining molded articles which shall beV simple `to r'actice, which shall iishall be adapted to yHeretofore, it has been-customary to join composite articles comprisin fibrous matel0 rial and a heat-'hardened bin er b insertin `such molded'members in a 'suitab e mold o the saine lcontour and shape as the articles to be joined, roughening their surfaces where it is desired to eect a bond, -coating said I surfaces with a liquid binder having the characteristic of hardening under heat and pressure, such as a phenohc condensation product, inserting'the mold between a pair of heated platens of a hydraulic'press and i0 applying heat and lpressure thereto to form an integral structure. My invention is an improvement over this process in that my method does not I elu re the use of la mold which has been consi ered 8,5 as necessa tojprevent blistering and dis-v tortion of e surface layers. I have found that, by employinv relatively low temperatures, as compar with the temperatures l used-instandard practice, I am able to effect .I0 a bond between two or -more 'molded memberswighout causing distortion or blistering thereof. l In the accom anyin'g drawing constituting a part hereo and in which'li e reference Figure 1 is an exploded view oftwo layers of molded sheet material;

Fi .'2 is a side elevationalview-showing the a ers of 1 joined in accordance 60 with t is invention;

Fig. 3 is an loded view showin avpair l of'she'ets of mol ed material and a p urality of strips -of like material; Fig. lis aside elevational viewshowing the strips and sheets of Fig. 3 joined by molding;

Fig., 5 is a to structure having si and p 6 is a side elevational view thereof.

plan vvie-w of la similar agonally', disposed strips;

teit is desired to jona plurality'of molded plates `1 and 2 comprising a plurality o f la ers of fibrous sheet material consolidat b a heat-hardened binder, I roughen the sur aces 3 by means of sandpaper or by any foth'er suitable means, apply a coating -of a solution of a phenolic condensation product thereto, join the two pieceswith their coated surfaces `in enga ement and in- -sei'tjthe'm between a pair of cated platens of a hydraulic press. A temperature of approximately125 C. and a pressure of approximately one-helften er square inch of engaging surfacef are applied thereto fora suilicient length of time to ermit the binder to cure, the article being t en cooled inthe press and removed. y

This much of the process 'diers fromthe method heretofore employed in that a lower temperature is utilized' which produces a more eiicient bond or joint, and where it is desired to join a plurality of strips 4 and layers v5 Vand 6 (Fig. 3), my process will prevent those parts '7 and 8 of the surfaoesof, the plates and strips, respectively, which Aand pressure are appliedwithin the limits enumerated above-t0 consolidate the bled membersl and form an integral v struc- ".ture. l

Ihave found that, by employing a strip of fibrous sheet material impregnated with a phenolic condensation product between the members to be joined, instead of the varnish,

a mechanically stronger joint can be pro :duced but this is not essential excepting {wher-'e strength is the main factor. l They process of molding is the same as thatem- 85 are not-in-contact with the pressure latens, i'

I ployed for the and the resulting product is equivalent in strength and physical characteristics to one formed of a molded compotion or laminated material. It will be noted that the layers to be joined ma'be coated with the hinder in several ways. he

. binder may be applied as a varnish and the solvent removed; or a sheet of material may be im regnated with a solution of the bmder and t e solvent removed, and the impregnated sheet may be then applied as a coating between the layers to be joined; or solid binder or compositions inc uding the same may be placed therebetween to provide the Figs. and 6 illustrate an article formed in the above specified manner which is cut into strips and commonly employed as ventilatin strips in transformer construction. It is o vious that a structure of this type can not be manufactured in a practical and economical manner excepting by the method lherein described, as, bythe old process, 1t

would be essential to insert metal strips between the molded strips while'molding them together to prevent blistering and distortion of the material, whereas, by my process, this as the forming of ventilating strips and blood glue, or the like. "adapted to join articles of various shapes ving heat and pressure t general insulating materials having a structural body shape to provide the requislte strength and surface contour.

Although I `have described a specific embodimentof my invention, it will be obvious to those skilled in that art that various modifications may be made in the details of my mcgsawithout departing from the principles ereln set forth. For instance, my method is adapted to join sheets and strips of liber, wood and `similar materials, and the binder may be of any suitable type, such as casein, This process is also and contours and is not limited to flat-surface materials, as illustrated in t-he drawings. I claim as my invention: 1. A me/thod of joining molded articles which comprises roughening the surfaces to. be joined, placin on said rou hened `surfaces a binder w ich is adapte to harden under the iniuence of heat and pressure, inserting said articles in a press with their treated' surfacesin .enga ement and applyhereto to forman integral structure. v

2. A method of joining molded articles which comprises roughening the' surfaces to be joined, placing onsaid roughened surfaces a .phenolic `condensation product, in-

serting said varticles in ai press with their treated" surfaces in engagement and applying heat'and Epressure thereto to form an integral structure. I

3. Al method of joiningmolded articles which comprises roughening the surfaces to be joined, placing on said roughened surfaces a phenolic condensation product, inv serting said articles in a press with their treated surfaces in engagement and applying a relatively low temperature and a high pressure thereto.

4.-. A method of joining molded articles which comprises roughening the surfaces to be joined, placing on saidroughened surfaces a phenolic condensation product, in

`be joined, placing en said roughened surfaces a phenolic condensat-ion product, inserting said articles in a press with their treated surfaces in engagementv and applying a.- temperature ranging between and 125.'C. thereto. n

6.- A Vmethod of joining. molded articles Awhich comprises roughening the surfaces to be joined, placing on said roughened surfaces a phenolic condensation product, insertin said articles in a press with their treate surfaces in engagementand applyin a tem erature ranging between 100 and 125 and a pressure of approximately onehalf ton per square inch of molding surface thereto. 1

7. A method of joining molded articles which comprises roughening Vthe surfaces to be joined, interposmg a layer of fibrous sheet material im regnated with a binder between said roughened' surfaces, inserting said articles in a. press and ap lylng a relatively low temperature and a 'gh pressure thereto to form an integral structure.k

8. kA method of joining moldedl articles' which comprises roughening the surfaces to be joined, interposing a. layer of fibrous sheet material impregnated with a phenolic condensation product between said roughened surfaces, inserting said articles in a pressand applying a relatively low .temperature` and ahigh pressure theretoto form an integral structure.

, 9. A method of joining molded articles which comprises roughenlng the surfaces to^ be joined, interposin a la er of fibrous sheet material impregnate wit a binder between said roughened surfaces inserting said articles in a press and app ying a temperature which comprises roughening the surfaces to be joined, interposing a layer of fibrous sheet material impre tween said roughene surfaces, inserting said v articles in a press and applying a temperature ranging between 100 and 125 C. thereto to form an integral structure.

v11. A method of joining molded articles i which comprises roughening the surfaces to be joined, interposing a layer of fibrous sheet material impregnated with a binder between said roughened surfaces, inserting said articles in a ress and applying a temperature ranging etween and 125 C. and a pressure of approximately one-half ton per square inch of molding surfaces thereto to form an integral structure.

12. A method of joining a plurality of articlesof fibrous material consolidated by a heat-hardened binder which comprises roughening the surfaces to be joined, interposing a layer of fibrous sheet material impregnated with a binder between said roughened surfaces, insertin said articles in a press and a plying are atively low temperature and a ighpressure thereto to form an integral structure.

13. A method of joining a plurality of articles of fibrous sheet material consolidated by a heat-hardened binder which com rises roughening the surfaces to be joined, Interated with a binder beposing a layeriof fibrous 'sheet material im- 35 pregnated with a binder between said roughened surfaces, inserting said articles in a press and a plying a temperature below C. and a r atlvely high pressure thereto to form an integral structure.

14. A method of joining a lurality of articles of fibrous sheet materia and a phenolic condensation product which comprises roughening t-he surfaces to be joined, lnterposlng a layerbf fibrous sheet material imprenated with a binder between said roughene surfaces, inserting said articles in a press and applying ate'mperature below a relatively high pressure therel 125 C. and to to form an integral structure.

V15. In the art of joining .a plurality of strip-like members to a sheet-bke member,

jthe method which comprises disposing said strip-like members in spaced relation along said sheet-like member with adhesive material between adjacent surfaces thereof, and applying pressure to and elevating the temperature of said members while maintaining open spaces between said strip-like members.

16. In lthe art of joining a lurality 'of strip-like members to a sheet-l e member,

the method which comprises disposing .said

sheet-like member with binder-impregnated sheet material between adjacent vsurfaces thereof, and applying pressure to and elevating the temperature of said members.

FRANK H. TUPPER.

str ip-like members in spaced relation along sai

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