US2475431A - Method of making tapered ground joints - Google Patents

Description

`July 5, 1949- w. o. LUERTZING 2,475,431

METHOD OF MAKING TAPERED GROUND JOINTS Filed Feb. 28, 1948 1N ENTOR ATTORNEYS Patented July 5, 1949 METHOD F MAKING TAPERED GROUND JOINTS Walter 0. Luertzing, Vineland, N. J., assignor to Lurex Manufacturing Company,

Vineland,

N. J., a corporation of New Jersey Application February 28, 1948, Serial No. 12,073

11 Claims.

This invention relates to the manufacture of glassware for chemical and like use and is concerned more particularly with a novel method of forming on a glass article a circumferential enlargement of tapering diameter which is receivable in a tapered socket to make a sealed joint of the plug and socket type. The method of the invention may be utilized in making articles of various kinds and may be employed to especial advantage in the manufacture of thermometers for use in chemical apparatus. The application of the new method in connection with the production of thermometers will, accordingly, be illustrated and described in detail for purposes of explanation, although it will be apparent that the utility of the method is not restricted to that specific use.

It is now common practice to construct thermometers, which are to be mounted in an opening in the wall of a vessel forming part of chemical apparatus, with a circumferential enlargement of plug form and having a ground outer surface of tapering diameter. The vessel is then made with a socket having a ground surface or corresponding taper and, when the thermometer is seated in the socket, the ground surfaces make a tightly sealed joint. Heretofore, the enlargement on the thermometer has been made by heating the thermometer stem between its ends with a flame and then slowly and carefully forcing the ends of the stem toward one another to force the softened glass outwardly to increase the outer diameter of the stem. The operation is carried on along the stem, until an enlargement of suitable diameter and length has been made, and it must be performed with great skill and attention, in order to avoid closure or distortion of the small passage through the stem. Because of the delicacy and skill required in the operation and the time consumed, the production of such thermometers is not only expensive but also most trying to the glass workers.

The present invention is directed to the provision of a method for making an enlargement on a glass article, such as a thermometer, which is relatively easy to perform, can be carried out rapidly, and is not likely to cause injury to the article, even though performed with only a modcrate degree of skill. In the practice of the new method, a length of glass tubing is telescoped over the article and then secured thereto at the place, where the enlargement is desired, so that it forms an integral part of the article. The attaching of the tube to the article is effected by operations requiring a minimum distortion of the article and, after the tube is in place, its outer surface can be finished by the usual operations.

For a better understanding of the invention, reference may be made to the accompanying drawings, in which Fig. 1 is a view in side elevation of a thermometer, the stem of which has been provided with. an enlargement of plug form by the practice of.- the new method;

Fig. 2 is a View in side elevation of a portion of' the stem of the thermometer and illustrates therst step in the practice of the method;

Figs. 3 and 4 are longitudinal sectional views; through the stem of the thermometer and illustrate subsequent successive steps in the method;

Fig. 5 is a longitudinal sectional view through the stem of the thermometer on which an enlargement has been formed by the method;

Fig. 6 is a longitudinal sectional view through the stem of the thermometer showing the enlargement in its final form;

Fig. 7 is a view similar to Fig. 3 but showing a step in a modified form of the method; and

Fig. 8 is a longitudinal sectional view of the final form of the thermometer stem and enlargement made by the method involving the operation of Fig. '7.

The thermometer shown in Fig. 1 has the usual glass stem I U terminating at one end in a bulb i l and formed with a capillary tube I2 leading from the bulb to the other end of the stem. Between its ends, and preferably nearer the bulb end, the stem is formed with an enlargement i3, which has an external ground surface of tapering diameter, so that the enlargement can be seated in a corresponding ground tapered socket to make a tight sealed joint.

In the production of the thermometer shown in Fig. l by the method of the invention, the stem is first heated over narrow circumferential areas Hl, l5 spaced apart a distance corresponding to the length of the enlargement to be made. The areas are heated separately by a flame and, when the glass in an area is softened, the ends of the stem are forced toward one another to cause the softened glass to bulge outwardly. Small similar circumferential collars Illa, IEa are thus formed and, since the external diameter of the collars is not substantially greater than that of the stem, the collars can be readily made without distortion of the passage I2.

When the collars have been completed, a length of straight glass tubing I6 of uniform diameter and wall thickness and sufliciently long to span the distance between the collars is slipped.

"which the interior `of'theftubing is'evacuated vand 3 over the stem and collars. The tubing preferably has an internal diameter not substantially greater than the external diameter of the collars and the wall thickness of the tubing is such as to provide the necessary amount of glass to make the enlargement. When the tubing has been placed in positiony'a flame, indica-ted'at Il, `is applied to-the'l tubing outside one collar, forfxample, the collar Illa, and, as the tubing is heated, the stem and tubing are rotated and the glass'f the tubing softens and seals to thevoutersurface of the collar at its plane of 'greatestdiameten A hose I8 is then telescoped over the stem and the end of the tubing i6 remote from-"collar"` Ma. "The hose is connected to a Vacuum*flpumpllandftvith the pump operating, the flame is applied"'to"the outer surface of the tubingc-ad-jacent-collarMa and the tubing is progressivel;7` heated toward collar Ia. As the tubing softens, it is collapsed against the surface ofthe stem by the vacuum fand adheres'to thestem, untilrlally thetubing :is attached tothercutersurface of the stemfbe- Itween the .planes of isgreat'estdiameter Iof the t collars.

The hose I3 is 4then disconnectedfrom'the and removed. Any sharp edgesa'longthe-lines of fracture may be smoothed? by means of ythe-llame. 1 "The length? of "tubing thatl has' thus'been attached to the outside/of the stemis-substantally vof-fthe .-'rshapeof 'the enlargement i9. Thereafter, the enlargement `is finished by grinding itsouter` surface-2 to the fdesirediinal'ftaperingfdiameterlandil .f preferably, *the `vsurface T42 I connecting the'flarge `end of the 'ground-fsiirfacewith fthe outerv surface of the'stem is `given alightflnishinggrind.

In the modi-lied? 4form ofi the-method illustrated -in Figs. Tand-B, thestemt-ofithefthermometer'is" heated as before at spacedpoints tof formcollars end of the enlargement, isffof-l somewhat greater size than collar22. After formation'ofi the'icollars, -a lengthbf-glass-tubing-24 of atslightly' .greater length than the'distance betweenthe Icollars is slipped over the stem of theltherinometer. VThe inner diameter Yof 'the' tubing is fnot subfstantially greaterthantlie-'outer diameter of' col- `will telescope overcollarfilS. eAf'tel'rthe tubingfis `in place, the flared-'e-ndfis heated-until itisoftens I andseals to the` outer surfaceof ycol-lar f23, after heated to cause'the tubing-to collapse and adhere to the surface of the stem of -thethermometer between the` planes yof" greatest-diameter' of l the collars. When thetubing-hasthusbeen 7attached to the stern,` thefree endbf'the vtubing ibeyond collar 22 is broken off and thelstemis thus formed `with an enlargement,` which can lbel-groundfJtothe Y final tapered formshownatit. The-ground surface lies approximately Vtangent to-Ythe surfacejfof the `large collar-ZB-and, asl-the surfacefZSf ofthe' collar is smooth, vit-doesl not require* any-finish #grinding With the method -described,.thefstem-of the article is' subjected `to* only. 'minor -1 distortion` l-to form the spaced collarsf-atfopposite endscf-theenlargement and, in the case-cfathermometer,

lthe collars can rbe-rea'dily formed without-distor- 4tion of the capillaryftube. Themse?oftheh'length of tubing makes the provisionV of 'the Anecessary body of .glass V-to form the f plug enlargement onv an 'fen'lar'genient receivable; iny a :groundsocket to make a tight joint, the steps of heating the artifcle over narrow circumferential areas to soften it and forcing its ends together to form circum- Aferei'itial collars at spaced points, telescoping a length of glass tubing over the article, the tubing extending from-'onecollar to the other, heating `$1.5'ithetubi'ng tol-soften it, and, while the tubing is being' heated, evacuating its interior to cause it to be drawn inwardly to adhere to the article.

2. lIn a method of forming a glass article with @anenlargement receivable in a ground socket to make a tight joint, the steps of heating the article over l narrow ycircumferential areas to soften it an-d f forcing its endsA together toform circuml ferential collars at spaced points; telescoping: over `the-article and collars a-lengthof glass tubing Q5 eXtendingvfr-omone collar-to the othergheating the tubing adjacent one collar to cause the tubl ing' to'vadhere to the collar-entirely -around ythe latter; evacuating the interiorof :the tubing betweenthe collars, and heating the 'tubing uprogressively from the collar,'to-w-hich= the tubing'is VVconnected, to the other collar to'softenthe tubing, until the vacuum within the -tubing draws it into contact with thearticle.

-3. In -a method of forming a'glassv article with I an enlargement receivable Yin -a ground: socket to make'a tight ljoiI-1t,vthe`A steps -ofheating the article over narrow circumferential areasto'soften it andY forcing its endsftogether to4v form circumferentiall collarsat spaced points, ,telesccping a 40 lengthA ofglass tubing over thel articleto enclose the collars-and` the-portion ofl-the'article between them, heating the' tubing at one collar untill the tubing `softens and becomessealed t0 the surface ofthe collar,rconnectingtheend ofthe tubing adjacent-the second collar to a sourcelofvacuum, progressively heating the v tubing from lthefirst coll-ar -to Ythe second, -until'the Ytubingcollapses against the surface 'oflthearticle andy adheres thereto, and breakingoffffree portions of "the vtubing beyondthecollars.

4. In'a-` method of forming-a glass articlewith an .enlargement receivable in# aground socket to :make a tightjoint,l thesteps of heating the article over -narrow circumferential areas to soften -it -and forcing itsends togethento form collars'lof approximately the same external'- diameter at fspaced poin-ts-,telescopi-nga-length'of glass tubing of substantially-uniform internal diameter and Wall thickness overf--the articleand f collars, heatingf the tubingad-jacent one-collar tocause the tion is continui-ng tubing -to adhereto :thearticlei entirely' around the latter, evacuating thef-interiorof the tubing from its connection -to -thecollarcthrough the opposite Iend `of the tubing;ar1d,-while the evacua- -progressivelyfheating'the tub- 1 ingfrom its yconnection'to said vcollar to the-'other collar,` until the tubi-ng" collapsesandf adheres to the -article atand between the-collars.

5.- In a methodfofforminga glass article -vwith 7o-1an enlargement4 receivable lin aground socket-to make a tight-joint, the steps of hea-tingl thefarticle i over narrow-=circum-ferential areasto 'sof'tenh-it and-forcing its ends together -to form -circumferential 'collars'atv-spaced points', one of the' co1- larsbeingy of i larger-external-diameterthanthe other, telescoping a piece of glass tubing with a flared end over the article, the flared end overlying the large collar and the tubing extending past the small collar, heating the tubing at the liared end until the tubing adheres to the outer surface of the large collar, evacuating the tubing through the opposite end, and, while the evacuation is continuing, progressively heating the tubing from the large collar toward the small collar, until the tubing collapses against the other surface of the article and adheres thereto between and at the collars.

6. A method of forming a glass article with an enlargement receivable in a ground tapered socket to make a tight joint, which comprises heating the article to soften it over narrow circumferential areas and forcing its ends together to form circumferential collars at spaced points, telescoping a length of glass tubing over the article, the tubing extending from one collar to the other, evacuating the interior of the tubing, heating the tubing, while the evacuation is continuing, to cause the tubing to collapse and adhere to the article between and at the collars, and grinding the outer surface of the tubing to a tapering diameter.

7. A method of forming a glass article with an enlargement receivable in a ground tapered socket to make a tight joint, which comprises heating the article to soften it over narrow circumferential areas and forcing its ends together to form circumferential collars at spaced points, telescoping a length of glass tubing over the article, the tubing extending from one collar to the other, evacuating the interior of the tubing,

heating the tubing, while the evacuation is continuing, to cause the tubing to collapse and adhere to the article between and at the collars, cutting off `the tubing at the collars, and grinding the outer surface of the tubing to a tapering diameter.

8. A method of forming a glass article with an enlargement receivable in a ground tapered socket to make a tight joint, which comprises heating the article to soften it over narrow circumferential areas and forcing its ends together to form circumferential collars at spaced points, telescoping a length of glass tubing over the article, the tubing extending from one collar to the other, evacuating the interior of the tubing, heating the tubing, while the evacuation is continuing, to cause the tubing to collapse and adhere to the article between and at the collars, cutting off the tubing at the collars, grinding the outer surface of the tubing to a tapering diameter, and grinding the surface connecting the surface of the article with the large end of the tapered surface.

9. A method of forming a glass article with an enlargement receivable in a ground tapered socket to make a tight joint, which comprises heating the article over narrow circumferential areas to soften it and forcing its ends together to form circumferential collars at spaced points,

one collar being larger than the other, flaring one end of a straight piece of glass tubing having an internal diameter not substantially greater than the external diameter of the small collar, so that the flared end will receive the large collar, telescoping the piece of tubing over the article with the flared end receiving the large collar and the small collar lying within the portion of the tubing of uniform diameter, sealing the flared end of the tube to the surface of the large collar, evacuating the interior of the tubing, progressively heating the tubing from the seal at the large collar toward the small collar, while the evacuation continues, to cause the tubing to collapse and adhere to the surface of the article and the small collar, and grinding the outer surface of the tubing to a diameter tapering toward the small collar.

10. A method of forming a glass article with an enlargement receivable in a ground tapered socket to make a tight joint, which comprises heating the article over narrow circumferential areas to soften it and forcing its ends together to form circumferential collars at spaced points, one collar being larger than the other, flaring one end of a straight piece of glass tubing having an internal diameter not substantially greater than the external diameter of the small collar, so that the flared end will receive the large collar, telescoping the piece of tubing over the article with the flared end receiving the large collar and the small collar lying within the portion of the tubing of uniform diameter, sealing the flared end of the tube to the surface of the large collar, evacuating the interior of the tubing, progressively heating the tubing from the seal at the large collar toward the small collar, while the evacuation continues, to cause the tubing to collapse and adhere to the surface of the article and the small collar, cutting off the free end of the tubing beyond the small collar, and grinding the outer surface of the tubing to a diameter tapering toward the small collar.

11. In a method of forming a glass-stemmed thermometer with an enlargement of plug form receivable in a ground socket to make a tight joint, the steps of heating the stem of the thermometer over narrow circumferential areas to soften it and slowly forcing the ends of the stem together to form circumferential collars at spaced points without substantial distortion of the capillary tube through the stem, telescoping a length of glass tubing over the stem, the tubing extending from one collar to the other, heating the tubing to soften it, while evacuating the interior of the tubing to cause it to collapse and adhere to the surface of the stem, cutting off the tubing at the collars, and grinding the external surface of the tubing to a diameter tapering toward the bulb end of the thermometer.

WALTER O. LU'ERTZING.

No=references cited.

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