US568591A

US568591A - Francis samuel tomey

Info

Publication number: US568591A
Authority: US
Publication date: 1896-09-29
Anticipated expiration: 1913-09-29

Description

(Specimens.)

P. S. TOMBY.- MANUFACTURE OF THBYRMOMETBR TUBING.

wmvsssas. I I E iJ/ (M7 Maw 1 UNITE STATES FRANCIS SAMUEL TOME Y, OF BIRMINGHAM, ENGLAND.

MANUFACTURE OF I'HER'MOMETER-TUBING.

SPECIFICATION forming part of Letters Patent No. 568,591, dated September 29, 1896. Application filed August 3,1895- SeIial No. 558,109. (Specimens) To all whom it may concern:

Be it known that I, FRANCIS SAMUEL TO- MEY, glass-tube manufacturer, of 142 Victoria Road, Aston, Birmingham, in the county of Warwick, England, have invented a new and useful Improvement in the Manufacture of Thermometer-Tubing, of which the following is a full, clear, and exact description.

This invention relates to the manufacture of tubing for clinical, chemical, and other thermometers that are intended to have the graduations and figures of the thermometric scale etched upon the rear of the stem, so as to be visible when viewed through the stem, upon an enamel ground behind the bore. WVith this object in view it has long been desired to draw'the tube with a very thin external coating of enamel applied, preferably, upon a flat surface, which when the thermometer is finished would form the back of the stem and upon which surface the scale would be marked by etching through the enamel. A thermometric scale so produced would be practicallyindestructible, since, the divisions and figures being etched through the enamel, the scale would be visible even should all the black filling be removed by acids or by cleaning. It has not, however, been possible to produce commercially and by the ordinary methods of manufacture enameled thermometer-tubing suitable for the purpose of being so etched, owing to the impossibility of applying a sufficiently thin coating of enamel to so extended a surface as that of what is known in the trade as the piece. The ordinary method of applying the enamel is to gather the required quantity onto a pontil and fiatten it, then to warm it again at the pot-mouth, and while very hot to apply it in the required position but experience has heretofore shown that when the enamel has been flattened thin enough for the desired purpose it has invariably run into corrugations immediately upon being exposed to the heat preparatory to being applied to the required position on the piece, to which it never could be applied without air-blisters being left between itself and the flint metal and without such unevenness in thethickness of the coating of enamel as to cause it to break while being drawn out. Even were it found possible to apply a sufficiently thin coating of enamel to the piece and that the piece so coated were drawn out in the form of a thermometer-tube,

the thickness of the enamel has un avoidablybeen so variable as to render impossible the proper performance of the etching operation, inasmuch as it is not practically possible to obtain sufficient action of the acid to produce the required depth of etching on the parts where the enamel is thick and yet prevent excessive action of the acid where the enamel is thin.

Reference is to be had to the accompanying drawings, in which Figure 1 is a cross-sectional View of the piece; and Fig. 2 is a broken elevation, partly in section, of the furnace containing the enamel-pot and illustrating the manner of applying the enamel.

c is the piece, having a bore hand a flat face on which is applied the coating of enamel designated a.

In Fig. 2, c is the enamel-pot, located upon a suitable support cl and provided with an open neck 0, disposed toward an opening 6 in the wall 6 of the furnace. A scraper s is arranged in the mouth of the enamel-pot, said scraper being beveled to a true knife-edge and is made smooth and polished after grind- 1n g.

To overcome the difficulties inherent to the above -described usual process of making thermometer-tubing, I blow the ball and form the bore in the usual way, omitting, however, the enamel. I then cover the ball with metal to the required thickness and marver it to a cylindrical form. Then, having reheated it, I carefully flatten the back of the piece a upon a marver or other suitable surface. I then dip the piece carefully into the fluid enamel f, contained in the pot 0, taking especial care to prevent contact of the enamel with any but just the flattened surface of the piece, and having allowed the enamel to drain oif I carefully draw the fiat surface of the piece over the knife or scraper s (fixed in the mouth 0' of the enamel-pot) before the enamel on the piece has had time to become chilled in the slightest degree. All the superfluous enamel is thus removed from the coated flat side of the piece, the enamel coating being left in the form of a perfectly flat film of absolutely uniform thickness and free from blisters. The piece is then marvered and heated and drawn out into the form of thermometer-tubing in the usual way.

It is to be observed that the enamelin which the piece is thus dipped must be very hot and as fluid as possible and must be of such a composition that its coefficient of contraction and expansion under variations of temperature will be the same as that of the flint metal of which the piece is made.

I claim- The hereiu-described method of manufacturing enameled tubing for thermometers which are to have the scale etched through the enamel, which method consists in form In presence of- JAMES OLEWs, JOsEPI-I BENJAMIN FREEMAN.