Title:
Cylindrical hairspring form
United States Patent 2457631


Abstract:
This invenition relates to an apparatus for fotdhilng 'hairsprings for marine chronometers or siitilat'timepieces. Th obýect 'of the t present'invention is to provide a fermn:on-which an untreated wire can be wound and fromn which the heattreated wire may be'removed without in'any way bending...



Inventors:
Bennett Jr., William Ogle
Application Number:
US50339843A
Publication Date:
12/28/1948
Filing Date:
09/22/1943
Assignee:
HAMILTON WATCH CO
Primary Class:
Other Classes:
29/896.9, 968/701
International Classes:
G04D3/00
View Patent Images:
US Patent References:
2306925Electrode and its fabrication1942-12-29
2236907Hairspring bending apparatus1941-04-01
2236206Art of spring manufacture1941-03-25
2142865Method of manufacturing filaments1939-01-03
1928727Method of treating wire1933-10-03
1483985Method of making spiral coils1924-02-19
1215775N/A1917-02-13
0477525N/A1892-06-21
0109826N/A1870-12-06
0025294N/A1859-08-30



Description:

This invenition relates to an apparatus for fotdhilng 'hairsprings for marine chronometers or siitilat'timepieces.

Th obýect 'of the t present'invention is to provide a fermn:on-which an untreated wire can be wound and fromn which the heattreated wire may be'removed without in'any way bending or stressing the ecoils of'thVe treated spring. Iri'-high grade mairie-chronometers and timepiecs -of a similar nattire where there: is need f6or'avery unritshal-degree of accuracy, the slightestt ltik; bend' or strain which causes internal stresses 'in the metal will affect the timing, particularly whet-in:i the metal :of the hairspring.

Thfs -spring' is -generally- made in the form of a flat spiral for most timepieces but for the more accurate instruments such as'chronometers it has been found-advantageous:to, iake-the hairspring in the form of a cylinder. In lmakidiga cylindrical hairspring it is- necessary that -each end be inturned to reach the positffon of tthd barance staff and blance cock to which'they are fastened.

As'hairsprihgs are made by winding untreated wite on ,a-'fbrm; heat treating the wire while on thforinm, and removing -the wire -from the form it'became' necessary to providd@a form' which a cylindrital- hairspring-with its initutned ends could be removed' without in-any' why straining the treated wire. It is the purp6se of the present inVention-to '-provide an -appjaratts upon' which th1 -cylindrical -shaped 'hairspriing- formnied with intutned end-'could-be-fastene@d heat treated and removed without bending or distorting any part of the spring.

It is a further object of the invention to produce a spring which requires no cold working.

It is a further object of the present invention to provide a form which may be used repeatedly.

It is a further object of the present invention to provide a form made up of a number of sections which interfitted together provide the complete form and which may be removed separately without distorting the finished product.

It is a still further object of the present invention to provide a form which insures the correct curves for the ends of the hairspring.

The invention is illustrated in the accompanying drawing in which: Fig. 1 is a front elevation of the assembled form.

Fig. 2 is an end view of the form.

Fig. 3 is a perspective showing the removal of the sections of the form from the completed spring.

Fig. 4 is a view of the alignment pin.

Fig. 5 is a view of the arbor.

Fig. 6-is a view of the endcap.

Figs; 7 through 20-areviews of theseveral sections, making -up the form.

Fig .-21 is a-view of the wedge pin.

In' the drawings -an arbor' IF provided with an anaular shoulder 2, central section 3; a threaded section 4- suipports a series' of discs which, when assbembled; pr6vide- a- form 5 having a helical gufideway ,6--or-the- reception of-a: spring 7. The:forni :5is made up:;of- sections 8, 9, 10;i I', 12, 13,2 1 i15;,6 1, 1, 8,.19, 20 and 21 all of which ari-formed-vith-.a- central hole 22 to' receive the' central' section 3-of the arbor I. All of theý discs except the two'efind'iscs'8-and'21 areformed-with anýaligning--hrle,2 ,aidd-al threaded opening 24.

Theidisc sections91 0;'l.;I'; 17, 198, l9Sand-20-are also formed:' with a hold tdo'receive a wedge pin' 25. A-capbnut:26firinmlIyholds all,-of these- discs on the central section,' 3obfthe arbor I. In' assembling'the form, 5 the- end of the arbor I is clamped inma vice with the section 8 :abutting' the shbulder :2:recivegsection'9; the cut-out portion 2t;fitting the'end'section 8. The disc section 10 is now applied' to-the ceiter section- 3,'the holes 23 being aligned and the pin 28 inserted' in holes 23. In turn, each of the sedtions ae: mounted oiittthe'central' section 3,'the'correct angular position- being--determined 'by: the''respective relations of 'the hold 23 in the successive discs. The end-section 2 t isfi'ed i a depression'fi.the-disc 20'similar to ddpression 27i ri the-disc 9,and the cap:'lnUt 26 'screwed' firmly:in- place:r The form is: then ready to receive the soft wire used to form the hairspring.

The form 5 is removed from the vice inserted in a chuck which is not shown as it forms no part of the invention other than to provide a convenient means for turning the form. Turning of the form 5 wraps the wire 7 around the form following the spiral 6, the initial holding of the spring wire 7 being made by fitting the wire in the groove 33 formed between the end section 8 and the cut out portion 27 of section 9, the wire being wedged against the edge 29 by the wedging pin 2-5 in the hole 30. A pin 31 mounted at the point where the wire makes a sharp bend prevents any buckling or backing up of the wire at the time the wedge pin is driven in. This, of course, is not important in initially securing the wire but after the spring has been wound the importance of preventing any slack in the wound wire while securing the loose end cannot be stressed too strongly. After having been wound on the form 5, the loose end of the spring is secured in a manner similar to the first fastening by a wedge pin 25 used against the side of disc 21 in a manner similar to that previously described. The wound wire is then given the necessary heat treatment, cooled and ready for removal of the form 5 from the completed spring.

It is necessary that the removal of the form be accomplished without in any way cold working either by forcing or bending the spring wire, although a small movement of the spring which does not produce a permanent distortion will not affect its timekeeping qualities.

In the removal of the spring the form 5 is again held in a vice, the cap nut 4 unscrewed and the central arbor I removed. With the removal of the arbor the openings 23 are exposed and the aligning pin 28 may be driven out. The device is then removed from a vice by means of a jack screw 32, having a threaded end which fits the threaded opening 24, the discs are separated and removed one at a time. The relation of the successive discs are such that no two successive threaded holes are aligned and the tool 32 having a threaded portion greater than the thickness of any one disc will, on being threaded into the opening of any disc, bear against the metal of the sucessive disc and gently separate the successive discs one at a time. It is then possible to spread the coils of the finished spring slightly so that these thin discs may be passed between the coils as shown in Fig. 3, as it is impossible to slide the spring off the form or the form from the spring because of the preformed inturned ends. In this way the spring 7 is removed from the form 5 by having the form removed from the spring a section at a time. It is thereby possible to produce a spring in which the convolutions have not been disturbed and in which there is no internal stress or strain which has always been present in hairsprings of this type. Such a spring has produced a notable increase in the timekeeping qualities of the more accurate instruments such as marine chronometers and has materially lessened the job of assembling the hairsprings which formerly had to be bent by hand to the correct curve to fit the balance end.

What is claimed is: 1. A form for holding cylindrical hairsprings with preformed inturned ends during heat treatment comprising an arbor, a series of discs consisting of inner discs and end discs, said inner disc being substantially identical and said end disc being formed to receive the ends of the spring in a predetermined configuration, discs being adapted to be placed upon the arbor, means for aligning said discs in predetermined position, a spiral guideway formed by the periphery of said discs to receive a wire and means for anchoring the inturned ends of said wire at each end of the assembled discs.

2. A form for holding cylindrical hairsprings with preformed inturned ends during heat treatment comprising an arbor, a series of discs formed with a central opening receivable on said arbor, said series of discs including two end disc sections and a number of substantially identical intermediate sections, the periphery of the intermediate sections forming a spiral guideway to receive a wire, the two end sections formed to receive the ends of the wire in a predetermined manner, means for holding the discs in close relation and means for anchoring the ends of said wire. 3. A form for holding cylindrical hairsprings with preformed inturned ends during heat treatment comprising an arbor, an annular shoulder on said arbor, a series of discs each formed with a central opening, an aligning opening and a threaded opening positioned on said arbor each of said discs having a peripheral groove and together forming a cylinder having an external spiral guideway, to receive a wire, an alignment pin passing through the aligning holes and properly positioning said discs, wedge pins securing the ends of said wire and a jack screw fitting the threaded opening of the discs for removing said discs sucessively without: distortion of the wire subsequent to spring forming process.

WILLIAM OGLE BENNETT, JR.

REFERENCES CITED The following references are of record in the file of this patent: 40 UNITED STATES PATENTS Number 25,294 109,826 477,525 1,215,775 1,483,985 1,928,727 2,142,865 2,236,206 2,236,907 2,306,925 Name Date Weimer ---------- Aug. 30, 1859 Kline ------------- Dec. 6, 1870 Ferrell -- --- June 21, 1892 Campbell ---------- Feb. 13, 1917 Price .---. -----.. Feb. 19, 1924 Johnson ------- - Oct. 3, 1933 Zabel ------------ Jan. 3, 1939 Becker ----------- Mar. 25, 1941 Hoffsommer - ------. Apr. 1, 1941 Aicher --------- Dec. 29, 1942