US2584786A - Method for providing timepieces with spiral-helix hairsprings - Google Patents

Description

Feb. 5, 1952 L R. BURGHOFF METHOD FR PROVIDING TIMEPIECES WITH SPIRAL-HELIX HAIRS Filed May 4, 1948 PRINGS Atforrzeys Patented Feb. 5, 1952 METHOD FOR PROVIDING TIMEPIECES WITH SPIRAL-HELIX HAIRSPRINGS Louis B. Burghofi, Forestville, 001111., assignor to The E. Ingraham Company, Bristol, Conn., a corporation of Connecticut Application May 4, 1948, Serial No. 25,055

The present invention relates to improvements in the art of manufacturing escapement timepieces such, for instance, as spring-driven clocks and watches, and relates more particularly to methods for providing escapement timepieces with spiral-helix hairsprings.

Most escapement timepieces as heretofore produced have employed spiral hairsprings each of which has had its convolutions arranged in sub- 'stantially a common plane. Other escapement timepieces have also been proposed in which a given hairspring has had certain portions displaced out of the usual common plane but such constructions have been expensive to produce and have not been otherwise fully satisfactory.

One of the main objects of the present invention is to provide a superior method whereby escapement timepieces may be provided with spiral-helix hairsprings at low cost.

Another object of the present invention is to With the above and other objects in view, as I will appear to those skilled in the art from the present disclosure, this invention includes all features'in the said disclosure which are novel over the prior art.

In the accompanying drawings, in which cer- 1 tain modes of carrying out the presentinvention are shown for illustrative purposes:

Fig. 1 is a. broken face view of a clock movement showing a hairspring installed therein in ordinary spiral form, and prior to being converted into combined spiral-helix form in accordance with the present invention;

.xFig. 2. is. an edge view thereof;

Fig. 3 is a view similar to Fig. 2 but showing the displacement of the inner portion of the hairspring relative to its outer portion, to thereby convert the said hairspring into spiral-helix form; I 1 Fig. 4 is. a broken sectional view on an enlarged scale taken on the line 4-4 of Fig. 3 but with some of the outer convolutions of the hairspring left in elevation;

Fig. 5 is a broken view similar to Fig. 2 and showing another mode of carrying out the in- 1 Claim. (Cl. 229-177) vention, with the hairspring shown prior to having its outer end displaced with respect to its inner end; and

Fig. 6 is a view similar to Fig. 5 but showing the anchoring-stud forced inwardly to convert the hairspring into spiral-helix form.

The showing of Figs. 1 to 4 inclusive In Figs. 1 to 4 inclusive is illustrated in a fragmental manner, a clock movement which comprises two complemental movement-plates i0 and H which are held in spaced relationship by means of a suitable number of pillars [2. The said parts may be regarded as a frame.

Extending inwardly through the movementplate It is a bearing-stud l3 and similarly extending inwardly through the complemental movement-plate II is a bearing-stud [4, both of which are in axial alignment. Supported for oscillation at its respective opposite ends in the bearing-studs l3 and I4 is a balance-staff 1-5 upon which is rigidly mounted a usual balance wheel Mounted upon the balance-staff [5 above referred to at a point intermediate the balance wheel 16 and the movement-plate I0, is a collet I! which is rigid on the said balance-staff for all normal operating strains which may be axially moved on the said balance-staff for purposes as will hereinafter appear. The said collet may be regarded as an inner fastening-member for reasons as will hereinafter appear.

Fastened in any suitable manner to the collet l I is the inner end of a hairspring I8 which has its outer end passed through an aperture l9 formed in an anchoring-stud 20 which acts as an outer fastening-member. The outer end of the hairspring is fixedly mounted in the aperture [9 in any suitable manner such, for instance, as by means of a wedge-like retaining-pin 2| driven into said aperture.

The anchoring-stud 20 above referred to extends inwardly through the movement-plate' l0 and is rigidly secured thereto in any suitable manner such, for instance, as by staking the said anchoring-stud as at 22.

Mounted for turning movement on the bearing-stud l3 and against the outer face of the movement-plate In is a regulating-lever 23 which is provided with an aperture 24 through which the outer portion of the hairspring l-B extends, in a manner common in the art.

It may here be explained that it is customary to set hairsprings such as [8 in a simple spiral form prior to installation in a timepiece. In Figs. 1 and 2, the hairspring I8 is shown as so installed.

Following the assembly of the hairspring with the remaining parts described as above, a suitable tool schematically indicated by the broken lines 25 in Fig. 2, may be inserted between the inner face of the movement-plate l and the opposing face of the collet ll. After such insertion, the said tool may be forced toward the balance wheel Hi, to thereby shift the collet I! toward the balance wheel |C-, into substantially the position in which it is indicated in Fig. 3. In the manner just described, the hairspring i8 or its equivalent is converted into a compound spiralhelix form, which form has many advantages.

The unit comprising the parts I 5, l6, l1 and !8 maybe tested for timing, either while in the conditions illustrated in Figs. 1 and 2, or when in the conditions illustrated in Figs. 3 and 4.

The showing of Figs. 5 and 6 The parts shown in Figs. 5 and 6 correspond to the parts shown in the preceding figures and bear like reference characters with the exception that the anchoring-stud previously described is replaced by an anchoring-stud generally designated by the reference character 26. The said anchoring-stud is generally of T-shaped form and includes a head 21 and a stem or leg 28. The stem or leg 28 just referred to is adapted to tightly extend through a passage 29 in the movement-plate ID with a force fit.

The leg 28 of the anchoring-stud 26 is provided with an aperture 30 adapted to receive the outer end of the hairspring l6 and in which the latter may be secured by means of a retaining- Pin 3 I.

In its initial condition, a is indicated in Fig. 5, the anchoring-stud is only partl forced through the passage 29 in the movement-plate l9, and the outer end of the hairspring I8 is secured to the said anchoring-stud by the retainins-p n Following the assembly of the parts into the relationships in which they are shown in Fig. 5, the anchoring-stud may be forced further inwardly through the passage 29 in the movementplate 10, to bring its head 2'! into seated engagement with the outer face of the said movementplate, in the manner indicated in Fig. 6. The described movement of the anchoring-stud will convert the nominally spiral form of the hairspring into the compound spiral-helix form shown in Fig. 6.

If desired the anchoring-stud 26 may be forced only slightly inwardly toward the position in which it is shown in Fig. 6, and the collet i"! may be shifted slightly in the opposite direction to thus impart the desired spiral-helix form to the hairspring.

Rsum

From the foregoing, it will be apparent that by first installing an ordinary spiral hairspring in a standard manner in a time-movement, the said ordinary hairspring may be converted into spiral-helix form and in simple and inexpensive manner, to thus obtain the advantages inherent in the said spiral-helix form.

The hairspring in the spiral-helix form serves to not only minimize the clashing of its convolutions in the event of over-banking, but also minimizes the effect of magnetism, should the hairspringbecome magnetized.

By means of the present invention, it is possible to make use of slightly defective hairsprings and hairspring-and-collet assemblies without any harmful effect upon the timekeeping properties of the clock or Watch in which such hairsprings or assemblies may be installed.

Thus, should a hairspring have one or more of its convolutions slightly deflected out of a common plane with the remaining convolutions, or should it be imperfectly mounted upon a collet so as to tilt with respect thereto, the said defects lose their significance in most instances, when, in accordance with the present invention, the hairspring is converted from a simple spiral form into the compound spiral-helix form shown and described.

As distinguished from a preformed helical hairspring, due to the fact that the hairspring of the invention is axially resiliently expanded in its final helix-like disposition, the latter is prevented from setting up adversely effective constantly-reversing axial thrust in the balance staff, and instead sets up a. slightl varying substantially uni-directional thrust in the staff, whereby wear of the bearing surfaces is kept at a minimum.

It will be noted by reference to the drawings, that the pitch in axial direction of the outer convolutions of the hairspring after the same has een forced into the combined spiral-helix form, is preferably in excess of the width of the hairspring itself.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present em.- bodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claim are intended to be embraced therein.

I claim:

The method of providing an escapement timepiece with a spiral-helix hairspring, comprising the steps of securing the inner and outer ends of a flat spiral hairspring to anchor members on a balance-staff and on the frame, respectively, of the timepiece without substantially axially distorting the spring; and subsequently deliberately shifting at least one of said anchor members away from the other anchor member axially of said staff, into its permanent disposition, through such a distance that said spring is axially resiliently expanded into helical disposition to such an extent that said spring will exert a substantially uni-directional thrust only on said balancestaff when the timepiece is running.

LOUIS R. BURGHOFF.

REFERENCES CITED The following references are of record in the file of this patent:

I UNITED STATES PATENTS Number

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