US3236041A

US3236041A - Collet for fixing the inner end of a balance-spring of a timepiece

Info

Publication number: US3236041A
Application number: US415275A
Authority: US
Inventors: Marquis Amedee; Charpilloz Arnold
Original assignee: CHARPILLOZ
Current assignee: CHARPILLOZ
Priority date: 1963-12-17
Filing date: 1964-12-02
Publication date: 1966-02-22
Anticipated expiration: 1983-02-22
Also published as: CH1534163A4; GB1079497A; CH407881A

Description

Feb. 22, 1966 ARQU HAL 3,236,041

GOLLET FOR FIXING THE INNER END OF A BALANCE-SPRING OF A TIMEPIECE Filed Dec 2, 1964 United States Patent 3,236,041 COLLET FOR FIXING THE INNER END OF A BALANCE-SPRING OF A TIMEPIECE Arnde Marquis, Mervelier, Bern, and Arnold Charpilloz, Bevilard, Bern, Switzerland; said Marquis assignor to said Charpilloz Filed Dec. 2, 1964, Ser. No. 415,275 Claims priority, application Switzerland, Dec. 17, 1963, 15,341/ 63 6 Claims. (Cl. 58-115) The present invention relates to a collet for fixing the inner end of a balance-spring of a timepiece. This collet is characterized in that it comprises a cup and radially split ring, engaged in said cup, the cup having, from its bottom provided with a central hole, bores of increasing diameter and, in its side wall, at least a cut-out part extending over a portion of its height, the ring and the cup being arranged so as to form therebetween an annular chamber receiving a portion of the balance-spring, the inner bent end of which is hooked in the split of the ring, the ring having in addition a diametral groove in one of its faces, the diameters of said bores being such that the ring, when it is partially introduced into the cup, may be turned with an easy fit in the cup and that, when it is completely pushed, it is firmly held in position in the cup, while it may still be turned in order to adjust the active length of the balance-spring and the position of its point of attachment.

The accompanying drawing shows, by way of example, two embodiments of the invention.

FIGURE 1 is a diametral cross-sectional view of the first embodiment along the line II of FIGURE 2.

FIGURE 2 is a top plan view of same.

FIGURE 3 is a cross-sectional view of the second embodiment along the line III-III of FIGURE 4.

FIGURE 4 is a top plan view of same.

In the first embodiment (FIGS. 1 and 2), the reference numeral 1 denotes the outer cup of the collet. The cup 1 includes a bottom 2 provided with a central hole 3 and has three

coaxial bores

4, 5 and 6 of increasing diameter. The bore 4 has the shape of a circular groove which leaves a rib 7 between itself and the hole 3 of the bottom 2. The

bores

4, 5 and 6 are interconnected by surfaces inclined at 45.

Two grooves 8 extending along secants which are symmetrical and make between each other an acute angle, are provided in the wall 9 of the cup 1. These grooves 8 are partially cut by the

bores

5 and 6 of larger diameter. Instead of the two grooves 8, it would also be possible to provide a single wider groove, disposed only on one side of the cup 1.

The collet includes in addition an inner ring 10 adapted to cooperate with the cup 1. The ring 10 consists of a cylindrical body provided at its ends with two collars 11 and 12 and has in its centre a hole 13. The bottom corresponding to the collar 11 has a circular recess 14 the depth of which is slightly greater than the height of the rib 7 of the cup 1, the diameter of the recess 14 being slightly greater than the outer diameter of said rib 7. The outer diameters of the collars 11 and 12 are chosen in such a manner that the ring 10 may be inserted with an easy fit into the upper portion of the cup 1, the collar 11 being in contact with the intermediate bore 5 of the cup 1. The collars 11 and 12 have at their lower portion bevelled edges inclined at 45 corresponding to the abovementioned surfaces inclined at 45 interconnecting the

bores

4, 5 and 6 of the cup 1.

The ring 10 is radially split as at 15, the split being somewhat wider than the thickness of the balance-spring used. The ring 10 has in addition a diametral groove 16 provided in its top surface, said groove being adapted to receive a tool for turning the ring 10 within the cup 1. The space lying between the collars 11 and 12 forms a groove which defines, with the wall 9 of the cup 1, an annular chamber 17 adapted to receive the inner portion of the balance-spring 18, as explained later.

The fixing of the inner end of the balance-spring 18 to the collet as shown and described is made as follows:

The split ring 10 is partially introduced into the top portion of the cup 1, With the collar 11 engaging the bore 5, so that the split 15 faces one of the grooves 8. The choice of either of the grooves 8 will depend on the direction of Winding of the balance-spring 18. Then, the bent end of the balance-spring 18 is placed in the split 15 and the groove 8 so that the balance-spring 18 is at the level of the groove lying between the collars 11 and 12. Thereafter, by means of a suitable tool introduced into the groove 16, the ring 10 is turned in the Winding direction of the balance-spring 18, i.e. in the counterclockwise direction in FIG. 2, up to the position illustrated in FIG. 2, for instance, which corresponds to a rotation of about Then, the ring 10 is pushed completely into the cup 1, so that the collar 11 enters the bore 4 of the cup 1 and the collar 12 enters the bore 5; the diameters of the

bores

4 and 5 are slightly smaller than the diameters of the corresponding collars, so that the ring 10 is radially contracted and is firmly held in position in the cup 1. However, the ring 10 may still be turned by means of the above-mentioned tool. At this moment, the frequency of the oscillations of the sprung balance is compared with that of the oscillations of a calibrated reference sprung balance. If necessary, the ring 10 is turned in the one or the other direction, which permits to adjust, on the one hand,the active length of the balance-spring and, on the other hand, the position of its point of attachment. The frequency of the oscillations is again checked until the sprung balance oscillates in synchronism with the reference sprung balance.

It will immediately be seen the great advantage afforded by the collet as shown and described over the collets in use up to now. If, after checking the oscillations, the inner end of the balance-spring had to be shortened, for instance, it was necessary to detach from the collet the bent end of the balance-spring, to cut a portion of the balance-spring, to bend the new end of the balance-spring, to fix again the balance-spring to the collet, and to thus proceed for each checking operation, which represented a long and tiresome work. If a too long portion of the balance-spring had been inadvertently cut, it was no longer possible to correct this error and the entire operation had to be made again with a new balance-spring.

The work of searching the correct point of attachment of the balance-spring is greatly simplified with the collet described. It, on calibrating, the point of attachment has been passed beyond, it suflices to turn the ring 10 slightly backwards for effecting the correction. When the point of attachment has been determined, the outer end of the split 15 makes a certain angle with the ends of the grooves 8. On mounting the balance-springs of a same series, it will suffice to turn the ring 10 by the same angle in order that the point of attachment be correct for each of the balance-springs.

The second embodiment, illustrated in FIGS. 3 and 4, is somewhat simplified, but shows the same advantages as the first embodiment. The cup 19 includes a bottom 20 provided with a central hole 21 and has three

bores

22, 23 and 24 of increasing diameter.

A cut-out part 25, consisting of a milling, is provided in the wall 26 of the cup 19. It is partially cut by the

bores

23 and 24 of larger diameter.

The collet includes in addition an inner ring 27, adapted to cooperate with the cup 19. The ring 27 consists of a cylindrical body provided at its top end with a collar 28 and has in its centre a hole 29. The outer diameter of the cylindrical body of the ring 27 is chosen in such a manner that the ring 27 may be introduced with an easy fit into the upper portion of the cup 19, said cylindrical body being in contact with the intermediate bore 23 of the cup 19.

The ring 27 is radially split as at 30, the split being somewhat wider than the thickness of the balance-spring used. The ring 27 has in addition a diametral groove 31 provided in its top surface, said groove being adapted to receive a tool for turning the ring 27 within the cup 19. The collar 28 defines, with the wall of the cylindrical body of the cup 27, a shoulder 32 of the cup 19 and the wall 26 of the cup 19, an annular chamber 33 adapted to receive the inner portion of the balance-spring 34.

The fixing of the inner end of the balance-spring 34 to the collet described is substantially the same as for the first embodiment. The ring 27 is partially introduced into the top portion of the cup 19, with the cylindrical body of the ring 27 engaging the bore 23, so that the split 30 faces the cut-out part 25. Then, the bent end of the balance-spring 34 is placed in the split 30 so that the balance-spring 34 is situated below the collar 28. Thereafter, by means of a tool inserted into the groove 31, the ring 27 is turned in the winding direction of the balancespring 34, i.e. in the counter-clockwise direction in FIG. 4, up to the position illustrated in FIG. 4, for instance. Then, the ring 27 is pushed completely into the cup 19, so that the cylindrical body of the cup 27 enters the bore 22 of the cup 19 and the collar 28 enters the bore 24; the diameters of the

bores

22 and 24 are slightly smaller than the diameters of the cylindrical body of the ring 27 and of the collar 28, respectively, so that the ring 27 is radially contracted and is firmly held in position in the cup 19. However, the ring 27 may still be turned by means of the above-mentioned tool. At this moment, the frequency of the oscillations of the sprung balance is compared with that of the oscillations of a calibrated reference sprung balance. If necessary, the ring 27 is turned in the one or the other direction, until synchronism is attained between the oscillations of the sprung balance and those of the reference sprung balance.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What we claim is:

1. A collet for fixing the inner end of a balance-spring of a timepiece, characterized in that it comprises a cup and a radially split ring, engaged in said cup, the cup having, from its bottom provided with a central hole, bores of increasing diameter and, in its side wall, at least a cut-out part extending over a portion of its height, the ring and the cup being arranged so as to form therebetween an annular chamber receiving a portion of the balance-spring, the inner bent end of which is hooked in the split of the ring, the ring having in addition a diametral groove in one of its faces, the diameters of said bores being such that the ring, when it is partially introduced into the cup, may be turned with an easy fit in the cup and that, when it is completely pushed, it is firmly held in position in the cup, while it may still be turned in order to adjust the active length of the balance-spring and the position of its point of attachment.

2. A collet as claimed in claim 1, characterized in that the split ring has two end collars, the space lying between said collars forming a groove which defines, with the wall of the cup, an annular chamber adapted to receive the inner portion of the balance-spring.

3. A collet as claimed in claim 2, characterized in that the bottom of the cup has inwardly a rib surrounding its central hole, and that, facing it, the face of the ring has a recess in which is disposed with play the said rib.

4. A collet as claimed in claim 2, characterized in that the bores of the cup are interconnected by surfaces inclined at 45 and the collars are bevelled also at 45 5. A collet as claimed in claim 2, characterized in that said cut-out part consists of a groove extending along a secant.

6. A collet as claimed in claim 1, characterized in that the split ring includes a cylindrical body provided with a single end collar, said collar defining, with the wall of the said cylindrical body of the ring, a shoulder and the wall of the cup, an annular chamber adapted to receive the inner portion of the balance-spring.

No references cited.

LEO SMILOW, Primary Examiner.

Claims

1. A COLLET FOR FIXING THE INNER END OF A BALANCE-SPRING OF A TIMEPIECE, CHARACTERIZED IN THAT IT COMPRISES A CUP AND A RADIALLY SPLIT RING, ENGAGED IN SAID CUP, THE CUP HAVING, FROM ITS BOTTOM PROVIDED WITH A CENTRAL HOLE, BORES OF INCREASING DIAMETER AND, IN ITS SIDE WALL, AT LEAST A CUT-OUT PART EXTENDING OVER A PORTION OF ITS HEIGHT, THE RING AND THE CUP BEING ARRANGED SO AS TO FORM THEREBETWEEN AN ANNULAR CHAMBER RECEIVING A PORTION OF THE BALANCE-SPRING, THE INNER BENT END OF WHICH IS HOOKED IN THE SPLIT OF THE RING, THE RING HAVING IN ADDITION A DIAMETRAL GROOVE IN ONE OF ITS FACES, THE DIAMETERS OF SAID BORES BEING SUCH THAT THE RING, WHEN IT IS PARTIALLY INTRODUCED INTO THE CUP, MAY BE TURNED WITH AN EASY FIT IN THE CUP AND THAT, WHEN IT IS COMPLETELY PUSHED, IT S FIRMLY HELD IN POSITION IN THE CUP, WHILE IT MAY STILL BE TURNED IN ORDER TO ADJUST THE ACTIVE LENGTH OF THE BALANCE-SPRING AND THE POSITION OF ITS POINT OF ATTACHMENT.