CH327796A - Flat hairspring - Google Patents

Description

  

  Flat hairspring The present invention relates to a flat hairspring which can be used in watchmaking, for example.



  In portable watches, especially in wristwatches, a flat hairspring (Archimedes) is preferably used, which nevertheless has the drawback of eccentric development, which causes an imbalance of the regulating part and in particular exerts a pressure. Lateral tension on the balance pivots, pressure which causes disturbances in running and wear of the components. The eccentricity of the hairspring is due in large part to the development of the outer coil and the inner coil. The adjustment of the watch in the different positions is thus made difficult.

    To overcome this drawback, we observe the attachment point where, in neat watches, a Breguet hairspring with Phillips curve, inside and outside, is used. The application of the attachment point and the Breguet hairspring with outer and inner terminal curves requires very expensive skilled labor.



  On the other hand, a Breguet hairspring used in a wristwatch increases the risk of the hairspring catching on the pins or the eyebolt.



  The balance spring according to the invention is characterized in that at least part of the blade has a cross section different from that of the rest of the blade, with a view to obtaining, during operation, a concentric development of the balance spring. .



  The accompanying drawing represents, by way of example, one embodiment of the object of the present invention and several variants.



  Fig. 1 is a schematic plan view of a flat hairspring.



  Fig. 2 is a section along the line C-C.



  Fig. 3 is a section along line D-D. Figs. 4 to 11 are variants of the profile shown in FIG. 3.



  The flat hairspring shown in Figs. 1 and 2 comprises a blade S fixed to a pin P and passing between a pin and a rack key G. The ferrule is designated by V.



  The outer part AB of the blade forms an angle (3 of about 70. Its straight section (fig. 3) is different from the profile (fig. 2) of the rest of the blade. It was obtained from the normal profile. hairspring (fig. 2) by bending. It gives part AB greater rigidity than the rest of the hairspring. This part AB can extend at most over an angle of 180. It can also start towards the pin of snowshoe or extend to the peak.



  The section of the outer coil A-G extends over an angle α of approximately 40.



  The A-B part of the blade has the great advantage of forcing the outer half of the spiral spiral to develop concentrically.



  The inner part H-L of the inner coil extends over a. angle 8 of about 70.1. Its cross section is similar to that of part <I> A-B. </I> It gives this part greater rigidity than that of the rest of the hairspring. This H-L part can also extend over an angle of 180 # 1. It can also extend to the ferrule.



  The beginning of the interior H-E extends over an angle <I> y </I> of approximately 40.



  The H-L part of the blade has the great advantage of forcing the inner half of the spiral's turns to develop concentrically. In variants, the rigidity could be increased only of part A-B or only of part H-L of the hairspring.



  The bending of the parts A-B and H-L of the blade can be obtained by means of simple tools. We could also increase the rigidity of the parts AB and HL by bending the blade in another way (fig. 4 and 5), by bending it (fig. <B> 6 </B> and 7), or by twisting it to 90 (fig. 8).



  It is also possible to reinforce the parts A-B and H-L of the blade by adding material to them by a galvanic process or by welding for example (fig. 9).



  It would also be possible to use a more rigid blade and weaken the parts A-P, B-L and H-E by rolling or by a chemical or other process.



  Parts A-B and H-L can also be reinforced by applying a U-shaped sheath to the blade (fig. 10) or by surrounding it with an O-shaped tube (fig. 11).

 

Claims (1)

CLAIM Flat hairspring, characterized in that at least part of the blade has a straight section different from that of the rest of the blade, with a view to obtaining, during operation, a concentric development of the hairspring. SUB-CLAIMS 1. Spiral according to claim, characterized in that several parts of the blade have cross sections different from that of the rest of the blade. 2. Spiral according to claim, characterized in that said part is folded lengthwise, so as to increase its rigidity. 3. Spiral according to sub-claim 2, characterized in that said part has a U-shaped cross section whose legs touch each other. 4. Spiral according to claim, characterized in that said part is twisted at 90. 5. Spiral according to claim, characterized in that said part is reinforced by an addition of material. 6. Spiral according to claim, characterized in that said remainder of the blade is thinned with respect to said part. 7. Spiral according to claim, characterized in that said part is reinforced by a sheath. 8. Spiral according to claim, characterized in that said part is reinforced by a tube. 9. Spiral according to claim, characterized in that the blade is bent at a right distance of about 401 from that of gripping ment of the racket pins. 10. Spiral according to sub-claim 9, characterized in that said part belongs to the outer coil and extends over an arc comprised between 700 and 180 ,,. 11. Spiral according to claim, character ized in that said part extends by shooting from the location of the bolting towards the inside of the spiral. 12. Spiral according to claim, character ized in that the section of the blade extending between the place of attachment to the ferrule and said part, corresponds approximately to 40o 13. Spiral according to claim, character ized by the fact that said part extends over an arc between 701 and 1800. 14. Spiral according to claim, characterized in that said part extends from the place of attachment to the ferrule towards the outside of the spiral.