US3481140A - Escapement lever for a timepiece - Google Patents

Description

Dec. 2, 1969 P. TUETEY 3,481,140

ESCAPEMENT LEVER FOR A TIMEPIEGE Filed March 20, 1967 H62 H63 3 H51 United States Patent Int. Cl. B21b13/02; B23p 13/00 US. Cl. 58116 3 Claims ABSTRACT OF THE DISCLOSURE An escapement lever for a timepiece including pallets fitted on to the body of the lever comprising locating surfaces formed on a face of the lever adapted to hold the pallets in their exact position and means for permanently affixing the pallets on the lever.

On manufacturing escapement levers for timepieces, a single method for assembling the pallet-stones and the lever is universally used, in which the positioning of each pallet-stone is ensured by means of a notch forming a slide-way in which the pallet-stone is held by a resilient effect until it is sealed by means of a thermoplastic glue, e.g. shellac. It is to be noted that in this method the pallet-stone may be displaced later on if the shellac is softened by heating. This is an operation which forms a part of the escapement-making and which is intended for adjusting the functions of the escapement and for compensating the irregularities of the manufacture of the lever as well as those of the watch movement.

Due to the ever increasing precision of the modern manufacturing processes, the correction operation is more and more rare. It is therefore possible to contemplate its suppression, which enables to realize other positioning methods of the pallet-stones and to replace the shellac by a thermosetting glue, such as Araldit (trade name), which has much better fixing properties and which is insensible to the cleaning products usually used by the watchmakers (especially alcohol containing substances) Up till now, owing to the relative strength of the shellac and to its sensibility to heat and certain solvents, it was indispensable to reinforce the gluing action by a permanent means for holding the pallet-stone by the resilient effect exerted thereon by the outer lip of the notch.

The present invention aims at overcoming these drawbacks. It relates to a method of manufacturing an escapement lever for a timepiece, said lever including pallets fitted on to the body of the lever, this method being broadly characterized by forming On a face of the lever posi-,

tioning means adapted to hold the pallets in their exact position during the period immediately preceding their fixation on the lever, and then fixing the pallets on the lever. In other words, the invention provides positioning means integral with or rigidly connected to the lever, by means of which it is possible to hold the pallets in their definitive place during the time necessary for the setting of the glue, in conjunction with a temporary pressure means independent of the lever and necessitating no precise construction. The positioning means are not sufficient per se to hold the pallets in their position, as this is the case in the well-known conventional mounting method. In addition, the pallet is glued on the plane of the lever by one of its nonfunctional faces (perpendicular to the lockingface), which has the advantage that in certain cases it is possible to glue the whole surface of the pallet on the lever and thus increase the strength of the assembly. This 3,481,140 Patented Dec. 2, 1969 strength may be further increased by avoiding to polish the face of the pallet that is to be glued, which increases the adherence of the glue. In the case of metallic or metallized pallets, the same elements as described above will facilitate the mutual positioning of the parts during the welding operation.

The accompanying drawing shows, by way of example, an embodiment of the invention.

FIG. 1 is a plan view of a lever equipped with its two pallet-stones.

FIG. 2 is a cross-sectional view through one of the pallet-stones fixed to the lever.

FIGS. 3 and 4 are cross-sectional views similar to FIG. 2, showing modified embodiments.

The lever illustrated in FIGS. 1 and 2 is denoted by the reference numeral 1 and its arbor by the reference numeral 2. The pallet-stones are denoted by the reference numerals 3. In order to form the positioning means for the pallet-stones 3, one resorts to the partial blanking or punching method, which consists in causing a punch to penetrate into a portion of the thickness of the lever so as to leave the chip in its place. Thus, at least three supports or studs 4, 5 and 6, for instance of a rectangular shape, are created. The surface of the lever having been preliminarily coated with glue, it is sufficient to place the pallet-stone in its right position by pressing it against the surface of the lever and against the studs 4 to 6, so that the correct positioning of the pallet-stone is ensured. The studs 4 to 6 might also be obtained by swaging.

In a first modification, not shown, the same method as described above is used, but a chip having the exact shape of the pallet-stone is partially cut out.

According to a second modification (FIG. 3), the pallet receiving place or berth is formed by making a recess 7 in the lever 1 by means of a punch or by swaging.

In another modification (FIG. 4), a recess 8 may be obtained on the lever 1 by removal of material by a chemical or electrochemical attack or by electro-erosion, according to the known techniques used for instance in the photo-engraving processes.

It is also possible to form permanent or temporary positioning elements by electro-deposition or by the application of a varnish, the zones which must remain free being protected during the application by masks or screens.

The use of these several methods involves that the pallet-stones 3 are no longer in the plane of the lever 1, but above this plane. The escape wheel being notably thinner than the height of the pallet-stone, its plane will also be situated above that of the lever. Thus, it is no longer necessary, in certain embodiments, that the functional extremity of the pallet-stone (impulse-face 9) extends beyond the outline of the lever 1 (see the dotted line in FIG. 1). This will particularly facilitate the use of a part of the means above described.

The positioning means above described make possible to define exactly the position of the pallet and it is sufficient, during the period of setting of the glue, or during the welding operation, to exert a pressure on the upper face of the pallet by simple means and without precision to insure the efiiciency and the precision of the assembly.

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 I claim is:

1. In a timepiece movement,

an escapement lever having a fiat surface portion on 3 4 one side thereof perpendicular to the axis upon References Cited which the lever iS IIlOlllltCd, the flat portion being UNITED STATES PATENTS bounded on at least three sides thereof by locating 114 372 5/1871 Wadsworth 58 116 Surfaces 856,091 6/1907 Ohlson 58116 a pallet havlng a body provided with a surface seated 5 3 248 783 5/1966 Tuetey 29 178 upon said flat surface portion and of a shape to non- 1:327:226 1/1920 DeLong frictionall seat within close roximit to said locatting surfa es with said pallef outstanid ing from said FOREIGN PATENTS one side of the escapement lever, 241,452 3/1946 Switzerland. and means for permanently afiixing said pallet to said 10 342,397 9 0 Sw land. escapement lever. 347,140 6/ 1960 Switzerland. 2. In a timepiece movement according to claim 1 1,163,692 9/1958 Francewherein said locating surfaces comprise studs projecting 1,266,560 6/1961 Franceoutwardly from the plane of the escapement lever. 15 JOHN F. CAMPBELL, Primary Examiner 3. In a timepiece movement according to claim 1 wherein said fiat surface portion and said locating sur- REILEY Asslstant Examlner faces define forming a recess at one face of said escape- US. Cl. X R.

ment lever. 29-177, 178; 74-15

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