US2700869A - Watchcase - Google Patents

Description

Feb; 1, 1955 MQRF 2,700,869

WATCHCASE Filed Jan. 7, 1952 United States Patent WATCHCASE Ernest Morf, La Chaux-de-Fonds, Switzerland ApplicationJanuary 7, 1952, Serial No. 265,289

Claims priority, application Switzerland September 28, 1951 4 Claims. (Cl. 58-90) This invention relates to hermetically closed (watertight) watch cases.

Watch cases of this kind as hitherto on the market, are often provided with a bottom screwed down on the case.

In these cases tight closure of the screwed-on bottom is secured as a rule by a packing of compressible material which is inserted between that bottom and the frame of the case. Such cases involve the drawback that frequent screwing and unscrewing of the bottom leads to rapid wear of the packing. Another drawback is the necessity of making the bottom of stainless steel (which does not lend itself to ready machining) in order to avold the influences of transpiration.

It is a well known fact that a piece made of plastic material, for instance so-called unshatterable glass, can

easily be mounted in a metal frame with altogether satisfactory tightness without the insertion of a special packing. Watch cases have even been placed on the market which are provided with a bottom of plastic material. One drawback of these transparent bottoms consists therein that they are liable to be damaged when being lifted to open the case, and their transparency is not fancied by the public which prefers metal bottoms.

It is therefore an object of this invention to cover entirely by a metal cap a bottom of plastic material which is held in place by friction on the case frame by means of a border rim of the bottom, the metal cap being retained on the bottom only.

The advantage offered by this combination of a plastic bottom with a metal cover or cap consists in the fact that the bottom can be imparted any desired appearance, for instance that of the other parts of the casing, while hitherto one was frequently limited to the use of the particularly unesthetic stainless steel bottoms on golden, plated or chromed cases.

It is another object of this invention to provide the plastic bottom in one piece with the metal cap, whereby an annular projection of the metal cap is embedded in the plastic material for the purpose of preventing it from separating from the metal cap.

Still another object of this invention consists therein that the rim on the bottom be utilized for the axial maintaining in place of the clockwork within the case.

In the drawings afiixed to this specification and forming part thereof two embodiments of the invention are illustrated diagrammatically by way of example.

In the drawings:

Fig. 1 is a plan view, taken from below and common to all three embodiments, of a watertight watch case with the bottom mounted in place on the case.

Figs. 2 and 3 are diametral sections on the line II--II in Fig. 1, each of them illustrating a different embodiment,

Fig. 2 shows a plastic bottom covered with a metal cap in which tightness is obtained by a rim flange on the bottom and the case frame in which the bottom is held by friction;

Fig. 3 illustrates a metal cap with an annular projection embedded in the plastic material, this being the preferred form of the invention. Here the clockwork is shown as being held in place in axial direction by the rim of the bottom.

Referring to the drawings and first to Fig. 1, 1 is the frame of the case and 14 is a circular ring formed on the lower part of the frame. This case may also be formed with loops to which a bracelet may be attached. The

. 2,700,869 Patented Feb. 1, 1955 ring 14 is formed with two diametrically arranged semicircular indentations 16 between the two loops, the purpose of which will be explained farther below.

In the embodiment of Fig. 2 the bottom 3 consists of plastic material and the frame 1 is formed with a slightly frustoconical wall 2 in which the rim 4 integral with the bottom and being shaped in correspondence with this wall can be compressed. The angle 19 of the rim 4 is so chosen as to facilitate the introduction of the bottom into contact with wall 2.

The face of the bottom directed towards the outer surface of the case, when the bottom is seated in place, is covered completely by a metal cap 12 held fast on the bottom. The cap 12 is formed with a projecting edge 13 which is completely surrounded by the circular ring 14 presenting the indentations 16.

A metal ring 501 is inserted in a ring groove of the rim 3 to reinforce it. The circular ring 14 is so shaped that the projecting edge 13 is altogether lodged within the interior of the frame, in order that the bottom 3a which provides the tightness of the case, cannot be withdrawn accidentally without using a special tool.

In order to enable the bottom to be withdrawn when it is desired to open the case, it is merely necessary to introduce into the indentations 16 a tool of corresponding configuration, for instance a long thin blade with a semi-circular projection, fitting the indentations, provided for instance on one side of the blade. When this tool has thus been introduced, a torsional movement may be imparted to it by which axial pressure is exerted on the projection 13. After this tool has been introduced into both indentations 16 the bottom can easily be withdrawn from engagement with the wall 2a of the frame.

The case of Fig. 4 again shows the slightly frustoconical groove in the frame 1. The plastic bottom 3 is formed with a rim 4 of corresponding configuration and a metal ring 5a is provided as a reinforcement for the rim which bears against the lower side 6 of a metal lining 7 which adjusts the clockwork laterally and axially within the casing owing to the fact that it is itself adjusted with strong friction between the case frame and the clockwork and that its top extends into contact with a shoulder 8 of the clockwork 9 which it supports in such manner as to press the peripheral edge of the dial 10 against a flange 11 of the frame.

In order to impart to the bottom the metallic appearance desired, for instance the same as the case proper, it is covered with a metal cap which is held in position on the bottom only.

In order to firmly secure the plastic material in the metal cap, this material is preferably moulded within the cap by hot-pressing.

In the second embodiment one might also effect the assembly of these parts by simply setting the cap on the bottom. Since the coeflicients of thermic expansion of the plastic material and the metal are not strictly the same, it might happen that the bottom might separate, at least in part, from the cap which would of course spoil the appearance. In order to avoid this, an annular projection 20 integral with the cap may be embedded in the plastic material. This projection may be produced by hammering the peripheral part of the metal cap and produce by milling a groove 21 in this part, taking care that the projecting flange 20 extend normally to the metal cap.

In order to enable the bottom to be taken off without damaging the plastic material, the metal cap may be formed with a peripheral portion 13 projecting from the bottom section of the frame. In order, however, to prevent the bottom from being taken off too easily, for instance by way of accident, the projecting portion 13 may be embedded completely in the interior of the circular ring 14 which is made integral with the frame 1.

Here also semi-circular indentations 16 may be provided in the ring 14.

I wish it to be understood that I do not desire to be limited to the details shown and described for obvious modifications will occur to a person skilled in the art.

I claim:

1. Watchcase comprising in combination, a case frame,

a bottom of plastic material formed with a substantially cylindrical border flange held by strong friction in said frame, and a metal cap firmly secured to said bottom, said cap having a first flange embedded in said bottom material and a second flange projecting from said cylindrical border flange of the bottom.

2. The combination of claim 1, in which the cap flange embedded in the bottom material is a projection of the cap, which extends from the inner surface of this cap, substantially at right angle therewith.

3. The combination of claim 1, in which the outer surface of the border flange of the bottom is slightly conical as well as the surface portion of the case in which the bottom is engaged and held by strong friction, these two conical surface portions thereby having the same aperture angle and being opened towards the exterior of the case.

4. The combination of claim 3, in which a metal lining is inserted between the watch movement and the case, this lining thereby holding the movement in place within the case, radially by contacting two cylindrical surface portions both of the movement and of the case, and axially by contacting both a shoulder of the movement and the border flange of the bottom.

References Cited in the file of this patent UNITED STATES PATENTS 2,158,044 Haller May 9, 1939 2,446,603 Morf Aug. 10, 1948 2,459,543 Schmerheim Jan. 18, 1949 2,547,090 ONeill Apr. 3, 1951 2,621,468 Colomb Dec. 16, 1952 FOREIGN PATENTS 4,657 Switzerland Feb. 24, 1892 221,351 Switzerland Aug. 17, 1942 243,386 Switzerland Dec. 16, 1946 252,576 Switzerland Oct. 1, 1948 262,326 Switzerland Sept. 16, 1949 975,724 France Oct. 17, 1950

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