Method And Apparatus For Testing A Watch For Tightness

Abstract

A watch movement is operated in an associated watch housing. Said watch housing containing said operating watch movement is subjected to an air pressure which differs from a normal or atmospheric air pressure. Any change in the accuracy of the operation of said watch movement in said housing when the latter is subjected to said different air pressure compared to the accuracy of the operation of said watch movement in said housing when the latter is under said normal or atmospheric air pressure is detected.

Description

This invention relates to a method and apparatus for testing watches, particularly wrist watches, for tightness.

When a wrist watch has been completely assembled in a watch housing, it is conventional to test the watch for water- and airtightness. For this purpose, the watch is placed in a water container and the water pressure is increased. Watches which are not tight thereafter contain water droplets in their interior. The watches which are rejected for this reason must not only be provided with a new housing seal but the watch movement must be taken apart immediately and dried, re-oiled and reassembled. These operations are time-consuming and expensive.

This disadvantage is eliminated by the present invention. The method according to the invention is characterized in that the watch housing which contains the watch movement, which is operated, is subjected to an air pressure which differs from and preferably exceeds the normal or atmospheric pressure, and changes in the accuracy of the operation of the watch movement are detected. The method may be carried out in that a watch housing containing a watch movement is placed on a microphone to which an electronic chronograph is connected, and the watch housing is subjected to pressure changes in a pressure chamber while the electronic chronograph is operated.

Apparatus for carrying out the method comprise suitably a microhpone provided with a holder for carrying the watch housing containing a watch movement, and means operatively connecting the microphone to the electronic chronograph, which microphone is contained in a pressure chamber provided with pressure gauge.

According to another feature of the invention, the apparatus according to the invention is characterized in that a sealing cover of the pressure chamber is connected to a linkage, which tends to close the cover in response to an increase of the pressure in the pressure chamber. To that end, the pressure in the pressure chamber is applied to a piston, which is operatively connected to the closing cover by linkage tending to exert on the cover a force which acts in the closing sense and is several times larger than the pressure force acting on the piston. This arrangement enables an automatic opening and closing of the sealing cover during the operation of the pressure chamber, i.e., the admission of the compressed air and the pressure relief.

Further details of the apparatus according to the invention will be described hereinafter with reference to the drawing, in which two embodiments are shown by way of example.

FIGS. 1 and 2 are sectional views taken at right angles through a first embodiment of the apparatus.

FIG. 3 shows test charts recorded during tests of two watches.

FIGS. 4 and 5 are sectional views showing the second embodiment of the apparatus with the sealing cover in closed and open positions, respectively.

FIG. 6 is a top plan view showing the apparatus of FIGS. 4 and 5 with the sealing cover removed so that the holder for the watch is visible.

The first embodiment shown in FIGS. 1 and 2 comprises a pressure chamber body 1 provided with a cover 2, which can be removed, e.g., unscrewed, and is provided with a sight glass 3. A pressure chamber 4 contains a retaining spring 5 for receiving a watch housing 6 to be tested, which contains a watch movement. The watch housing is engaged by transmission pins 7, which transmit the ticking of the watch (this ticking is due to the oscillations of the balance wheel) to a piezoelectric quartz 8. The oscillating quartz 8 converts the acoustic oscillations in known manner into electric signals, which are conducted in known manner by the lead 9 to the electronic chronograph.

Air pressure is applied to the pressure chamber 4 of the pressure chamber body 1 along path A from an inlet pipe 10 through a three-way valve 11, which is controlled by a switch 12. The pressure rise is indicated by a pressure gauge 13. Air enters the pressure chamber 4 through a nozzle 14 so that a too sudden pressure change is avoided, just as during a pressure relief. The pressure relief is initiated by a shifting of the three-way valve 11 so that the air can escape along path B through an outlet 15. If the watch housing is tight, the record of the chronograph shows no change in accuracy compared to normal pressure conditions. If the watch housing is not tight, the test watch shows a distinct lag because the oscillation of the balance wheel is influenced by the changed pressure in such a sense that the watch is slower. This is recorded or indicated by the chronograph. The sight glass 3 enables an observation of the operation of the watch because if the watch is tight the watchglass may press on the hands to stop the watch.

FIG. 3 shows a chart plotting the records of two tested watches. The change in accuracy reported as pitch difference in seconds per day or .DELTA. s/d, is plotted as a function of the pressure rise p (in kilograms per square centimeter) for a tight watch housing of the first tested watch (curve a) and for the same watch housing which has been rendered untight (curve b), also for a tight watch housing of the second tested watch (curve c) and for the same watch housing which has been rendered untight (curve d). It is apparent that the untightness is indicated by a change in accuracy compared to normal pressure.

The second embodiment shown in FIGS. 4 to 6 comprises a pressure chamber body 21 and a removable cover 22, which is provided with a clamping rim 23. There is no sight glass in this embodiment. A pressure chamber 24 contains again a retaining spring 25 for receiving a watch housing 26 to be tested, which contains a watch movement. The watch housing 26 is engaged by transmission pins 27, which transmit the ticking of the watch (this ticking is due to the oscillations of the balance wheel) to a piezoelectric quartz 28. These pins serve in this case also to hold the watch. By the piezoelectric quartz 28, the acoustic oscillations are converted in known manner into electric signals, which are conducted by a lead 29 to an electronic chronograph. Air pressure is applied to the pressure chamber 24 in the pressure chamber body 21 from an inlet pipe 30 along path A through a three-way valve 31, which is controlled by a switch 32. The pressure rise is indicated by a pressure gauge 33. Air enters the pressure chamber through a nozzle 34 so that there is no too sudden pressure change, just as during a pressure relief. When the three-way valve 31 has been shifted, pressure is relieved through an outlet 35 to the outside. The effects regarding the accuracy of the watch when the watch housing is tight and untight, respectively, are the same as described in connection with the first embodiment.

In the second embodiment, a piston chamber 36 is disposed below the pressure chamber 24 and is connected by a passage 37 also to the passage through which compressed air is admitted and through which the air is exhausted for a pressure relief. Such air thus acts on the piston 38. The piston 38 comprises a sealing cup 39, which is held by screws 40 and is engaged by, for instance, three clamping levers 41, which also engage the clamping ring 23 of the sealing cover 22 on the inside. When compressed air is admitted (path A in FIG. 4), these levers serve to increase the sealing force. During a pressure relief (path B), return springs 42 acting on the piston 38 return the latter so that the clamping levers 41 pivoted at 43 disengage the rim 23 and the cover 22 can be opened as is shown in FIG. 5. The sealing cover 22 is thus automatically closed and opened in response to the air pressure so that there is no need for a manual unscrewing or unclamping and the manufacture in large quantities is facilitated.

Claims

What is claimed is;

1. A method of testing a watch for tightness, which comprises

operating a watch movement in an associated watch housing,

placing said watch housing containing said operating watch movement in a pressure chamber and subjecting said watch housing containing said operating watch movement to an air pressure which differs from atmospheric air pressure, and

detecting any change in the accuracy of the operation of said watch movement in said housing when the latter is subjected to said different air pressure compared to the accuracy of the operation of said watch movement in said housing when the latter is under said atmospheric air pressure.

2. A method as set forth in claim 1, in which said different pressure is higher than said atmospheric pressure.

3. A method of testing a watch for tightness which comprises

operating a watch movement in an associated watch housing,

placing said watch housing containing said operating watch movement in a pressure chamber,

changing the air pressure in said pressure chamber from atmospheric air pressure to an air pressure which is different from said atmospheric air pressure while said watch housing containing said operating watch movement is in said pressure chamber, and

detecting any change in the accuracy of the operation of said watch movement in said watch when the watch housing is subjected to said different air pressure compared to the accuracy of the operation of said watch movement in said watch housing when the watch housing is under said atmospheric air pressure, comprising

converting acoustic oscillations produced by said operating watch movement into electric signals when said watch housing in said pressure chamber is under said atmospheric air pressure and under said different air pressure, and

chronographically recording said electric signals to detect any changes in the accuracy of the operation of said watch movement in response to the change from said atmospheric air pressure to said different air pressure in said pressure chamber.

4. Apparatus for testing a watch for tightness, which comprises

means defining a pressure chamber,

means for holding a watch housing containing a watch movement in said pressure chamber,

means for subjecting said watch housing in said pressure chamber to a pressure which differs from atmospheric pressure, and

means for detecting during the operation of said watch movement in said housing in said pressure chamber any changes in the accuracy of said operation when said housing is subjected to said different pressure compared to the accuracy of the operation of said watch movement in said housing when the latter is under said atmospheric pressure.

5. Apparatus as set forth in claim 4 wherein

said means for detecting any change in the operation of said watch movement in said watch housing includes a microphone which is arranged to receive acoustic oscillations produced by said watch movement when the same is operating in said pressure chamber and to convert said acoustic oscillations into electric signals when said watch housing in said pressure chamber is under said atmospheric air pressure and under said different air pressure, and

a chronograph arranged to receive and record said electric signals and to indicate any changes in the accuracy of the operation of said watch movement in response to the change from said atmospheric air pressure to said different air pressure in said pressure chamber.

6. Apparatus as set forth in claim 5, in which

said microphone is contained in said pressure chamber and electrically connected to said chronograph, and

a pressure gauge is connected to said pressure chamber.

7. Apparatus as set forth in claim 4, in which said means defining a pressure chamber comprises a body having an opening and a sealing cover adapted to seal said opening and provided with a sight glass enabling an observation of said watch when the latter is supported in said pressure chamber.

8. Apparatus as set forth in claim 5, which comprises a three-way valve, which is shiftable between a first position for connecting said pressure chamber to a source of compressed air and a second position for pressure-relieving said pressure chamber.

9. Apparatus as set forth in claim 4, in which

said means defining a pressure chamber comprise a body having an opening and a sealing cover adapted to seal said opening and

means are provided which are responsive to the pressure in said chamber and adapted to force said sealing cover into sealing engagement with said body with a force which increases in response to a pressure rise in said chamber.

10. Apparatus as set forth in claim 9, in which said pressure-responsive means include a force-increasing lever means.

11. Apparatus as set forth in claim 10, in which

said pressure-responsive means comprise a piston which is responsive to the air pressure in said pressure chamber and

said force-increasing lever means are adapted to increase several times the force exerted on them by said piston.

12. Apparatus as set forth in claim 11, in which

said pressure-chamber defining means define a piston chamber,

said pressure chamber communicates with a passage for applying air pressure to and for pressure-relieving said pressure chamber,

said piston chamber communicates with said passage,

said piston is contained in said piston chamber and responsive to the pressure therein,

said lever means comprise a plurality of force-increasing levers, and

said piston is arranged to exert on said levers a force which varies with said pressure in said piston chamber.