US3646653A

US3646653A - Method and tool for making a watch dial with raised symbols

Info

Publication number: US3646653A
Application number: US817970A
Authority: US
Inventors: Pierre Richard
Original assignee: JAP
Current assignee: JAP
Priority date: 1968-04-26
Filing date: 1969-04-21
Publication date: 1972-03-07
Anticipated expiration: 1989-03-07
Also published as: AT300674B; DE1919388B2; DE1919388C3; CH524173A; FR1597916A; JPS5120911B1; GB1227913A; DE1919388A1; CH623668A4

Abstract

A depression in the die is filled with a liquid or pasty substance which supports the dial blank. A descending punch pushes the blank part way into the depression causing the substance of the cushion to force the blank into the punch hollows corresponding to the symbols to be raised. The die depression is surrounded by an upstanding rim that penetrates part way into the blank when the latter is pressed by the punch.

Description

United States Patent Richard [451 Mar. 7, M72

[5 METHOD AND TOOL FOR MAKING A References Cited WATCH DIAL WITH RAISED SYMBOLS UNITED STATES PATENTS 2,726,973 12/1955 Corral ..72/54 X [72] Inventor. Pierre Richard, Porrentruy, Switzerland 2,728,317 12/1955 Clevenger et a1. W29 I 421 X [73] Assignee: Jap S.A., Berne, Switzerland 3,277,562 10/1966 Huguenin ..29/ l77 [22] Filed: 1969 Primary Examiner-John F. Campbell [2]] Appl. No.: 817,970 Assistant ExaminerVictor A. DiPalma Attorney-Stevens, Davis, Miller & Mosher [30] Foreign Application Priority Data ABSTRACT Apr. 26, 1968 Switzerland ..6236/68 A depression in the die is fined with a liquid or p y Substance 52] us. Cl l l l i 29/177 29/42 1 72/54 which supports the dial blank. A descending punch pushes the 72/66 blank part way into the depression causing the substance of 51 Int. Cl ..B23p 13/00 the Shim! the blank Punch [58] Field of Search ..29/177, 179, 421; 72/54, 55, responding to the Symbols to be raised- The die depression is 2 7 58/127 surrounded by an upstanding rim that penetrates part way into the blank when the latter is pressed by the punch.

8 Claims, 2 Drawing Figures METHOD AND TOOL FOR MAKING A WATCH DIAL WITH RAISED SYMBOLS BACKGROUND OF THE INVENTION The invention relates to a method for making watch dials with raised symbols that are formed in one piece out of the dial during fabrication of the latter, one part of the forming tool having hollows corresponding to the symbols to be raised. The invention also relates to a tool for carrying out the method and to the raised dial obtained with the method of the invention.

In some of the known methods of this kind, the raised symbols are obtained by stamping a dial blank having a thickness corresponding to that of the final dial, the thickness of the stamped blank then being equal to that of the dial. In the case of thin dials, such as watch dials, which commonly have a thickness of forty one-hundreths mm., it is not easy to stamp symbols in high relief out of the blank. It is necessary to use extremely powerful presses that are expensive and rapidly wear the tools.

These drawbacks are of a less serious nature in other known methods using a blank that is much thicker than the final dial. After stamping, however, the thickness of the blank must be reduced by machining its reverse face, entailing an additional operation that is laborious and delicate.

In still other known methods, the raised symbols are formed using male and female dies. This operation can be performed using presses less powerful than the stamping presses for the previously described known methods. To form the symbols, there is required not only a female die having hollows corresponding to the negative of the symbols that are to be raised but also a male die incorporating the positive of these symbols. Moreover, the male and female dies must precisely match. Consequently, the tools required for this kind of stamping are much more expensive than those for the kind of stamping previously described.

With these known methods, furthermore, it is not easy to obtain, in a single forming step, symbols with sharply defined faces meeting along sharp comers.

Another disadvantage of these known methods is that the dial blank must be formed while still unfinished, because of the very great stresses to which it is subjected during stamping. One consequence of this disadvantage is that the raised symbols are in the way when later finishing the background of the dial. Since it is impossible to work up to the very edges of the symbols when finishing the dial background, it is useless to employ those finishing operations intended to give the very finest appearance to the dial background, because an unfinished margin is always left surrounding each symbol.

Another consequence of this disadvantage is that a series of dials that have been ordered cannot be worked on until the forming tool is at hand, because it is required for the very first ste "I here are other known methods that avoid these disadvantages. They obtain the raised symbols by partly punching them out of the dial blank. With these known methods, however, the height of the symbols is limited by the thickness of the dial.

SUMMARY OF THE INVENTION An object of the invention is a method for obtaining watch dials with raised symbols that avoids all of the aforementioned disadvantages.

Another object of the invention is a forming tool for carrying out the method of the invention.

A further object of the invention is the watch dial with raised symbols obtained with the method of the invention.

These and other objects of the invention will be apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described, with reference to the Figures of the accompanying drawing, wherein:

FIG. 1 is a side view partly in section showing the dial blank and the forming tool at one step of the method; and

FIG. 2 is a view similar to that of FIG. 1, showing a second step of the method.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the Figures, the forming tool comprises a first part consisting of a die I. The die embodies in its upper face a bowl-shaped depression 2, the diameter of which is less than that of the dial blank 3, but larger than that of the final dial. The die 1 has two blind holes 4 which receive the dial feet 5. The diameter of these holes is slightly greater than that of the feet so as to provide a small amount of play within the holes. The holes 4 are deeper than the feet 5 are long. An annular projection 6, triangular in cross section, forms the rim of the depression 2. A flat face 7 surrounds the projection. The height of the projection 6 above the face 7 is less than the thickness of the blank 3. If the latter has a thickness of forty one-hundredths mm., the height of the projection 6 above the face 7 is preferably between twenty and twenty-five one-hundredths mm.

The forming tool illustrated comprises a second part consisting of a punch 8, which has the same outer diameter as the die face 7. The lower face 9 of the punch is flat, and incorporates hollows l0 constituting the negative of the symbols that are to be raised in the dial.

In accordance with the method of the invention, the first step is to fill the depression 2 and the holes 4 completely with a substance that forms a cushion l l. The cushion can consist of any liquid or pasty substance, such as water or of an aqueous solution of starch, of oil, or of a heavy grease. A transparent substance is preferably chosen, making the holes 4 visible through the cushion l 1.

If the substance used is a liquid, the depression 2 is filled up until the cushion 11 forms a convex meniscus above the upper edge of the projection 6, thereby ensuring that the entire central part of the reverse side of the blank 3, extending above the depression 2, is in direct contact with the cushion 11, when the blank is placed on the die 1, as shown in FIG. 1. If, on the other hand, the cushion is made of a pasty material, care is taken to fill the depression 2 with a sufficient quantity of the material to ensure the same direct contact.

After having filled the depression 2 in the manner described, the blank 3 is placed in the position seen in FIG. I, the feet 5 being introduced into the die holes 4. Since the depression 2 is brimming over with the liquid or pasty substance, the blank does not immediately fall to the position shown in FIG. 1; instead, it floats on the cushion 11, above the annular projection 6. If the blank is slightly pressed on, the excess amount of substance in the depression 2 flows over the projection 6 until the blank rests on the latter, as seen in FIG. 1, in which the dial blank is in position for forming.

The forming is done by forcibly and abruptly lowering the punch 8 against the blank until there is reached the position seen in FIG. 2. As soon as the punch face 9 contacts the obverse of the blank, the pressure on the latter causes the projection 6 to penetrate into the reverse of the blank. At the same time, the cushion 11 is subjected to tremendous pressure, since the central part of the blank is forced within the depression 2, as seen in FIG. 2. In as much as the liquid or pasty substance of the cushion 11 is incompressible and, moreover, as the projection 6 holds the substance within the depression, the pressure of the blank on the cushion 11 is spread over the entire area of the latter, causing those parts of the blank located opposite the punch hollows 10 to enter the latter and to form the raised symbols 12. Since both liquids and pasty substances easily take on the shape of the container holding them, the portions 11a of the cushion 11 enter the punch hollows l0, forcing the material of the blank 3 into intimate contact with the sides and bottoms of the hollows 10.

The forming operation described can be carried out using a small friction fly press developing a maximum of 30 or so tons pressure. At the end of the operation, the punch 8 compresses on the die face 7 the blank edge 13 located outside of the projection 6, as seen in FIG. 2.

Since the volume occupied by the blank 3 in the depression 2 is substantially greater than the sum of the volumes of the cushion portions 1 la forced into the punch hollows 10, it is essential that the projection 6 does not constitute a perfectly sealed joint. It must permit the liquid or paste of the cushion 11 to escape between the blank and the projection 6, when the blank has already been raised against the bottom of the hollows 10 while the punch 8 continues to descend. Otherwise, the joint constituted by the projection 6 must not permit the liquid or the paste of the cushion 11 to escape until the symbols are completely formed. If necessary, the effectiveness of this joint can be improved by tiny projections or grooves (not shown) incorporated in the punch face 9 opposite the projection 6. To the same end, a second projection (not shown), concentric to the projection 6, can be provided in the die face 7.

Tests employing the method described have shown that the raised symbols have perfectly flat side and upper faces meeting in sharp and very well defined corners. The symbol 12 shown in the drawing is constituted by a bar. The method of the invention can be used, however, to form in the blank 3 raised symbols of any desired shape in plan view. These symbols can be Arabic numerals or a trademark consisting of letters or of a design.

When using the method of the invention, it is not at all necessary that the feet 5 are previously fixed to the blank; instead, they can be fixed after the forming. As illustrated in FIG. 2, the raised symbols can be formed in any area of the dial and completely independently of the position occupied by the feet 5. In the example shown, the foot 5 comes to be positioned within the symbol 12. Tests undertaken with the foot coming to be positioned on the sides 14 of the symbol 12 (the foot having been soldered to the blank before forming) demonstrate that this location is not disadvantageous; the solder connection of the foot to the side 14 holds perfectly, and the foot remains held to the side with all of the tightness desired. A play of a few hundredths of a millimeter of the feet 5 in their holes 4 is sufficient to ensure that the pressure caused by part of the blank 3 forced into the depression 2 is transmitted to the liquid or paste at the bottom of these holes.

in principle, the method described can be used at any stage during the manufacture of the dial. in particular, it is altogether possible to carry out all of the finishing operations on the obverse 15 of the blank. The finest surface finish is not harmed by the forming operation. The manufacturer is therefore free to prepare a number of blanks beforehand, and to finish the obverses 15 of these blanks while preparing the forming tools, particularly the punch 8, which is the part of the forming tool requiring the most time to be made ready.

it will be noticed that the openings embodied in the blank 3 for the hands do not prevent use of the described method. While forming, these openings are actually closed by the punch face 9. It is only necessary to prevent droplets of the substance constituting the cushion 11 from passing through these openings and onto the obverse 15 of the blank, when the latter is placed on the die 1. For this purpose, the openings can be covered with adhesive paper.

If the dial is intended for a calendar watch having a date aperture that is to be surrounded by a raised frame, the forming can be done by the method described, the date aperture being cut out only after the forming is completed.

The raised symbols obtained with the method of the invention can be faceted, of course, after the forming.

After the finishing operations on the dial obverse 15, where these are done before the forming, the finished face of the blank 3 can be covered with a protective coat of lacquer of the sort regularly used in the manufacture of dials. Tests have shown that the described forming method does not damage this coating, and after forming the coating was removed from only those areas of the symbols that were to be faceted. These uncovered areas can be colored as desired, with a view to obtaining the wanted contrast with the dial background.

In order to apply to the sides 14 of the symbols 12 a color different from that of the dial background, the obverse 15 of the blank must be covered with a protective coating that is destroyed in those areas where the symbols are raised out of the surface of the blank. To this end, adhesive paper or a hard lacquer can be applied to the blank.

After forming, the blank is easily taken up by a suction gripper for the purpose of removing the edge of the blank by turning on a lathe, for example, and to give the dial its final diameter. During this operation the dial can also be cambered.

The dial obtained with the method of the invention has the appearance of a dial with applied symbols, but at a much lower cost price.

Although the preferred embodiment of the invention has been described, the scope of, and the breadth of protection afforded to, the invention are limited solely by the appended claims.

What I claim is:

1. A method for making watch dials with raised symbols that are formed in one piece out of the dial during fabrication of the latter, including the step of stamping a dial blank with a forming tool comprising two parts consisting of a punch and of a die, one of these two parts incorporating hollows corresponding to the negative of the symbols to be raised in the dial blank, and wherein the improvement comprises the further steps, before stamping, of filling a depression of the other part of the forming tool with a liquid or pasty substance for forming a cushion in the depression and of placing the blank on the cushion so that it is in direct contact therewith.

2. The method as defined in claim 1, including the step, while stamping, of pressing the obverse of the blank into a raised projection surrounding the depression as a rim thereof to cause the blank to move part way into the depression and to exert a sufficiently high pressure over the entire area of the cushion to cause the substance of the cushion to push the blank into the hollows of the one part of the forming tool.

3. The method as defined in claim 1, including a step of fixing dial feet to the blank before the latter is placed on the cushion, and of inserting the feet into blind holes embodied in the depression and freely accommodating the feet, when placing the blank on the cushion.

4. The method as defined in claim 1, including the step of performing on the obverse of the blank all finishing operations for the dial before said stamping step.

5. The method as defined in claim 4, including the step, before said step of placing the blank on the cushion, of covering the finished obverse of the blank with a protective coating that is then destroyed, during said stamping step, in those areas of the blank where the symbols are raised.

6. A press-forming tool for making watch dials with raised symbols integrally formed in said dials comprising two parts, a punch and a die, a first one of said two tool parts having a depression for holding a liquid or pasty substance to act as a cushion and support for a blank when said two parts press against each other, a second one of said two tool parts having hollows corresponding to the negative of the symbols that are to be raised in the die blank; and wherein the blank is larger in diameter than a final dial formed therein and said depression is round in plan view and has a diameter between those of the blank and of the dial.

7. The forming tool as defined in claim 6, wherein said depression incorporates a raised annular rim for supporting the blank during an intermediate stage of the forming operation.

8. The forming tool as defined in claim 7, further including a face embodied by said first tool part and surrounding said annular rim, for supporting the blank during a final stage of the forming operation, and wherein the height of said annular rim, measured from said face, is less than the thickness of the blank.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION v March 7, 1972 Patent No. 3,646,653 Dated Inventor(s) Pierre RICHARD It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Jap S. A. Berne, Switzerland instead of Assignee:

Jap S. A. Bure, Switzerland Signed and sealed this 1st day of August 1972.

(SEAL) Attest:

EDWARD M.FL1:;TCHER,JR. ROBERT GUTTSCHALK Commissioner of Patents Attesting; Officer USCOMM-DC 60376-P69 R US4 GOVERNMENT PRINTING O FICE: 1969 O'356-33l FORM PO-1050 (10-69)