Hard Metal Watch Band

Abstract

A mar-proof watch-band is made of materials having a hardness greater than Hv 1,000. Suitable materials are hard nitrides, oxides and carbides, in combination with metallic binders. Such materials may be ground to a mirror-finish.

Description

BACKGROUND OF THE INVENTION

Watch-bands having a useful life exceeding that of leather have generally been made of stainless steel or silver or gold alloys. Such materials, whether in their natural state or plated with a metal, are nevertheless subject to scratching and abrasion by concrete, dust and the like so that it is difficult, if not impossible, to maintain such watch-bands in a condition in which they have a high lustre. In view of the relative softness of such materials, even in the case of stainless steel, it is impossible to maintain a mirror-finish. The wearer of such a watch-band must therefore resign himself to a decrease in the attractiveness of the watch-band or to relatively frequent refinishing of the watch-band.

SUMMARY OF THE INVENTION

A watch-band, in accordance with the present invention, is made of a hard nitride, a hard oxide or a hard carbide, where the material, in powdered form, is bound together by a suitable metallic binder. Such materials, when properly prepared, can be polished to a mirror finish which is essentially mar-proof due to the fact that select materials of this type have hardnesses in excess of Hv 1,000. Flexibility of such a watch-band is obtained by making the watch-band of individual links each of which has a tongue at one end and a groove at the other end, each link being held to the adjacent link by one or more pins passed through a cylindrical cavity in the walls of one groove and an aligned cylindrical cavity in the tongue of the adjacent link.

Accordingly, an object of the present invention is to provide an improved watch-band of high hardness.

Another object of the present invention is to provide an improved watch-band which can be finished to a mirror-like appearance.

A further object of the present invention is to provide an improved watch-band of a powdered nitride, carbide or oxide bound together with a metallic binder.

An important object of the present invention is to provide an improved watch-band which is essentially non-metallic in character.

A significant object of the present invention is to provide an improved watch-band having non-metallic links having a tongue at one end and a groove at the opposite end, said links being held together by pins passing through the sidewalls of said grooves and through said tongue.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises compositions and an article of manufacture consisting of said compositions possessing the features, properties, and the relation of elements which will be exemplified in the article and compositions hereinafter described, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of a watch-band in accordance with the present invention;

FIG. 2 is a plan view in partial section showing a mode of joining two adjacent links in said watch-band;

FIG. 3 is a side view in section showing how relative rotation between links is provided for;

FIG. 4 is a side view in section of two adjacent links in a second embodiment;

FIG. 5 is a sectional side view of a third embodiment of said links; and

FIG. 6 is a plan view in partial section of two adjacent links wherein a single pin fastens each pair of links together rotatably.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Compositions suitable for the manufacture of watch-band links therefrom, where the watch links can be ground and polished to a mirror finish are as follows:

EXAMPLE 1

All quantities are in parts by weight

WC -- 82

Co -- 18

EXAMPLE 2

WC -- 75

TaC -- 3

Co -- 22

EXAMPLE 3

WC -- 78

TiC -- 6

Co -- 16

EXAMPLE 4

WC -- 70

TaC -- 5

TiC -- 3

Co -- 18

Ni -- 4

EXAMPLE 5

Al.sub.2 0.sub.3 -- 70

Cr -- 30

EXAMPLE 6

TiN -- 70

Ti -- 25

Mn -- 5

EXAMPLE 7

Si.sub.3 N.sub.4 -- 60

Ni -- 20

Co -- 20

To prepare watch-band links from any of the above compositions, the components of the composition, in powdered form, are placed in a ball mill having extra hard balls therein as well as a quantity of liquid such as benzene and the ball mill is rotated for about 24 hours. Following conventional procedures, a small quantity of wax is incorporated into the composition which is molded to the desired form, heated to remove the wax and finally sintered in vacuo at a temperature such that the metallic binder melts and wets the carbide, oxide or nitride as the case may be. The molded piece is in the form of a sheet having a tongue at one end and a groove at the opposite end as shown in FIG. 1, wherein a link 1 has a groove therein leaving sidewalls 1a and also has a tongue 1b fitting between the sidewalls 1a with clearance.

The partial sectional view of FIG. 2 shows how adjacent links may be joined. Sidewall 1a has a cylindrical cavity therein in which is placed a plastic bushing 2. Tongue 1b of the adjacent link has a cylindrical cavity therein in which is placed the bushing 3. The cavity in the sidewall 1a of the left hand link and the cavity in the tongue 1b of the right hand link of FIG. 2 are aligned so that a single pin 4 can be inserted into both cavities. In the embodiment shown pin 4 is stepped to form an interference fit with bushing 2 and a clearance fit with bushing 3. This construction provides for rotation of the links relative to each other around the axis of pin 4. The other sidewall 1a of the left hand link is similarly joined by a second pin (not shown) at the bottom of the tongue 1b.

As is evident, rotation could also be achieved while holding the pin firmly in place by having an interference fit between pin 4 and bushing 3 and a clearance fit between pin 4 and bushing 2. The cavities in the sidewalls and tongue may be formed during the molding operation using an insert which burns away during the sintering operation, or may be bored into the links using a diamond drill.

It is not necessary that separate pins be used for each sidewall of each link. In the embodiment of FIG. 6, a single cylindrical cavity passes through the entire length of the tongue 1b. This cylindrical cavity has a bushing 10 therein and a pin 11, which, in the embodiment shown provides an interference fit with the pin 11. Alternatively, there could be a clearance fit between the bushing 2 and the pin 11 and an interference fit between the bushing 10 and the pin 11.

In order to provide for rotation around the pin 4 or pin 11, clearance must be provided between the tongue and groove bottom of adjacent links.

In the partial sectional view of FIG. 2 clearance is shown between the surface 6 of a groove and the surface 5 of a tongue. The clearance needed is minimal in a construction shown in sectional side view in FIG. 3, where the right-hand link has a surface 5 which is a half cylinder. Slightly more clearance is needed where a corner such as 7 (FIG. 4) is present at the end of the right-hand link. In this case clearance is measured between the left-hand link and the circle 8 passing through the corners of the right-hand link.

In the embodiment of FIG. 5, rotation is limited by the fact that corner 9 can interfere with the bottom of the groove of the adjacent link. Such intereference is undesirable because the wedging action resulting in such a construction can result in fracture of the material of which the watch-band link is made or shearing of the pin 4.

In general, the materials comprising the watch-band links in accordance with the present invention have a hardness greater than 100 Hv, and consequently can be ground and polished economically only with a diamond wheel. A mirror finish can be achieved which matches that generally found on fine watches. The line finish which results from machining is completely avoided.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficient attained, and since certain changes may be made in the above composition and the above article without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Claims

What is claimed is:

1. A mar-proof watch-band, comprising a plurality of links of a material having a hardness of at least Hv 1,000, each of said links having a groove at one end thereof and a tongue at the opposite end thereof, each tongue being of such size that it fits with clearance within the groove of an adjacent link, each of said tongues having at least one cylindrical cavity therein, each of the sidewalls of each of each of said grooves having a cylindrical cavity therethrough, a plastic bushing in each of said cavities, the cavities and bushings in the groove sidewalls of one link being aligned with said cavity and bushing in the tongue of an adjacent link, and at least one pin seated in said aligned bushings, said pin having an interference fit with one of said bushings and being received with clearance in an adjacent bushing.

2. A watch-band as defined in claim 1, wherein said material comprises a member selected from the group consisting of hard carbides, hard nitrides and hard oxides as its principal constituent.

3. A watch-band as defined in claim 2, wherein said hard nitride is Si.sub.3 N.sub.4.

4. A watch-band as defined in claim 2, wherein said hard carbide is selected from the group consisting of WC and TiC.

5. A watch-band as defined in claim 2, wherein said hard oxide is Al.sub.2 O.sub.3.

6. A watch-band as defined in claim 2, wherein said member comprises a metal which melts at a lower temperature and which wets said hard oxide, nitride or carbide and is resistant to corrosion by perspiration.

7. A watch-band as defined in claim 1, wherein each of said links has a mirror finish.

8. A watch-band as defined in claim 1, wherein each tongue has a single cylindrical cavity passing completely therethrough, the wall cavities and the tongue cavity of a pair of adjacent links being aligned whereby a single pin may be passed through said wall cavities and said tongue cavity each having a plastic bushing therein, to hold said adjacent links together and provide for relative rotation with respect to each other, said pin having an interference fit with one of said tongue bushing or said groovewall bushings and a clearance fit with the other.

9. A watch-band as defined in claim 1, wherein said links have a composition which is a member of the group consisting of 82%, 18% Co; 75% WC, 3% TaC, 22% Co; 78% WC, 6% TiC, 16% Co; 70% WC, 5% TaC, 3% TiC, 18% Co, 4% Ni; 70% Al.sub.2 O.sub.3, 30% Cr, 70% TiN, 25% Ti, 5% Mn; and 60% Si.sub.3 N.sub.4, 20% Ni, 20% Co.