Citizen Watch Company, Ltd.

Hitoshi Uchida

Junji Satoh

Kouji Fujii

Ryo Fujita

Norio Hashimoto

Junji Satou

A brazing filler metal is composed of gold, silver, copper, and an additive element including at least one kind of element out of aluminum, bismuth, gallium, germanium, indium, antimony, silicon, tin, lead, tellurium, and thallium, as main constituents thereof, wherein a total composition ratio of the additive element is in a range of more than 1 wt. % to less than 36 wt. %, and a composition ratio of the gold is less than 80 wt. %, and a composition ratio of the silver is less than 42 wt. %, so that the brazing filler metal joins metals for use as members of which decorativeness in external appearance is required, such as stainless steel and so on, at a low temperature which does not cause the crystal structure thereof to be coarsened, while securing excellent corrosion resistance and sufficient joining strength.

Brazing filler metal

A wristwatch case () and a method of manufacturing the case, the wristwatch case comprising a wristwatch case body () made of titanium or stainless steel and a crown pipe () fixed to each other, wherein a stem hole () corresponding to the crown pipe () is formed in the wristwatch case body (), a small diameter part is formed in the crown pipe (), and a small diameter part corresponding to the a small diameter part of the crown pipe is formed in the stem hole (), the method comprising the step of fitting the crown pipe () into the stem hole () in the wristwatch case body () to form a solid phase diffusion joining part at a portion where the small diameter parts thereof are fitted closely to each other, and to form a brazed connection part at a portion other than that where the small diameter parts are fitted closely to each other, whereby a watch external part having excellent corrosion resistance and waterproof and a large number of design variations can be provided.

Timepiece external part and method of manufacturing the part

One wristwatch case, wherein a pipe is fixedly connected thereto and a connection interface between the wristwatch case and the pipe is not present substantially; the method of fixing the wristwatch, comprising the steps of providing a through-hole in the wristwatch case, press fitting the pipe of 0 mm or larger in press fitting tolerance (pipe outer diameter&#x2014;through-hole diameter) between the through-hole and the pipe, and heating the wristwatch case after the press fitting step; the other wristwatch case, wherein a pipe is fixedly connected thereto through a diffusion layer; the method of fixing the pipe of the wristwatch case, comprising the steps of forming a through-hole in the wristwatch case, press fitting the pipe of 0 mm or larger in press fitting tolerance (outer diameter of pipe having a metal film formed on the surface thereof&#x2014;diameter of through-hole) between the through-hole and the pipe having a metal film formed on the surface thereof, and heating the wristwatch case in vacuum or reducing gas atmosphere after the press fitting step.

Growing community of inventors

Kodaira, Japan

Hitoshi Uchida