The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 30, 1996
Filed:
Apr. 04, 1994
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho, Kariya, JP;
Abstract
A method of joining a ball member to an end of a cylindrical matrix plunger body by resistance welding thereby to make a plunger for use in a directional control valve for controlling fluid communication in said valve is disclosed. A resistance welder for the method has a pair of electrodes. The ball member is placed in contact with a conical recess within the matrix plunger body and with a conforming surface of one of said electrodes so as to form a circular first contact between the ball member and the matrix plunger body and a spherical second contact between the ball member and the one electrode such that electrical contact resistance at the first contact is greater than that at the second contact. Then, an electric current at a constant rate flows for a controlled period of time through the first and second contacts with the ball member which is kept in contact with the matrix plunger body under pressure by the electrode. When the electric current passes through the electrodes, the greatest resistance and hence the greatest heating effect takes place at the first contact, where a solid-phase joint is formed.