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US 4,365,495 AGranted
Method of making a mandrel for a self plugging blind rivet
AssigneeAerpat A.G.
InventorAlbert C. Francis
Life of this patent
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AssigneeAerpat A.G.
InventorAlbert C. Francis
Estimating the term…
A mandrel for a blind rivet is made by first forming a mandrel blank from wire stock in a series of cold heading operations which include forming an enlarged head at one end of an elongate stem, and then scraping material from the peripheral surface of part of the head adjacent to the stem and moving the material in a direction away from the stem so as to leave a core and to form a circumferential flange-like boss from the scraped material. The mandrel blank thus produced is then subjected to a rolling operation in which the mandrel blank is rolled between contoured mandrel-rolling dies and thereby formed into a finished mandrel. In particular, the contours of the rolling dies are such as to form a breaker groove at the junction between the head and stem of the blank and to cause the material of the flange-like boss to flow over the scraped surface of the core of the head and towards the stem and form a skirt peripherally of the core while confining the material of the boss so that it does not flow across the breaker-groove. Pulling grooves are rolled in the mandrel stem and the external surface of the skirt is rolled to a cylindrical shape with, optionally, a peripheral groove therein.
A method of making a mandrel for a blind rivet, which method comprises first forming a blank having a generally cylindrical stem and a head, which head comprises a cylindrical core portion adjacent to and of substantially the same diameter as the stem, a boss spaced from the stem by the core portion and having a diameter greater than the core portion, and an end portion adjacent to the boss and having a diameter greater than the boss, and then rolling the boss downwardly toward the stem and over the core portion to form a skirt which peripherally surrounds the core portion and which has a greater diameter than the stem, forming a portion of said skirt into a shoulder extending transverse to the direction of the stem, and confining the material of said skirt so that said skirt surrounds only said core portion.
A method of making a mandrel for a blind rivet, which method comprises first forming a blank having a generally cylindrical stem and a head, which head comprises a cylindrical core portion adjacent to and of substantially the same diameter as the stem, a boss spaced from the stem by the core portion and having a diameter greater than the core portion, and an end portion adjacent to the boss and forming a breaker groove at the junction of the stem and the core and urging the material of the boss to flow over the surface of the core portion and towards the stem to form a skirt which peripherally surrounds the core portion and which has a greater diameter than the stem.
A method of making a mandrel for a blind rivet, which method comprises first forming a blank having a generally cylindrical stem and a head, which head comprises a cylindrical core portion adjacent to the stem and having a diameter of the same as or minutely greater than that of the stem, a boss spaced from the stem by the core portion and having a diameter greater than the core portion, and an end portion adjacent to the boss and having a diameter greater than the boss, forming a breaker groove at the junction of the stem and the core, and then urging the material of the boss to flow over the surface of the core portion and towards the stem to form a skirt which peripherally surrounds the core portion and which has a diameter greater than that of the stem.
A method of making a mandrel for a blind rivet, which method comprises forming a blank precursor having a generally cylindrical stem and a head, wherein the head comprises a first part adjacent to the stem and of substantially greater diameter than the stem, and an end part of greater diameter than the said first part, and then scraping peripheral material from the surface of the said first part of the head in a direction away from the stem to leave a cylindrical core adjacent to the stem and having a diameter the same as or minutely greater than that of the stem, and forming a circumferential flange-like boss out of the said peripheral material at a position spaced from the stem by the cylindrical core, and thereby forming a mandrel blank, and then rolling the mandrel blank so as to urge the material of the boss to flow over the surface of the core in a direction towards the stem and thereby forming a skirt which peripherally surrounds the core and a cylindrical cleavage between the skirt and the core.
Dependencies are inferred from the claim text.