Patent GB-955813-A (GB)
Title: Methods of securing an insert of solid material in a sheet of solid material and inserts therefor
Inventor: HOWARD GILES PHILIP ELIOT
IPC: B21D39/03
Filed: 1960-08-04
Abstract: 955,813. Perforating. J. & S. ENGINEERS Ltd. Aug. 4, 1961 [Aug. 4, 1960; Nov. 9, 1960; Nov. 11, 1960; March 1, 1961; July 14, 1961], Nos. 27050/60, 38464/60, 38801/60, 7456/61 and 25708/61. Headings B3U and B3W. In a method of securing an insert in a sheet in which the sheet and insert are interposed between a punch and die and the insert cooperates with the die to shear a piece from the sheet, the leading end of the insert is other than flat or is of a contour substantially different from the die. Two plates 1 and 2 are placed over a die 3 which has an aperture 5 surrounded by a ridge 12. A punch 6 slides in a holder 7 which has spring-loaded radial pins 9 which prevent the insert 8 falling out. The meeting faces of the punch and insert are both flat, and a little below its upper end the rivet has a minimum diameter so that a downwardly facing shoulder 11 is formed, and the diameter of the insert then increases uniformly to the bottom. The leading end of the insert is conical, and is greater in diameter than the die aperture. As the punch 6 descends the insert, which is harder than the plates, shears therefrom a portion which is of the same contour as the die cavity and the insert enters the hole formed. The ridge 12 is forced into the under-surface of the plate 2, the leading end of the insert enters the die aperture 5 and an outward flow of the material of the insert occurs and this material 14 forms for itself a cavity in the surrounding material of the plate 2. The upper part of the insert is forced into the plate 1. In a modification (Fig. 4, not shown), the insert is a straight-sided cylinder with a conical leading face, and a conical recess in the top which co-operates with a complementary form on the punch. In a further modification (Fig. 8), the insert is of truncated conical form and has an enlarged longitudinally knurled central portion 17. The insert has a threaded bore 16 and concave recesses at each end. Again the small end of the rivet is of larger diameter than the die aperture. In a further embodiment (Fig. 14), a disc 20 of rubber is secured to a steel disc 21 by an insert 22 which comprises a head 24, a portion 30 which fits a preformed hole in the rubber disc, a knurled portion 29 and a leading end 28 which is small enough to pass into the aperture 27 of a die 26. In use, the head 24 is supported in a punch 25, the rubber disc is placed on the portion 30 and the steel disc is positioned on the leading end 28. The die descends and leading end 28 shears a piece from the steel disc which is then driven on to the knurled portion 29. A ridge 35 on the die then displaces the material 36 of the steel disc which flows into a groove 32 above the knurled portion 29. There is a ridge 34 on the head 24 which bites into the rubber disc. In a further embodiment (Fig. 16, not shown), the insert comprises a tapped bush with a waist of minimum diameter about mid-way between its ends, a recess in the upper larger end and a conical or domed leading face. The lower part of the insert may have external axially-extending grooves, Fig. 20, which may be formed by machining or swaging, in the latter case there will be protruding ribs associated with the grooves, which key with the surrounding material to prevent the insert turning. The lower face of the punch may have a number of inwardly tapering radially-extending projections which indent the top of the insert so that portions of it are peened over the top surface of the sheet material.