US3473363A - Steel fastening pin for a draw die bead - Google Patents

Description

Oct. 21, 1969 w. R. HERMAN ETAL 3,473,363

STEEL swims PIN FOR A mmw DIE BEAD Filed March 17, 1957 FIG. .2

R HERA/IA N KOR TESOJA INVENTORS A7 TORNEVS United States Patent 3,473,363 STEEL FASTENING PIN FOR A DRAW DIE BEAD William R. Herman, Allen Park, and Victor A. Kortesoja, Livonia, Mich., assignors to Ford Motor Company,

Dearborn, Mich., a corporation of Delaware Filed Mar. 17, 1967, Ser. No. 623,870

Int. Cl. D21d 22/00; F16d /06 US. Cl. 72347 2 Claims ABSTRACT OF THE DISCLOSURE This invention is concerned with a particular construction of rivet employed in securing draw die beads to the surface of draw dies and to the combination of the draw die, the draw die bead and the draw die bead steel fastening pin.

BACKGROUND OF THE INVENTION Draw dies are widely used in the fabrication of sheet metal parts which must be produced in large volume. These draw dies are routinely provided with draw die beads which are so located as to secure the sheet metal being drawn firmly between the cooperating dies while the draw is being made so that the metal cannot flow except in the direction for which the dies have been designed and constructed. The use of such draw die beads is conventional and shall not further be described.

The means used to secure the draw die beads to the draw dies have in the past been far from satisfactory. Such fastening means must be cheap, reliable and totally resistant to the high mechanical stresses incident to operation and to the thermal stresses sometimes encountered in the local heat treatment of the dies. This invention is addressed to the provision of such a fastening means and the cooperating draw die and draw die head.

3,473,363 Patented Oct. 21, 1969 DESCRIPTION OF THE INVENTION This invention is best understood in conjunction with the drawings in which:

FIGURE 1 is a view of the draw die bead steel fastening pin upon which this invention is predicated; and

FIGURE 2 is an enlarged section of a portion of the serrations shown in gross in FIGURE 1; and

FIGURE 3 is a cross section taken through the serrated portion of the draw bead steel fastening pin showing the air escape groove; and

FIGURE 4 is a cross section of a portion of the draw die, the draw die bead and the draw die bead rivet taken normal to the axis of the draw die bead.

The draw die bead steel fastening pin depicted in FIG- URE 1 has been fabricated from SAE 1045 steel to take advantage of the economy and ready hardenability of this steel. One end of this rivet is serrated as shown in FIG- URE 1 in gross and in detail in FIGURE 2. This serrated portion is 0.75 inch (1.91 cm.) long. The diameter of the teeth of the serrations is from 0.200 to 0.198 inch (0.508 to 0.503 cm.) and the diameter of the base of the serrations is from 0.180 to 0.177 inch (0.456 to 0.450 cm.). A cylindrical section 0.125 inch (0.317 cm.) long separates the serrated portion from the tapered end portion. It is preferred that elements of the truncated cone represented by this tapered portion include an angle of about four degrees although under some circumstances this taper may be replaced by a straight cylinder.

This draw die steel fastening pin is received in coaxial holes in the draw die and the draw die bead. The diameter of the hole in the draw die should be about 0.191 inch (0.485 cm.). The diameter of the coaxial hole in the draw die bead should be large enough to permit passage therethrough of the serrated portion of the draw die steel fastening pin and to interfere with the tapered portion. A suitable diameter has been found to be 0.203 inch (0.516 cm.). The draw die bead steel fastening pin is hardened in the portion in contact with the draw die and less hard in the portion in contact with the draw die head.

The following tabulation is presented to demonstrate the results obtained with this type of fastening between a draw die and the draw die bead.

1 Present standard draw bead steel 1,730 pounds.

fastening pin in .1865" diameter holes.

2 Present standard draw bead steel 1,760 pounds.

fastening pin in .1865 diameter holes, epoxy glued.

3 .200" Q.D. knurled draw bead steel 1,035 pounds.

fastening pin in .191 diameter holes.

4 .200 OD. knurled draw bead steel 2,450 pounds.

fasteciliing pin in .191 holes, epoxy g ue 5 .200 O. D. draw bead steel fastening 4,610 pounds broke bead, one draw pin with circular teeth in .191 dibead steel fastening pin, pulled up. ameter holes.

6 .200" O. D. draw bead steel fastening 3,650 pounds broke one draw bead steel pin with circular teeth in .191 (11- fastening pin and bead. ameter holes.

7 .200 0.1). draw bead steel fastening 1,500 pounds draw bead steel fastening p n with circular teeth in .193.195 pins pulled out of hole. diameter holes.

8 .200" OD. draw bead steel fastening 1,340 pounds draw bead steel fastening pin with circular teeth in .196 dipins pulled out of hole. ameter holes.

9 .200 OD. draw bead steel fastening 1,750 pounds draw bead steel fastening pin with circular teeth, tapered pins pulled out of holes.

head so no peening needed in .195- .196" diameter holes.

We claim as our invention:

1. A draw die and a draw die bead securely fastened together, said draw die bead and said draw die having coaxial openings for the reception of a draw die bead steel fastening pin and a draw die bead steel fastening pin occupying such openings, said draw die bead steel fastening pin being hardened in the portion in contact with the draw die and being less hard in the portion in contact with the draw die bead, said hardened portion of the draw die bead steel fastening pin being serrated and in which 10 2,967,448

the serrations are constructed to favor penetration of the draw die bead steel fastening pin into the draw die and to oppose the withdrawal of the draw die bead steel fastening pin, the upper end of the draw die bead steel fasten- 4 2. The structure recited in claim 1 in which the portion of the draw die bead steel fastening pin in engagement with the draw die bead is tapered with the lesser end or the taper adjacent the draw die.

References Cited UNITED STATES PATENTS 1,978,329 10/1934 Rosenberg 85-21 2,028,528 1/1936 Sipe 852l 1/1961 Hallock 85-21 MILTON S. MEHR, Primary Examiner U.S. Cl. X.R.

ing pin being no higher than flush with the draw die bead. 15 72- 350; 8521

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