Lobular pin

Details

Inventors: Ferguson, Peter J.;
Assignee: Research Engineeering & Manufacturing, Inc. (New Bedford, MA)
Primary Examiner: Kundrat; Andrew V.
Assistant Examiner:
Attorney, Agent or Firm: Olson, Trexler, Wolters, Bushnell & Fosse, Ltd.

A pin has a pilot point of uniform width throughout 360.degree. and a body containing a cross section of arcuate polygonal lobular configuration, also of uniform width but wider than the point. The pin may be driven into a circular hole in a member such that the lobes of the pin are elastically deformed in compression to enhance the grip between the pin and the member and with there being regions of stress relief on the member intermediate the lobes. The hole in the member may also be reshaped into a lobular form. The uniform body width approximates the minimum diameter of the hole in the member. Furthermore, the pin is of a range of lobulation sufficient to span a wide range of hole diameter tolerances.

DETAILED DESCRIPTION Referring now more particularly to FIGS.
1 and 2 there is shown a pin 2 having a pilot point 4 and a body 6 both of which are centered on a longitudinal axis 8.
The point 4 is a circular cross section.
The point 4 joins the body 6 through a conically tapered transitional section 10.
The body 6 is of an arcuate, lobular polygonal configuration and comprises an odd number of lobes which are separated by relatively long arcuate sides.
In the form of the invention herein shown there are three lobes 12,14,16 which are separated by arcuate sides 18,20,22.
The radii of the lobes are substantially less than the radii of the arcuate sides as will be apparent from FIG.
2.
The basic geometry of the lobular form or cross-section is shown in FIG.
10.
Such form is generally known from U.
S.
Pat.
to Phipard, Jr.
No.
3,195,156, dated July 20, 1965.
Suffice it to say that the out of round or lobulation K is the difference between C and D where C is the diameter of the cirle in which the lobular cross section is inscribed.
The short radius r of each lobe 12,14,16 is centered at an apex of a basic equilateral triangle having a side 24 equal to R-r and inscribed in a circle centered on the axis 8 and having a radius N.
The long radius R of each arcuate side 18,20,22 is at an apex that is most remote from the arc or side to which the radius R relates.
Each lobe 12,14,16 extends over an arc (having radius r) of 60.
degree.
and side 18,30,22 extends over an arc (having radius R) of 60.
degree.
.
The dotted lines 26 each extends through the center of the equilateral triangle, and also through an apex thereof, and the peak or center of a lobe.
The points 28 and 30 designate the ends of a lobe (e.
g.
lobe 16) while the points 28 and 32 designate the ends of a side (e.
g.
side 22).
From FIG.
10 it can be derived that R = 0.
5C + N-K.
It is also known that: 2N = (R-r)/Cos 30.
degree.
= 2N-K/Cos 30.
degree.
; therefore N = 3.
732K and therefore, R = 0.
5 C + 2.
732K and r = 0.
5C - 3.
732K From the above formulas the values of R and r may be computed for given values of C and lobulation K

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