1. A SHELL CASING FOR AN EXPLOSIVELY-OPERATED TOOL COMPRISING: A HOLLOW, GENERALLY CYLINDRICAL MEMBER HAVING AN INTERNAL SURFACE AND AN EXTERNAL SURFACE, SAID INTERNAL SURFACE HAVING A CONSTANT DIAMETER, SAID EXTERNAL SURFACE DEFINING A FRUSTO-CONICAL CONFIGURATION AND INCLUDING A SERIES OF CIRCUMFERENTIAL RIBS, A WALL MEMBER CLOSING ONE END OF SAID CYLINDRICAL MEMBER, THE OTHER END OF SAID CYLINDRICAL MEMBER BEING OPEN, SAID CYLINDRICAL MEMBER BEING INTEGRALLY FORMED OF PLASTIC MATERIAL, EACH OF SAID RIBS TAPERING FROM A MAJOR THICKNESS PROXIMATE TO THE ONE END
March 16, 1965 w. F. BROSKE 3,173,359
EXPLOSIVE SHELL FOR POWDER ACTUATED TOOL Filed Nov. 23, 1962 2 Sheets-Sheet l Ii [III i: 1o 4 -P,
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Filed Nov. 23, 1962 2 Sheets-Sheet 2 INVENTOR.
(J man F. BROSKE United StateshPatent Ofitice 3,173,369 Patented Mar. 16, 1965 3,173,369 EXPLOSIVE SHELL FOR POWDER ACTUATED TOOL William F. Broske, Camp Hill, Pa-, assignor to AMP Incorporated, Harrisburg, Pa. Filed Nov. 23, 1962, Ser. No. 239,618 2 Claims. (Cl. 10238) This application constitutes a continuation-in-part of my prior application, Serial No. 206,768, filed July 2, 1962, now abandoned.
In the use of powder-actuated tools for industrial purposes, it has been discovered that a plastic shell having a plastic plug and an explosive charge may be utilized to retain the high combustion gases within the shell during the firing cycle, as described in my'prior application, Serial No. 793,814, filed February 17, 1959, now Patent No. 3,007,409.
This type of shell has been found particularly useful in devices for pressure-forming electrical connectors onto conductors, as described in a prior application, Serial No. 172,183, filed February 9, 1962. However, in industrial tools of the type described, it has been found that the presence of a grease or a lubricant on the outer surface of the plastic shell may tend to cause the shell to rupture during the firing cycle. It has not been completely established why this result occurs under these conditions, but it may be that the ungreased shell is frictionally constrained from outward flow by the chamber of the barrel. The presence of grease or lubricant may reduce this frictional constraint, thus permitting sufiicient extrusion of the plastic to cause rupture.
Whatever the reasons, I have discovered that if the outer surface of the shell is tapered so that the crosssection is thicker at the base and thinner at the open end, and the firing chamber is similarly tapered, rupture of the shell is prevented even when the shell is coated with grease.
One embodiment of a shell made according to the teaching of the invention includes a tapered shell having fluted ribs on the outer surface to effect the taper. This reduces the amount of material required to make the shell, as well as dissipating the shock wave of the explosion.
Thus, it is an object of this invention to provide a plastic shell of the type described, which will not rupture during firing even though coated with grease. It is also an object of this invention to prevent the shell from rupturing during the firing cycle by tapering the thickness of the shell in cross-section. I have also discovered that providing a tapered shell to fit into a tapered firing chamber increases the facility with which the shell may be removed. This is particularly true in industrial tools where the plastic shell may be expanded during the operation of the tool.
Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there are shown and described illustrative embodiments of the invention; it is to be understood, however, that these embodiments are not intended to be exhaustive nor limiting of th e invention but are given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.
In the drawings:
FIGURE 1 is a perspective view, partially cut away, illustrating one embodiment of the invention;
FIGURE 2 is a cross-sectional View taken along plane 22 of FIGURE 1;
FIGURE 3 is a sectional view taken along plane 33 of FIGURE 1;
FIGURE 4 is a fragmentary view showing the device of FIGURE 1 fitted in a firing chamber of an industrial tool;
FIGURE 5 is a perspective view of another embodiment of the device incorporating the principles of the invention;
FIGURE 6 is a view taken along plane 6-6 of FIG- URE 5; and
FIGURE 7 is a sectional view taken through plane 77 of FIGURE 6.
One embodiment of the invention (FIGURE 1), the shell casing, generally designated C, includes a base member 10 which is in the form of a disk closing off one end of a cylindrical member 12. The disk 10 and cylinder 12 may be integral. The preferred embodiment is achieved by molding the casing from polyethylene. The disk 10 has a flange 14 projecting outside the surface of the cylinder to permit the shell to be retained in a tool.
Also, as shown in FIGURE 1, the inner surface 16 of the casing C has a constant internal diameter. The outer surface has a larger external diameter at the base portion 18 than at the nose portion 20. Thus the outer surface provides a tapered, frusto-conical configuration. As shown in FIGURES 2 and 3, the thickness of the cas ing in the base portion 18 is greater than the thickness of the casing at the nose portion 20.
In addition to the casing, the shell comprises a plug 22 (preferably of polyethylene) which has an outside diameter forming a friction-fit with the inside surface of the casing 16. The plug 22 has a primer 24 on its exterior surface, a central axial opening 26, and a circular aperture 28. When the shell is assembled (as shown in FIG- URE 1), an explosive charge 30 is located within the easing adjacent the inner surface of the disk 10 and retained in place by plug 22.
As shown in FIGURE 4, the shell is adapted to fit into a firing chamber 40 of an industrial tool (e.g., as shown in the prior application, Serial No. 172,183, filed February 9, 1962), having a cap 44 secured to the end thereof, and a ram 46 adapted to fit into the cylindrical shell. A firing pin 48 on one end of the ram is adapted to strike the primer 24 to actuate the powder charge.
As shown in FIGURE 4, the firing chamber 40 has an inner tapered surface 50 which corresponds to the taper on the outer surface of the casing C. When the ram 46 is driven against the primer 24, the primer explodes to ignite the powder charge 30. The powder charge 30 drives the plug 22 toward the nose portion 20 of the casing C, and thus drives the ram 46 ahead of it to operate the device.
A pin 52 may be located in the cap 44 to release combustion gases, as described in my prior application, Serial No. 164,756, filed January 8, 1962.
Another embodiment of the invention, as shown in FIGURES 5-7, includes a casing C with a base member 10' closing one end of the cylinder 12. The disk 10' also has a plane 14' having an inner surface 16' of a constant internal diameter. As shown in FIGURES 6 and 7, the tapered outer surface comprises a plurality of ribs 18' which provide a fluted or scalloped cross-sectional configuration. The ribs 18' taper from the base 10' toward the nose portion 20 of the casing C, at which point they blend into the outer surface of the cylinder 12'. As shown in FIGURE 6, the thickness of the cylindrical member 12' is constant when measured at the low point between the ribs 18'. However, when the thickness is measured across the ribs 18', the exterior surfaces of the d ribs converge from a maximum thickness at the base 10 to a minimum thickness at the nose portion 20.
The shell, shown in FIGURES 57, also comprises a plug 22', with a primer 24, and axial opening 26', circular apertures 28' and an explosive charge 30' all assembled in the same fashion as disclosed in the embodiment of FIGURES 1-3. The casing C may be inserted into a tool and fired in the same manner as illustrated in FIGURE 4.
Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art. 1
1. A shell casing for an explosively-operated tool comprising: a hollow, generally cylindrical member having an internal surface and an external surface, said internal surface having a constant diameter, said external surface defining a frusto-conical configuration and including a series of circumferential ribs, a Wall member closing one end of said cylindrical member, the other end of said cylindrical member being open, said cylindrical member being integrally formed of plastic material, each of said ribs tapering from a major thickness proximate to the one end of the cylindrical member to a minor thickness remote from the one end, an explosive charge in said cylindrical member adjacent the one end, a plug in said cylindrical member retaining said explosive charge in place, a surface of said plug facing the open end of the cylindrical member, and means in said plug for igniting said explosive charge.
2. A casing according to claim 1 wherein the thickness of the cylindrical member between the ribs is constant.
References Cited in the file of this patent UNITED STATES PATENTS 1,233,071 Lindquist July 10, 1917 1,940,657 Woodford Dec. 19, 1933 2,953,990 Miller Sept. 27, 1960 3,007,409 Broske Nov. 7, 1961 FOREIGN PATENTS 884,934 Great Britain Dec. 20, 1961