US3481143A

US3481143A - Chamber erosion preventing powder actuated tools

Info

Publication number: US3481143A
Application number: US675140A
Authority: US
Inventors: Yung Shing Hsu
Original assignee: Omark Industries Inc
Current assignee: Omark Industries Inc; Thomas and Betts Holdings Inc
Priority date: 1967-10-13
Filing date: 1967-10-13
Publication date: 1969-12-02
Anticipated expiration: 1986-12-02
Also published as: GB1217198A; DE1803000A1

Description

3,481,143 CHAMBER EROSION PREVENTING POWDER ACTUA'I'ED TOOLS Filed Oct. 15, 1967 YUNG SHING HSU 2 Sheets-Sheet l YUNG SHING HSU lA/VE'NTOR mm .m

BUCKHOR/V, BLORE, KLAROU/ST 8 SPAR/(MAN ATTORNEYS Dec. 2, 1969 YUNG SHING Hsu 3,431,143

CHAMBER EROSION PREVENTING POWDER ACTUATED TOOLS Filed Oct. 13, 196? 2 Sheetsfimen 2 FIG 6 FIG 3 YUNG SH! NG H SU INVENTOR BUG/(HORN, BLORE, KLAROU/ST 8 SPAR/(MAN A TTORA/E Y5 United States Patent US. Cl. 6026.1 17 Claims ABSTRACT OF THE DISCLOSURE A powder actuated tool has a breech portion 12 which is separable from a barrel portion 14 to permit removal of a sleeve 16 having an enlarged head 18 having a cartridge chamber 20. The sleeve 16 carries a captive piston 22 provided with an ejector pin 24 having a tapered end portion 26 adapted to engage a crimped end 28 of a cartridge case 30 to precisely position the captive piston for firing. A shoulder 32 of a cylindrical portion 34 of the ejector pin is adapted to engage the end of the case 30 after the cartridge has been fired and to positively push the case 30 out of the chamber. The rounded portion 26 provides, with forward portion 36 of the chamber, a streamlined flow for gases of explosion.

DESCRIPTION This invention relates to chamber erosion preventing powder actuated tools, and more particularly to powder actuated tools having erosion preventing ejector pins.

Some powder actuated tools of the captive piston type have had ejector pins which fit into an end of a cartridge chamber and engage the crimped ends of the cartridge cases to properly position the captive pistons for firing. When the cartridge is fired in such a tool, the gases of explosion first impinge on the end of the ejector pin and move the captive piston until the ejector pin is moved out of the chamber and then the gases expand into a larger boreat the end of the cartridge chamber and drive the captive piston on in its fastener driving stroke. As the hot gases of explosion are driving the ejector pin out of the chamber, they are deflected laterally by the end of the pin, which is fiat, against the walls of the chamber and erode the lower portion of the Walls. This erosion enlarges the lower end of the chamber and undercuts the chamber so that the cartridge case expands into the undercut portion of the chamber, sometimes beyond the ejector pin, and makes ejection of the cartridge case very difiicult.

An object of the invention is to provide chamber erosion preventing powder actuated tools.

Another object of the invention is to provide powder actuated tools having erosion preventing ejector pins.

A further object of the invention is to provide an ejector pin having a tapered end portion for engaging the end of a cartridge case to position a captive piston carrying the ejector pin and to guide gases of explosion along the chamber. Another object of the invention is to provide a powder actuated tool having a captive piston carrying a smaller ejector pin having a tapered end portion with a rounded end.

The invention provides powder actuated tools having ejector pins provided with tapered end portions adapted to engage ends of cartridge cases to locate captive pistons precisely for firing and to guide gases of explosion along the cartridge chambers with minimal lateral deflection to eliminate erosion. The pins preferably are provided with shoulders extending laterally beyond the tapered end portions and adapted to engage expanded end portions of the a fastener pin (not shown).

cartridge cases for pushing the cartridge cases out of the chambers.

A complete understanding of the invention may be obtained from the following detailed description of chamber erosion preventing powder actuated tools forming specific embodiments, when read in conjunction with the appended drawings, in which:

FIG. 1 is a side elevation view in partial section of a chamber erosion preventing powder actuated tool forming one embodiment of the invention;

FIG. 2 is a vertical sectional view taken along line 22 of FIG. 1;

FIGS. 3 and 4 are enlarged, partially sectional, perspective views of the tool of FIG. 1 showing an ejector pin thereof in a position ready for firing in FIG. 3 and in a position just after firing in FIG. 4;

FIG. 5 is an enlarged sectional, perspective view of a powder actuated tool forming an alternate embodiment of the invention;

FIG. 6 is an enlarged, partially sectional, perspective view of a powder actuated tool of the prior art with an ejector pin in a position ready for firing; and

FIG. 7 is an enlarged, partially sectional perspective view of the powder actuated tool of FIG. 6 just after a cartridge therein has been fired.

Referring now in detail to the drawings, there is shown in FIGS. 1 to 4 a powder actuated tool 10 forming one embodiment of the invention and including a breech portion 12, which is movable between a closed position relative to a barrel portion 14 and an open position relative to the barrel portion 14. When the breech portion is in its closed position, it retains a sleeve 16 having an enlarged head 18 in a bore 19 in a barrel 21, the head 18 fitting into a counterbore 23 in the barrel. The barrel is carried in a barrel housing 25. The head 18 has a cartridge chamber 20 therein, and the sleeve 16 carries a captive piston 22 provided with an ejector pin 24 having a tapered end portion 26 adapted to engage a tapered, crimped end 28 of a rimmed cartridge case 30 to precisely position the captive piston for firing. The ejector pin has an annular shoulder or laterally projecting portion 32 of a larger cylindrical body portion 34 of the ejector pin, and the shoulder engages the end of the crimped portion 28 after it has been expanded by the firing, and after opening the breech and barrel portions and removing the sleeve and the captive piston from the barrel, the captive piston is pushed rearwardly in the sleeve to push and eject the cartridge case out of the cylinder. Insertion of a new cartridge into the chamber then moves the captive piston to its firing position, and friction of a ring 38 holds the piston in this position.

The sleeve 16 and the captive piston 22 form a power plug or piston assembly, and the piston ring 38 in a groove 40 of a head 42 of the piston frictionally engages the wall of an enlarged bore 44 of the sleeve 16 to seal the piston in the bore and to hold the piston with a predetermined force against movement 'along the sleeve. The piston also has a ram or plunger portion 46 joined to the head by a tapered portion 48 and adapted to move freely through a tapered stop 50 and a reduced bore 52 to drive The tapered end portion 26 of the ejector pin 24 is frustoconical except for a rounded end or dome 60 thereof. The end 60 serves to engage the inner portions of the deeply crimped convolutions of the cartridge case 30 when the cartridge case is in its normal or unfired condition, a Wad (not shown) of the cartridge being spaced rearwardly from the forward end of the cartridge case to provide clearance. This engagement positions the shoulder 32 somewhat forwardly of the adjacent end of forward portion 36 of the chamber 20. The portion of the chamber 20 along the crimped forward portion 28 of the cartridge case tapers inwardly proceeding forwardly to the forward portion 36, which is substantially cylindrical.

When the piston 22 is in its normal position, the shoulder 32 is positioned somewhat forwardly of the forward end of the chamber and this and the fact that the portion 34 of the pin is slightly smaller in diameter than the diameter of the portion 36 of the chamber 20 provide an escape passage 70 from the chamber to the enlarged portion 44 of the bore. This permits easy escape from the chamber of the gases of explosion which are directed to the passage 70 by the domed tapered portion 26 as illustrated by the arrows in FIG. 4. The dome 60 and the tapered portion 26 direct the gases from the cartridge case primarily longitudinally of the chamber and the gases escape freely through the passage 70 so that erosion of the chamber does not occur. Also, this free initial escape of the gases causes the cartridge case to be opened only partially to leave deep convolutions in the crimped portion 38 of the cartridge case 30. After the gases enter the enlarged portion 44, they push the piston 22 forwardly to drive the fastener (not shown). Exhaust ports 72 are provided in the sleeve 16 to remove the drive of the piston after the head 42 has moved to the exhaust ports. Preferably the ejector pin and the captive piston are separate elements with the portion 34 of the ejector pin being drive fitted into a bore 76 (-FIG. 3) in the piston 42.

EMBODIMENT OF FIG.

A powder actuated tool 110 (FIG. 5) forming an alternate embodiment of the invention is like the tool (FIGS. l-4) except for a captive piston 122 thereof which differs from the captive piston 22 in that an ejector pin 124 is integral with a piston portion 142, the captive piston 122 being forged. The piston 122 has a fillet 125 and a somewhat rounded head end 127. The ejector pin 124 has a cylindrical portion 134 having a planar annular shoulder 132 and a tapered or generally conical end portion 126 having a rounded or domed end 160 and identical with the end portion 26 and its domed end 60. A sleeve 116 identical with the sleeve 16 as a chamber 120 with a forward end portion 136 and adapted to receive a cartridge case 130 identical with the cartridge case 30. The sleeve 116 has an enlarged bore 144 closely and slidably receiving the piston portion 142 which has a ring 138 which seals and grips the wall of the bore 144.

The ejector pin 124 engages crimped end 138 of the unfired cartridge case 130 to precisely position the piston r 122 for firing, and the adjacent ends of the cylindrical portion 134 and the forward portion 136 of the chamber define an escape passage 170 for the gases of explosion which prevents build-up of excessive pressure of the gases in the chamber and allows the gases to flow from the cartridge chamber with large components longitudinally of the chamber rather than transversely against the walls of the portion 136 of the forward portion 136 of the chamber. This substantially completely eliminates erosion of the walls of the chamber 136.

PRIOR ART OF FIGS. 6 AND 7 A sleeve 216 shown in FIG. 6 in a new or unused condition and in FIG. 7 after a number of firings which should be only a small fraction of the number of firings possible therewith but in which a forward portion 236 of its chamber 220 has been eroded excessively because of its use with a prior art ejector pin 224 of a captive piston 222. As shown in FIGS. 6 and 7, the ejector pin 224 has a flat end 232 and fits closely in the forward portion 236 of the chamber and initially engages crimped end 238 of a cartridge case 230 like the cases and 130 to properly position the captive piston 222 in the sleeve 216. When the cartridge is fired, the crimped end 238 opens,

the gases of explosion from the cartridge case impinge of the flat end 232 and are deflected laterally as shown by arrows 231 against the walls of the end portion 236 and erode the portion 236 to its condition shown in FIG. 7. Also, while the ejector pin has a flat or relieved portion 233 providing some escape, this does not adequately relieve the excessive pressures of the hot gases, such relief occurring only after the piston has been moved forwardly sufficiently to move the pin 233 substantially beyond the forward end of the chamber. The erosion creates an undercut shape of the chamber and the high explosion pressures tend to expand the crimped end under overhanging edge 239 to make ejection of the cartridge case very difficult. This is contrasted with the tools 10 and in which the gases are directed longitudinally of and out of the chambers so that the pressures are not excessive and erosion does not occur.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. In a powder actuated tool,

a captive piston,

an ejector pin having a tapered breech end portion and secured at its other end to one end of the piston, and piston guiding means having a bore and a cartridge chamber at one end of the bore,

the ejector pin in a firing position being positioned by the piston adjacent to a cartridge in the chamber and in alignment with the cartridge chamber and spaced from the cartridge chamber for guiding along the forward end portion of the chamber gases of explosion from the cartridge in the chamber and means on the ejector pin and adapted to push the case of the cartridge rearwardly in the chamber after firing.

2. The powder actuated tool of claim 1 wherein the breech end portion of the ejector pin is rounded at its tip.

3. The powder actuated tool of claim 1 wherein the ejector pin includes an annular end surface surrounding the tapered breech end portion adapted to engage the end of the case of the cartridge.

4. The powder actuated tool of claim 1 wherein the cartridge chamber is longer than the cartridge and the tapered breech end portion of the ejector pin extends into the cartridge chamber and engages the forward end of the case of the cartridge when the captive piston is in its firing position.

5. The powder actuated tool of claim 1 wherein the portion of the bore adjacent the forward end of the chamber is substantially larger than the forward end of the chamber and the tapered breech end portion of the ejector pin and the forward end of the chamber define an escape passage from the chamber to the bore when the piston is in its firing position.

. 6. The powder actuated tool of claim 5 wherein the escape passage is annular.

. 7. The powder actuated tool of claim 5 wherein the ejector pin includes a radially projecting portion at the forward end of the tapered breech end portion for engaging the case of the cartridge for pushing the cartridge rearwardly in the chamber.

8. The powder actuated tool of claim 1 wherein the cartridge chamber and the bore are centered relative to each other and the ejector pin and the captive piston are centered relative to each other.

9. The powder actuated tool of claim 1 wherein the tapered breech end portion of the ejector pin is adapted to extend partly into a crimped end of the case of the cartridge when the case is in unfired condition.

10. The powder actuated tool of claim 3 wherein the annular end surface of the ejector pin is positioned forwardly of the forward end of the chamber when the cartridge is positioned fully in the chamber and the tapered breech end portion of the ejector pin is in engagement with the forward end of the case of the cartridge,

the portion of the ejector pin extending forwardly from the annular end surface being adapted to fit closely and slidably in the forward end portion of the chamber.

11. In a powder actuated tool,

a barrel having a bore,

breech means,

a cylindrical sleeve adapted to be inserted into and removed from the breech end of the barrel and having a rimmed cartridge chamber longer than a cartridge case insertable thereinto and having a forward end portion of a predetermined diameter extending forwardly from the forward end of the cartridge case when the cartridge case is fully inserted into the chamber,

th cylindrical sleeve having a bore of a diameter substantially larger than said predetermined diameter and extending from the forward end of the chamber to the forward end of the sleeve,

a captive piston having a piston portion fitting closely and slidably in the bore,

and an ejector pin secured to the breech end of the piston and having a cylindrical body portion adapted to fit slidably in the forward end of the chamber,

the ejector pin also having a breech end tip portion at the end of the body portion,

the breech end portion of the ejector pin being smaller at the tip thereof than at the end thereof adjacent the body portion.

12. The powder actuated tool of claim 11 wherein the breech end portion of the body portion of the ejector pin extends radially outwardly from the tip portion to define a shoulder for engaging the end of the cartridge case and push the cartridge case rearwardly along the chamber.

13. The powder actuated tool of claim 12 wherein the shoulder is annular.

14. The powder actuated tool of claim 12 wherein the tip portion is of a size such as will extend only partially into a crimped end portion of the cartridge case when the case is in unfired condition and will extend fully into the case when the case has been fired.

15. In combination,

barrel means having a chamber portion,

charge means positioned at the rear of the chamber portion,

and a cylindrical member fitting closely in the barrel means and having a conical rear end portion tapering from a predetermined diameter at its forward end to a second diameter no greater than a small fraction of said predetermined diameter at its rear end and adapted to spread gases of combustion as the cylindrical member is driven along the barrel means, the conical portion having a transverse cross sectional area such that it is spaced laterally from the chamber portion when a rear most firing position adjacent the charge means, and the rear most position of the conical portion is less than one-half of the diameter of the corresponding chamber portion when the member is in a rear most firing position.

16. The combination of claim 15 wherein said conical rear end portion is substantially fully conical.

17. The combination of claim 16 wherein the rear end of said conical rear end portion is rounded.

References Cited UNITED STATES PATENTS 3,064,262 11/1962 Kopf et al 227l0 3,119,289 8/1965 Ramsay et al -26.1 3,204,400 9/1965 Kvavle 6026.1

CARROLL B. DORITY, 1a., Primary Examiner US. Cl. X.R. 22710 Po-ww UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3.48l.143 V Dated ngg h z 2 1269 Inventofls) Yung ng vfiSl-l It is certified that error a'ppears 1n the above-identified patent and that said Letters Patent are hereby corrected as shown below:

ColunTn 3, line 43, "as" should be has Column 4, line 2, "of" should be on In the references,"Ramsay et 2.1 3,119,289" should be Ramsay et a1 3,199,289

SIGAED AND SEALED FEB 2 4 1970 (SEAL) Amt:

- M M, Fletcher, 11'' I E mm x. soaumn, Atteslmg Officer missienar of Patent