CA1268939A - Detonation-gas apparatus for applying coatings - Google Patents

Abstract

DETONATION-GAS APPARATUS FOR APPLYING
COATINGS
Abstract The essence of the invention resides in that the apparatus comprises a gas distribution unit for distributing inert gas, oxidant and fuel gas, and has a cylinder provided with a headpiece. Walls of the cylinder have ports communicating its interior with gas sources, whereas the headpiece includes passages to convey gases from the interior of the cylinder to a barrel.

Description

:~2~1~939 FIELD ~F T1~ INVEl~TION

~ his invention relates generally to apparatu~-es ~or ~praying and applying coating~ to surfaces of bodies, and more particularly to detonation-gas apparatu~ for applying coatings to surface~ of bodi-es~
r~he invention can find application for applying rnetal, ~.etal-ceramic, oeramic, wear-resistant,heat-re~i~tant, electroinsulatin~, electroconducting andother ~ypes of coatin~s to maohine part~ and equip-r~nt of variou~ de~i~nation. In addltion, ~he ~ppa-ratus embodying the preGent iqlvention can be used ~or 2rindin~ powder materials, cleaning and local heatin~ o~ surfaces, welding so~ non-metal materi-als and piercing holes in them, obtaini~ powders with new properties, producing structural changes in the surface layer~ of material~, and alse~here.
At present~ the ever increasin~ specific loads exerted on working surfaces, higher temperatures to which machlne part~ are subjected during opera-tion, and more corrosive~ atmosphere in which they operate call for improved quality of cOatlngs ap-plied by utilizing detonation waves, as well as :~
rnore e~icient methc)ds and device~ for coatin~ ap-plicationA ~hese requlremen~s are met by a numbér .. : ~ :
of prior art apparatuses. ~ ~
~; ' For example, there i known an apparatus for - ? - ~

, `, ~26~39 applying coatings to surface~ of bodies ~tilizing de-tonation gas ~ave B (C f., U.S. Pat. No~ 3,150,828, Cl. 239-79, published 1964). ~his apparatus compris-es sources o~ fuel gas, oxidant and inert gas, a 5 gas distribution unit connected to these sources by way of gas conduits, a gas flow :restricting me-ans having a ~as conduit for connecting with the gas distribution unit, a powder sprayer, a Darrel, a system for igniting the ga~es, and a cam mechani~m 10 cooperating with the gas distribution unit and with tl~ ~a~ ignition ~y~tem. In this apparatu~ the g~s d~stribution unit includes three valve arxang~ement~, for each gas seF)arately, each euch valve arran~ement Q
comprising a val~e having a valve head and a spring-15 loaded valve ~tem secured in a guide sleeve provid-ed in the housing of the gas distribution unit. In order to ensure reliable valve operation an~ pre-vent &ases from leaking through the guide sleeve and valve seat, it i~ necessary to provide a high-20 ly accurate fit o~ the va~ve ~tem in the sleeve andsetting of the valve head on the valve seat. Open-: ing and closing of the valves iB done here by the cam mechanism in the form of two cams with substan-tially flet tappets, the CamB being secured on a 25 common shaft ~hich also carries a belt drive pulley and ~ oam o~ the ignition system interrupter. Such . .
a cam mechanism needs precise timing to adjust the ~ ':

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working cycle. In addition, the housing of the gas di~tribution unit i8 provided with ca~ities to ac-commodate the valve heads in lifted position.
~ 'lhen inert ~a~ i8 passed throu~h these cavitiest the velocity of gas the ~low drops to result in the Yormation of stagnation zone~ occupied by ~ mixture o~ inert gas and detonatable constituent~, which prevents proper purging of the gas distribution unit.
When feedin~ thc constituents of detonatable mix-ture, o~idant and fuel gas are vigorously mixedYJith nitrogen present in the valve cavitie~, ~here-by a ]o~r~ quality mixture with retarding add:Ltiona o~ inert ga~ (vi~., nitroge~ obtained. In ord-er to obviate this disadvanta~e, it i8 necessary to increa~e the ~low rate~ of both the inert gas to purge the oxidant and ~uel gas from the valve cavi-tie B and the oxidant with the fuel gas to purge ni-trogen from these cavities. Another di~adv~ntage of such gas di~tribution resides in that the jet of gas flo~ing along the tapered generating line of the val~e head actively mixes with the gases pre-sent in the valve cavity rather than sweeps them out.
In addition, the ~as ~lo~ restrictin~ means :
;~ 25 is connected to the barrel by means of t~o counter-flow gas conduits, which fail to s~/eep the spent inert ga~es ~rom the barrel~when the detonatablé
mi~ture is admitted, but~which promote mixing of . ., detonatQble constituents with the inert gases. This entsils poor quality of the detonatable mixture, low purging efficiency, and inaccurately metered fill-ing of the gas flow restricting means of the gas S blanketing arrangement prior to detonation to result in increased ~low of working gases, impaired effici-ency of the apparatus and low quality coatings.
SU~RY 0~ ~`HE Il~'IO~
It is therefore an object o~ the present in-ventlon to obviate disadvantages inherent in theprior art device~ and provide a novel axld improved detonation~~ apparatu~ for applying coating~ to su~aces o~ bodie~, Another object is to provide an appsratus which would use less working gases for its opera-tion.
One more object is to provide an apparatus hich would be highly efficient and ensure hi~h qua-lity coatings.
Yet another object is to provide an apparatus which would be simple in ¢onstruction.
; These and other objects and ~ttending advant-ages are attained by that in a detonation-gas appa-ratu~ for applying coatings to surfaces of bodies comprising a barrel with a spark plu~, a spra~er of powder materials arranged inside the barrel, source~ of fuel gas, oxidant, and inert gas, a gas '' .

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di~tribution unit connected to the gas ~ource~, a 8as flow restricting means communicating with the gas di~tribution unit and with the barrel7 an igni-tion systern for detonating the gases in the barrel;
and a cam mechanism cooperating wi.th the gas dis-tribution unit and with the ~as ignition system, according to the invention, the gas distribution unit includes a cylinder ~lalls of which are provid-ed with rad.ial ports arranged in three ro~s in terms of hei~ht thereo~ to col~nunicate the interior o~ the cylinder with the ga~ ~ource~, the cyl.i~der havin~ a headpiece with pa~sage~ to convey the ~a~-es from the intel'ior of the cylinder to th~ barrel through the gas flow restricting means, and a pis-ton arranged in the interior o~ the cylinder to re-ciprocate and cooperate with the cam mechanism~
: Thanks to such a structural arrangement, the inert ga~ conveyed from the source of inert gR~
to th~ barrel has along its travel path practical-ly no stagnatio~ zones and cavitie~ o~ ~ubs-tantial capacity, because the only cavity in the cylinder above the piston ha~ at this point in time a rnini- :
: mum volume deterr~ned by the intermediate position : : of the piston, ~ld there~ore the interior o* the ::
: 25 .cylinder is easily purged by:several gas streams lowi-ng frorn the ~Jal~B o~ the cylinder to the cent-er o~ the headpiece. This in turn provide~ a poa- :
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lZ~3939 sibility to u~e small quantities of inerb gas fDr purging the detDnatiD~ chamber subsequent to detona tiDn and the gaa flDw restricting mea~s priDr bD detDtla-tiDn~ which res ~ts in imprDved purging effieicienc~.
~he cDnstituents of the detonatable mixture, viz.
Dxidant and fuel gas, entering bhe barrel after tha inert gas alDng the tubular gas conduibs are admitb-ed to the inberiDr of the c~linder abDYe the pis~Dn during tbe 1DW PDSitiOn assumed by the piston when the cylinder interior is expanded; however, the vo-lumes used Yor prDviding a detDnatable mixture Df these gases considerably exceed the volume Df tbe cylinder interior, whareas the gas sbreams flowing frDm the walls of tha c~linder tD the center of the headpiece promptly sweep bhe remnants of nibrogen away. In addition, b~ virtue of the facb that the pressure of gases present in the cylinder interiDr is somewhab lower bhan that in the passages of the cylinder, gases at various pressures ca~ freel~
pa9s tharebbrougb; i~ otber words9 no resistanGe to the g~ses at lDwer pressures is produced. It is therefore possible to obbain ~ high-qualiby com-po~ition of tbe debo~atable~ mixbure containi4g ne-gligeable amGunts of foreign constituenbs which mig~t weaken detonationO
Preferably, half of the pDrt8 in the row Df : : pDrts remote ~rDm the he~dpiece communicate wib~
th~ sDurce of inert gas, whereas the other hslf of r . --. --. .

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~26~939 the ports in thi~ row o~ ports communicate with the ports in the roY~ of ports adjacent the headpiece;
one port in the middle row of ports co~municate~
with the source of fuel ~as, whereas the other ports in thi~ row of ports cor~municate with the ~ource of oYidizing ga~.
~ hanks to ~uch an arrangementj-the constitute9 of the detonatable mixture are fed to the ports of the middle rovJ of port~ of the cylinder at a pres-sure ~ubstantially below the pres~ure of the inert~as and invariably from above, whereas from helow the~e detonatable constitutes are surrounded or blanketed by the inert ga~ -to thereby prevent the e~cape of the detonatable mixture outsi~e. ~his re-sult~ in higher explcsion sa~ety and more effici-ent operation.
It is further advisable thst the pi~ton would -have ~itted thereon elastic ~eal rings end ~aces of which have the form of tapered concave ~urfaces, and interpo~ed betNeen the~e seal rings spacer rings and ga~-valving ring~ end faces of which have the form of tapered convex surfaces correcponding :to the tapered ~ur~ace~ of the seal rings, the piston preferably carrying a nut adjacent t~e ~aal : 25 rine and serving to adjust a clearance between the cylinder and seal rings7 the gas-valving rin~ al.so . .
~ havin~ a groove at the outer ~urface thereo~ to en-: . - 8 -'.'.-- : : . .

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~ure the pas~a~e of inert gas from its source to the port~ in the row of port~ adjacent the headpiece of the cylinder.
By virtue of the above piston arrangement 9 it is possible to maintain a r~nimum clearance between the cylinder and ~eal rings of the piston to ensure free travel of the oiston and prevent rnixin~ of the constituents through this clearance. Thi~ results in an improved compo~ition of the detonatable mig ture of ga~es, which in turn enables to consume les~
arnounts of workin~ gases and obtain hi~ller quality coatings .
Desirably, the ga~ di~tribution unit compri~es a ~eallng connection of the pi~ton with the head-piece of the cylinder formed by annular projectionspro~ided at the end face of the pi~ton and annular recesses at the end face of the headpiece in the interior o~ the cylinder.
Such~ ealing-connection provides a local hydrodynamic resistance to soften the back-flash of gase B prOpagatin~t from the detona-tion chamber through the g&s flow restricting rneans to the gas distribution unit resulting in a more efficient operation of the apparatus. ~
~avourably, the carr mechanism engageable ~ith the piston comprise~ a cam of such a shape as to provide the travel of the piaton to succes~i~ely g _ :
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~Z~8~339 open and close the ports in the cylinder in accord-ance with the working cycle pha~esc This arrangement makes it po~sible to dispense with bringin~ into synchroni~m several cams to ad-just the cycle, since the sequellce and timing of thecycle are gueranteed by the configruration of a sin-gle cam; a chan~e in the rotational speed of the cam ent~il3 corre~ponding variations in tlnling. Thi~ i~
advantageous, because the frequency of detonation pul~es can be varied within a wide range to again nake the apparatu~ more effioient.
Advi~ably, the ~ag flow re~trictin~ menns com-F~ es ga~ conduits arranged tangentially ~o the croes-~ection of the barrel and co~!unicating the 15 interior o~ the cylinder through the passages of the headpiece ~ith the barrel.
~ he tan~ential positioning of the inlet of the gas conduits in the detonation chamber o~ the bar-rel promotes the formation of a stable vortex flow of gases which act9 to ~weep by its wave front the ~pent and inert ga~es while failing to mix there-with behind the wave front line. It is for -this re-: ason tha-t the detonatable mi~ture fed to the barrel contains negligeable amounts of detona.tion-retard-ing ingredients, whereby high-power detonatlon~puls-es are developed to re~ult in improved quality of : : coatings and higher production efficienc~. :
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BRIEF DESCRIPTIOI~ 0~ DRAWIl~GS

The invention will now be dec,cribed in greater detail with reference to a ~peci~ic embodirnent thee reof taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a longitudina~ ~ectional vlew of a delonatiGn-~as appar&tus ~or applying COatingB to surfaces of bodies according to the invention;
Fig. 2 is a lon~itudinal section illu~trating the po~ition of a pi~ton in a cylinder duri.n~ the ~dmi~ion o~ inert gas to tlle interlor o:E the oylind-er;
. Fig. 3 i5 a longitudinal sectional view of the position a~sumed by the piston in the cylinder dur-in~ the admi3sion to the interior of the cylinder of fuel gas and oxidant;
Fig. 4 is an e~larged sectlon taken along the line IV-IV in Fig. 1; and Fig. 5 i~ an enlarged view taken along the line V-V in Fig. 1.
13EST MODE 0~ CAR~YING (:)UT THE INVl~l~lTIOI~
De~scription in ~he Statics he propos~d detonation-gas apparatu~ for ap-25 pIying coatings to surfaces of bodie~ represented ~ .
in Fig. 1 Co~priBes: a water-booled barrel 1: hayin~ :
an acceIeration portion 2~and a detonation chember;

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3 acco~nodating a ~park plug 4; a feeder 5 of powd-er materials including a meterin~ mean9 6 and a sprayer 7 a~ranged in6ide the barrel 1; a source 8 of inert gas, a source 9 of oxidizing ga9, and a source 10 of fuel gas; a gas distribution unit in-dicated at 11 and connected to-the ~as sources B, 9 and 10; a gas flow restricting mean~ 12 communica- .
ting with the ga~ distribution unit 11 and with the barrel 1; an ignition system for detonating gase~
in the barrel 1 includin~ a dir~ct current source 13, a voltage transformer 14, and a current inter-rupter 15 electrically wired to the spark plug 4;
and a cam mechanism cooperatillg ~Jit~ the g~ dis-tribution unit 11 and gaB lgnition ~y~tem.
According to one feature of the invention, the gas distribution system 11 compriseæ 2 cylinder 17 (Figs 2 and 3) termi~ating-in a headpiece 18, and a piston 19 arranged in interior 20 of the cy-linder 17 with a clearance to ensure that it reci-procates and cooperates with--the cam mechanism 16.
~ '~alls 21 of the cylinder 17 have radial ports 22, 23 and 24 communicatin~ the interior 20 of the cylinder 17 with the as sources B, 9 and l0 and arranr~ed in three rows in terms of the height of the cylinder 17~ Each ~uch ro~ ha~ at lea~t two : ports. Alternetively,:~each such roy may lnclude any even number of port~s~
.
~ 12 -~268~3139 The headpiece 18 has a central passage 25 and radial passages 26 for the ga~es to flow from the interior 20 of the cylinder 17 to the barrel 1 thro-ugh the flow re~tricting means 12.
~1alf of the ports 22 in the row of portR remote from the headpiece 1~ communicate by vJay of a gas conduit 27 (~ig. 1) with the source 8 of inert gas, whereas the other half of the ports in this row com-municate in pairs with the ports 24 in the row of ports adjacent the headpiece 18 by way of a gas conduit 28. One p~rt 23 in the middle ro~ of ports communicates through a gas conduit 29 with the 80-urce lO of' fuel ~a~, the other port~ 23 of thi~
middle row cor~nunicatine by way of a gas conduit 30 with a source 9 of oxidizing gas.
~ itted on the piston 19 are seal rings 31, spac-er rings 32 interposed between the seal rings 31, and a gas-valving ring 33, all these rings being ; drawn together by a nu~ 34 having a stop 35 and serving to adjust the clearance between the cylind-er 17 and seal rings 31.
~ nd faces 36 of the seal rings 31 have the form of concave tapered surface~, whereas end faces 37 and 3~ of the spacer rings 32 and gas-valving ring 33~ respectively3 have the form of convex tapered surfaces correspondlng~to the tapered surfQces of the end ~aces 36 of the~seal ~rings 31. Provided ~ 13 -', ~
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at the outer surface of t~e gae-valving rin~ 33 is a groove 39 intended to ensure the pas~age of inert gas from the ~ource 8 thereof to the ports 24 in the cylinder 17 adjacent the headpiece'18.
The gas di~tribution unit 11 comprises a sealing connection bet~een the pi~ton 19 and headpiece 18 of the c~linder 17 which is defined by annular pro-jections 40 (~i~s 2 and 3) provided at the end face of the piston 19, and annular reces~es 41 made at the end face of the headpiece 18 in the interior 22 of the cylinder 17.
rrhe oam mech~ni~m 16 cooperatin~ with the pi~ton 19 includes a cam 42 (Fig. 1), a push rod 43 w.ith a roller 44, and a ~pring 45. ~he cam 42 i8 rotated 15 by an electric motor 46 through a reducing gear 47 and ha~ a shape which en~ures such a travel of the piston 19 as to succe~sively open and close the ports 22, 23 and 24 in the cylinder 17 according to the working cycle phases9 for which purpose it i9 de-20 fined '~y three arcuate sur~ace~ 48 and four interme-diate surface portions 49. Angles of the arcuate surfaces act to execute -the cycle timing~
~ 'he flo.J restricting mean~ 12 include3 gas con-duits 50 (Fig. 4 ? arranged tangentially to the cro~-25 section of the barrel 1 and communicating the interi-or 20 of the cylinder 17 wi-th the barrel 1 through : the passage~ 25 and 26 of the headpiece 18 :~ - 14 -. ............. . ..

~ 39 Operating Principle ~he propo~ed apparatus operates in the follow-ing manner.
Inert ga~, oxidizing gas and fuel gas are ad-mitted9 a~ ~hown in Fig. 1, to the port~ 22, 23 and 24 of the gas distribution unit 11 through the ga~
conduits 27, 29 and 30, re~pectively.
When the cam 42 i9 rotated, the piston 19 is caused to move down by the spring 45 to open the radial port~ 24 in the row of port~ adjacent the headpiece 1fl, while ~imultaneou~ly regi~tering the ga~-~alv.in~ rin~ 33 with the radial port~ 22 :Ln the row of ports remote from the lleadpiece 18. ri`here-after~ the pi~ton 19 stops temporarily in the in- :
terrnediate po~ition, and within thi~ space of time the inert gas N2 (Fi~ 1 and 2) flo~s from the in- :
ert gas source 8 along the ga~ conduit 27 to the interior 2~ of the cyIinder 17) pa~es throu~h th~ gas-valving ring 33 (Fig. 5) to e~cape from the interior 20 of the cylinder 17 and then be again received by ths interior 20 o~ the cylinder 17 through the port~-24. The gas flows further al~
.
o~g~the pa~ages 25 and 26 in the headpiece 18 of : 25 the cylinder 17 to be divided into t~llo streams and enter throueh the flov~ res~ricting~ means 12 :
alon~ the tangential conduits 50 I~ig. 4) the detonatlon ohamber 3 of the barrel 1 (Fig. 1), - 15 - :

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where it is swirled to svJeep by the ~tream ~ront detonation gases out of the chamber and thus exe-cute the pur~ing phase.
The cam 42 continues to rotate, and the piston 19 i~ lowered a second time clo~ing the ports 22 in the ro~J of port~ remote from the headpiece 18 to terminate the *low of the inert ga~ from the so-urce 8 and, ~hile opening the ports 23 in the l~ddle row of ports, stops ten,porarily in the intermediate position (~ig~ 1 and 4). 1,iithin thi~ space of time the oxidant and fuel ~aaes flow alon~ the gas con-duits 29 and 3~ to enter the interior 2~ o~ the cy-lincler 17 to pas~ further along the pas~a~e's 25,26 and flow restricting mean~ 12 directly to the deto-nation chamber 3 of the barrel 1, where they are svJirled to force by the stream front the purgi~g gas from the chamber 3 to the acceleration portion

2 thu~ completing the phase of filling the detonP-tion chamber 3 with the fuel mi~ture.
A still further rotation of the cam 42 causes the piston 19 to ascend, and while a~cending to clo~e the ports23 ~the middle ro~ o~ ports, open th~ ports 24 in the row of ports adjacent the head-: ~ piece 18, and re~ister the ga3-~alving ring 33 ~ith ~ 25 the ports 22 in the row of ports remote ~rom the : headpiece 18. '~hen the ~iston 19 5tops in the in.-termediate position (~igs 1, 2 and 5)) whereby~
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lZ6~39 the sprin~ 45 is compressed. During this space of time only the flo~l restrictin r.leans 12 i8 ~illed with the inert gas thu~ providing gas blanketing.
A subsequent rotation of the cam 42 makes the piston 19 ascend to clo~e all the ports 22~ 23 and 24 of the cylinder 17~ stop the admission of ~ases, and mate the an~ular projection 40 with the annular recess 4l thus completing preparation procedures prior to detonation (Fig. 1~. Concurrently, ~vith the approach of the piston to the topmost position a lug of th~ pusher rod 43 forces the interrupter 15 to break the contact, whereby hi~h voltage from the vol~a~e tran~ormer 14 i~ applied to the ~park plug 4 to initiate detonation. Detonation is com-pleted while the piston rests in the topmos-t positi-on, and the powder material to be sprayed is heat-ed and accelerated. ~'he entire cycle-i~ repeated after rotation o~ the cam 427 A 9pecific ~eature of the aforedescribed gas dis-~ tribution system is advanta~eous in that the deto-natable ga~e~ are fed to the rr, ddle row of ga~ port~
in the cylinder at a pressure substantially below the pressure of the inert gas and always from above thu~ blanketing them from below by the inert gas.
Such a con~truction of the proposed apparatus make~
operation ler~ explosion hazardou~.
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In order to change the frequency of detonation - 17 ~

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3LZ689i3a3 pulses, it is sufficient to vary the direct current voltage apolied to the electric motor 30 and change the flow rate of gases accordingly. It is therefore possible to gradually attain the ma~imum frequency of detonation pulses to operate ~ith the utmost ef-ficiency.

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Claims (6)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A detonation-gas apparatus for applying co-atings to surfaces of bodies comprising: a barrel, a spark plug accommodated inside said barrel; a sprayer of powder materials arranged inside said barrel; sources of fuel gas, oxidizing gas and in-ert gas; a gas flow restricting means communicat-ing with said barrel; an ignition system for deto-nating said gases in said barrel; a unit for dis-tributing said gases connected to said gas sources;
a cam mechanism cooperating with said gas distri-bution unit and said ignition system for detonat-ing the gases in said barrel; a cylinder of said gas distribution unit; an interior of said cylind-er; walls of said cylinder; radial ports provided in the walls of said cylinder arranged in three rows in terms of height thereof and intended to com-municate the interior of said cylinder with said gas sources; a headpiece of said cylinder; passages in said headpiece serving to convey the gases from the interior of said cylinder to said barrel thro-ugh said gas flow restricting means; a piston arren-ged in the interior of said cylinder to be capable of reciprocating and cooperating with said cam me-chanism.

2, A detonation-gas apparatus as defined in claim 1, in which half of said ports in the row of ports remote from said headpiece communicate with said source of inert gas, whereas the other half of said ports in this row of ports communicate with said ports in the row of ports adjacent said head-piece, one said port in the middle row of ports communicating with said source of fuel gas, the oth-er ports in said middle row of ports communicating with said source of oxidizing gas.

3. A detonation-gas apparatus as defined in claim 1, in which said piston has fitted thereon elastic seal rings end faces of which have the form of tapered concave surfaces, and interposed between these seal rings spacer rings and gas-valving rings end faces of which have the form of tapered convex surfaces corresponding to the tapered surfaces of the seal rings, the piston carrying a nut adjacent one of said seal rings and serving to adjust a clearance between said cylinder and said seal rings, the gas-valving ring having a groove at the outer surface thereof providing the passage of inert gas from its source to the ports in said row of ports adjacent said headpiece of said cylinder.

4. A detonation-gas-apparatus as defined in claim 1, in which said gas distribution unit com-prises a sealing connection of said piston with .
said headpiece of said cylinder defined by annular projections provided at the end face of said piston and annular recesses provided at the end face of said headpiece in the interior of said cylinder.

5. A detonation-gas apparatus as defined in claim 1, in which said cam mechanism has a shape pro-viding the travel of said piston to successively open and close said ports in said cylinder in ac-cordance with working cycle phases.

6. A detonation-gas apparatus as defined in claim 1, in which said gas flow restricting means comprises gas conduits arranged tangentially to the cross-section of said barrel and communicating said interior of the cylinder through said pasages in said headpiece with said barrel.