US 2332251 A
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, H. W. PARRISH SURFACE TREATING DEVICE 2 Sheets-Sheet 2 7 27 7 27' 7 Z2 Z2 /5 5/ [Q m M M, M- F765. F/ci 6. 65
74 a g /7 1Q 74 W. 2 /7 /5 3/ 2:5 /8 /Z A? 50 T /4 3/ /4 L0 6/ F g /6 g? 91 /a 7/ Q I I 5 g6 Q27 27 m 45 5/ /a INVENTOR.
M445 W P212245 Patented Oct. 19, 1943 one;
SURFACE TREATING DEVICE-la HaleWr-Pa'rrish; South Bend, lnrl assignor 150* Application January 23; 1941, 'S eiial .No.\375,587h- 6 Claims: (01. 51 -14) This invention :relates; to. surface; treating tie vices; and more-particularlyio .surface "treating devices :of the. soecallecl sand blast i, type; n 0116122 purpo segfor which the instant device sis especiallv adapted is the :graining of metal printing plates; v
An engraved or-Jetched printing plate has=,-sha1-. low surface impressions.;. Hence; after=thenusesoio a plate 1 having one impression. is completed, the plate imay be1resuriaceda and. grained-and ,a sec- 1' 5 0nd impression ;made..v.-.therein.. Bveregraininggwlo plates, it is'possiblezto.=. useieach; plate-1a number oftimesu andv thus lconserve;ztheplmetal. thereof The present practices and-devices conventionallv, employed foreresurfacingmnd.igraining: .a .-plate are slowwand expensive. For examp1e.,..:-..one.."l5 methodis to immerse platesinfla liquid containers, and to roll-J shot: .or ;other' spherical;elements; thereover to grind: down the face impressionand. produce the-desired grained effect.
Present sandblast; devices :are wnot adapt-ed for: plate graining because they' do unoti operate-s, successfully at IQWWeIocity-ieed of theabrasivem as I :would. berequired i110 avoidvundueabrasion- 22 and-wear =of"the race and to obtain the proper grained effect." Also-y conventionalsand blast-25 devices operate at high: air :pressures, 1 which pressures cannot be -sealed --withinthe -containerr or'ehamber of the'device successtully'and,hence,' cause leakage of dust from thedeviceeltt'will be'flobvious that sand: blast devices-operating at high air pressures cannot beinstalled near pre cision machinery, such as -.=nearthe printing pressesin a print shop; be'causesof the abrasive dust which escapes to the atmosphere fromisuchsandblast-devicesw a The primar-v'object of this invention is to pro-=-- vide-a :novel sand -blast -device -for projec-ting abrasive particles against a work'lpiece at low VGIOCltiBSu I A "further object -is 'to provide a sand blast- 40 'deviceiwith a; workchamber'wherein: air-apress worker v A flllllhfilhObjGCihilS to .prpvideaa sandsblastwdevice zwiths ea wor-k. chamber shaving? opepinesa-s thereinnfompassage of -oneizor more: runssof. a 1, flat:;feed.--web,- and-i rollers bearing? upon ropposite r: faceswofesaidiiwebyandeagainstz the iwallsvofsthe e; chamber around, thevopen'ing; latnleast the work a engagingygrol-lersbei-ng compressible. Y
A ifurthereiobjeet is toizprpvide a sandsblast device in: which .dust and abrasive particleseare completely:confinekzl againstslealeage oridischarseptoatmosphere: v p
A :further objectL-is tor prpvidema rsanda-bmstsu device: with: airecirculating i means servingi tow withdratvain-irom ztha aworhichamberaand comeneotedvwith the abrasive feed means,.to--.return:
to. the:- cha-mbera'a .eselected repqr-tioni of- ,:the eairsi Fignrfi is a longitudinal:verticalwsect-ionaluviewe;
ofcanotherembodiment of my-dnventiom:
Fig.1 6 -i-s;a longitudinalevertical(sectional'vwiewn\ of another:iemhodimentrof my: invention; a
Figai'? isga fragmentary;transversmvertical seceiz -i tional detaileviewutaken on line:J-1 0f1FiE- L4. Referringztotthe:drawings, iandpjparticularlv to L \Figsfiiil to 3; .vvhichzsillustratei thepreferred; emzezbodiment of .theiinvention::thernumeralxlnidesigns nates; a work chamberm Chamber: M3 is ;formed from; endzwalls I; I sidezwallsz-l 2'; toprl 3; tapering: 9
bottom :wallsn-l 4, sandria: downwardlyf extending central shopper @l 5: 'a; The; I chamben; is tpreferablvi made.- .Of-ZShBBt'f metal; ansdcalh :j oints. :thereofearer sealed,:'.aS ;-by welding oravby theAiuse;ofwsealingq gaskets;.:e,tc:.--, Chamhen [this mounted-mpomsui-t ablerlegs pr; supports zl 5 which: positibrn'theohop .iperr: l 5-; abovev the leve-lmfvthe, floor: uponrwhichm s the chamber is (mounted. V v V Each:;o'f: thetend Wall-1S3; l -:ofzthe;chamber- Iii-:5:
is provided-ewithta rectangula aopeningn l 1.1 T upperaa d O Qr iportionsof: eachopening .1] area; a spanned/bx :sheetsafl 'formedrof rubber':or other h resilient material, secured to the walls I in sealing relation at their margins and drawn taut to maintain a desired substantially planar position. In spaced relation to each end of the work chamber ID are positioned vertical supports I9 which are connected with the chamber by horizontal frame elements 28. The supports |9--29 journal shafts 2|. A pulley 22 is mounted upon each shaft 2|. Suitable driving means (not shown) is associated with one of the shafts 2| to drive the same. A wide fiat belt 23, preferably formed of rubber or composition material which will stand impact of abrasive material thereagainst, is trained around and between the pulleys 22, and passes through the work chamber l through the openings |1 between the inner edges of the sheets I8. The width of belt 23 is preferably substantially equal to the horizontal dimension of the openings |1 so that only a small clearance is provided between the edges of said belt and the side edges of said openings. The work pieces 24, such as flat metal printing plates, are adapted to be positioned in desired relation upon the belt 23 atone end thereof exteriorly of chamber ID, to be carried through the work chamber II) to the discharge end of the belt exteriorly of the opposite end of the work chamber.
A pair of spaced parallel vertical metal plates 25 is carried by each end wall I I in perpendicular relation thereto. Plates 25 are positioned with their inner faces substantially flush with the adjacent vertical edges of the openings l1, whereby said plates 25 are spaced apart a distance slightly wider than the belt 23 to accommodate free movement of said belt 23 therebetween. Plates 25 are preferably of a height greater than the vertical dimension of the openings I1, and project both above and below said openings. The ends of a shaft 26 are journaled in the plates 25 of each pair, and said shaft mounts a roller 21 preferably formed of rubber or other resilient and compressible material. The roller 21 is so positioned that its circumferential or cylindrical face bears against the belt 23 and also against the inner face of the upper closure sheet l8. The ends of a shaft 28 are journaled in plates 25 of each pair adjacent the center of said plates. Shaft 28 mounts a roller 29. If desired, roller 29 may be formed of-rubber or other compressible, also. The diameter of the roller 29 is substantially equal to the diameter of the pulleys 22, and roller 29 is so positioned that it will engage the inner faces of both the upper and lower runs of the belt 23. The ends of a third shaft 30 are journaled in plates 25 of each pair, and said shaft mounts a roller 3|. roll 3| bears against the lower face of the lower closure sheet |8. Each of the rollers 21, 29, and 3| is of a length equal to the spacing between the plates 25, so that the opposite ends of said rollers bear against said plates 25 at all times.
A hopper 32 for abrasive material is suitably supported in spaced relation above the container I0. The hopper preferably is provided with lower tapering walls 33 which merge with a downwardly tapering spout portion 34 at the center of the bottom of the hopper. Suitable means are provided for regulating the discharge of abrasive from hopper 32. As here illustrated, the regulating means may comprise a wedge member whose major transverse dimension is greater than the width of the opening between the bottom 33 of the hopper and the upper end hopper of spout 34. Wedge member 35 is preferably mounted upon a vertical shaft or support 36 astaei which may be vertically adjusted relative to the hopper by suitable adjusting means (not shown).
A housing 31 is secured at 38 to the bottom of the hopper 32, as by welding, to render the joint between the housing 31 and hopper 32 air tight, for purposes to be set forth hereinafter. The housing 31 is provided with downwardly tapering bottom walls 39 which merge with a downwardly tapering neck 40 from which a feed nozzel 4| projects. Tapering portion 49 receives the lower end of the tapered spout 34 of the hopper. 32. It will be understood that the spout 34 of the hopper 32, and the nozzle 4| are both of elongated cross-sectional shape, and that the major horizontal dimension of the nozzle 4| extends transversely of and s preferably greater than the width of belt 23, as best illustrated in The cylindrical face of Fig 3 A fan or blower 42 of any desired or conventional character or construction is mounted upon'the top [3 of the chamber l0. Blower 42 is provided with an intake conduit 43 which communicates with an opening (not shown) in the top l3 of chamber I0. Blower 42 is also provided with a pair of outlets 44 and 45. Outlet 44 is preferably open to atmosphere and outlet 45 communicates with chamber 31. v
The hopper l5 at the bottom of the chamber I0 is provided with a suitable feed screw 45 mounted upon shaft 41 for discharging abrasive particles collected within the hopper l5 to a suitable elevator 48 which serves to convey the abrasive to the upper hopper 32.
It will be understood that the chamber i0 is of A substantially air tight construction at all joints thereof, and is open only at opening l1 and at the opening communicating with, intake 43 of blower 42. Hence, in the operation of the device, when blower 42 operates to withdraw air from the chamber, the onlypossibility for uncontrolled entry of air into the chamber is through the openings If. These openings l1 are substantiallysealed by the engagement of the belt 23 and plates 25 by the rollers 21, 29, and 3|, and by the engagement of closure sheets It by the rollers 21 and 3| throughout the lengths of said rollers. This construction of the chamber l0 and of the multiple rollers relative to the feed belt- 23 permits the feed belt 23 to operate to carry the Work piece 24 into the chamber I0 without any substantial leakage of air through openings l1. It will be understood, of course, that this construction, entailing as it 'does the movement of the belt 23. and the rotation of the rollers 21, 26, and 3| does not effect a positive and hermetic seal for the chamber, I0, but it does serve to-reduce leakage to such a small amount that it can be economically overcome, and a small subatmospheric condition can be maintained in chamber H], by operation of the blower 42. In this connection, note that the formation of the upper roller 21 particularly, and if desired, the rollers, 29 and 3| from rubber or other compressible material, serves to enhance the quality of the seal. Thus, Fig. 1 illustrates the engagement of rollers 21 with a workpiece 24, wherein said rollers 21 are compressed and have a tight face engagement with the work piece. This construction, in whichit will be understood that each roller 21, 29, and 3| is an idler, insures the air tight condition without interfering with the feed or discharge of the work relative to the chamber.
It will be observed that blower 42 may be made of a capacity to withdraw air from the chamber ID at a much greater rate than air can enter While each of the embodiments has been illustrated with both runs of work feed belt 23 passing through work chamber HI, it. will be obvious that only the. feed run need extend into said.
chamber to the abrasive nozzle. Also, the feed belt need not extend completely through chamber H], but may terminate therein, if the belt drive is accommodated for reciprocation.
I claimz- 1." A surface treating device comprising a chamber having at least one opening therein, a
belt shiftable in said opening-a pair of rollers rotatably carried by said chamber adjacent said opening and bearing against opposite faces of said belt and against the walls of said chamber to seal said opening, at least the upper roller being formed from yieldable material, and abrasive feed means directed toward said belt. v
2. A surface treating device comprising a chamber having an opening therein, a belt having spaced oppositely moving runs passing through said opening, an intermediate roller rotatably carried by said chamber and positioned between and engaged by both runs of said belt and bearing against said chamber at its ends, a pair of rollers rotatably carried by said chamber and engaging the outer faces of said runs and the chamber walls at the peripheries and ends thereof, at least the uppermost roller being resilient, and means for discharging abrasive on the upper run of said belt.
3. A surface treating device as defined in claim 2, and resilient strips covering the upper and lower portions of said opening and engaged by the last-named rollers.
4. In a surface treating device, a chamber having an opening in one wall thereof, a pair of vertical plates projecting inwardly from said wall at opposite. edges of said opening, a flat web shiftable in said opening, means spaced from said wall for shifting and supporting said web, and a pair of idler rollers journaled in said plates to rotatably engage opposite faces of said web, said rollers bearing against saidplates'at their ends and against the inner face of said wall throughout their length. i
5. The combination defined in claim 4, wherein rubber sheets carried by said wallclose opposite portions of said opening and are engaged by the peripheries of said rollers.
6. A surface treating device comprising a chamber having openings in opposite walls, a belt shiftable through said openings, means spaced from said chamber for supporting and shifting said belt, means for substantially sealing said openings including idler rollers bearing against opposite faces of said belt and against the walls of said chamber adjacent said opening, means for discharging abrasive at low velocity onto said belt, and means for withdrawing air from said chamber in greater volume than supplied to said chamber by said abrasive discharging means.
HALE W. PARRISH.