FR2524823A1 - ELEMENT AND PACKAGE ASSEMBLY FOR PROTECTIVE HOUSING OF A PROJECTION WHEEL, SUPERIOR WALL FOR CLOSING THE HOUSING, AND METHOD FOR PRODUCING A TRIM ASSEMBLY HAVING INTERCHANGEABLE ELEMENTS - Google Patents

Abstract

TRIM KIT INTENDED FOR THE PROTECTIVE CASE OF AN ABRASIVE SPRAY WHEEL. IT IS CONSTITUTED OF SEVERAL PLATES, WHICH MAY BE THICK AND RELATIVELY DUCTILE 52, OR THIN AND RELATIVELY HARD 54. THESE PLATES ARE CONNECTED TO EACH OTHER BY ASSEMBLIES 64, 170, 172 WHICH FORM LABYRINTH JOINTS, WATERPROOF WITH ABRASI. VARIOUS PLATE ARRANGEMENTS MAY BE FIXED TO THE WALLS 108 OF AN ABRASIVE SPRAYING APPARATUS PROTECTION CASE, USING NUTS 122 AND THREADED MOUNTING ORGAN 118. FIELD OF APPLICATION: CLEANING, ABRASION, HAMMING OR OTHER TREATMENT OF SURFACES BY PROJECTION OF PARTICLES.

Description

The invention relates to a packing assembly for coating the

  internal surfaces of the walls of a protective casing of a projection wheel of the type used to project material particles using centrifugal force, the particles being projected at the ends of the blades of a wheel rotating on an object or a surface to clean, erode, hammer

or otherwise treat.

  U.S. Patent Nos. 3,319,383 and 3,100,990 disclose a projection apparatus of US Pat.

  particles of the type comprising a wheel which rotates in the in-

  the interior of a protective casing to force a particle flow through an opening formed in the protective casing, so that these particles strike against the surfaces of objects or parts to be cleaned, eroded, hammered or otherwise treated Each protective casing has a front wall, a rear wall, two end walls and an upper closure wall. A trim assembly is for coating the front, rear, end and top walls. The wear pad assemblies described in the patents above mentioned total twenty-three pieces Some or all of these parts are made of cast iron

  very brittle, of the type described in the US Pat.

United States of America No. 2,355,726.

  Although cast iron castings are highly resistant to abrasion, they are very prone to breakage, especially in the corner areas and along the edges, where the ends of the packing pieces have relatively thin sections. The very hard material which constitutes these pieces of packing has an optimal thickness to have

  desired type of behavior This optimum thickness

  male is relatively weak; however, the material itself is difficult to cast into section pieces

  relatively thin or complex or rounded shapes.

  In addition, the hardness of the material makes machining or grinding of the packing pieces impossible for cost reasons Therefore, the packing pieces are difficult and expensive to manufacture and

  they form relatively fragile structures, capable of

  be easily broken, which must be transported, stored and handled with care. Although the very hard cast iron whose pieces of

  packing are formed usually presents an excellent

  abrasion resistance sometimes, particles of excessively large dimensions sometimes accidentally reach the projection wheel housed inside the packing assembly. Broken fins can be thrown against brittle lining pieces, causing breakage of the lining In other cases, parts being processed may bounce inside the wheel enclosure and cause the lining to break In fact , breakage of the packing plates are very frequent and the downtime associated with the replacement of parts

pose a problem.

  A disadvantage of the packing assemblies disclosed in the aforementioned patents Nos. 3,319,383 and 3,190,990 is the relatively large number of packing elements required to form a complete package.

  filling, with the difficulties and the resulting deadlines

  In addition, the work of handling the large number of fastening bolts used to hold such a large number of plates in position increases undesirably.

the downtime.

  Although U.S. Patent No. 3,191,346 describes a packing assembly having a relatively small number of elements, this patent, as well as the patents mentioned above, does not deal with certain problems. In some markets, it is desired to have a liner assembly having a smaller dimension and using a less expensive technique to seal a wheel shaft. A desirable lining assembly has the lowest possible number of elements while simultaneously achieving an inexpensive sealing device for the shaft, comprising a seal

suitable abrasive.

  The invention aims at the aforementioned drawbacks as well as other disadvantages affecting the prior art packing assemblies and its purpose is to eliminate these disadvantages by means of an improved packing assembly which (1) uses a low number of pieces to completely cover the protective casing of a particle projection apparatus, (2) simplifies the replacement of broken and worn packing pieces and thus minimizes downtime associated with part replacement, (3) form abrasive-proof labyrinth seals, which are very effective between the adjacent lining pieces and a wheel shaft, (4) enables the lining parts to be associated with one another;

  relatively thin and brittle to pieces of

  wise relatively thick and ductile, so that the cast

  brittle whose packing parts are usually

  not be used other than more ductile molten steel to form the various parts of the packing assembly, and (5) provides a seal adjacent to the periphery of the packing assembly and the protective casing so that it is no longer necessary

  to use a reported sealing plate.

  An important feature of the invention

  lies in the use of packing pieces which

  use overlapping or interlocking assemblies which not only form abrasive-proof labyrinth seals, but also allow one to be selected,

  pieces of packing to be made of cast iron

  brittle, of relatively thin section, or

  relatively ductile molten steel, of relative

  Thanks to this arrangement, a set of garments

  may consist mainly of relatively thin brittle cast iron packing plates, or a blend of thin and thick

  brittle material and ductile material, respectively.

  By allowing a selection of thin and thick plates used simultaneously in a lining assembly, the invention offers for the first time to the user the possibility of independently determining whether some, chosen, cladding plates should take the form of thin structures. and brittle or thick and ductile structures Thus, thin and brittle plates can be used in areas of high impact, where the resistance to abrasion must be maximum, and thick and ductile plates

  can be used in the desired areas.

  The joining system used to form abrasive-impervious labyrinth seals between adjacent lining plates is characterized by the presence of plate edges of maximum thickness, which cover adjacent plate edges or interlock with edges. makes that the edges of the plates

  covering or interlocking have a maximum thickness

  male increases the strength of the plates and minimizes

risk of rupture of the plates.

  The reduction of the number of pieces of lining

  necessary for the formation of a complete set of

  minimizes the number and length of assemblies in assembled packing By minimizing the number and length of assemblies, the risk of abrasive leakage through assemblies is minimized.

  same as the problem of wear due to such leaks.

  The preferred embodiment of the packing assembly according to the invention can be substituted for packing assemblies such as those described in US Pat. Nos. 3,319,383, 3,191,346 and 3,160,361. In addition, an embodiment of the invention will be described hereinafter in which it is not necessary to use an attached sealing plate, and in which also an improved labyrinth seal for abrasives is provided for the shaft of the wheel, which allows the use

  a less expensive shaft seal.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting examples and in which:

  FIG. 1 is a perspective view,

  exploded, elements of a preferred form

  embodiment of the lining assembly according to the invention.

  tion; Figure 2 is an exploded perspective view of the elements of this set, placed on a flat surface; FIGS. 3 and 4 are enlarged sections of the parts of the packing assembly according to the invention, respectively along the lines 3-3 and 4-4 of FIGS. 1 and 3, the parts being laid in a

  protective casing of a party projection apparatus

  cles; FIG. 5 is an enlarged partial sectional view of a detail of FIG. 3, showing relatively thin brittle cast iron cladding plates placed inside a protective casing; Figures 6 and 7 are sections along lines 6-6 and 7-7 of Figure 5; Figure 8 is a partial sectional view similar to that of Figure 5, but showing relatively thick ductile steel cladding plates placed within a protective casing; Figures 9 and 10 are sections along the lines 9-9 and 10-10 of Figure 8; Figure 11 is a partial sectional view similar to that of Figures 5 and 8, but showing a combination of relatively thick and thin molten metal packing plates secured within a protective housing; Figures 12 and 13 are sections along the lines 12-12 and 13-13 of Figure 11; Figures 14 to 17 are sections following

  line A-A in Figure 1, extreme plates of

  characterized in that features of the invention, FIGS. 14 and 15 for comparing upper end plates of relatively thick and thin packing, and FIGS.

  lower end plates of relative packing

  thick and thin; FIGS. 18 and 19 are sections along the line BB of FIG. 1, upper closure packing plates according to the invention, FIG. 18 showing a relatively thick packing plate and FIG. 19 showing an interchangeable packing plate, but relatively thin; Fig. 20 is a section along the line -20 of Fig. 3; FIG. 21 is a section similar to that

  of FIG. 4, of a variant of the set of

  according to the invention, mounted in a variant of

  protective casing of a projection apparatus of

  ticles; and Figures 22 and 23 are sections following

  lines 22-22 and 23-23 of FIG. 21.

  As shown in FIGS. 1 and 2, the elements of a packing assembly intended to coat a protective casing of a projection wheel are

  indicated overall by reference numeral 10.

  The packing assembly 10 comprises a structure of

  lining 12 of the front wall, a filling structure

  wise 14 of the back wall, packing structures

  16 and 18 of the extreme walls and a structure of

wise 20 of the upper wall.

  The lining structure 12 of the front wall comprises left, right and central lining plates 22, 24 and 26 The lining structure 14 of the rear wall comprises left, right and central lining plates 32, 34 and 36 The plates The central plates 26 and 36 are identical. The left and right plates 22 and 24 are symmetrical with each other, as are the left and right plates 32 and 34. As shown, the left and right plates 32 and 34 comprise projections 38 in the shape of a segment. moldings, although these projections may consist of one or more

  Sieur patches, if desired.

  The extreme wall packing structure 16 comprises upper and lower packing plates 42 and 44. The end wall packing structure 18 comprises upper and lower packing plates 52 and 54. The upper plates 42 and 52 are identical.

  as are the lower plates 44 and 54.

  The lining structure 20 of the upper wall

  A housing 64 is provided in the top wall packing plate 62 to receive the upper edges of the plates 22, 24, 26, 32, 34, 36, 42 and 52. front, back and extreme walls

  to form between them a labyrinth seal.

  The plates 22, 24, 26, 32, 34, 36, 42, 44, 52, 54 and 62 form an eleven-element packing assembly. However, in reality, this set comprises only eight different plate shapes to be

  stored as spare parts.

  A characteristic of the eleven-piece packing assembly is that it can be substituted for the twenty-three-piece packing assemblies described in the aforesaid patents Nos. 3,319,383 and 3,190,990, and that it can be laid in the protective housings described in these same patents without it being necessary to modify the said existing protective casings. Reference may be made to the particle projection apparatus described in the aforementioned patents, which are examples of typical apparatus and media in 3 and 4 of the accompanying drawings correspond to FIGS. 1 and 2 of the two aforementioned patents, and show how packing elements according to the invention can be substituted for items

  packing of the type described in these two aforementioned patents.

  Referring briefly to FIGS. 3 and 4, there is shown a boot-shaped protective casing of substantially trapezoidal cross-section, indicated generally by numeral 100. The casing 100 has a front wall 102, a rear wall 104,

  inclined end walls 106 and 108 and a top wall

  110 Closure members Threaded members 112 for securing

  The threaded members 114 secure the lining structure 14 to the rear wall 104. Threaded fasteners 116 and 118 secure the lining structures 16 and 18 to the end walls 106 and 16. Fastening threaded members 120 secure the packing structure to the top closure wall 110. Several packing members or plates 10 carry embedded nuts 122 which receive the threaded fasteners 112, 114, 116 and 118 as described in FIG. licences

  No 3 319 383 and No 3 160 990, so that these

  The sealing insert 124 is disposed in the immediate vicinity of the lower peripheral edge of the packing assembly 10 and the casing 100. The plate 124 pockets particles of material from the casing. arrive at the crankcase side of the lining assembly. The packing plates of the assembly 10 have overlapping or interlocking edges, which cooperate to form labyrinth seals, sealed

  abrasives, between adjacent packing plates.

  The design of the elements of the packing assembly avoids the formation of any openings allowing the projected material to pass directly through the

packing assemblies.

  The left and right lining plates 22, 24, 32 and 34 have U-shaped grooves 140 into which opposite edges of the end plates 42, 44, 52 and 54 penetrate to form enveloping labyrinth seals, shaped in shape. As shown in FIG. 6, the top end packing plate 52 has an edge 150 which enters a

  groove 140 formed along one side of the

  The throat 140 has left and right and base surfaces 142, 144, and 146. The edge 150 extends narrowly along the left surface 142 and abuts against the base surface 146. 52 have inner surfaces 152 and 154 which intersect in substantially perpendicular planes. When the material to be projected is propelled towards the junction of the plates 24 and 52, it must change direction several times substantially at right angles to penetrate the labyrinth seal.

  enveloping, U-shaped, formed by this assembly.

  Similarly, as shown in FIG. 7, the bottom end trim plate 54 has an edge 160 which penetrates the groove 140 formed along one side of the wall trim plate 24

  The edge 160 extends narrowly along the

  right face 144 and abut against the base surface 146.

  When the material to be projected is propelled towards the junction of the plates 24 and 54, it must change several times of direction substantially at right angles to be able to penetrate into the enveloping labyrinth seal, of shape

  in U, constituted by this assembly.

  The various packing plates which each form structures 12, 14, 16 and 18, have overlapping edges, which constitute labyrinth seals between the different adjacent plates. As an example, as shown in FIG. upper end 52 has a remote edge 170 which cooperates with an edge 172 of the lower end plate 54 to form a right-angle labyrinth seal. The edge 170 is L-shaped and has a surface 174 facing downwards and a surface 176 turned inward The trim plate 54 from the end

  bottom has a surface 178 facing the interior

  which is adjacent to the inner surface 154 of the packing plate 52 of the upper end, and its upper end 180 abuts against the surface 174 when the material to be sprayed is propelled towards the junction of the plates 52 and 54 , it must change direction approximately at right angles to enter the formed L-shaped labyrinth seal

between plates 52 and 54.

  Similar L-shaped labyrinth seals are formed between other plates constituting the structures 12, 14, 16 and 18. For example, as shown in FIG. 20, the packing plates 22 and 26 of the The front wall has overlapping edges 190 and 192 which form a labyrinth seal between them. No direct opening allows the projected material to traverse the lining assembly in a straight line. The packing plates of the assembly 10 and the assemblies formed together when the elements are assembled, are configured in such a way that some of the elements comprising these plates can be selected.

  selectively made of a brittle metal, relatively

  thin, or of a relatively thick ductile metal.

  By way of example, FIG. 5 illustrates the use of relatively thin upper and lower end plates 52 and 54, covering the end wall 108 of the protective casing, while FIG. 8 illustrates the use of upper and lower plates 52. a and 54 has relatively thick, covering the end wall 108 of the guard, and that Figure 11 illustrates the use of a combination of thick and thin plates 52a and 54 covering the end wall 108 of the housing

protection.

  Thin packing plates are conventionally used in casings for protecting projection wheels, since the extremely hard, brittle alloy of which these plates are made (this alloy being described in the aforementioned US Pat. No. 2,355,726) exhibits a certain behavior. Optimal at a relatively low thickness When these plates are made to a thickness greater than the optimum value, their abrasion resistance significantly decreases When an alloy more

  ductile must be used, for example steel with manganese

  of Hadfield, such material can not be properly cast into thin-section

  therefore thicker packing plates.

  According to a feature of the invention

  The overall thickness of the upper packing plates 52 and 52a, this thickness being indicated by the dimension "X" in FIGS. 14 and 15, is kept constant irrespective of the thin or thick plates 52 or 52a. Similarly, the overall thickness of the lower packing plates 54 and 54 a, indicated by the dimension "Y" in Figures 16 and 17, is minent constant, as thin plates

  or thick 54 or 54 a be used Similarly, the thick

  The overall size of the upper packing plates 62 and 62a, indicated by the dimension "Z" in FIGS. 18 and 19, is kept constant, whether thin or thick plates 62 or 62a are used. Keeping the thicknesses, such as the overall dimensions X, Y and Z, it is possible to use thin and thick boards interchangeably to coat the end walls and upper 106, 108

and 110 of the housing 100 of protection.

  Although the plates of the set of 10

  are preferably made of molded metal as is obvious to those skilled in the art, these elements may also be made of other materials, such as forged metal, welds being used to form the parts constituting labyrinth seals

described and others.

  FIGS. 21 to 23 show a variant of the packing assembly 10 and the protective housing 100 previously described, these embodiments

  are respectively indicated by the references

  In contrast to the packing assembly 10 and the protective casing 100, the packing assembly 210 and the guard housing 300 are less expensive to manufacture, smaller in size and have a protective device. less expensive tree sealing. The lining assembly 210 comprises a lining structure 212 of the front wall, a lining structure 214 of the rear wall, lining structures 216 and 218 of the end walls, and a lining structure 220 of the top wall. The structure front wall packing liner 212 includes left, right and central lining plates 222, 224 and 226 The lining structure 214 of the rear wall comprises left, right and central lining plates 232, 234 and 236. 222 and 224 are symmetrical to each other, from

  same as the left and right plates 232 and 234.

  As shown, the left and right plates 232 and 234 have protrusions 238 in the form of ring segments, integrally molded.

  may consist of one or more pieces of

if desired.

  The central plate 236 has an opening 239 in which the shaft (not shown) of the wheel passes. Unlike the embodiment shown in FIGS. 1 to 20, the opening 239 is not formed.

  In addition, annular projections

  The projections 240 and 241 are substantially in the form of annular flanges which form labyrinth seals with the wheel shaft. A feature of the embodiment shown in Figures 1 to 20 is that the side packing plates 22, 24 and 26 can be removed without disassembly of the wheel rim

  nor other elements of the assembly comprising the wheel.

  In Figures 21 to 23, this feature does not exist, but a better labyrinth seal for abrasive

is made with the wheel shaft.

  The end wall packing structure 216 comprises upper and lower packing plates 242 and 244, and the end wall packing structure 218 comprises upper and lower packing plates 252 and 254. The upper plates 242 and 252 are identical, same as are the lower plates 244 and 254 The packing structure 220

  of the upper wall consists of a single plate of

  A housing 264 is provided in the top wall packing plate 262 to receive the upper edges of the front, rear, and rear wall plates 222, 224, 226, 232, 234, 236, 242 and 252. The labyrinth seals analogous to those shown in FIGS. 1 to 20 are used in the embodiment of FIGS. 21 to 23. The joint thus formed and used allows the placement of plates. thick or thin, like

  desired, and as described above.

  The guard housing 300, in the form of a boot, has a substantially trapezoidal section. It comprises a front wall 302, a rear wall 304,

  inclined end walls 306 and 308, and a top wall

  The latter comprises two parallel plates 312 and 314 which extend across the upper opening of the housing 300. The plate 312 has openings which can be aligned with openings in tabs 316 and 318 protruding laterally from the walls. 302 and 304, so that each pair of aligned apertures can receive a fastener such as a nut and a bolt 320, so that the top closure wall 310 can be fixedly bolted to the guard 300 This closure mode eliminates the knobs, profiles and eyebolts shown in the upper part of FIGS. 3 and 4, is of low weight and is relatively inexpensive to manufacture As in the embodiment of FIGS. 1 to 20, threaded members 322 are used to secure the plates 222, 224, 226, 232, 234, 236, 242, 244, 252, 254 and 262 on the parts

corresponding to the housing 300.

  The guard 300 of protection has an opening

  323 of discharge by which its wheel propels

  particles of matter under the effect of centrifugal force.

  The bottom trim plates 244 and 254 of the end walls have tabs 324 and 326 protruding laterally. These tabs 324 and 326 are adjacent to wall members 328 and 330 to which the casing 300

  is fixed by flanges 332 and 334 extending towards the former

  The tabs 324 and 326 prevent the projected material particles from reaching the meeting area of the wall members 328, 330, wings 332 and 334 and the faces of the plates 244 and 254 facing the housing.

  In the embodiment shown in FIGS. 21 to 23, the plates 222, 224, 226, 232, 234, 236, 242, 244, 252, 254 and 262 form an eleven piece packing assembly 210 but, in reality, this assembly comprises only nine different plate configurations to be stored as spare parts. In FIGS. 22 and 23, the central plates 226 and 236 do not have identical configurations, as is the case.

  central plates 226 and 236 of FIG.

  A feature of the set of garments

  is that it can be substituted for the twenty-piece packing assemblies described in the above-mentioned patents Nos. 3,319,383 and 3,100,990, and that it can be put in place in the protective casings described in these two patents. mentioned above, without the need

  modify the existing protective casings

  210 appears to lining and its protective casing 300 are smaller than the assembly 10 and the casing 100; the housing 300 and the assembly 210 are intended mainly for applications in which parts of dimensions

smaller ones are used.

  Although reference has previously been made to an orientation of the protective casings 100 and 300 such that their opening is turned downwards, a particle projection apparatus of the type described can be oriented so as to project particles in any direction. Therefore, it is obvious that terms such as "upper", "lower", "forward", "backward", "upward", "downward", and the like as used herein , are intended simply to facilitate the understanding of the relative orientations of various elements and that they are not given

as a limitation.

  It goes without saying that many modifications can be made to the packing assembly described

  and shown without departing from the scope of the invention.

Claims (27)

  Plate-shaped packing member for coating a portion of a protective housing (300) within which a projection wheel is rotatably mounted to propel particles of material under the effect of centrifugal force, through a discharge opening, the packing element being characterized in that it has a first surface exposed to particles of material propelled by the rotating projection wheel,   a second surface on the other side of the   the lining element relative to the first surface, and comprising means (122) for fixing the lining element to the housing, and a lug (324 or 326) projecting laterally and which can be placed near the opening in order to prevent the particles of matter from entering the area of the   second surface and in the protective casing.   2 Packing assembly for coating a portion of a protective casing (300) inside which is mounted a projection wheel which is carried by a shaft rotating it so that it propels   particles of matter under the effect of the cen-   trifuge, through a discharge opening, the assembly being characterized in that it comprises an element (236)   in the form of a plate intended to cover part of the   interior of the housing, this element having an opening (239) in which the shaft passes and this opening having a continuous peripheral edge which is delimited in   all by the plate-shaped element.   3 Packing assembly according to the claim   2, characterized in that it further comprises annular flanges (240, 241) surrounding the opening, on each side of the plate-shaped member, and   projecting laterally outwardly from this element.   4 Packing assembly for coating a portion of the interior of a protective casing (100) in which a projection wheel is rotatably mounted to project particles of material   under the effect of centrifugal force, through an opening   discharge, the packing assembly being characterized   characterized in that it comprises a first plate-like element (52) which can be assembled with a second plate-like element (54) to form an end wall (18) of the lining assembly, the elements in the form of a plate each having an inwardly facing surface which is exposed to the projection material propelled by the rotating wheel, the second member having a portion (172) extending along an edge of its rotated surface inwardly, the first plate-shaped member having a shaped portion (170) extending along an edge of its inward facing surface and which can be assembled with the portion (172) of the edge of the second member when the two members are abutted against each other to form a portion of a liner assembly, the shaped portion (170) being of sufficient width to accommodate a second member relatively thick or relative thinly, while maintaining a free, substantially uninterrupted surface exposed to the projected material, the assembly formed between the edge portion (172) and the shaped portion also constituting a material-tight seal projected.   Packing assembly according to claim 4, characterized in that the first plate-shaped element carries a nut (122) embedded, intended to receive a threaded fastener (118) designed for   connect this first element to the protective cover.   6 packing assembly according to claim 4, characterized in that the second plate-shaped member carries a nut (122) embedded, intended to receive a threaded member (118) for attachment designed to   connect the second element to the protective cover.   7 Packing assembly for a protective casing (100) in which a projection wheel is rotatably mounted to propel particles to be projected, under the effect of centrifugal force, through a discharge opening, to   the surface of a workpiece, the set of   characterized in that it comprises a first relatively thin metal packing plate (52), a second relatively thick metal packing plate (54) and being connectable with the first plate to provide a non-perforated surface each plate having a face on a first side and intended to be struck by a material to be sprayed,   and a mounting face located on the other side and comprising   both means (122) for securing the plate to safety cover.   8 Packing unit according to the claim   7, characterized in that the first lining plate is further away from the discharge opening   than the second trim plate.   9 Upper closing wall of a packing assembly (10) for lining the inner parts of the walls with a protective housing (100) in cooperation with side walls and end walls (12, 14, 16, 18 ), a projection wheel being mounted so as to rotate and propel particles   under the effect of centrifugal force, through an opening   discharge head, the upper wall being characterized in that it comprises a plate-like element (62) extending approximately horizontally and at least a part of the periphery of which has a groove (64) whose width is sufficient to receive an edge of a relatively thick or relatively thin plate-like member so that a   labyrinth, abrasive-proof, is formed.   A method of producing a protective casing (100) packing assembly (10), said packing assembly having first and second interchangeable packing plates (52,54), the first plate being made of relatively thin metal and the second plate being made of relatively thick metal, the method being characterized by producing a first relatively thin metal wall packing plate having a wear-resistant face on a first side and a face of mounting on its other side, the mounting face having a plurality of projections (122) for engaging an inner portion of a wall of a protective housing, producing a second relatively thick metal wall packing plate, having a wear-resistant face on a first side and a mounting face on its other side, the mounting face carrying a plurality of projections (122) for applied against an inner wall portion of a protective casing, to adapt the overall thickness of the first plate to a predetermined first dimension and to adapt the overall thickness of the second plate to a second predetermined dimension so that when one or the other of the first and second plates is mounted in the protective housing so that its projections abut against the inner wall portion of the housing, the wear-resistant surface of the thus mounted plate is placed in a position   predetermined and established, located at a predetermined distance   mined and established the inner wall of the protective casing.   The process according to claim 10, characterized   in that it further consists in giving the first predetermined dimension a value equal to the second predetermined dimension.   The method of claim 10, characterized   in that it furthermore consists in producing an additional packing plate (24) intended to abut one of the plates once mounted on the inner wall portion of the protective casing, to create a groove (140) of U-shape in the additional trim plate, which groove has a width sufficient to accommodate the thickness of an edge portion (150) of the first or second trim plate, and to introduce a edge portion of the first trim plate in the U-shaped groove, to attach the additional trim plate to the protective housing and establish between the two plates a labyrinth seal, impervious to the projected material. 13 Multi-piece packing set   intended to cover the inside of a casing (100) of   wherein a projection wheel is rotatably mounted to propel particles of material under the effect of centrifugal force, through a discharge opening, on the surface of a workpiece, the protective casing having a box configuration, comprising a front wall (102), a rear wall (104), two end walls (106, 108) and a   upper wall (110) of closure, the set of   characterized in that it comprises front wall packing means (12), comprising a plurality of front packing plates (22, 24, 26) for coating the inner surface of the front wall, packing means ( 14) of the rear wall comprising a plurality of rear lining plates (32,34,36) for coating the inner surface of the rear wall, two lining means (1,6,18) of the end walls comprising lining plates ( 42, 44,   52, 54) of the end walls intended to be coated.   inner faces of the end walls, upper wall packing means (20) comprising a plate (62) for coating the inner surface of the top closure wall, the front wall packing means and the packing means of the top wall; rear wall having U-shaped grooves (140) for receiving parts of   front and rear edges (150, 160) of the trim plates   wise extreme walls to achieve an assembly,   the lining means of the upper wall have   a housing (64) for receiving portions of the upper edges of the front, rear and end wall packing means, the front, rear, end and top wall plates having edges configured so that all the assemblies formed between adjacent plates form abrasive-impervious labyrinth seals to prevent the projected material from penetrating through the assemblies of the packing assembly.   14 Packing unit according to the claim   13, characterized in that selected ones of the lining plates have an inner face   smooth, uninterrupted and imperforate, and a sensi-   flat portion, at least one linear portion (170) of an edge of the body being offset from the plane of said body, said portion being configured to extend below a portion (172) of the edge of an adjacent one , packing plates and to cooperate with this part (172) so that the two parts <170, 172) form a joint   labyrinth sealed with abrasive.   Packing unit according to the claim   13, characterized in that selected ones of said plates each have a face facing an adjacent portion of the protective housing, and an inner face facing a central portion of the protective housing, the inner faces of the plates being smooth and not perforated and the faces of the plates facing the housing having spaced bosses which bear embedded nuts (122) for receiving threaded fasteners (118) for securing   said plates to the protective housing.   16 Packing unit according to the claim   13, characterized in that the lining plates (244, 254) of the end walls, closest to the discharge opening, comprise a tab (324, 326) projecting outwards and disposed in the vicinity of the discharge opening.   17 Packing unit according to the claim   13, characterized in that one, selected (236) of the rear lining plates has an opening (239) in which a wheel support shaft passes, said opening having a defined continuous peripheral edge   completely by said trim plate.   18 Packing unit according to the claim   17, characterized in that it further comprises annular flanges (240, 241) surrounding the opening, on each side of the trim plate, and protruding   laterally to the outside of this plate.   An eleven-piece packing assembly for receiving the inner surface of a protective casing (100) in which a projection wheel is rotatably mounted to propel particles of material under the effect of centrifugal force. through a discharge opening on the surface of a workpiece, the protective housing having a box configuration comprising a front wall (102), a rear wall (104), two end walls (106, 108) and an   upper wall (110) of closure, the set of   characterized in that it comprises lining means (12) of the three-piece front wall comprising a front left lining plate (22>, a front right lining plate (24) and a central front lining plate (26) for covering the inner surface of the front wall, three-part rear wall packing means (14) comprising a left rear lining plate (32), a right rear lining plate (34) and a central rear lining plate (36) for covering the inner surface of the rear wall, two groups of two-part outer wall lining means (16, 18), each group comprising an upper extreme lining plate (42 or 52) and a bottom end packing plate (44 or 54) for covering the inner surfaces of the end walls, means (20) for packing the top wall in one part, comprising an upper wall plate (62) for covering the inner surface of the top closure wall, the front wall packing means and the rear wall packing means each having two grooves (140) for receiving front and rear edge portions (150,) of the end wall packing means and forming assemblies therewith, the top wall packing means having a shaped portion (64) for receiving, forming an assembly, upper edge portions of the front, rear and end wall packing means, some of which are adjacent said plates, when assembled, having portions of their edges   overlap and, in co-operation with the assem-   made between the front, rear, end and top wall packing means, labyrinth seals, abrasive-proof, at all   junctions between the eleven plates of the set of gar-   nissage, adjacent to each other.   Packing unit according to the claim   19, characterized in that some of the selected packing plates have an inner face   smooth, uninterrupted and imperforate, and a sen-   at least a linear edge portion (170) of said body being offset with respect to the plane of said body, said portion being configured to extend below and to cooperate with a portion (172)   of an adjacent one of said trim plates   wise so that a labyrinth seal, abrasive-proof, formed between said parts.   21 Packing unit according to the claim   19, characterized in that each of the plates has a face facing an adjacent part of the protective casing, and an inner face facing towards a central part of the protective casing, the inner faces being smooth and non-perforated and the faces facing towards one another. the housing having bosses having embedded nuts (122) for receiving threaded fasteners (118) adapted for   secure the plates to the protective housing.   22 Packing set according to one of   claims 13 and 19, characterized in that at least   one of the plates is formed in an alloy described   in U.S. Patent No. 2,355,726.   23 Packing unit according to the claim   22, characterized in that at least one of said other plates is made of manganese steel of the Hadfield type. 24 Packing set according to one of   claims 13 and 19, characterized in that at least   one of the plates is formed of manganese steel from Hadfield type.   25 Packing assembly according to the claim   19, characterized in that the bottom end packing plates (244, 254) each comprise a   part (324, 326) protruding laterally towards the ex-   inside and located near the discharge opening.   26 Packing unit according to the claim   19, characterized in that the central rear lining plate (236) has an opening (239) in which a wheel shaft passes, this opening   having a continuous peripheral edge delimited in   by the central rear lining plate.   -27 Packing assembly according to the claim   26, characterized in that it further comprises annular flanges (240, 241) surrounding the opening, on each side of the central rear lining plate, these flanges protruding laterally outwardly. of this plate.   28 Plate-shaped packing element   intended to cover part of a housing (100) of   within which a wheel of   projection that can rotate to propel   matter, under the effect of centrifugal force,   through a discharge opening, the element of gar-   characterized in that it has a first surface exposed to the particles of material propelled by the rotating projection wheel, a second surface disposed on the other side of the element with respect to the first surface and comprising means ( 122) for fixing the packing element to the housing, and a substantially flat body, at least a linear portion (170) of an edge of this body being deported   relative to the plane of said flat body.   29 Packing element according to claim 28, characterized in that it further comprises a tab   (324, 326) protruding laterally and located proximately   mity of the discharge opening to prevent particles of material from entering the area of the second surface and in the protective housing.   Filling element according to claim 28, characterized in that it is made of an alloy described in the United States patent No. 2,355,726.   Plate-shaped packing member for coating a portion of a protective casing (100) inside which is mounted a rotatable guard wheel for propelling particles of material,   under the effect of centrifugal force, through an opening   discharge, the packing element being characterized   risé in that it has a first exposed surface   particles of matter propelled by the wheel of pro-   jection in rotation, a second, -surface arranged on   the other side of the element in relation to the first over-   face and comprising means (122) for fixing the element to the housing, and a substantially flat body along at least a portion of the periphery of the auel extends a groove (64) which is sufficiently wide to receive a part of an edge of a relatively thick or relatively thin plate-shaped member such that a labyrinth seal, abrasive-proof, be trained.   32 Packing element according to the claim   31, characterized in that the groove has a U-shaped section.   33 Packing element according to the claim   31, characterized in that it is aligned with a portion of a side wall, substantially shaped trapeze, protective housing.   34 E 1 packing element according to the claim   31, characterized in that it is made of an alloy   written in U.S. Patent No. 2,355,726.