US3899043A

US3899043A - Machine cover

Info

Publication number: US3899043A
Application number: US492537A
Authority: US
Inventors: Guy E Hall
Original assignee: Steadley Co
Current assignee: Steadley Co
Priority date: 1974-07-29
Filing date: 1974-07-29
Publication date: 1975-08-12
Anticipated expiration: 1992-08-12

Abstract

A cover for various types of machines which operate at high noise levels comprises two or more shells of substantially rigid material shaped to the general configuration of the machine and having generally vertical side margins which are placed in registry and secured together to form a unitary enclosure. At least some of the shells have upper horizontal sections to overlie portions of the machine and complete the enclosure. The margins of the shells have outwardly extending flanges which are brought together and gripped by spring clips. Since the shells are rigid, they are free standing, not connected to the machine, and may be separated and slid away across the floor in moments to allow repair and maintenance. The total enclosure greatly reduces the volume of noise which would otherwise be transmitted to the surrounding area and prevents the spread of smoke and fumes. An exhaust conduit and fan carry away the pollutants. Various apertures are provided to allow access to the machine for inspection and adjustment and are covered by removable shields. At least one shield has a transparent area for visual inspection, and the shells are made of translucent material such as fiberglass to admit exterior shop light for such inspection, eliminating the need for interior auxiliary lighting.

Description

United States Patent [191 Hall [451 Aug. 12, 1975 154] MACHINE COVER [75] Inventor: Guy E. Hall, Denver, C010.

[73] Assignee: Steadley Company, Inc., Carthage,

221 Filed: July 29,1974

211 App]. No.: 492,537

[52] US. Cl. 181/33 K; 52/79; 52/144;

98/33 R [51] Int. Cl. E048 l/82 [58] Field of Search 181/33 K; 312/283, 284,

[56] References Cited UNITED STATES PATENTS 2,701,618 2/1955 Montgomery 181/33 K UX 3,087,578 4/1963 Reed et a1. 181/33 K UX 3,102,365 9/1963 Whitesell 52/306 X 3,302,547 2/1967 Wasserman 98/33 R 3,700,068 10/1972 Francis 181/33 K 3,773,140 11/1973 Mahajan et a1. 181/33 K 3,775,919 12/1973 Fulton et a1. 52/79 X FOREIGN PATENTS OR APPLICATIONS 1,459,167 10/1966 France 181/33 K OTHER PUBLICATIONS Butler, B. H., A Noise-Reducing Enclosure for a Four-Die Swager, Sound, 2(4), pp. 30-32, July-August, 1963.

Primary Examiner-Joseph W. Hartary Assistant Examiner.lohn F. Gonzales Attorney, Agent, or F irmSheridan, Ross & Fields [5 7 ABSTRACT A cover for various types of machines which operate at high noise levels comprises two or more shells of substantially rigid material shaped to the general configuration of the machine and having generally vertical side margins which are placed in registry and secured together to form a unitary enclosure. At least some of the shells have upper horizontal sections to overlie portions of the machine and complete the enclosure. The margins of the shells have outwardly extending flanges which are brought together and gripped by spring clips. Since the shells are rigid, they are free standing, not connected to the machine, and may be separated and slid away across the floor in moments to allow repair and maintenance. The total enclosure greatly reduces the volume of noise which would otherwise be transmitted to the surrounding area and prevents the spread of smoke and fumes. An exhaust conduit and fan carry away the pollutants. Various apertures are provided to allow access to the machine for inspection and adjustment and are covered by removable shields. At least one shield has a transparent area for visual inspection, and the shells are made of translucent material such as fiberglass to admit exterior shop light for such inspection, eliminating the need for interior auxiliary lighting.

17 Claims, 8 Drawing Figures PATEMEU AUG 1 21975 3, 899 O43 SHEET 4 l' 5| Ill MACHINE COVER BACKGROUND OF THE INVENTION This invention lies in the field of covers for processing machines of various types which emit undesirable noise during operation and frequently also produce smoke or fumes or heat which spread through the surrounding shop area. It is particularly directed to a cover for such machines which is easy to assemble in place, does not require modification of machine or cover for attachment, and performs its functions in a simple and reliable manner.

Many different kinds of covers have been proposed and adopted for attenuating machine noise or for reducing the pollution of the atmosphere in the machine area, and the results achieved are usually satisfactory. However, they frequently suffer from some disaavantage, such as cost, weight or complexity, or are difficult to remove when maintenance or adjustment is necessary.

Some covers are mounted directly to the machine, which normally requires modification of both the ma chine and the cover. Removal requires disconnection of various fastening means. If it is desired to merely swing the covers out of the way, the mounting means become more complicated.

Other covers are fixedly mounted on the floor adjacent to the machine and have movable sections which swing into place to form a cover. These devices are cumbersome and time consuming to manipulate, and cannot be moved away to avoid interference with maintenance or adjustment operations.

Still others are formed with a rigid framework to which a flexible cover of some kind is attached to be draped around the machine. The flexible cover is unwieldy to handle and difficult to move out of the way. It is readily damaged by rough handling and has a relatively short shop life.

SUMMARY OF THE INVENTION The apparatus of the present invention overcomes the disadvantages mentioned above and provides a simple and durable structure which is not attached to the machine and which may be dismantled and removed in moments to provide complete access to any part of the machine.

Generally stated, the apparatus of the invention comprises two or more shells of rigid material which have generally horizontal bottom margins for self-supporting contact with thhe floor around the machine. The shells as a group are designed to be secured into a unitary assembly which surrounds the machine, and the shells have upper horizontal wall portions overlying portions of the machine and meeting along their margins to form a complete enclosure.

The side walls of the shells have vertical margins provided with outwardly extending flanges along their lengths and the marginal portions of perimetrally adjacent shells lie in a common plane, with the opposing faces of the flanges in juxtaposition, and spring clips are secured at spaced points to the flanges to yieldingly urge them toward each other to produce a unitary assembly. Preferably, elastomeric strips are interposed between the flanges to accommodate manufacturing variations and to seal the joints against the emission of noise or pollutants. Ordinarily, all of the margins of the upper horizontal wall portions or sections are similarly provided with upwardly extending flanges juxtaposed along common vertical planes and provided with spring clip securing devices and seal strips.

In addition to direct prevention of the spreading of pollutants produced by the machine, the enclosure is provided with means to dispose of them. An air inlet port is formed in a lower side wall of the enclosure and is fitted with a filter to protect the machine itself against the entry of pollutants already present in the surrounding shop area. An air outlet port is formed in the upper horizontal wall portion or section and fitted with an exhaust fan to draw air through the inlet port and across the machine to the outlet port where it flows into an exhaust conduit leading to the external atmosphere or to special air purifying apparatus.

Apertures are formed in the walls of the enclosure at appropriate points for inspection or adjustment of the machine without the need to remove the enclosure. Shields are provided for the apertures to complete the enclosure, and at least one shield has a transparent area for visual inspection. In order to obviate the need for auxiliary lighting inside the cover to facilitate such visual inspection, the shells themselves are made of translucent material, preferably fiberglass, which transmits sufficient exterior light to the interior of the cover to carry out the desired visual inspection. Neither the inner nor the outer surfaces of the shell walls are covered with insulation because the opacity would defeat the purpose of the translucent material. Of course, opaque attachments such as instruction and warning plates and the like may be applied so long as their area is a minor portion of the total area and they are not located where they would block light from parts which need to be inspected.

The fiberglass material serves another important function. It can be molded to any desired shape and therefore the shells may be originally formed to correspond closely to the overall outlines of portions of the machine, so that the total enclosure will take up a minimum of floor space. In addition the individual shells are rigid enough to be self-supporting and light enough to be readily moved along the floor by one man.

BRIEF DESCRIPTION OF THE DRAWINGS Various other advantages and features of novelty will become apparent as the description proceeds in conjunction with the accompanying drawings, in which:

FIG. 1 is a right front perspective view of the assembled enclosure;

FIG. 2 is a left front perspective view of the enclosure;

FIG. 3- is a rear perspective view of the enclosure;

FIG. 4 is a top plan view of the enclosure;

FIG. 5 is an exploded view in perspective of the components of the enclosure;

FIG. 6 is a sectional view taken on line 66 of FIG.

FIG. 7 is a sectional view taken on line 77 of FIG. 1; and

FIG. 8 is a perspective view of a spring clip to hold the shells in assembled relation.

DESCRIPTION OF PREFERRED EMBODIMENTS A typical multi-part machine cover incorporating the features of the invention is diagrammatically illustrated in perspective in FIGS. 1 to 3, in which the total cover is made up of three principal components, solely as an example,

shells

12, 14, and 16. There may be as few as two shells or as many as desired without affecting the principles of the invention. Each of the shells is formed to correspond generally with the three-dimensional outline of a portion of machine 18, shown in broken lines in FIG. 1, and consequently the assembly corresponds to the outlines of the total machine, taking up a minimum of added floor space. Although the use of the invention is not limited to any particular type of machine, the cover is shown for purposes of illustration and explanation as applied to the coil spring forming machine 18 which has a generally cross-like planform and components located at different elevations. The portion 20 which extends out to the right as viewed in FIG. 1 represents the wire-feeding and wirestraightening section, while the portion 22 which extends out to the left represents a delivery trough for finished springs. Spool 24 represents the storage supply of wire 26 to feed the machine.

In the example shown, shell 12 is the major component, extending across the full lateral width of the machine and having an extensive front wall 28, a projection 30, and an end wall or marginal portion 32 at the right end as well as a similar end wall or marginal portion 34 at the left end. It also has an upper generally horizontal wall portion or section 36 overlying a part of the machine. The actual margins 38 of the upstanding

marginal portions

32 and 34 and the upper horizontal section 36 all lie in a common vertical plane, and flange 40 extends along the lengths of the margins. As can be seen best in FIG. 7, it extends outwardly at right angles to the plane of the marginal portions and its one face 42 lies in the common vertical plane of the margins.

Shell 14 extends to the rear of the machine and has an extensive side wall 44 and a projection 46 including an upstanding wall or marginal portion 48, together with an upper generally horizontal wall portion or section 50 overlying another part of the machine. The actual margins 52 of the upstanding marginal portion 48 and horizontal section 50 lie in a common vertical plane, and flange 54 extends along the lengths of these margins. As can also be seen in FIG. 7, it extends outwardly at right angles to the planes of the marginal portions and its one face 56 lies in the common vertical plane of these margins.

Shells

12 and 14 are formed of substantially rigid material and are free standing and in self-supporting contact with the machine-supporting floor, and are assembled by moving them along the floor into the positions shown in FIGS. 1 to 4 with

marginal portions

32 and 48 in a common vertical plane and their

margins

38 and 52 as well as their

flanges

40 and 54 juxtaposed in registry. A strip 58 of elastomeric material such as rubber or plastic foam is preferably located between faces 42 and 56 to accommodate irregularities in the surfaces and to seal against emission of noise and pollutants. The strip is preferably secured to one of the flanges by cementing or riveting. To force the flanges toward each other and in contact with the seal strip, a spring clip 60 is applied at spaced points along their lengths and engages the exposed surfaces of the flanges.

The rearwardly directed margin 62 of section 50 is similarly provided with a flange 64 for connection to the third shell 16. The 'upper horizontal section 66 of shell 16 has a margin 68 and flange 70 formed to register with the opposed corresponding margin and flange of shell 14, and also a margin 72 and flange 74 formed to register with the opposed corresponding margin and flange of section 36. Also its upstanding marginal portion 76 has a margin 78 and flange 80 to register with the opposed corresponding margin and flange of marginal portion 34. When shell 16 is moved into registering position as indicated in FIGS. 1 to 4, additional spring clips are applied to the juxtaposed flanges and the shells are secured together into a substantially unitary enclosure. It will be noted that margin 82 of upstanding marginal portion 84 of shell 16 has no attaching flange. It merely abuts side wall 86 of shell 14 as seen in FIG. 3. However, it is held in contact with the side wall by virtue of the various spring clips, and a sealing strip may be applied along the line of jointure if desired.

Additional means may be provided for guiding the shells into registry and for preventing adjacent marginal portions from being displaced out of their common plane. As seen in FIGS. 5 and 6, these means comprise guide tabs 88 which are secured at intervals to the inner faces of the various marginal portions and extend outward beyond the margins to contact the inner faces of the adjacent marginal portions and guide the two shells into proper registry. After the assembly is completed, they also serve to maintain alignment because if either marginal portion is urged out of the common plane the contact of the opposing tabs with the inner surfaces prevents such movement.

Many machines, such as the spring machine indicated in FIG. 1, apply heat and lubricant to the work pieces, resulting in the emission of waste heat, smoke, and fumes as well as noise. To deal with this problem an air inlet port 90 is provided in the lower part of side or rear wall 92 of shell 14, and a filter 94 is mounted in the port to reduce the entry of pollutants which may already be in the adjacent shop areas to protect the machine itself. An air outlet port 96 is provided in the upper horizontal wall section 66 of shell 16 and is connected to exhaust conduit 98 which may lead to the exterior atmosphere or to an air purifying apparatus, not shown. An exhaust fan 100 may be provided on the roof of the building to pull air through conduit 98 but is shown as being mounted in conduit 98 for illustrative purposes only. The fan will draw air in through port 90 and across the machine to cool the machine and to draw pollutants created by the machine out through conduit 98.

The shells making up the enclosure are formed of substantially rigid translucent material such as fiberglass which will transmit a large proportion of the exterior shop light to the interior of the enclosure for a purpose to be described. Since fiberglass can be readily molded to any desired shape it is ideal for producing shells which correspond closely to the threediniensional outlines of portions of the particular machines with which they are to be used, thus taking up a minimum of shop floor space when they are in use. In addition, the shells are rigid enough to be free standing and self-supporting on the shop floor and light enough to be easily moved by one man.

Various apertures 102 are formed through the walls of the shells at selected points to provide access to the machine for adjustment or minor maintenance. These apertures are covered by shields 104 pivoted at 106 in order to complete the enclosure. At least one of the shields is provided with a transparent area, indicated by the window 108, through which an important operation such as coil forming may be viewed and inspected without opening the shield. Since the shell material is translucent, enough light enters the enclosure to illuminate the various parts of the machine, and the need for internal auxiliary lighting is obviated. Sound insulation is not provided because it would defeat the light transmitting capacity of the shell material but the noise is greatly attenuated by the low vibration characteristic of the fiberglass'Various opaque attachments such as instruction or warning signs are permissible so long as they cover only a minor portion of the total area of the shells and are not placed in locations where they would directly block the incidence of light on areas to be inspected.

In order to provide for entrance of the wire 26 into the wire feed and straightener 20, opposed Cut-out portions 110 are formed in the

margins

38 and 52 of

marginal portions

32 and 48 to define a passage 112. Metal guard strips 114 are secured on the edges of portions 110 to prevent abrasion of the fiberglass material by contact with the moving wire. An aperture 116 is formed in wall 34 of shell 12 to accommodate the extension of delivery trough 22 to the exterior of the enclosure.

The spring clip 60 is illustrated in FIG. 8. It is made up of a length of spring wire formed into two

elongate sections

118 and 120 arranged generally parallel to each other and adapted to engage the exposed faces of the flanges as indicated in FIG. 7. Two identical crossmembers 122 join the ends of the elongate members. A first cross-member comprises a U-shaped bail with two depending arms 124 joined at their lower ends to ends 126 and 128 of

sections

118 and 120. The second cross-member is provided with depending arms 124 joined at their lower ends to ends 130 and 132 of

sections

118 and 120. An intermediate portion 134 of section 120 is formed to extend out of the plane containing the major portion of the elongate sections to serve as a handle for applying and detaching the spring clip. The ends of the length of wire are welded at 136 to form a closed loop.

It will be apparent that the invention described above provides a simple and durable machine cover having very few parts, which may be assembled or removed readily and in a short space of time, and which performs all of the functions required of such apparatus with complete reliability.

What is claimed is: 1. A noise-reducing and pollution-controlling machine cover comprising:

a plurality of free standing shells adapted to be secured together to enclose a processing machine;

each shell being formed of substantially rigid translucent material with the major portion of its internal and external surface areas free of opaque attachments or coatings;

the lower margin of each shell lying generally in a horizontal plane for supporting contact with a floor, with the upstanding side margins and upper margins lying in vertical planes and sized and shaped to register with the opposed margins of adjacent shells;

means to detachably secure the shells together with their opposed corresponding margins in registry into a unitary noise-reducing enclosure encompassing the machine and standing in self-supporting contact with the machine-supporting floor;

apertures through the wall of at least one shell to provide access to the machine;

and shields for each of said apertures to complete the enclosure;

at least one of said shields having a transparent area for visual inspection of the machine;

the translucent material of the shells serving to transmit exterior light to the interior of the enclosure to facilitate such visual inspection.

2. A cover as claimed in claim 1; in which elastomeric strips are arranged between the confronting margins of adjacent shells to compensate for surface irregularities and complete the sealing of the enclosure.

3. A cover as claimed in claim 1; in which outwardly extending flanges are provided along the upstanding and upper margins of each shell;

elastomeric sealing strips are arranged between the confronting flanges of adjacent shells;

and removable fasteners are secured to the flanges at spaced points along their periphery to force them toward each other into clamping relation with the sealing strips.

4. A cover as claimed in claim 3; in which the removable fasteners are spring clips having portions formed to engage the exposed faces of adjacent flanges and yieldingly urge the flanges toward each other.

5. A cover as claimed in claim 1; in which guide tabs are secured to the inner surfaces of at least some of the shells and extend out beyond the margins to engage the inner surfaces of the marginal portions of the adjacent shells to guide them together and to prevent displacement of either shell out of the common plane of the two shells.

6. A cover as claimed in claim 1; in which the shells are formed of translucent fiberglass material.

7. A cover as claimed in claim 6; in which the enclosure is sized and shaped to encompass a spring forming machine and comprises a first shell covering the front portion of the machine and at least a second shell covering a rear portion of the machine;

the end walls of the shells having a vertical line of jointure at one side of the machine and having opposed cut-out portions in their margins defining between them an aperture for wire to be drawn into the machine, each cut-out portion being provided with a metal guard strip to prevent abrasion of the fiberglass material by contact with the moving wire.

8. A cover as claimed in claim 7; in which an aperture is formed in the opposite end of the first shell to accommodate the extension beyond the cover of a delivery trough for the springs made by the machine.

9. A noise-reducing and pollution-controlling machine cover comprising:

a plurality of free standing shells adapted to be secured together to enclose a processing machine; the shells being substantially rigid to be selfsupporting on a floor; at least the major part of the cover being formed of translucent material;

the lower margin of each shell lying generally in a horizontal plane for supporting contact with a floor;

the margins of the upstanding portions of each shell being sized and shaped to register with the opposed corresponding margins of adjacent shells;

and shields for the apertures to complete the enclosure;

at least one of the shields having a transparent area for visual inspection of the machine;

the translucent material serving to transmit exterior light to the interior of the enclosure to facilitate such visual inspection.

10. A cover as claimed in claim 9; in which the translucent material is fiberglass.

11. A cover as claimed in claim 9; in which outwardly extending flanges are provided along the opposed corresponding margins of each shell;

and removable fasteners are secured to the flanges at spaced points along their periphery;

the fasteners comprising spring clips having portions formed to engage the exposed faces of adjacent flanges and yieldingly urge them toward each other.

12. A noise-reducing and pollution-controlling machine cover comprising:

a plurality of free standing shells adapted to be secured together to enclose a processing machine; the shells being substantially rigid to be selfsupporting on a floor;

at least two perimetrally adjacent shells having upstanding marginal wall sections lying in a common vertical plane when assembled, with their opposed corresponding margins juxtaposed along a line of jointure extending generally vertically;

each corresponding margin being provided with an outwardly extending flange along the major portion of its length, with the confronting faces of the flanges lying substantially in a common vertical plane perpendicular to the common plane of the marginal wall sections;

and quick detachable fasteners secured to the flanges at spaced points along their length to force the flanges toward each other to produce a unitary enclosure encompassing the machine and standing in self-supporting contact with the machine supporting floor.

13. A cover as claimed in claim 12; in which the two perimetrally adjacent shells also include upper generally horizontal wall sections overlying the machine and lying in a common horizontal plane when assembled, with their opposed corresponding margins juxtaposed along a line of jointure extending generally horizontally;

each corresponding margin being provided with an upwardly extending flange along the major portion of its length, with the confronting faces of the flanges lying substantially in a common vertical plane perpendicular to the common plane of the upper wall sections;

and quick detachable fasteners secured to the flanges at spaced points along their length to force the flanges toward each other to produce a unitary enclosure.

14. A cover as claimed in claim 12; in which the quick detachable fasteners are spring clips having portions formed to engage the exposed faces of adjacent flanges and yieldingly urge the flanges toward each other.

15. A cover as claimed in claim 12; in which apertures are provided through the wall of at least one shell to provide access to the machine;

and shields are provided for each of the apertures to complete the enclosure;

at least one of said shields having a transparent area for visual inspection of the machine.

16. A cover as claimed in claim 12; in which guide tabs are secured to the inner surfaces of at least some of the shells and extend out beyond the margins to engage the inner surfaces of the marginal portions of the adjacent shells to guide them together and to prevent displacement of either shell out of the common plane of the two shells.

17. A cover as claimed in claim 12; in which an air inlet port is provided in a lower side wall of the cover;

a filter is mounted in the inlet port;

an air outlet port is provided in the top of the cover;

an exhaust conduit is connected to the outlet port;

and an exhaust fan is mounted in the conduit.

Claims

1. A noise-reducing and pollution-controlling machine cover comprising: a plurality of free standing shells adapted to be secured together to enclose a processing machine; each shell being formed of substantially rigid translucent material with the major portion of its internal and external surface areas free of opaque attachments or coatings; the lower margin of each shell lying generally in a horizontal plane for supporting contact with a floor, with the upstanding side margins and upper margins lying in vertical planes and sized and shaped to register with the opposed margins of adjacent shells; means to detachably secure the shells together with their opposed corresponding margins in registry into a unitary noisereducing enclosure encompassing the machine and standing in self-supporting contact with the machine-supporting floor; apertures through the wall of at least one shell to provide access to the machine; and shields for each of said apertures to complete the enclosure; at least one of said shields having a transparent area for visual inspection of the machine; the translucent material of the shells serving to transmit exterior light to the interior of the enclosure to facilitate such visual inspection.

3. A cover as claimed in claim 1; in which outwardly extending flanges are provided along the upstanding and upper margins of each shell; elastomeric sealing strips are arranged between the confronting flanges of adjacent shells; and removable fasteners are secured to the flanges at spaced points along their periphery to force them toward each other into clamping relation with the sealing strips.

7. A cover as claimed in claim 6; in which the enclosure is sized and shaped to encompass a spring forming machine and comprises a first shell covering the front portion of the machine and at least a second shell covering a rear portion of the machine; the end walls of the shells having a vertical line of jointure at one side of the machine and having opposed cut-out portions in their margins defining between them an aperture for wire to be drawn into the machine, each cut-out portion being provided with a metal guard strip to prevent abrasion of the fiberglass material by contact with the moving wire.

9. A noise-reducing and pollution-controlling machine cover comprising: a plurality of free standing shells adapted to be secured together to enclose a processing machine; the shells being substantially rigid to be self-supporting on a floor; at least the major part of the cover being formed of translucent material; the lower margin of each shell lying generally in a horizontal plane for supporting contact with a floor; the margins of the upstanding portions of each shell being sized and shaped to register with the opposed corresponding margins of adjacent shells; means to detachably secure the shells together with their opposed corresponding margins in registry into a unitary noise-reducing enclosure encompassing the machine and standing in self-supporting contact with the machine-supporting floor; apertures through the wall of at least one shell to provide access to the machine; and shields for the apertures to complete the enclosure; at least one of the shields having a transparent area for visual inspection of the machine; the translucent material serving to transmit exterior light to the interior of the enclosure to facilitate such visual inspection.

11. A cover as claimed in claim 9; in which outwardly extending flanges are provided along the opposed corresponding margins of each shell; and removable fasteners are secured to the flanges at spaced points along their periphery; the fasteners comprising spring clips having portions formed to engage the exposed faces of adjacent flanges and yieldingly urge them toward each other.

12. A noise-reducing and pollution-controlling machine cover comprising: a plurality of free standing shells adapted to be secured together to enclose a processing machine; the shells being substantially rigid to be self-supporting on a floor; at least two perimetrally adjacent shells having upstanding marginal wall sections lying in a common vertical plane when assembled, with their opposed corresponding margins juxtaposed along a line of jointure extending generally vertically; each corresponding margin being provided with an outwardly extending flange along the major portion of its length, with the confronting faces of the flanges lying substantially in a common vertical plane perpendicular to the common plane of the marginal wall sections; and quick detachable fasteners secured to the flanges at spaced points along their length to force the flanges toward each other to produce a unitary enclosure encompassing the machine and standing in self-supporting contact with the machine supporting floor.

13. A cover as claimed in claim 12; in which the two perimetrally adjacent shells also include upper generally horizontal wall sections overlying the machine and lying in a common horizontal plane when assembled, with their opposed corresponding margins juxtaposed along a line of jointure extending generally horizontally; each corresponding margin being provided with an upwardly extending flange along the major portion of its length, with the confronting faces of the flanges lying substantially in a common vertical plane perpendicular to the common plane of the upper wall sections; and quick detachable fasteners secured to the flanges at spaced points along their length to force the flanges toward each other to produce a unitary enclosure.

15. A cover as claimed in claim 12; in which apertures are provided through the wall of at least one shell to provide access to the machine; and shields are provided for each of the apertures to complete the enclosure; at least one of said shields having a transparent area for visual inspection of the machine.

17. A cover as claimed in claim 12; in which an air inlet port is provided in a lower side wall of the cover; a filter is mounted in the inlet port; an air outlet port is provided in the top of the cover; an exhaust conduit is connected to the outlet port; and an exhaust fan is mounted in the conduit.