CA1045761A - Deeply embossed sheet and method for the production thereof - Google Patents
Deeply embossed sheet and method for the production thereofInfo
- Publication number
- CA1045761A CA1045761A CA241,160A CA241160A CA1045761A CA 1045761 A CA1045761 A CA 1045761A CA 241160 A CA241160 A CA 241160A CA 1045761 A CA1045761 A CA 1045761A
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- Prior art keywords
- hills
- sheet
- protuberances
- sheet material
- height
- Prior art date
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Abstract
Abstract of the Disclosure A method and apparatus for the deep embossing of sheet material, generally metal, is disclosed. A relief pattern comprising a plurality of spaced-apart hills is first embossed across the entire sheet and thereafter a deep embossment of spaced-apart protuberances is imparted to the sheet. Both patterns in combination produce a sheet useful for reflective thermal insulation without the risk of significantly puncturing the sheet.
Description
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DEEPLY EMBOSSED SHEET
The invention herein relates to deeply embossed sheet material and to a method and apparatus for the production thereof. More specifically the present invention relates to deeply embossed single sheets of sheet metal su;table for use in reflective thermal insulation structures.
Reflective thermal insulation structures are constructed of metallic enclosing frames containing therein a plurality . .
of spaced-apart reflective metal sheets. A number of such structures are in use in the nuclear power industry~ where reflective insulation is widely used for the thermal insulation of nuclear reactors and associated piping. In one such type of structure individual reflective metal sheets are separated by protruding standoffs embossed from the surfaces of each sheet. Reflective thermal insulation structures for use with piping are known as well as flat panel insulation structures.
: i , Sequential forming of sheet metal is also known.
Prior art reflective thermal insulation structures u~ilizing semi-rigid or rigid sheet metal with standoff protuberances or spacers commonly have holes and tears.
These holes and tears are often formed in the metal sheet as ;
the sheet metal is being embossed with the protuberances. A
j., ;~ ^ disadvantage of these holes and tears is that they allow convective heat transfer (loss) from one layer of air formed between stacked sheets of the embossed sheet metal to another ... .
; layer oF air. This interface and movement of air between layers substantially lowers the thermal efficiency of the reflective insulation structure. Thus, in an ideal situation there are no ruptures or breaks in the sheet metal to permit ~- 30 heat transfer by air convection currents. Another disa~vantage '' ' ':
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1 of the ruptures and breaks in the sheet metal is that if the standoff protuberances are significantly torn, their integrity ~- may be affected to such an extent that the protuberances will collapse and cause the stacked sheets to have a greater surface area ;n contact with each other resulting in an increase of heat transfer by direct conduction.
It is an object of the present invention to overcome the disadvantages of prior art reflective thermal insulation structures by providing a method and appara~us for the production of a deeply embossed sheet material especially suitable for use in reflective thermal insulations in which any appreciable tearing or puncturing of the sheet material is eliminated.
Accordingly, the present invention provides a method for the deep embossment of sheet material especially suitable for use in reflective thermal insulation, the method comprising first embossing the sheet material with a relief pattern of a plurality of spaced-apart hills not more than 1 cm. in height, the area around the hills forming a plurality of intersecting valleys, and thereafter, embossing on the . .
; relief pattern, a deep embossment pattern comprising a plurality of large protuberances projecting outwardly from a surface of :
the sheet material, each protuberance having a base wider than its apex, wherein the base is sufficiently large relative to the hills to include at least portions of several of the hills and wherein the height of the protuberances is greater than the height of the hills.
The present invention also provides an apparatus for the deep embossment of sheet material especially suitable for use in reflective thermal insulation, the apparatus comprising a first pair of rolls~ at least one of the rolls of the first ~ 57~
1 pair having an embossment pattern suitable for embossing a relief pattern on the sheet material, and a second pair of rolls having a surface pattern suitable for embossing deep protuberances from a surface of the sheet material on the relief pattern.
The present invention further provides a sheet of ; sheet material especially suitable for use in reflective thermal insulation, the sheet having on a surface thereof a relief pattern comprising a plurality of hills and intersecting valleys, the hills being spaced from each other and projecting outwardly from a surface of the sheet material not more than 1 cm., and superimposed thereon a deep embossment pattern comprising a plurality of protuberances, each protuberance having a base wider than its apex, wherein the base is sufficiently large relative to the hills to include at least portions of several of the hills and wherein the height of the protuberances is greater than the height of the hills.
The present invention also provides a reflective thermal insulation comprising a plurality of the embossed sheets manufactured according to the present invention and a plurality of spacer sheets, each of the embossed sheets :; manufactured according to the present invention being separated by a spacer sheet positioned in an abutting relationsh~p with `
only the apices of the protuberances.
The present invention also provides a reflective insulation comprising a plurality of the embossed sheets manufactured according to the present invention, each of the embossed sheets being positioned in an abutting relationship with only the apices of the protuberances of another of the sheets.
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~ -3-1 The product of the present invention is especially suitable for use in reflective thermal insulation structures.
The deep protuberances formed in the sheet material separate adjacent sheets when stacked in an insulation structure ,~ such that the only contact points between adjacent sheets are at the apices of the protuberances. This minimal contact between adjacent sheets stacked in an insulation structure minimizes heat transfer by conduction and the absence of ..
significant tearing of the sheets minimizes heat transfer by convection, thus providing an e~ficient reflective insulation structure which is relatively inexpensive to manufacture when compared to known reflective thermal insulations which use expensive non-integral spacers to separate individual ., sheets of reflective sheet material.
FIG. 1 illustrates schematically one embodiment of ,~.;
~` the apparatus according to the present invention for the deep embossing of sheet material.
~i~ FIG. 2 is a partial elevation view showing a typical surface configuration of a pair of relief patterned embossing rolls.
FIG. 3 is a cross-sectional view of the relief patterned embossing rolls taken on line 3-3 of FIG. 2, also showing the relief pattern embossing of a sheet of sheet ; material.
FIG. 4 is a perspective view of a portion of a sheet of sheet material prior to the deep embossing having the relief pattern embossed thereon.
FIG. 5 is a partial elevation view showing a . ~
; typical surface configuration of a pair of deep embossing rolls.
FI6. 6 is a cross-sectional view of the deep embossing ' ': ' ''', ; , ~
57~1 1 ro~ls taken on line 6-6 of FIG. 5, also showing the deep embossing of a sheet of sheet material. ..
.. FIG. 7 is a perspective view of a segment of sheet. material having thereon both the relief pattern and the deep embossment pattern.
FIG. 8 is a partial perspective view of a typical reflective insulation structure manufactured in accordance : with the present invention.
FIG. 9 is a frontal view of one embodiment of a projection used in cooperation with a hole in one of the deep ` embossing rolls. .
FIG. 10 is a partial cross-sectional frontal elevation . of another embodiment of a projection showing the projection; with a core pin and a collar.
,, . The apparatus as a whole is illustrated schematically i in FIG. 1. A sheet material 2 to be embossed, normally 1 to ~ 5 mils thick, is typically a reflective metal foil such as : aluminum or stainless steel. The sheet material 2 passes from a supply roll 3 through a series of straightening rollers -generally designated by a reference numeral 69 into a cutter 9 which severs the continuous sheet material into individual . . , segments 11 of a predetermined length. The straightening rolls 6 and the cutter 9 are conventionally designed and nnrmally operate automatically. Suitable conventional means (not shown) may be used to regulate the length of the metal sheet material segments 11.
The individual metal sheet material segments (here-inafter referred to simply as "sheets") are then transported by a conveyor 12 into the nip 17 between a pair of rolls 15 and 18 which together constitute a relief patterning unit . . .
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generally reFerred to by reference numeral 21 and illustrated in more detail in FIGS. 2 and 3. The relief patterned embossing rolls 15 and 18 impart the pattern exemplified in FIG. 4 to the surfaces of the sheet material segments 11. The surfaces of the illustrated rolls 15 and 18 have the configuratiorl so as to form small hills across both surfaces of the sheet material, reduce the sheet material in overall width and length slightly, and provide a degree of "slack" in the sheet material which permits the subsequent impressment of a pattern .
of deep protuberances by a deep embossing unit 30. To this ` end the rolls 15 and 18 have a pattern of counterpart elevations 36 and depressions 39. This pattern of depressions and elevations can be in the form of "pebbled" surfaces, or raised and depressed pyramids, squares, rectangles and the like of the type which produce a "hills and valleys" pattern.
The "hills-and-valleys" pattern comprises a plurality of small "h~lls" and intersecting "valleys" wherein the hills are spaced apart and no more than 1 cm. in height, usually only about 0.5 to 5 millimeters. The spaces between the hills are . ~
referred to as "valleys". A typical pattern for the relief patterned embossing rolls 15 and 18 for embossing both surfaces of a sheet is shown in FIG. 2.
The sheet may also be embossed with the raised ` surfaces (hills) all projecting from one surface of the sheet. A typical configuration for a pair of relief patterned embossing rolls for embossing only one surface of a sheet would include only one patterned relief roll; the opposing roll would have a smooth, compressible surface, e.g. rubber, ., which would permit the embossment of the hills across a surface of the sheet when elevations on the patterned roll .:
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The exact nature of the l'hills-and-valleys" pattern is not critical, so long as the depth and frequency of the hills and valleys provide sufficient slack in the sheet , ,: .
material to allow the subsequent formation of the deep protu-berances without significant tearing of th~ sheet material.
In one suitable pattern the hills are spaced-apart in two substantially mutually perpendicular directions. In another suitable pattern, the hills are positioned randomly so that ;i~, ~ 10 there are only short segments of directionality, the overall - effect being multi-directional. A uni-directional pattern, such as simple parallel or essentially parallel corrugations, ho~ever, is unsuitable since such a pattern does not provide sufficient slack in the sheet material to permit the subsequent deep impressment of the protuberances. The spaced-apart hills and intersecting valleys thus cooperate to form a pattern - extending across at least one surface of the sheet, the hills of the pattern being spaced-apart raised squares, rectangles, or the like each not exceeding about 10-20 millimeters in -`i` 20 ind;vidual width and length. For example, a pattern of 5 ~ -millimeter square elevations (the "hills") separated by approximately 3 millimeter spaces (the "valleys") and embossed to a depth of approximately 1 millimeter, the hills extending in two directions across both surfaces of a 3 mil thick .
stainless steel sheet, permits the subsequent embossment of a pattern of deep conical protuberances ~2.
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The relief patterning unit 21 produces a relief patterned sheet 16 illustrated in FIG. ~. Also, as shown in - FIG. ~, the relief pattern of sheet 16 is generally not in ~: 30 sharp relief. The relief patterned sheet 16 is typically an ~,.
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intermediate product which is subsequently transported by ` conveyor 22 into the nip 26 of a pair of rollers 24 and 27 which together constitute the deep embossing unit 30 illustrated in FIGS. 5 and 6. The deep embossing unit 30 imparts an additional pattern of large protuberances 42 which project outwardly from a surface of the relief patterned sheet 16. As shown in FIGS. 5 and 6, the deep embossing rolls 24 and 27 ; have a configuration so as to form the spaced-apart conical protuberances 42 projecting in alternate directions ~rom both surfaces of a sheet (see FIG. 7). In one embodiment, the deep embossment pattern is formed by the cooperation of a pattern of projections 48 in one roll corresponding with a pattern of holes 51 in the opposing roll.
The projections 48 are designed such that when e~tended through their corresponding hole to a desired depth, there is sufficient clearance between the outer circumference of the projections and the circumference of their corresponding ; hole to accommodate the thickness of the sheet. In one embodiment, as exemplified in FIG. lO, the projec~ion 48 comprises a metal core pin 44 over which is placed a collar 47. The core pin 44 is fastened to one of the deep embossing rolls by a conventional fastening means such as by cooperating threads or by a "push-fit". The tip of the pin is preferably rounded (e.g. spherical) to minimize the possibilities oF the metal tearing when the protuberances are formed. The collar 47 is a hollow truncated cone which fits over the pin 44 and is retained thereon by frictional contact or is fastened in position by some conventional means. The collar is preferably manufactured from a material that does not build up heat due 30 to its frictional contact with the sheet being embossed. One ~ ~. . . ' ' . , ' ' ' ' " .' . ' ' ' ' ' " ': ' ' ' ' ~ ~q~5~
; 1 material which has been found to be especially suitable is a durable, heat resistant urethane. Other materials, of course, can be used provided that they do not tend to build up frictional heat and so long as any projections comprised of the material are sufficiently durable to withstand the forces exerted on them when pressed into the metal sheet.
In another embodiment, the projections are a plurality of rounded-apex cones 49 with an attachment means 50 (see FIG.
- 9). The rounded (e.g. spherical) apex cone 49 is comprised of the same type of material suitable for use in the collar 47 discussed above.
The conical or semi-conical shape of the projection is very advantageous since such shapes increase the surface area of contact between the projection and the sheet, thus decreasing the amount of deformation stress exerted on a unit area of the sheet, especiially on that point of the sheet which is first contacted by the projection. By deminimizing the .
~ amount of stress exerted on a unit area of the sheet, the ; likelihood of tearing the metal during the formation of the protuberances is also minimi~ed.
Impressment of the protuberances 42 from both ., .
surfaces of the sheet is accomplished by having both the ; projections 48 and the holes 51 on each o~ the deep embossing ~ rolls 24 and 27. In the configuration shown there are an ~ .
' equal number of projections 48 and holes 51 on each roll;
; however, this is not essential. A predominance of the conical . ..~
~ protuberances 42 could be projected from one surface of the ri sheet by constructing one deep embossing roll with a pre-:.
~, dominance of the holes and the other deep embossing roll with a predominance of the corresponding projections 48. This , ,, - .
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1 concept can, of course~ be ultimately extended to the placement of all the proiections ~8 on one deep embossing roll and all of the holes 51 on the opp~sing deep embossing roll to form the protuberances 42 such that they project entirely from only one surface of the sheet.
Like the "hills and valleys" pattern, the conical protuberances also extend in two directions across at least one surface of the sheet material. Depending on the configura-tion of the deep embossing rolls 24 and 27, the pattern of ` 10 protuberances may be somewhat random or may have varying degrees of regularity. The base of the protuberance 42 is sufficiently large relative to the hills of the relief pattern that each base includes at least pGrtions of several of the hills formed by the relief patterning unit 2l. The height of the protuberances is such that if a sheet of sheet material is positioned in an abutting relationship with the apices of the protuberances on another sheet of sheet material, the apices ' - of the protuberances will generally provide the only points of contact between the two sheets. For example, in one embodiment - 20 of the present invention protuberances 42 are approximately 50millimeters in diameter, 15 millimeters in height, and spaced on approximately lO0 millimeter centers. Thus, the deep ;~ embossment of the sheet material by deep embossing unit 30 forms the protuberances which serve as separators or spacers when individual sheets of sheet material are stacked as components of a thermal insulation structure.
It has been found that these two embossing steps (wherein a relief pattern is first embossed and then a pattern of deep protuberances) are necessary in order to obtain a sheet as shown in FIG. 7 without significant puncturing or , .
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l tearing of the sheet. Merely attempting to impress deep protuberances in a non-embossed shee-t is generally unsatis-factory, for instead of forming protuberances, a single step deep embossing procedure often results in the puncturing or tearing of the rigid or semi-rigid sheet material. The sequential embossment of the two patterns as taught in the present invent;on, however, results in forming deep protu-berances without s;gnificant tearing of the sheet material since the first embossment of the sheet by the relief patterned ` 10 rolls provides more metal ;n a unit of area than was i~ the same unit of area prior to the relief patterning of the sheet ; material. Thus, when the deep protuberances 42 are subsequently formed, the metal is not stretched beyond the point at which the metal fails. Consequently, the two steps oF embossing are critical to this invention and it is necessary that the relief patterning step precede the deep embossing step.
; Following the deep embossing step, the individual sheets 75 (now containing the relatively deep protuberances 42 as well as the hills-and-valleys pattern) are transported by a conveyor 31 to a collecting device 33, as exemplified in FIG.
l by a simple collection bin or rack.
. . , The apparatus of the present invention is constructed of any suitable conventional material, normally steel.
O~viously, the heavier the gauge of sheet material to be , embossed, the more rugged the surfaces oF the rolls 15, 18, 24and 27 and the elevatlons 36 and the projections 48 must be.
As illustrated in the accompanying figures, the embossing units 21 and 30 provide only repeated embossments .
of the relief pattern and the deep embossment pattern.
However, it is within the scope of this invention to provide i ,.' .'., , :. , : ~ , . .
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1 easily interchangeable rolls to vary the embossing patterns as desired. The rolls can also be adjustable so as to be able to vary the amount of clearance between the rolls constituting an embossing unit.
Further, although FIG. 1 shows the sheet material being cut by the cutter 9 into individual sheets 11 prior to the embossment steps, it is also within the scope of the this invention to cut the sheet material into individual segments either after the relief embossment step or after the deep embossment step.
A typical reflective thermal insulation structure utilizing the sheets manufactured in accordance with the ` present invention is shown in FIG. 8. A plurality of sheets 75 having the deep protuberances 42 and a plurality of spacer sheets 77 are partially enclosed in a caslng 78. The spacer sheets 77 do not have the deep protuberances 42 impressed ,:
therein. Although the surfaces of the spacer sheets can be entirely non-embossed, in a preferred embodiment of this . .
invention, both surfaces of the spacer sheets are embossed with some type of relief pattern. For example, the spacer sheets may comprise a plurality of the relief patterned sheets 16. The conical protuberances 42 separate the sheets 75 from adjacent spacer sheets 77 positioned in an abutt;ng relationship with the apices of the protuberances, and ~enerally the protuberances 42 form the only points of contact between j the adjacent sheets 75 and 77. The insulation structure can .
be flat as shown in FIG. 8 or curved. The number of sheets , necessary depends on the size of the insulation structure ; and the quantity of heat to be contained, but ordinarily about 5 to 24 sheets are found sufficient. The sheets 75 and 77 are.,, ~:
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1 retained in the casing 78 by a means such as straps 81, per-forated plates, or the like.
While the spacer sheets 77 are used in the preferred embodiment of a reflective thermal insulation structure, this ; is not essential. A plurality of sheets 75 can be positioned in an adjacent relationship such that the only points of contact between adjacent sheets 75 are at the apices of the protuberances of each sheet.
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DEEPLY EMBOSSED SHEET
The invention herein relates to deeply embossed sheet material and to a method and apparatus for the production thereof. More specifically the present invention relates to deeply embossed single sheets of sheet metal su;table for use in reflective thermal insulation structures.
Reflective thermal insulation structures are constructed of metallic enclosing frames containing therein a plurality . .
of spaced-apart reflective metal sheets. A number of such structures are in use in the nuclear power industry~ where reflective insulation is widely used for the thermal insulation of nuclear reactors and associated piping. In one such type of structure individual reflective metal sheets are separated by protruding standoffs embossed from the surfaces of each sheet. Reflective thermal insulation structures for use with piping are known as well as flat panel insulation structures.
: i , Sequential forming of sheet metal is also known.
Prior art reflective thermal insulation structures u~ilizing semi-rigid or rigid sheet metal with standoff protuberances or spacers commonly have holes and tears.
These holes and tears are often formed in the metal sheet as ;
the sheet metal is being embossed with the protuberances. A
j., ;~ ^ disadvantage of these holes and tears is that they allow convective heat transfer (loss) from one layer of air formed between stacked sheets of the embossed sheet metal to another ... .
; layer oF air. This interface and movement of air between layers substantially lowers the thermal efficiency of the reflective insulation structure. Thus, in an ideal situation there are no ruptures or breaks in the sheet metal to permit ~- 30 heat transfer by air convection currents. Another disa~vantage '' ' ':
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1 of the ruptures and breaks in the sheet metal is that if the standoff protuberances are significantly torn, their integrity ~- may be affected to such an extent that the protuberances will collapse and cause the stacked sheets to have a greater surface area ;n contact with each other resulting in an increase of heat transfer by direct conduction.
It is an object of the present invention to overcome the disadvantages of prior art reflective thermal insulation structures by providing a method and appara~us for the production of a deeply embossed sheet material especially suitable for use in reflective thermal insulations in which any appreciable tearing or puncturing of the sheet material is eliminated.
Accordingly, the present invention provides a method for the deep embossment of sheet material especially suitable for use in reflective thermal insulation, the method comprising first embossing the sheet material with a relief pattern of a plurality of spaced-apart hills not more than 1 cm. in height, the area around the hills forming a plurality of intersecting valleys, and thereafter, embossing on the . .
; relief pattern, a deep embossment pattern comprising a plurality of large protuberances projecting outwardly from a surface of :
the sheet material, each protuberance having a base wider than its apex, wherein the base is sufficiently large relative to the hills to include at least portions of several of the hills and wherein the height of the protuberances is greater than the height of the hills.
The present invention also provides an apparatus for the deep embossment of sheet material especially suitable for use in reflective thermal insulation, the apparatus comprising a first pair of rolls~ at least one of the rolls of the first ~ 57~
1 pair having an embossment pattern suitable for embossing a relief pattern on the sheet material, and a second pair of rolls having a surface pattern suitable for embossing deep protuberances from a surface of the sheet material on the relief pattern.
The present invention further provides a sheet of ; sheet material especially suitable for use in reflective thermal insulation, the sheet having on a surface thereof a relief pattern comprising a plurality of hills and intersecting valleys, the hills being spaced from each other and projecting outwardly from a surface of the sheet material not more than 1 cm., and superimposed thereon a deep embossment pattern comprising a plurality of protuberances, each protuberance having a base wider than its apex, wherein the base is sufficiently large relative to the hills to include at least portions of several of the hills and wherein the height of the protuberances is greater than the height of the hills.
The present invention also provides a reflective thermal insulation comprising a plurality of the embossed sheets manufactured according to the present invention and a plurality of spacer sheets, each of the embossed sheets :; manufactured according to the present invention being separated by a spacer sheet positioned in an abutting relationsh~p with `
only the apices of the protuberances.
The present invention also provides a reflective insulation comprising a plurality of the embossed sheets manufactured according to the present invention, each of the embossed sheets being positioned in an abutting relationship with only the apices of the protuberances of another of the sheets.
~' ~
~ -3-1 The product of the present invention is especially suitable for use in reflective thermal insulation structures.
The deep protuberances formed in the sheet material separate adjacent sheets when stacked in an insulation structure ,~ such that the only contact points between adjacent sheets are at the apices of the protuberances. This minimal contact between adjacent sheets stacked in an insulation structure minimizes heat transfer by conduction and the absence of ..
significant tearing of the sheets minimizes heat transfer by convection, thus providing an e~ficient reflective insulation structure which is relatively inexpensive to manufacture when compared to known reflective thermal insulations which use expensive non-integral spacers to separate individual ., sheets of reflective sheet material.
FIG. 1 illustrates schematically one embodiment of ,~.;
~` the apparatus according to the present invention for the deep embossing of sheet material.
~i~ FIG. 2 is a partial elevation view showing a typical surface configuration of a pair of relief patterned embossing rolls.
FIG. 3 is a cross-sectional view of the relief patterned embossing rolls taken on line 3-3 of FIG. 2, also showing the relief pattern embossing of a sheet of sheet ; material.
FIG. 4 is a perspective view of a portion of a sheet of sheet material prior to the deep embossing having the relief pattern embossed thereon.
FIG. 5 is a partial elevation view showing a . ~
; typical surface configuration of a pair of deep embossing rolls.
FI6. 6 is a cross-sectional view of the deep embossing ' ': ' ''', ; , ~
57~1 1 ro~ls taken on line 6-6 of FIG. 5, also showing the deep embossing of a sheet of sheet material. ..
.. FIG. 7 is a perspective view of a segment of sheet. material having thereon both the relief pattern and the deep embossment pattern.
FIG. 8 is a partial perspective view of a typical reflective insulation structure manufactured in accordance : with the present invention.
FIG. 9 is a frontal view of one embodiment of a projection used in cooperation with a hole in one of the deep ` embossing rolls. .
FIG. 10 is a partial cross-sectional frontal elevation . of another embodiment of a projection showing the projection; with a core pin and a collar.
,, . The apparatus as a whole is illustrated schematically i in FIG. 1. A sheet material 2 to be embossed, normally 1 to ~ 5 mils thick, is typically a reflective metal foil such as : aluminum or stainless steel. The sheet material 2 passes from a supply roll 3 through a series of straightening rollers -generally designated by a reference numeral 69 into a cutter 9 which severs the continuous sheet material into individual . . , segments 11 of a predetermined length. The straightening rolls 6 and the cutter 9 are conventionally designed and nnrmally operate automatically. Suitable conventional means (not shown) may be used to regulate the length of the metal sheet material segments 11.
The individual metal sheet material segments (here-inafter referred to simply as "sheets") are then transported by a conveyor 12 into the nip 17 between a pair of rolls 15 and 18 which together constitute a relief patterning unit . . .
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generally reFerred to by reference numeral 21 and illustrated in more detail in FIGS. 2 and 3. The relief patterned embossing rolls 15 and 18 impart the pattern exemplified in FIG. 4 to the surfaces of the sheet material segments 11. The surfaces of the illustrated rolls 15 and 18 have the configuratiorl so as to form small hills across both surfaces of the sheet material, reduce the sheet material in overall width and length slightly, and provide a degree of "slack" in the sheet material which permits the subsequent impressment of a pattern .
of deep protuberances by a deep embossing unit 30. To this ` end the rolls 15 and 18 have a pattern of counterpart elevations 36 and depressions 39. This pattern of depressions and elevations can be in the form of "pebbled" surfaces, or raised and depressed pyramids, squares, rectangles and the like of the type which produce a "hills and valleys" pattern.
The "hills-and-valleys" pattern comprises a plurality of small "h~lls" and intersecting "valleys" wherein the hills are spaced apart and no more than 1 cm. in height, usually only about 0.5 to 5 millimeters. The spaces between the hills are . ~
referred to as "valleys". A typical pattern for the relief patterned embossing rolls 15 and 18 for embossing both surfaces of a sheet is shown in FIG. 2.
The sheet may also be embossed with the raised ` surfaces (hills) all projecting from one surface of the sheet. A typical configuration for a pair of relief patterned embossing rolls for embossing only one surface of a sheet would include only one patterned relief roll; the opposing roll would have a smooth, compressible surface, e.g. rubber, ., which would permit the embossment of the hills across a surface of the sheet when elevations on the patterned roll .:
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The exact nature of the l'hills-and-valleys" pattern is not critical, so long as the depth and frequency of the hills and valleys provide sufficient slack in the sheet , ,: .
material to allow the subsequent formation of the deep protu-berances without significant tearing of th~ sheet material.
In one suitable pattern the hills are spaced-apart in two substantially mutually perpendicular directions. In another suitable pattern, the hills are positioned randomly so that ;i~, ~ 10 there are only short segments of directionality, the overall - effect being multi-directional. A uni-directional pattern, such as simple parallel or essentially parallel corrugations, ho~ever, is unsuitable since such a pattern does not provide sufficient slack in the sheet material to permit the subsequent deep impressment of the protuberances. The spaced-apart hills and intersecting valleys thus cooperate to form a pattern - extending across at least one surface of the sheet, the hills of the pattern being spaced-apart raised squares, rectangles, or the like each not exceeding about 10-20 millimeters in -`i` 20 ind;vidual width and length. For example, a pattern of 5 ~ -millimeter square elevations (the "hills") separated by approximately 3 millimeter spaces (the "valleys") and embossed to a depth of approximately 1 millimeter, the hills extending in two directions across both surfaces of a 3 mil thick .
stainless steel sheet, permits the subsequent embossment of a pattern of deep conical protuberances ~2.
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The relief patterning unit 21 produces a relief patterned sheet 16 illustrated in FIG. ~. Also, as shown in - FIG. ~, the relief pattern of sheet 16 is generally not in ~: 30 sharp relief. The relief patterned sheet 16 is typically an ~,.
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intermediate product which is subsequently transported by ` conveyor 22 into the nip 26 of a pair of rollers 24 and 27 which together constitute the deep embossing unit 30 illustrated in FIGS. 5 and 6. The deep embossing unit 30 imparts an additional pattern of large protuberances 42 which project outwardly from a surface of the relief patterned sheet 16. As shown in FIGS. 5 and 6, the deep embossing rolls 24 and 27 ; have a configuration so as to form the spaced-apart conical protuberances 42 projecting in alternate directions ~rom both surfaces of a sheet (see FIG. 7). In one embodiment, the deep embossment pattern is formed by the cooperation of a pattern of projections 48 in one roll corresponding with a pattern of holes 51 in the opposing roll.
The projections 48 are designed such that when e~tended through their corresponding hole to a desired depth, there is sufficient clearance between the outer circumference of the projections and the circumference of their corresponding ; hole to accommodate the thickness of the sheet. In one embodiment, as exemplified in FIG. lO, the projec~ion 48 comprises a metal core pin 44 over which is placed a collar 47. The core pin 44 is fastened to one of the deep embossing rolls by a conventional fastening means such as by cooperating threads or by a "push-fit". The tip of the pin is preferably rounded (e.g. spherical) to minimize the possibilities oF the metal tearing when the protuberances are formed. The collar 47 is a hollow truncated cone which fits over the pin 44 and is retained thereon by frictional contact or is fastened in position by some conventional means. The collar is preferably manufactured from a material that does not build up heat due 30 to its frictional contact with the sheet being embossed. One ~ ~. . . ' ' . , ' ' ' ' " .' . ' ' ' ' ' " ': ' ' ' ' ~ ~q~5~
; 1 material which has been found to be especially suitable is a durable, heat resistant urethane. Other materials, of course, can be used provided that they do not tend to build up frictional heat and so long as any projections comprised of the material are sufficiently durable to withstand the forces exerted on them when pressed into the metal sheet.
In another embodiment, the projections are a plurality of rounded-apex cones 49 with an attachment means 50 (see FIG.
- 9). The rounded (e.g. spherical) apex cone 49 is comprised of the same type of material suitable for use in the collar 47 discussed above.
The conical or semi-conical shape of the projection is very advantageous since such shapes increase the surface area of contact between the projection and the sheet, thus decreasing the amount of deformation stress exerted on a unit area of the sheet, especiially on that point of the sheet which is first contacted by the projection. By deminimizing the .
~ amount of stress exerted on a unit area of the sheet, the ; likelihood of tearing the metal during the formation of the protuberances is also minimi~ed.
Impressment of the protuberances 42 from both ., .
surfaces of the sheet is accomplished by having both the ; projections 48 and the holes 51 on each o~ the deep embossing ~ rolls 24 and 27. In the configuration shown there are an ~ .
' equal number of projections 48 and holes 51 on each roll;
; however, this is not essential. A predominance of the conical . ..~
~ protuberances 42 could be projected from one surface of the ri sheet by constructing one deep embossing roll with a pre-:.
~, dominance of the holes and the other deep embossing roll with a predominance of the corresponding projections 48. This , ,, - .
.
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1 concept can, of course~ be ultimately extended to the placement of all the proiections ~8 on one deep embossing roll and all of the holes 51 on the opp~sing deep embossing roll to form the protuberances 42 such that they project entirely from only one surface of the sheet.
Like the "hills and valleys" pattern, the conical protuberances also extend in two directions across at least one surface of the sheet material. Depending on the configura-tion of the deep embossing rolls 24 and 27, the pattern of ` 10 protuberances may be somewhat random or may have varying degrees of regularity. The base of the protuberance 42 is sufficiently large relative to the hills of the relief pattern that each base includes at least pGrtions of several of the hills formed by the relief patterning unit 2l. The height of the protuberances is such that if a sheet of sheet material is positioned in an abutting relationship with the apices of the protuberances on another sheet of sheet material, the apices ' - of the protuberances will generally provide the only points of contact between the two sheets. For example, in one embodiment - 20 of the present invention protuberances 42 are approximately 50millimeters in diameter, 15 millimeters in height, and spaced on approximately lO0 millimeter centers. Thus, the deep ;~ embossment of the sheet material by deep embossing unit 30 forms the protuberances which serve as separators or spacers when individual sheets of sheet material are stacked as components of a thermal insulation structure.
It has been found that these two embossing steps (wherein a relief pattern is first embossed and then a pattern of deep protuberances) are necessary in order to obtain a sheet as shown in FIG. 7 without significant puncturing or , .
.,' .
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l tearing of the sheet. Merely attempting to impress deep protuberances in a non-embossed shee-t is generally unsatis-factory, for instead of forming protuberances, a single step deep embossing procedure often results in the puncturing or tearing of the rigid or semi-rigid sheet material. The sequential embossment of the two patterns as taught in the present invent;on, however, results in forming deep protu-berances without s;gnificant tearing of the sheet material since the first embossment of the sheet by the relief patterned ` 10 rolls provides more metal ;n a unit of area than was i~ the same unit of area prior to the relief patterning of the sheet ; material. Thus, when the deep protuberances 42 are subsequently formed, the metal is not stretched beyond the point at which the metal fails. Consequently, the two steps oF embossing are critical to this invention and it is necessary that the relief patterning step precede the deep embossing step.
; Following the deep embossing step, the individual sheets 75 (now containing the relatively deep protuberances 42 as well as the hills-and-valleys pattern) are transported by a conveyor 31 to a collecting device 33, as exemplified in FIG.
l by a simple collection bin or rack.
. . , The apparatus of the present invention is constructed of any suitable conventional material, normally steel.
O~viously, the heavier the gauge of sheet material to be , embossed, the more rugged the surfaces oF the rolls 15, 18, 24and 27 and the elevatlons 36 and the projections 48 must be.
As illustrated in the accompanying figures, the embossing units 21 and 30 provide only repeated embossments .
of the relief pattern and the deep embossment pattern.
However, it is within the scope of this invention to provide i ,.' .'., , :. , : ~ , . .
, ~4~716~
1 easily interchangeable rolls to vary the embossing patterns as desired. The rolls can also be adjustable so as to be able to vary the amount of clearance between the rolls constituting an embossing unit.
Further, although FIG. 1 shows the sheet material being cut by the cutter 9 into individual sheets 11 prior to the embossment steps, it is also within the scope of the this invention to cut the sheet material into individual segments either after the relief embossment step or after the deep embossment step.
A typical reflective thermal insulation structure utilizing the sheets manufactured in accordance with the ` present invention is shown in FIG. 8. A plurality of sheets 75 having the deep protuberances 42 and a plurality of spacer sheets 77 are partially enclosed in a caslng 78. The spacer sheets 77 do not have the deep protuberances 42 impressed ,:
therein. Although the surfaces of the spacer sheets can be entirely non-embossed, in a preferred embodiment of this . .
invention, both surfaces of the spacer sheets are embossed with some type of relief pattern. For example, the spacer sheets may comprise a plurality of the relief patterned sheets 16. The conical protuberances 42 separate the sheets 75 from adjacent spacer sheets 77 positioned in an abutt;ng relationship with the apices of the protuberances, and ~enerally the protuberances 42 form the only points of contact between j the adjacent sheets 75 and 77. The insulation structure can .
be flat as shown in FIG. 8 or curved. The number of sheets , necessary depends on the size of the insulation structure ; and the quantity of heat to be contained, but ordinarily about 5 to 24 sheets are found sufficient. The sheets 75 and 77 are.,, ~:
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. - .. .. .. . . . . . .
5~6~
1 retained in the casing 78 by a means such as straps 81, per-forated plates, or the like.
While the spacer sheets 77 are used in the preferred embodiment of a reflective thermal insulation structure, this ; is not essential. A plurality of sheets 75 can be positioned in an adjacent relationship such that the only points of contact between adjacent sheets 75 are at the apices of the protuberances of each sheet.
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Claims (7)
1. A method for the deep embossment of sheet material especially suitable for use in reflective thermal insulation, said method comprising first embossing the sheet material with a relief pattern of a plurality of spaced-apart hills not more than 1 cm. in height, the area around said hills forming a plurality of intersecting valleys, and thereafter embossing on said relief pattern a deep embossment pattern comprising a plurality of large protuberances pro-jecting from a surface of said sheet material, and each pro-tuberance having a base wider than its height, wherein the base is sufficiently large relative to the hills to include at least portions of several of said hills and wherein the height of each of said protuberances is greater than the height of said hills.
2. A method according to Claim 1 wherein the step of embossing the relief pattern includes forming hills which project outwardly from both surfaces of said sheet material and the step of embossing the deep embossment pattern forms protuberances which project alternately from both surfaces of the sheet material.
3. The method according to either Claim 1 or 2 wherein said hills of the relief pattern are spaced apart in two directions substantially perpendicular to each other across a surface of said sheet material.
4. The method according to either Claim 1 or 2 wherein said relief pattern comprises a plurality of approxi-mately 5 mm square hills separated by approximately 3 mm valleys, said hills being embossed to a dimension of approxi-mately 1 mm from a surface of the sheet, and said protuberances having dimensions of approximately 50 mm diameter and 15 mm height and being spaced on approximately 100 mm centers.
5. A sheet of material especially suitable for use in reflective thermal insulation, said sheet having on a surface thereof a relief pattern comprising a plurality of hills and intersecting valleys, said hills being spaced from each other and projecting outwardly from a surface of said sheet material not more than 1 cm, and superimposed thereon, a deep embossment pattern comprising a plurality of protuberances, each protuberance having a base wider than its height, wherein the base is sufficiently large relative to the hills such that it encompasses at least portions of several of the hills and wherein the height of each protuberance is greater than the height of said hills.
6. The sheet according to Claim 5 wherein said protuberances are generally conical and project alternately from both surfaces of the sheet.
7. The sheet according to either of Claims 5 or 6 wherein said relief pattern comprises a plurality of approximately 5 mm hills separated by approximately 3 mm valleys, said hills and valleys being embossed to a dimension of approximately 1 mm from a surface of the sheet, and said protuberances having dimensions of approximately 50 mm diameter and 15 mm height and being spaced on approximately 100 mm centers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA241,160A CA1045761A (en) | 1975-12-05 | 1975-12-05 | Deeply embossed sheet and method for the production thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA241,160A CA1045761A (en) | 1975-12-05 | 1975-12-05 | Deeply embossed sheet and method for the production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1045761A true CA1045761A (en) | 1979-01-09 |
Family
ID=4104679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA241,160A Expired CA1045761A (en) | 1975-12-05 | 1975-12-05 | Deeply embossed sheet and method for the production thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1045761A (en) |
-
1975
- 1975-12-05 CA CA241,160A patent/CA1045761A/en not_active Expired
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