CA1239300A - Blind rivet - Google Patents
Blind rivetInfo
- Publication number
- CA1239300A CA1239300A CA000462868A CA462868A CA1239300A CA 1239300 A CA1239300 A CA 1239300A CA 000462868 A CA000462868 A CA 000462868A CA 462868 A CA462868 A CA 462868A CA 1239300 A CA1239300 A CA 1239300A
- Authority
- CA
- Canada
- Prior art keywords
- rivet
- head
- mandrel
- shear
- sleeve means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Insertion Pins And Rivets (AREA)
Abstract
ABSTRACT
The invention relates to a blind rivet having a shear portion that is accepted within aligned apertures in a workpiece. The rivet has a pre-formed head at one end of the shear portion and a central aperture therethrough for the acceptance of a headed mandrel. An incompletely polymerized thermoset resin portion of the rivet is disposed about the mandrel at the opposite end of the shear portion from the head thereon. Tensioning of the mandrel effects compression of the incompletely polymerized portion which is softened due to the application of heat. The mandrel forms a radially extending blind head that is interlocked with the shear portion of the rivet to draw the workpieces together and which, when fully polymerized, forms a permanent thermoset riveted connected.
The invention relates to a blind rivet having a shear portion that is accepted within aligned apertures in a workpiece. The rivet has a pre-formed head at one end of the shear portion and a central aperture therethrough for the acceptance of a headed mandrel. An incompletely polymerized thermoset resin portion of the rivet is disposed about the mandrel at the opposite end of the shear portion from the head thereon. Tensioning of the mandrel effects compression of the incompletely polymerized portion which is softened due to the application of heat. The mandrel forms a radially extending blind head that is interlocked with the shear portion of the rivet to draw the workpieces together and which, when fully polymerized, forms a permanent thermoset riveted connected.
Description
~3~3(~0 BLIND RIVET
BACKGROUND OF THE INVENTION
The aircraft industry has developed a number of airframe components utilizing modern composite materials, for example, carbon fiber reinforced resins.
Despite the fact that such materials exhibit outstanding strength to weight characteristics, use thereof has been limited by the difficulty of fastening such materials. Conventional fasteners have proved to be unsatisfactory for several reasons. One kirk-touristic of composite materials is that the material adjacent the periphery of an aperture therein is sub-jet to shattering or cracking when relatively high unit pressure is brought to bear there against. For example, conventional metal rivets often exhibit metal flow incident to the head upsetting operation that induces high unit pressure on the periphery of the rivet hole. Failure of the composite structure under or adjacent the rivet head may not be evident or even immediate. However, subjection of an airframe to the vibratory environment encountered during normal flight conditions or severe loading as is experienced in inclement weather conditions may result in failure of the composite structure.
While plastic rivets or rivets having plastic heads have been utilized heretofore, such rivets generally do not exhibit characteristics suitable for aircraft applications or applications requiring relate-.. ,.. ,~, , ' ~3930~
very high strength. For example, the patent to Lute 2,366,274, granted January 2, 1945 teaches forming a plastic rivet by the application of heat to mold soften and cure a thermoplastic material. Lute teaches the use of a thermoplastic material that is initially in the form of a powder that is supported within dies in registry with apertures in two parts to be joined.
The powdered material is thereafter cured to form a thermos plastic rivet.
I
Similarly, the patent to Baker 2,391,938, granted lo January l, 1946 teaches molding of a plastic rivet about both sides of a workups having an aperture therein. A suitable moldable material which may be thermoplastic or thermosetting in nature is induced into a cavity surrounding the aperture in the workups and thereafter cured.
It is evident, however, that riveting of come posit subassemblies on a production basis does not allow for the utilization of dies placeable on opposite sides of a work-piece to contain and thereafter cure a moldable resin in either liquid or powder form. Moreover, since most aircraft assemblies are relatively large in terms of surface area, it is preferable - that rivets utilized to hold, for example, skins to supporting structures, be capable of assembly from only one side of the workups. Such rivets are known in the art as "blind" rivets.
Another desirable feature of an aircraft rivet is that it be capable of installation by relatively small tools that do not exhibit vibratory interaction with the rivet.
Marc i~393~
SUMMARY OF TIE INVENTION
Broadly speaking, the problems of the prior art are overcome by the present invention which provides a blind rivet for installation in a workups having an aperture therein, said rivet comprising:
an elongated mandrel having a radially enlarged anvil at one end and a gripping portion at the other end, and workups gripping sleeve means disposed about the mandrel comprising a shear portion having a radially extending head at one end thereof for engagement with one side of a workups and a partially polymerized thermosetting plastic portion between the shear portion and the anvil on the mandrel, the plastic portion being formable into a blind head at the other end of the sleeve means, the plastic portion of the sleeve being continuously maintained at a first temperature sufficiently low to preclude significant further polymerization thereof, the plastic portion of the sleeve means being axially and radially deformable upon heating thereof above the first temperature and upon axial movement of the anvil on the mandrel toward the head at the one end of the shear portion of the sleeve means to form a blind head for engagement with the other side of the workups thereby to grip the workups upon full polymerization of thy blind head.
The blind rivet of the present invention utilizes a shear portion that is accepted within aligned apertures in a workups. The rivet has a performed head at one end of the rn/jc lX39300 -pa-shear portion and a central aperture there through for the acceptance of a headed mandrel. An incompletely polymerized or "B' stage thermoses resin portion of the rivet is disposed about the mandrel at the opposite end of the shear portion from the head thereon Tensioning of the mandrel effects compression of the "B" stage thermoses resin portion which is softened due to the application of heat. The mandrel forms a radially extending blind head that is interlocked with the shear portion of the rivet to draw the work pieces together and which, when fully polymerized, forms a permanent thermoses riveted connection.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an elevation Al view of a blind rivet in accordance with the instant invention;
Figure 2 is a cross-sectional view of an embodiment of the instant invention wherein the preformed head and shear portion of the rivet are metal and the formable head thereof is "B" stage thermoses resin, Figure 3 is a view, similar to Fig. 2, wherein the performed head and shear portions of the rivet are fully cured thermoses resin, the formable head is "B" stage thermoses resin, and the mandrel is metal;
m/`
~39300 Figure 4 is a view similar to Fig. 2 wherein the preformed head and shear portion of the rivet are fully polymerized thermoses resin, the formable head is us" stage thermoses resin, and the mandrel is fully polymerized thermoses resin;
Figure 5 is a view of another embodiment of the instant invention wherein the preformed head and shear portions of the rivet are fully polymerized, the formable head portion is partially polymerized resin, and the mandrel is metal.
Figure 6 is a view similar to Fig. 5 illustrating tensioning of the mandrel to form a blind head on the rivet;
Figure 7 is a view similar to Fig. 5 of yet another embodiment of the instant invention utilizing a plastic mandrel; and Figure 8 is a view of the rivet of Fig. 7 wherein the mandrel is tensioned to form a blind side head on the rivet.
DETAILED DESCRIPTION OF TOE PREFERRED
EMBODIMENT OF THE INVENTION
-As best seen in Fig. 1 of the drawings, a blind rivet 10 in accordance with a constructed embody-mint of the instant invention comprises a head portion 12, a shear portion 14, a partially polymerized or "B"
stage resin head forming portion 16 and a mandrel 18.
The mandrel 18 has an anvil 20 at one end thereof and a tensioning stem 22 at the other end thereof. The mandrel 18 extends through complementary apertures 24 330~1 and 26 in the shear and head forming portions 14 and 16, respectively, ox the rivet 10.
In the embodiment shown in Fig. 1, the shear portion 14 of the rivet 10 has a cylindrical outer sun-face 28 that is coextensive with the cumulative thickness of a pair of work pieces 30 and 32. The end of the shear portion 14 opposite from the head 12 is provided with a truncated conical surface 34 to facile-late axial movement and radial expansion of the head forming portion 16 there over. The end of the conical surface 34 also functions as a stop for the anvil 20 of the mandrel 18.
As best seen in Fig. 2, the mandrel 18 is pulled to the left, as seen in the drawings, by a suitable tool 36 having heated jaws, 38 and 40, and a head portion 42 which engages the head 12 of the rivet 10 to maintain a bias there against, to the right as seen in the drawings, whereby the rivet 10 is held against the workups 30. Tension on the mandrel 18 to the left, as seen in the drawings, results in displace-mint of the "By stage thermoses resin head forming port lion 16 into the mushroom configuration shown in sea-lion. The bias on the mandrel 18 it maintained for the length of time necessary to effect complete polymerize-lion of the "B" stage head forming portion 16 which results in locking of the rivet 10 within the apertures in the work pieces 30 and 32. It is to be noted that the head forming portion 16 is mechanically trapped behind the anvil 20 of the mandrel 18. The mandrel 18 can be mechanically clinched to the shear portion 14 or lZ39300 head 12 of the rivet 10, if desired. Alternatively, bonding of the "By stage thermoses resin to the anvil 20 is sufficient to retain the mandrel 18 in position relative to the shear portion 14.
Referring to Fig. 3 of the drawings, a second embodiment of the invention comprises a rivet 50 having a head portion 52 and shear portion 54 of fully polyp merited thermoses resin. The head and shear portions 52 and 54 have a central aperture 56 therein for the acceptance of a mandrel 58. The mandrel 58, like the mandrel 18, has an anvil or head portion 60 thereon to effect compression of a "B" stage thermoses resin head forming portion 62. The dimensions of the blind rivet 50 are similar to those of the rivet 10 and setting of the rivet is similar thereto, the distinction being that the head and shear portions 52 and 54 of the rivet comprise fully polymerized thermoses resin.
With reference to Fig. 4 of the drawings, a blind rivet 70, comprises a head portion 72 and shear portion 74 made from fully polymerized thermoses resin.
The head and shear portions 72 and 74 have a central bore 76 therein for the acceptance of a mandrel 78 which also is made from fully polymerized thermoses resin. The mandrel 78 has an anvil 80 thereon for compression of a By stage thermoses resin head forming portion 81 in the manner described herein before.
As illustrated in Figs. 5 and 6, another embo-dominate of the instant invention comprises a blind rivet 90 having a head portion 92 and shear portion 94. The head and shear portions 92 and 94 comprise fully polyp I OWE
merited thermoses resin. A By stage thermoses rosined forming portion 96 is integral with the shear port lion 94 and, like the head and shear portions 92 and 94, respectively, has a central bore 98 therein for the acceptance of a mandrel 100. As best seen by comparing Figs. 5 and 6, tensioning of the mandrel 100 to the left, as seen in the drawings, effects compression and mushrooming of the "B" stage resin head forming portion 96 of the rivet 90. Thus, the embodiment of the instant invention shown in Figs. 5 and 6, results in a rivet having a one-piece, homogeneous shear portion 94, with oppositely disposed head portions 92 and 96.
As illustrated in Figs. and 8 of the drawings, another embodiment of the instant invention comprises a rivet 120 having a head portion 122 and intermediate shear portion 124 of fully polymerized thermoses resin and a head forming end portion 126 of "By stage thermoses resin. The distinction between the embodiment taught in Figs. 7 and 8 and the embodiment taught in Figs. 5 and 6 is that a mandrel 128 in the rivet 120 comprises fully polymerized thermoses plastic. As best seen by comparing Figs. 7 and 8, ten-stoning of the mandrel 128 to the left, as seen in the drawings, results in compression and mushrooming of the "B" stage thermoses resin head forming portion 126 to form a head on the rivet 120 at the opposite side of a pair of work pieces 128 and 130 from the head 122.
ilk respect to the partially polymerized head forming portions 16, 62, 80, 96 and 126 of the rivets 10, 50, 70, 90 and 120, respectively, which may be :~3930~) termed "B" stage thermoses resin portions, each of said portions is prepared using technology similar to the technology used to prepare powdered resin coatings or electronic encapsulation molding compounds. In this type of system an epoxy resin is blended with an aroma-tic amine curing agent and allowed to partially polyp Myers. Representative materials and proportions would be 157.5 parts of Shell 828 epoxy resin obtainable from the Shell Chemical Company and 42.5 parts of ethylene dianiline curing agent obtainable from BASS Wyandotte Corporation. When sufficient polymerization has occurred to produce a solid, then" stage material is pulverized into a powder. In the case of the rivets 10, 50 and 70 the powder is thereafter molded to form the discrete head forming portions 16, 62, and 80 thereof, respectively. When heat is applied to said head forming portions, the "B" stage material thereof will soften permitting movement of the mandrels 18, 58, and 78, respectively, to axially compress and radially expand said head forming portions 16, 62, and 80 which, when completely polymerized, "set" the rivets 10, 50, and 70, respectively.
In the embodiment of the invention illustrated in Figs. 5 and 8 of the drawings, the head, shear and head forming portions 92, 94, and 96 of the rivets 90 and 122, 124 and 126 of the rivet 120 are molded from the "By stage resin. Thereafter the head and shear portions 92 and 94 of the rivet 90 and head and shear portion 122 and 124 of the rivet 120 are fully polyp merited by the application of heat while maintaining 1~39300 the head forming portions 96 and 126 thereof surf-ficiently cool to preclude further polymerization. the application of heat to the head forming portion 96 and 126 of the rivets 90 and 120, respectively will con-diction the rivets for setting" in the manner discussed herein before.
It is to be noted that the application of heat to initiate softening and polymerization of the head forming portions of the rivets discussed above is a relative matter. For example, shelf life of the unset blind rivet can be extended by freezing the rivet.
Moreover, the amount and duration of heat applied is a function of the particular "B" stage resin utilized.
In a constructed embodiment, a blind rivet made in accordance with the constructed embodiment was main-twined at a temperature of 0 Fahrenheit and thereafter elevated to a temperature of 150 to 180 Fahrenheit by the application of heat to the mandrel of the rivet at which temperature softening was evidenced. Thereafter the temperature was raised to the range of 300 to 400 Fahrenheit to expedite polymerization.
From the foregoing description it should be apparent that the blind rivet of the instant invention is relatively easily set within a complementary aver-lure in a workups. Softening and polymerization of the "I" stage head forming thermoses resin is achieved by the application of heat that is relatively higher than the design storage temperature of the rivet. As discussed herein before, the addition of heat to the By stage resin head forming portion of the rivet can be ~;~39300 achieved by several means the important consideration being that the dormant "gun stage resin us activated by the addition of heat thereto which in turn softens the resin to facilitate compression and mushrooming of the head forming portion of the rivet to form a head on the blind side of the workups.
While the preferred embodiment of the invent lion has been disclosed, it should be appreciated that the invention is susceptible of modification without departing from the scope of the following claims.
'
BACKGROUND OF THE INVENTION
The aircraft industry has developed a number of airframe components utilizing modern composite materials, for example, carbon fiber reinforced resins.
Despite the fact that such materials exhibit outstanding strength to weight characteristics, use thereof has been limited by the difficulty of fastening such materials. Conventional fasteners have proved to be unsatisfactory for several reasons. One kirk-touristic of composite materials is that the material adjacent the periphery of an aperture therein is sub-jet to shattering or cracking when relatively high unit pressure is brought to bear there against. For example, conventional metal rivets often exhibit metal flow incident to the head upsetting operation that induces high unit pressure on the periphery of the rivet hole. Failure of the composite structure under or adjacent the rivet head may not be evident or even immediate. However, subjection of an airframe to the vibratory environment encountered during normal flight conditions or severe loading as is experienced in inclement weather conditions may result in failure of the composite structure.
While plastic rivets or rivets having plastic heads have been utilized heretofore, such rivets generally do not exhibit characteristics suitable for aircraft applications or applications requiring relate-.. ,.. ,~, , ' ~3930~
very high strength. For example, the patent to Lute 2,366,274, granted January 2, 1945 teaches forming a plastic rivet by the application of heat to mold soften and cure a thermoplastic material. Lute teaches the use of a thermoplastic material that is initially in the form of a powder that is supported within dies in registry with apertures in two parts to be joined.
The powdered material is thereafter cured to form a thermos plastic rivet.
I
Similarly, the patent to Baker 2,391,938, granted lo January l, 1946 teaches molding of a plastic rivet about both sides of a workups having an aperture therein. A suitable moldable material which may be thermoplastic or thermosetting in nature is induced into a cavity surrounding the aperture in the workups and thereafter cured.
It is evident, however, that riveting of come posit subassemblies on a production basis does not allow for the utilization of dies placeable on opposite sides of a work-piece to contain and thereafter cure a moldable resin in either liquid or powder form. Moreover, since most aircraft assemblies are relatively large in terms of surface area, it is preferable - that rivets utilized to hold, for example, skins to supporting structures, be capable of assembly from only one side of the workups. Such rivets are known in the art as "blind" rivets.
Another desirable feature of an aircraft rivet is that it be capable of installation by relatively small tools that do not exhibit vibratory interaction with the rivet.
Marc i~393~
SUMMARY OF TIE INVENTION
Broadly speaking, the problems of the prior art are overcome by the present invention which provides a blind rivet for installation in a workups having an aperture therein, said rivet comprising:
an elongated mandrel having a radially enlarged anvil at one end and a gripping portion at the other end, and workups gripping sleeve means disposed about the mandrel comprising a shear portion having a radially extending head at one end thereof for engagement with one side of a workups and a partially polymerized thermosetting plastic portion between the shear portion and the anvil on the mandrel, the plastic portion being formable into a blind head at the other end of the sleeve means, the plastic portion of the sleeve being continuously maintained at a first temperature sufficiently low to preclude significant further polymerization thereof, the plastic portion of the sleeve means being axially and radially deformable upon heating thereof above the first temperature and upon axial movement of the anvil on the mandrel toward the head at the one end of the shear portion of the sleeve means to form a blind head for engagement with the other side of the workups thereby to grip the workups upon full polymerization of thy blind head.
The blind rivet of the present invention utilizes a shear portion that is accepted within aligned apertures in a workups. The rivet has a performed head at one end of the rn/jc lX39300 -pa-shear portion and a central aperture there through for the acceptance of a headed mandrel. An incompletely polymerized or "B' stage thermoses resin portion of the rivet is disposed about the mandrel at the opposite end of the shear portion from the head thereon Tensioning of the mandrel effects compression of the "B" stage thermoses resin portion which is softened due to the application of heat. The mandrel forms a radially extending blind head that is interlocked with the shear portion of the rivet to draw the work pieces together and which, when fully polymerized, forms a permanent thermoses riveted connection.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an elevation Al view of a blind rivet in accordance with the instant invention;
Figure 2 is a cross-sectional view of an embodiment of the instant invention wherein the preformed head and shear portion of the rivet are metal and the formable head thereof is "B" stage thermoses resin, Figure 3 is a view, similar to Fig. 2, wherein the performed head and shear portions of the rivet are fully cured thermoses resin, the formable head is "B" stage thermoses resin, and the mandrel is metal;
m/`
~39300 Figure 4 is a view similar to Fig. 2 wherein the preformed head and shear portion of the rivet are fully polymerized thermoses resin, the formable head is us" stage thermoses resin, and the mandrel is fully polymerized thermoses resin;
Figure 5 is a view of another embodiment of the instant invention wherein the preformed head and shear portions of the rivet are fully polymerized, the formable head portion is partially polymerized resin, and the mandrel is metal.
Figure 6 is a view similar to Fig. 5 illustrating tensioning of the mandrel to form a blind head on the rivet;
Figure 7 is a view similar to Fig. 5 of yet another embodiment of the instant invention utilizing a plastic mandrel; and Figure 8 is a view of the rivet of Fig. 7 wherein the mandrel is tensioned to form a blind side head on the rivet.
DETAILED DESCRIPTION OF TOE PREFERRED
EMBODIMENT OF THE INVENTION
-As best seen in Fig. 1 of the drawings, a blind rivet 10 in accordance with a constructed embody-mint of the instant invention comprises a head portion 12, a shear portion 14, a partially polymerized or "B"
stage resin head forming portion 16 and a mandrel 18.
The mandrel 18 has an anvil 20 at one end thereof and a tensioning stem 22 at the other end thereof. The mandrel 18 extends through complementary apertures 24 330~1 and 26 in the shear and head forming portions 14 and 16, respectively, ox the rivet 10.
In the embodiment shown in Fig. 1, the shear portion 14 of the rivet 10 has a cylindrical outer sun-face 28 that is coextensive with the cumulative thickness of a pair of work pieces 30 and 32. The end of the shear portion 14 opposite from the head 12 is provided with a truncated conical surface 34 to facile-late axial movement and radial expansion of the head forming portion 16 there over. The end of the conical surface 34 also functions as a stop for the anvil 20 of the mandrel 18.
As best seen in Fig. 2, the mandrel 18 is pulled to the left, as seen in the drawings, by a suitable tool 36 having heated jaws, 38 and 40, and a head portion 42 which engages the head 12 of the rivet 10 to maintain a bias there against, to the right as seen in the drawings, whereby the rivet 10 is held against the workups 30. Tension on the mandrel 18 to the left, as seen in the drawings, results in displace-mint of the "By stage thermoses resin head forming port lion 16 into the mushroom configuration shown in sea-lion. The bias on the mandrel 18 it maintained for the length of time necessary to effect complete polymerize-lion of the "B" stage head forming portion 16 which results in locking of the rivet 10 within the apertures in the work pieces 30 and 32. It is to be noted that the head forming portion 16 is mechanically trapped behind the anvil 20 of the mandrel 18. The mandrel 18 can be mechanically clinched to the shear portion 14 or lZ39300 head 12 of the rivet 10, if desired. Alternatively, bonding of the "By stage thermoses resin to the anvil 20 is sufficient to retain the mandrel 18 in position relative to the shear portion 14.
Referring to Fig. 3 of the drawings, a second embodiment of the invention comprises a rivet 50 having a head portion 52 and shear portion 54 of fully polyp merited thermoses resin. The head and shear portions 52 and 54 have a central aperture 56 therein for the acceptance of a mandrel 58. The mandrel 58, like the mandrel 18, has an anvil or head portion 60 thereon to effect compression of a "B" stage thermoses resin head forming portion 62. The dimensions of the blind rivet 50 are similar to those of the rivet 10 and setting of the rivet is similar thereto, the distinction being that the head and shear portions 52 and 54 of the rivet comprise fully polymerized thermoses resin.
With reference to Fig. 4 of the drawings, a blind rivet 70, comprises a head portion 72 and shear portion 74 made from fully polymerized thermoses resin.
The head and shear portions 72 and 74 have a central bore 76 therein for the acceptance of a mandrel 78 which also is made from fully polymerized thermoses resin. The mandrel 78 has an anvil 80 thereon for compression of a By stage thermoses resin head forming portion 81 in the manner described herein before.
As illustrated in Figs. 5 and 6, another embo-dominate of the instant invention comprises a blind rivet 90 having a head portion 92 and shear portion 94. The head and shear portions 92 and 94 comprise fully polyp I OWE
merited thermoses resin. A By stage thermoses rosined forming portion 96 is integral with the shear port lion 94 and, like the head and shear portions 92 and 94, respectively, has a central bore 98 therein for the acceptance of a mandrel 100. As best seen by comparing Figs. 5 and 6, tensioning of the mandrel 100 to the left, as seen in the drawings, effects compression and mushrooming of the "B" stage resin head forming portion 96 of the rivet 90. Thus, the embodiment of the instant invention shown in Figs. 5 and 6, results in a rivet having a one-piece, homogeneous shear portion 94, with oppositely disposed head portions 92 and 96.
As illustrated in Figs. and 8 of the drawings, another embodiment of the instant invention comprises a rivet 120 having a head portion 122 and intermediate shear portion 124 of fully polymerized thermoses resin and a head forming end portion 126 of "By stage thermoses resin. The distinction between the embodiment taught in Figs. 7 and 8 and the embodiment taught in Figs. 5 and 6 is that a mandrel 128 in the rivet 120 comprises fully polymerized thermoses plastic. As best seen by comparing Figs. 7 and 8, ten-stoning of the mandrel 128 to the left, as seen in the drawings, results in compression and mushrooming of the "B" stage thermoses resin head forming portion 126 to form a head on the rivet 120 at the opposite side of a pair of work pieces 128 and 130 from the head 122.
ilk respect to the partially polymerized head forming portions 16, 62, 80, 96 and 126 of the rivets 10, 50, 70, 90 and 120, respectively, which may be :~3930~) termed "B" stage thermoses resin portions, each of said portions is prepared using technology similar to the technology used to prepare powdered resin coatings or electronic encapsulation molding compounds. In this type of system an epoxy resin is blended with an aroma-tic amine curing agent and allowed to partially polyp Myers. Representative materials and proportions would be 157.5 parts of Shell 828 epoxy resin obtainable from the Shell Chemical Company and 42.5 parts of ethylene dianiline curing agent obtainable from BASS Wyandotte Corporation. When sufficient polymerization has occurred to produce a solid, then" stage material is pulverized into a powder. In the case of the rivets 10, 50 and 70 the powder is thereafter molded to form the discrete head forming portions 16, 62, and 80 thereof, respectively. When heat is applied to said head forming portions, the "B" stage material thereof will soften permitting movement of the mandrels 18, 58, and 78, respectively, to axially compress and radially expand said head forming portions 16, 62, and 80 which, when completely polymerized, "set" the rivets 10, 50, and 70, respectively.
In the embodiment of the invention illustrated in Figs. 5 and 8 of the drawings, the head, shear and head forming portions 92, 94, and 96 of the rivets 90 and 122, 124 and 126 of the rivet 120 are molded from the "By stage resin. Thereafter the head and shear portions 92 and 94 of the rivet 90 and head and shear portion 122 and 124 of the rivet 120 are fully polyp merited by the application of heat while maintaining 1~39300 the head forming portions 96 and 126 thereof surf-ficiently cool to preclude further polymerization. the application of heat to the head forming portion 96 and 126 of the rivets 90 and 120, respectively will con-diction the rivets for setting" in the manner discussed herein before.
It is to be noted that the application of heat to initiate softening and polymerization of the head forming portions of the rivets discussed above is a relative matter. For example, shelf life of the unset blind rivet can be extended by freezing the rivet.
Moreover, the amount and duration of heat applied is a function of the particular "B" stage resin utilized.
In a constructed embodiment, a blind rivet made in accordance with the constructed embodiment was main-twined at a temperature of 0 Fahrenheit and thereafter elevated to a temperature of 150 to 180 Fahrenheit by the application of heat to the mandrel of the rivet at which temperature softening was evidenced. Thereafter the temperature was raised to the range of 300 to 400 Fahrenheit to expedite polymerization.
From the foregoing description it should be apparent that the blind rivet of the instant invention is relatively easily set within a complementary aver-lure in a workups. Softening and polymerization of the "I" stage head forming thermoses resin is achieved by the application of heat that is relatively higher than the design storage temperature of the rivet. As discussed herein before, the addition of heat to the By stage resin head forming portion of the rivet can be ~;~39300 achieved by several means the important consideration being that the dormant "gun stage resin us activated by the addition of heat thereto which in turn softens the resin to facilitate compression and mushrooming of the head forming portion of the rivet to form a head on the blind side of the workups.
While the preferred embodiment of the invent lion has been disclosed, it should be appreciated that the invention is susceptible of modification without departing from the scope of the following claims.
'
Claims (7)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A blind rivet for installation in a workpiece having an aperture therein, said rivet comprising:
an elongated mandrel having a radially enlarged anvil at one end of a gripping portion at the other end, and workpiece gripping sleeve means disposed about said mandrel comprising a shear portion having a radially extending head at one end thereof for engagement with one side of a workpiece and a partially polymerized thermosetting plastic portion between said shear portion and the anvil on said mandrel, said plastic portion being formable into a blind head at the other end of the sleeve means, the plastic portion of said sleeve being continuously maintained at a first temperature sufficiently low to preclude significant further polymerization thereof, the plastic portion of said sleeve means being axially and radially deformable upon heating thereof above said first temperature and upon axial movement of the anvil on said mandrel toward the head at the one end of the shear portion of said sleeve means to form a a blind head for engagement with the other side of the workpiece thereby to grip the workpiece upon full polymerization of said blind head.
an elongated mandrel having a radially enlarged anvil at one end of a gripping portion at the other end, and workpiece gripping sleeve means disposed about said mandrel comprising a shear portion having a radially extending head at one end thereof for engagement with one side of a workpiece and a partially polymerized thermosetting plastic portion between said shear portion and the anvil on said mandrel, said plastic portion being formable into a blind head at the other end of the sleeve means, the plastic portion of said sleeve being continuously maintained at a first temperature sufficiently low to preclude significant further polymerization thereof, the plastic portion of said sleeve means being axially and radially deformable upon heating thereof above said first temperature and upon axial movement of the anvil on said mandrel toward the head at the one end of the shear portion of said sleeve means to form a a blind head for engagement with the other side of the workpiece thereby to grip the workpiece upon full polymerization of said blind head.
2. A rivet in accordance with claim 1 wherein the shear portion of said sleeve means is metal.
3. A rivet in accordance with claim 1 wherein the shear portion of said sleeve means is plastic.
4. A rivet in accordance with claim 3 wherein the head forming portion of said sleeve means is integral with the shear portion thereof.
5. A rivet in accordance with claim 4 wherein the shear portion of said sleeve means is fully polymerized.
6. A rivet in accordance with claim 1 wherein said mandrel is metal.
7. A rivet in accordance with claim 1 wherein said mandrel is plastic.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462868A CA1239300A (en) | 1984-09-11 | 1984-09-11 | Blind rivet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462868A CA1239300A (en) | 1984-09-11 | 1984-09-11 | Blind rivet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1239300A true CA1239300A (en) | 1988-07-19 |
Family
ID=4128692
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000462868A Expired CA1239300A (en) | 1984-09-11 | 1984-09-11 | Blind rivet |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1239300A (en) |
-
1984
- 1984-09-11 CA CA000462868A patent/CA1239300A/en not_active Expired
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