CA1054411A

CA1054411A - Blind rivet and method of manufacture of same

Info

Publication number: CA1054411A
Application number: CA246380A
Authority: CA
Inventors: Kosaku Yoshida; Kunio Hara
Original assignee: NICHIEI BUSSAN CO
Current assignee: NICHIEI BUSSAN CO
Priority date: 1975-02-25
Filing date: 1976-02-23
Publication date: 1979-05-15
Also published as: FR2302442B1; US4222304A; DE2607689A1; BR5600215U; IT1057614B; AU511639B2; AU1141276A; DE2607689C2; FR2302442A1; GB1517624A

Abstract

BLIND RIVET

Abstract of the Disclosure:
Disclosed is a blind rivet which comprises a tubular female member provided on the outer periphery of the upper open end with a flange and a male shank member integrally engaging the hollow portion in said female portion. Said female member is provided in the tubular wall thereof with a plurality of elongate perforations in the longitudinal di-rection and said male member is provided at the lower end of the shank portion thereof with a swollen portion in tight contact with the lower portion of said female member. An extraction of the male member out of the female member re-sults in reduction in the length of said female member and consequent expansion of the tubular wall of the member in the shape of petals, causing articles subjected to riveting to be fastened up between the petalous expansion of said female member and the flange of said female member while locking means disposed on the male member and the female member co-operate to prevent the male member from being extracted from the female member.

Description

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This invention relates to a blind rivet. More particularly, the present invention relates to a blind rivet made of a plastic material and used as a pin for uniting a plu~ality of sheets piled up one on top of another or for fastenlng a part to its ba~sal plate or for serving as a leg by which a part is fastened to its basal plate.
Usually a blind rivet comprises a sleeve ~female member) having a flange formed at one end thereof and a pin (male member) having at the leading end thereof, a head of a diameter greater than the inside diameter of sa~d sleeve.
As disclosed by U.S.P. Nos. 3,178,989 and 3,230,81~, for example, the male and female members o the blind rivet are separately abricated with a malleable metal such as aluminum alloy, copper alloy or mild steel and they are assembled by having the pin inserted into the sleeve. In actual use of thi~ blind rivet, the pin i9 ~ecured by the ohuck of a tool and in~erted through a perforation bored in a basal plate sub~ected to riveting and then the pin is retrogressively extracted with the flange on the sleeve pressed fa~t again3t the basal plate, causing the basal plate to be tl~htened.
The metallic blind rivet is complicated to fab~icate and, after fabrication, entails the extra work of assembling its male and emale members. Each ri~et thus assembled must he fa~tened to the dhuck for the purpose of insertion and subse-quent fastening. When the pin is drawn out to provide re-quired tightening, the excess portion of the drawn pin must - be cut off. With a view to faciIitating the severance of such excess portion of the drawn pin after the step of riveting, . 2 ,`. . ~5 ' ,:
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there has been suggested a rivet which i~ provided on thc pin with a groove such that the pin is cut off along the groove automatically when the ten ile force exerted on the pin reachej a de~inite magnitude (U.S.P. No. 3,230,818).
~ith this rivet, however, thexe i~ a possibility that the pin will break before th2 rivet has provided perfect tighten-~ng of the basal plate. No continuous rivating work can be attained, therefore.
- To preclude possible release of the pin from the sleeve in the blind rivet of the foregoing description, there has - been proposed a bli~d rivet o~ a plastic material wherein the - pin has it~ leading end shaped in a bulbous fonm and the - ~leeve has its leading e~d shaped so as to accommodate ~aid buIbous end of the pin so that, when the rivet is passed through the basal plate and the pin i~ drawn out, the leading end of the pin i9 lodged fast within the sleeve to expand the wall of the sleeYe outwardly, with said expansion providing required tightening of the basal plate and prevent~ng otherwi~e po sible relea~e of the pin from the sleeve.
The blind rivet of plastic material, howeYer, has found virtually no acceptance because it fails to deform as designed, sustains breakage and, owing to elasticity, entails a possibility o~ the pin beifig pulled out of the slee~e after t the step of tightening.
An object of the present invention is to provide a blind - rivet of plastic material which pro~id~s infallible tightening and permits absolutely no pos~ibility of the male member being releas~d ~rom the female member ater the step o~ tightening.

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10544~1 ; Another object of the present invention is to provide a blind rivet o~ plastic material wh:ich is easy to manufacture and is completed by assembly of a female member and a male member.
Still another object of the present invention is to provide a blind rivet of plastic material which is easily mounted on the riveting tool and permits continued riveting operation.
It is also an object of this invention to provide a blind rivet of plastic material which allows for a wide variation 10 in the thickness of basal plates to be riveted and in the diameter of holes to be bored in said basel plates for insertion of the rivet.
In accordance with one aspect of the present invention, a blina rivet of plastics material is provided, which comprises a female member comprised of a flexible tubular wall defining ,. . .. .
a cavity and having an open upper end and a lower end, a flange `
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extending outwardly from the upper end of the tubular wall, the tubular wall defining a stepped portion in the cavity at the upper end and plurality of elongated apertures extending longitudinally of the wall, and a male member comprised of a shank inserted in the cavity and in intimate contact with the -tubular wall terminating in an expanded end portion in intimate contact with the lower end of the tubular wall of the female member, the shank having a series of peripheral ratchet-forming ,~ :
projections in engagement with the tubular wall, the shank of the male member being axially movable in relation to the tubul~r :;
` wall of the female member while the expanded end portion remains `~
engaged with the lower end of the tubular wall; whereby upon axial movement in one direction of the male member in relation to the female member the engaged expanded end portion forces . . , -~ the tubular wall to buckle outwardly to form portions which ;~

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ext~nd radially to form petals while one of the ratchet-forming projections snaps into ~astening engagement with the stepped portion, the flange of the female member and the petal portions - formed of the buckled tubular wall thereof cooperating to hold an article therebetween.
In another aspect of the present invention, a blind rivet .~ is provided of plastics material, which comprises a female -- member comprised of a flexible tubular wall defining a cavity - and having an open upper end and a lower end, and a flange extending outwardly from the upper end of the tubular wall, the tubular wall defining a stepped portion in the cavity at the upper end thereof and a plurality of elongate apertures 1~
extending longitudinally of the wall, and a male member comprised ~ ~:
of a shank and an expanded end portion, the shank having a series . of peripheral ratchet-forming projections, the female member r being molded about the shank of the male member, with the 1:
expanded end portion in intimate contact with the said lower end.
In a still further aspect of the present invention, a method is provided for the manufacture of a blind rivet of :
20 plastics material, comprising the steps of: (a) injection molding al .
molten plastics material under pressure into the cavity of a die shaped to form a male member comprised of a shank and an expanded - end portion, the die being shaped to provide the shank with a series of peripheral ratchet-forming projections and a portion ¦:
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-- of increased diameter opposite the expanded end portion, (b) placing, :`the molded male member expanded end portion lowermost into the ~
cavity of another die shaped to form a female member comprised of :.
` a tubular wall having an open upper end and a lower end, a .
flange extending outwardly from the upper end of the tubular ~- 30 wall and a plurality of elongate wall apertures extending ~........ longitudinally along the wall, and (c) injection molding a molten .; - 5 - ::
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plastics material under pressure into the cavity of the other die around the shank of the male member whereby a stepped portion is formed in the tubular wall around the increased diameter portion - of the shank and the tubular wall of the female member is formed : in intimate contact with the shank.
The other objects and characteristic features of the present invention will become apparent from the description to be ~- given in further detail hereinbelow with reference to the accompanying drawing. ' Fig. 1 is a partially sectioned frontal view illustrating ' , '''~ .
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the first preferred embodiment of the blind rivet of pla~tic ~ter~al according to the present invent~on.
Fig. 2~A~ is a ~rontal view of the m~le member of the ~ivet shown in F~g. 1.
Pig. 2~B) i~ a frontal v~ew o:f the female member o the ri~et shown ~n Fig. 1. . ::
Flg. 3 $8 a cross section taken along the line III-III
of the diagram of Fig. 2(B).
F~g. 4(A~ is a partially sectio~ed frontal view ~O illu-~trating the rivet of Fig. 1 at ~he ~ime that fastening of two plates p~led one on top o~ the other is started.
Fig. 4~B) i~ a partially ~ectioned frontal view illustrating the rivet of Fig. 1 at the time ~hat ~astening of two plates piled one on top of the other ha~ ~een completed~
Fig. 5 is a partially sectioned frontal view illustrating the condition assumed when the portion of the male member ~pwardly protruding from the flange of the female member is cut off with a too1 after ~he two plates have been fastened by u~e of the rivet of Fig. 1.
Fig. 6 is a partially sectioned frontal vlew illustrating the second preferred embodiment of the blind rivet of plastic - material according to the present in~ention. `:
~igsO 7(A~ and 7(B~ are partially sectioned frontal views , illu~trating ~he rivet of Fig. 6 at the time ~hat fastenin~ :
of two plates piled up one on top of the other is started and ; ;
~t the t~me ~hat said fastening han been cNmplete~.
- Yig. 8 i~ a per~pective view illustrating the lower half -part of ~he th~rcl preferred ~mbodiment of the blind rivet of ~ 7 ~
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plastic materlal according to the present invention.
~ig. 9~A) i~ an explanatory diagram ill~strating o~e wo~king example of the method for manuacturing the blind rivet of pla3tic material according ~o the prese~t inve~tion.
S ~g. 9(B) i~ a~ e~planatory diagram ~llustrating the ~ondition of the blind rivet of plastic material manufactured in accordance with ~he method of Fig. 9~A).
Fig. 10 is a perspecti~e view illustrating a typical condition in whi~ fastening of a molding is effected by use of the ri~et of this ~nvention.
Fig. 11 thro~gh 13 are perspecti~e view~ illustrating - typical working examples ~nvol~ing applications of ~he rivet - of the present invention. . . -.
-: Fig. 14 is an explanatory diagram show$ng a rivet of plastic material accord$ng to thi5 ~nvention as it is held by a riveting tool. ~ . , -- F$g. 15 is a rontal view lllustrating a condition in ~hich sivets of plastic materlal according to this invention are joined. . .................................................... - `
20 ~ Pigs. i through 3 ~ ~ustrate the first preferred ~ment of ths bl~d xivet of ~his i~vention~ A female ~ember 1 ha3 a tu~ular shape and is provided on the outér periphery of the ~pper open end 1~ of the tubular wall wi~h a flan~e 20 A male member 3 has a bar-like shank passea ~hro~1gh the hollow ~pace of sa~d female member 1 ana i3 provided at the upper end protr~ding from said upper open end 1' of the emal~ member with a heaa 5 and at the lower e~d protruding fr~m the lower open end of the female mem~er with .

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a swollen portion 6. Said female member 1 ha~ a small wall ~
th~ckne~ in it~ principal tubular section to enjoy flexi- r bility and is provided in the tubu:Lar wall thereo~ with ~wo ~longate perforations 7 in the lonqitudinal direction. Said elongate perforatlons 7 are dlsposed opposite each other r acro~3 the axl~ of th9 female member. They run substantially the ~hole length of the principal tubular wall of the female member with the exception of the upper and lower extremitie~
of sa~d wall. In the present preferred embodiment, ~he perforations have a greater width at the upper end ~han at ~he lower end so that the remainin~ tubular walls 7' have a - smaller width toward the upper end tha~ toward the lower end.
The shank portio~ of the male me~ber which is inserted in the hollow space 4 of said female member has a diame~er such that the outer surface of the shan~ comes into tight engagement with the inner surface at the hollow space of the fema}e member. Tne length of the shank is substantially greater than that of the female member in the present preferre~
embodiment, 80 that the swollen portion 6 at the lower end thereof engages the lower end o~ he female member and the upper end of the shank protrudes from the upper open end 1' of the ~emale member to- form a head 5. This head i9 intended as means ~or providing a secure catch on a tool to be u3ed for pulling the male member. It, therefore, may be given any æhape that suit~ the particular tool used for the purpose of ~ :~
~aid pulling, :
In the port:i on o~ the shank which is inserted in the - hollow space 4 of the f~male member 1, said male member ~s , _ g ~
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provlded ~ith a multiplicity of annulax check ~laws 8 dis-posed c~rcumferentially with their claw t~ps pvinting in the directlon from the upper end slde to the lower end side.
ThQ ~emale me~ber 1 which receives the shank of the male S member h ving such a contour as ~ust described has the diameter of the inner surface increased in the upper open -- end thereof so a3 to be provided wi~h a s~epped portion 9 - which permits any of said check claws 8 to be brought into tight engagement with said inner surface.
lQ The manner i~ which the nlind rivet of the c~nfiguration described above is used in joining t~o plates piled up o~e on fop of the other will be described with reference to Fig.
4. The two plates 10 and 11 are piled up one on top of the o~her, with their respective perforations 12 and 13 correctly registered. The rivet is inserted downwardly through the - perforations until the flange 2 formed at the upper end of the female member co~es into contact with the upper surface of the upper plate 10. Then; w~th the flange pressed against said upper plate, the male member 3 which is inserted - 20 in the female member is pulled upwardly with the aia of a -~
tool (no~ illustratea) so that ~he swolle~ portion 6 theréof~
-at the lower end forcibly ~rags ~he lower end of the female m~ber upwardlyO Consequer.tly, ~he female member 1 is `-pressed in the upper and lower directions at the same time.
As the mag~itude of the pressure i~cre~ses to surpass the ~m~t of plastici~y of the tubular portion, the elongate perforations 7 fo~med in thé tubular walls expand and the ~ntervening wall portions 7' definlng said elongate perfora-.

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t~ons arQ bent outwardly tF~g- 4(A~)O As the male member ~3 ~urther pulled out, the bent wall portions 7' of the female member are flattened out beneath the lower pl~e 11 ~n the shape of petals. The flatt:ened wall portions and S the flange 2 disposed opposite therefrom at the upper end of the female member ~ill come to hold the plates 10 and 11 : . in a joined state therebetween tFi.g. 4(B~). As the result, the shank of the male member protr~aes upwardly from the ' .
female member and part of the check claws 8 fo~med circum-10 ferentially on the ~urface of said shank expose themselves - . above the upper open end of the female member and one of the . .
~- e~posed check claws 8 falls into t~ght engagement wi~h the ~tepped portion 9 formed on the inner surface. Because of thi~ tight engagement, the portion of the male member which has been drawn out of the female member remains in its state and serves to immobilize the female member in the state having ~ts tubular wall expanded in the shape of petals. ;~
: : Ater the two plates have been united as described above, the portion of the shan~ of the male member protruding up-wardly from the flange of the female member is cut of by a : ;
~uitable method as illustrated in Fig. 5, bringing the whole riveting operation to an end. `~
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In thls particul~r preferred embodiment, the elongate . . ~
perforations 7 formed in the tubular wall of the female member : 25 are given a greater width at the upper end than~at the lower end and, consequently, the remaining wall portions 7' have a smaller width toward the upper end than toward the lower end, - so that the upper portion of the tubular wall offers less ~.
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rigidity tha~ the lower portion thereof. When the male me~ber is drawn out, therefore, the fe~ale meDber begi~3 to .
bend first in the portion along ~he lower surface of the lower plate 11, so that the wall portions are allowed to expand readily and completely in the shape of petals until they are flattened agains~ the upper surface of the plate 11 .~ opposite from the flange 2. In the preferred embodLment, two elon~ate perforation~ 7 are formed in the tubular wall of the female member 1 ~o that the tubular wall will expand in two directio~s. Entirely the same effec~ is ob~ained by increas~ng the nu~ber of elor,~ata perforations so that the ~-tubular wall will expand in a greater number of ~irections ~;~
- and fon~ as many flattened ~ends in the shape of p~tals. : :
The num~er of the elongate perforations thus formed may be : 15 selected freely to suit the wall thickness, diameter and other si~ilar factors of ~he ~emale member in use.
. F~gs. 6 and 7 depict the second preferred emkodiment of the blind rivet of plas~ic material accoraing to the present - invention. In ~e first preferred embodiment described abo~e, to pr~vent the male member from ~eing drawn back in-to the fe~ale ~e~ber, a mult plicity of check cla~s 8 are for~ed on the surface of the shank of the male me~ber a~d a :~
~tepped portion ~ is fonmed on the inner surface at the upper open end of '~he fe~.ale ~ember so that any of the check claws will be brought into tight engagement with the stepped ~ ;~
portion. In ~he second preferred e~odi~ent, the male .
member 3 is provided at one part of its shank with a swvllen .
portion 3' having a slightly greater diameter than the inside . . .

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diameter of the upper open end 1' of the female member 1.
Ths position of sa~d swollen portion 3' on the male member i~ such that the swollen portion will at least reach the upper open end of the female mem~e!r when the male member is drawn out o the maximum extent from the female member.
The upper end of said swollen po~:ion 3' should best be tapered upwardly.
~ o ~oin two plates piled up one on top of the other by u~e of the blind rivet of the configuration described above, the two plates 10 and 11 subjected to riveting are piled up~
with their respective holes 12 and 13 registered exactly.
~he rivet is inserted downwardly through the holes untll the flange 2 comes into contact with the upper surface of the upper plate 10. Then, with the flange pressed against the plate 10, the head 5 of the male member 3 which protrudes upwardly from the flange is pinched by a suitable tool tnot illustrated) and drawn out to have the shank of the male member pulled out of the female member. In consequence o~
- the upward movement of the shank, the swollen portion 6

2~ formed at the lower end of the shank of the male member 3 i~ pulled up. Consequently the female member 1 is pressed in the ~pper and lower directions at ~he same time. At the ; nome~t the female member can no longer withstand the magni-tude of the pressure thus applied, ~he elongate perforations 7 formed in the tubular wall 7' of the female member wide~
and the wall portions 7' con~aining the perforatio~s begi~
~; to bend outwardly (Fig. 7(A)). As the male member i~ further drawn out, the wall portions are expanded in the shape of - ' :
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petals beneath the lower plate 11. With the upward motion -~ of the portion of increased diameter 6, ~he expanded wall - portions are flattened out against the lower surface of the plate 11. In conjunctlon with said flange 2, the flattened 5 wall portions will come to hold the plates 10 and 11 in a ~oined state therebetween ~Fig. 7tl3~).
In this case, when the male m~mber 3 is drawn out as described above, the portion 3' of an increased diameter of the shank 3 forces itself into the upper open end 1~ of the female member as it expands said open end outwardly. Because of the contracting force exerted by the upper open end upon - the portion of the increased diameter, the male member which has been drawn out is immobilized in that state and said female member i~ immobilized in the state having said wall portions flattened in the shape of petals. Consequently, the two plates are united as they are piled up one on top o~ the other.
After the two plates have been joined, the portion of the shank o the male member which protrudes upwardly from the flange 2 of the female member is cut off by a suitable tool similarly to the preceding preferre~ embodiment, bringing the entire riveting operation to an end.
The number, shape and dimensions of the elongate - perforations formed in the tubular wall of the female member ~5 and the wall thickness and diameter of the female m~mber may - suitably be selected to meet~beYt the purposes to which the rivet is put.
Fig. 8 depicts the third preferred embodiment of the ; 14 ~05~
blind rivet of plasti~ material according to the present - ~vention. In this embodiment, the leading end of the -Qhank of the male member 3 is formed in the shape of a bar. That is, the swollen portion ~ ~s in this case a bar perpendi-cular relative to the æis of the rivet. The length of this portion is equal to the outside diameter of the female member 1. The bar-like swollen portion is adapted so as to be enclosed by the lower portion of the female member. A~
illutrated in Fig. 8, therefore, only the end surfaces 6' of the swollen portion expose themselves on the circumference of the female member 1, with the remaining part of said portion being enclosed within the f~male member. In this case, said end surfaces 6' of the swollen portion 6 are formed below the wall portions 7' wherein are formed the elongate perforations 7, namely the swollen portion 6 is below the wall portions destined to be expanded and flattened in the shape of petals, so that when the male member i5 .
, drawn out, the force will be exerted directly upon said wall ; portions 7' to facilitate the sidewise expansion of said . 20 ~all portions. For preventing the male member from being pulled back into the female member after the step of riveting, the same means are described in the first or second preferred embodiment may be adopted.
In effecting the desired union by use of the ~lind rivet of the design described above, since the lower end of the female member is formed integrally and further since the ~wollen portion at the lower end of the~shank of the male member is inserted into the female member, the force applied . .

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- to the male member for extracting i from the female member i~ exerted uniformly on the lower portion of the female mQmber, enabling th~ tubular wall of the female member to be expanded safely in the shape of petals. Said engagement S also serve~ the purpose of preventing the male member from being rotated around its axis independently of the female member after the rivet1~g.
Tha preceding embodiment has been described as havi~g the swollen portion at the lower end of the male member formed 10 in the shape of a bar. The thicknes~ of said bar may freely be selected. It may be ~n a trifurcated form or crossed form - a~ occasion demands. Further, the length of the swollen pcrtion may be slightly smaller than the outside diameter of the female mem~er 80 that the swollen portion of the shank will wholly be embraced within the lower portion o~ the ;
f~male member. `
Now the method for the manufacture of the blind rivet of this invention will be described. In metal dies shaped in advance to co~orm to the outer contour of ~he male member, a molte~ plastic material ls in~ectio~ molded to produce a male member. Then in metal dies shaped in ad~an~e to conform - to the overall contour of the rivet, the male m~mher obtained a~ above i8 placed and the molten plastic mate~ial i5 `~
introduced to f~ll up the cavity of the metal dies. By this double molding method, a blind rivet ha~ing the male member and the female me;mber assembled integrally ~s produced.
Conversely of the method just describea, the rivet may be manufactured by first molding a female member by placi~g .
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the molten plastic material in metal die~ shaped in advance to sonfonm to the contour of female member and subsequently placing the female member in metal dies shapea in advance to conform to the overall contour of the rivet and introducing the molten plastic material to fill up the cavity to give : rise to an integrally molded rivet. By e~-her o the methods described, the blind ri~et having the male member incorpo-rated in the female member can easily be produced by the ~ double molding technique.
~ typical method for the manufacture of the blind rivet of this invention will be described with reference to Flg.
` - 9~A). In a metal die 14, a path 15 for the molten plastic ;material is formed at the center. I~ ~he portion of the metal die upward from the path, cavities 16 for molding male ,; - ., .
members are arranged laterally in a row. In the portion of the metal die downward from the path, cavities 17 for molding .
r~vet~ in their final fonm are similarly arranged laterally in a row. The cavities 16 for male members and the cavities 17 for finished rivets are equal i~ ~umber and are arranged in the same direction and at the same intervals. In the -: . , . 5 metal die containing said cavities~ the molten plastic material is introduced via the path 15 into the cavities ~6 for male members and those 17 for finished rivets respectively.
m e series of male members and the-series of rivets (which are imperfect sol~d bodies in the f;rst molding) thus molded are removed from the metal dieO The imperfect rivet-shaped ^~
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bodies are discarded and the male members alone are placed ~-~
i~ the cavit~es 17 for finished rivets and the molten plastic *:
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~0~44~1 material is injected into each of the cavities. In this way, a seri~s of male members are molded in the cavities 16 and a series of rivets each having a male member incorporated into a f~male member are molded in the ca~ities 17. The blind rivets o~ the present invention, therefore9 can be continuously manuactured by repeating the procedure which comprises removing the moldea male members and finished ri~ets from the cavities, placing the removed male members into the cavit~es for finished rivets and injectin~ the 10 molten plastic material into the metal die. If in this case, a readily severable connecting portion 19 is formed to connected the heads 5 of the male members as illustrated in Fig. 9~B) so that the molded rivets can be retained in their ~erially connected from even after they have been cut off the runner ~O. The continuous rlveting operation described hereinbelow i~ thus made possible.
; The plas~ic material used as the starting material for the present invention may be freely selected from among the the moplastic ~ynthetic resins known to the art~ Examples of the synthetic resins which are usable include nylon, poly-carbonate, polypropylene, polyacetal and polyethylene. The plastic material i~ ~uitably selected to meet best the particular purpose to which the produced rivets are put.
The male member and the female member in one rivet may be produced from one same kind o plastic material or they may be made from different kinds of plastic materials.
When two differ~t kinds of plastic ma~erials are used, the melting point of the plastic material to be used in the ,:

~ 054~4~l former molding should be higher than that of the other plastic material to be used in thle latter molding. Otherwise, the male member may possibly be fused onto the female member in the molded rivet. More specifically, when the molding of the female member follows that of the male member, the plastic material used in the male member is required to have a melting point higher tha~ the plastic material u~ed in the female member. Where one same kind of plastio material is used or two different kinds of plastic materials having a caDmon melting point are usedJ possible fusion of the male and female members may be prevented by first coating the molded male member with a Xnown mold release agent such as, for example, silicone before it is placed in the mold for the female member and the molten pla~tic material is introduced.
The molding process descr~bed abo~e is carried out by fol~owing the known technique for the injection mo}ding u~ing a plastic material. Since the rivet o the present invention is manufactured by the double molding method as described a~ove, the two members of the rivet may be manufactured by using plastic materials different in color as well as in quality. Where the plastic materials are di~ferent in color, i~ the rivet is fastened on a basal plate, the flange of the female member exposed above the basal pl~te and the portion o~ the shank of the male me~b~r which protrudes from said flange have dif~erent colors. By appropriate shaping of said protruding portion of the shank, the rivet of the present invention may be used as a decorative arti~le.
Fig. 10 depicts a preferred embodiment wherein ~he .

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flange 2 of the female member is given a modified shape to permit attachment of some other article. A molding 18 may - readily be fastened to a lateral side of an automobile i the flange is given a square shap~s and a groove 2' is formed on each of an opposed pair of lat~eral sides o the square flange. The flange of the female member may be given a shape like a dish as illustrated in FigO 11 or the portion of the male member protruding above the flange may ~e given the shape of a stud as shown in Fig~ 12. If the rivet having sùch a flange or stud is fastened to a box of corrugated cardboard, the flange or stud may be used as a catah for the cord used to retain the lid of the box in its closqd position.
The head of the male member may be given a shape like a hook 5' as illustrated in Fig. 13. If the rivet containing such lS a male member is fastened onto a basal plate and the protrud-ing portion of the male member is left uncut, then the head of the male me~ber may be used as a catch.
By giving the flange of the emale member or the head of the male member which protrudes from the basal plate various shapes ~o suit particular purposes, the rivet of the present invention can be used as a leg for fastening an article to the basal plate or as a catch of a desired type.
As is evident from the forégoing description, tha blind rivet of this invention can easily be fastened onto the basal plate by the operation of drawing the male member from the female member incorporating said male member. Thus, the operation itself is easy and the required fastening can be accomplished from one side of the basal plats. Thus, the ~ 20 ~ r . . .

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rivet of this invention proves to be highly advantageou~
when it is used on a plate having a construction such that - the opposlte side thereof does not permit insertion of a tool or some other implement. Fuxther, since the rivet of - 5 this inventio~ has a configuratialn such that ~he extent to which the tubular wall of the female member is permitted to expand i5 variable with the length of the emale member, the rivet is not affected by the wall thickness of the basal plate or the diameter of holes bored therein. Thus, the :
rivet of this invention has an advantage that lt suits any plate thickness or hole diameter insofar as a sufflcient extent of expansion is obtainable.
It is also permissible for the head of the male member to be given a shape freely ~elected to permit ready catch by a tool being u3ed for pulling the male member. Unlike the conventional rivets which have to be held securely in the chuck of a tool one by one, the rivets of this invention can easily be mounted on the tool. As shown in Fig. 14, riveting can be accomplished by catching the rivet head 5 in ~he tool chuck 21 and then drawing ou~ the male member 3 while at the same time retaining flange 2 of the female member 1 with a flange retaining plate 2~. Therefore, rivets of the present invention manu~actured in varying sizes can be fa~tened by use of one same tool so fæ as their heads 5 which are to be - 2~ pl~ched by the tool are given one fixed shape. Moreover, if a readily severable connecting portion 19 is incorporated in the heads of the male members to connect the rivets ln a series as illustrated in Fig. 15, all the rivets in this l~)S4~
series can be continuously subjected to the riveting operation by mounting the series of rivets all at once ; ins~ead of causing the rivets to be mounted on the tool independently of one another. Incorporation of such a connecting portion 19 to the heads can readily be accom plished during the injection molding of plastic material.
This constitutes a feature unattainable with metallic ri~ets.
As described above, the rivets of pla~tic material according to the present invention can easily be mass produced so as to di~pense with the work of assembling the male members and female members. There is absolutely no posYibilit~ that the two members will come apart while the r~vets are being transported or stored. Qnce the rivet is fastened to the basal plate, the male member will never come out of the female member, so that the rivet pro~ides safe fastening. Besides serving to unite a plurality of plates piled up one on top of another, the rivets of the present invention are usable as legs, hooks or decorative items on partQ on which they are fastened when their por~ions protrud-ing from the basal plate are given varying shapes.

:
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVIEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A blind rivet of plastics material, which comprises (a) a female member comprised of a flexible tubular wall defining a cavity and having an open upper end and a lower end, a flange extending outwardly from the upper end of the tubular wall, the tubular wall defining a stepped portion in the cavity at the upper end and plurality of elongate apertures extending longitudinally of the wall, and (b) a male member comprised of a shank inserted in the cavity and in intimate contact with the tubular wall terminating in an expanded end portion in intimate contact with the lower end of the tubular wall of the female member, the shank having a series of peripheral ratchet-forming projections in engagement with the tubular wall, the shank of the male member being axially movable in relation to the tubular wall of the female member while the expanded end portion remains engaged with the lower end of the tubular wall; whereby upon axial movement in one direction of the male member in relation to the female member the engaged expanded end portion forces the tubular wall to buckle outwardly to form portions which extend radially to form petals while one of the ratchet forming projections snaps into fastening engagement with the stepped portion, the flange of the female member and the petal portions formed of the buckled tubular wall thereof cooperating to hold an article therebetween.

2. The blind rivet according to claim 1 wherein the lower end of the female member is open and the expanded end portion protrudes downwardly from the open lower end and engages the lower end face of the female member.

3. The blind rivet according to claim 1 wherein the expanded end portion is enclosed in the lower portion of the female member.

4. The blind rivet according to claim 3, wherein the expanded end portion is in the shape of a bar and the opposed ends of said bar-like portion are laterally exposed at the lower end of the female member.

5. The blind rivet according to claim 4, wherein the opposed ends of the bar-like expanded portion are positioned below the wall portions of the female member which are destined to expand in the shape of petals.

6. The blind rivet according to claim 1 further comprising a head on the shank of the male member, the head protruding upwardly from the open upper end of the female member and being shaped for gripping by a tool adapted to moving the male member axially in relation to the tubular wall of the female member.

7. The blind rivet according to claim 6 wherein the head of the shank has a constant shape which is not related to the size of the rivet.

8. The blind rivet according to claim 1 wherein the plurality of elongate apertures have a greater width toward the upper end thereof than toward the lower end thereof.

9. The blind rivet according to claim 1 wherein the male member and the female member are made of the same kind of plastics material.

10. The blind rivet according to claim 1 wherein the male member and the female member are made of different kinds of plastics materials.

11. A blind rivet according to claim 1 further comprising connecting portions extending from the head of the shank and to similar heads of like rivets thereby to form a joined row of like blind rivets.

12. A blind rivet of plastics material, which comprises;
(a) a female member comprised of a flexible tubular wall defining a cavity and having cm open upper end and a lower end, and a flange extending outwardly from the upper end of the tubular wall, the tubular wall defining a stepped portion in the cavity at the upper end thereof and a plurality of elongate apertures extending longitudinally of the wall, and (b) a male member comprised of a shank and an expanded end portion, the shank having a series of peripheral ratchet-forming projections, the female member being molded about the shank of the male member, with the expanded end portion in intimate contact with the said lower end.

13. The blind rivet according to claim 12, wherein the elongate apertures having a width gradually increasing towards the upper end of the tubular wall.

14. The blind rivet according to either claim 12 or 13 further comprising a head on the shank of the male member, the head protruding upwardly from the open upper end and being shaped for gripping by a forked drawing tool.

15. The blind rivet according to either claim 12 or or 13 further comprising connecting portions extending from the head of the shank and to the heads of like rivets, thereby to form a row of like blind rivets connected to each other at their shank head.

16. The blind rivet according to either claim 12 or 13 further comprising a shank portion of increased diameter opposite the expanded end portion and shaped for engagement with the stepped portion in the cavity.

17. A method for the manufacture of a blind rivet of plastics material, comprising the steps of:
(a) injection molding a molten plastics material under pressure into the cavity of a die shaped to form a male member comprised of a shank and an expanded end portion, the die being shaped to provide the shank with a series of peripheral ratchet forming projections and a portion of increased diameter opposite the expanded end portion, (b) placing the molded male member expanded end portion lowermost into the cavity of another die shaped to form a female member comprised of a tubular wall having an open upper end and a lower end, a flange extending outwardly from the upper end of the tubular wall and a plurality of elongate wall apertures extending longitudinally along the wall, and (c) injection molding a molten plastics material under pressure into the cavity of the other die around the shank of the male member whereby a stepped portion is formed in the tubular wall around the increased diameter portion of the shank and the tubular wall of the female member is formed in intimate contact with the shank.

18. The manufacturing method according to claim 17 wherein the cavity of the die for the male member is shaped to form a head at an outer end of the increased diameter portion of the shank.

19. The manufacturing method according to claim 17 wherein the molten plastics material is injection molded into a row of said dies to form a row of male members, and wherein a channel interconnects adjacent cavities whereby molten plastics material may flow to form plastics interconnecting. portions between the heads of adjoining male members.