GB2116102A - Riveting tool - Google Patents

Abstract

A pneumatically powered riveting tool for setting breakstem rivets has a riveting head (12) having means (26, 36, 38) for pulling a rivet stem so as to set the rivet and break off a tail part (46) of the stem, and an air injector (52, 50) which, when supplied with compressed air via a hose (76) and passages (78, 80, 82, 84, 64) induces a secondary flow of air whereby the broken off stem tails (46) are entrained so as to expel the stem tails from the riveting head (12) into a container (14) which is removably attached to the riveting head. A safety valve (94, 96) operates to disable the air injector (52, 50) and thus prevent ejection of stem tails when the container (14) is not in position to receive them. The safety valve operates to reduce the flow of air to the air injector (52, 50) either by cutting off the supply of air to the injector (52, 50) or by allowing the air supply to bleed away to atmosphere via the passage (84) before reaching the injector. <IMAGE>

Description

SPECIFICATION Riveting tool This invention relates to a riveting tool for setting breakstem rivets and having a removable receiver for receiving broken-off tail parts of the stems of set rivets which are expelled from the rivet setting mechanism of the tool, and more particularly to such a riveting tool having means operating as a safety device to prevent expulsion of the tail parts of stems when the receiver is not in position to receive them.

Riveting tools for setting breakstem rivets are well known, and generally comprise means for engaging the stem of a breakstem rivet, and then either rotating it or pulling it so as to set the rivet, the setting operation being terminated by the breaking of the stem of the rivet. One part of the broken stem usually remains within the body of the set rivet, and the other part or tail of the stem is discarded. Such tools may be either hand operated or power operated, especially by pneumatic power. In the case of pneumatically powered tools, it has become common to use the compressed air which is supplied primarily as the source of power for setting the rivets, also to extract the broken off stem tails from the riveting setting mechanism of the tool and to convey them to a collecting container.This is generally achieved by entraining the broken off stem tails in a stream of air travelling into the container, and it will be understood that the stem tails can be accelerated to speeds at which they have considerable energy. It will therefore be appreciated that if the tool should be operated with the container not in position to catch the expelled stem tail, then the stem tail may become a dangerous missile, or, at best, fall to the floor and there form a hazard underfoot.

According to the invention there is provided a riveting tool for setting a breakstem rivet, and comprising a riveting head having means for engaging the stem of the rivet and operative to set the rivet and break off a tail part of the stem, and means for expelling the broken off stem tail from the riveting head, the tool having means separable from the riveting head for receiving a stem tail expelled from the rivet head, wherein the riveting head includes disabling means which is rendered operative when the receiving means is separated from the riveting head, for disabling the means for expelling the stem tail.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation, generally in section, of a riveting tool embodying one form of the invention; Figure 2 is an enlarged fragment of Figure 1; Figure 3 is a fragment similar to that of Figure 2, but with a container for receiving stem tails removed from the tool; Figure 4 is a sectional elevation on the line A-A of Figure 3; Figure 5 is a fragmentary elevation, mainly in section, illustrating a riveting tool embodying an alternative form of the invention; Figure 6 is a view similar to that of Figure 5 but with a containerfor stem tails removed.

Referring first to Figures 1 to 4 of the drawings, the riveting tool of this embodiment is a pneumatic-hydraulic tool of a well known type adapted to set breakstem rivets of the pull-to-set type, and will be described only in such details as is necessary to understand the invention.

The riveting tool comprises a riveting head 12 having an associated container 14 for collecting broken-off stem tails of breakstem rivet, and a handle 16 which incorporates a hydro-pneumatic intensifier with a control trigger 18. The tool handle has an air inlet port 20 which, in use of the tool, is connected to a source of compressed air by a pneumatic hose (not shown). Operation of the trigger 18 by an operator allows compressed air to enter a pneumatic cylinder 22 oftheintensifier. A piston 23 is thereby moved upwardly (as viewed in the drawings), causing hydraulic fluid to be displaced from a hydraulic chamber 24 of the intensifier. The hydraulic fluid in turn drives a hydraulic piston 26 working in a substantially closed cylinder 28 in the riveting head.Thus, the hydraulic fluid enters the cylinder 28 on the left of the piston 26 and moves the piston rearwardly, that is to say, to the right as viewed in the drawings, compressing a helical piston-return spring 30. When the trigger is released, the pneumatic piston 23 is driven downwardly, due to the pressure generated in the hydraulic cylinder 28 by the compressed return spring ensuring that the hydraulic piston 26 returns for- wardly to its original position in the cylinder 28 displacing fluid into chamber 24.

The hydraulic piston 26 is secured to an elongated tubular drawbar 32 intermediate between the ends of the drawbar. Part of the drawbar extends forwardly of the piston 26 and into a nose part 33 of the riveting head. The forward end of the nose 33 is substantially closed by an annular anvil 34 for supporting a rivet during a setting operation, and within the nose is a stem gripping means comprising a collet 36 which secured to the forward end of the draw-bar 32, and jaws 38 within the collet. When the piston 26 is driven rearwardly it moves the drawbar and attached collet rearwardly, causing the jaws to close on and pull a rivet stem which has been inserted through the anvil into position between the jaws. As the body of a rivet is then supported by the anvil, the effect of pulling the stem is to set the rivet, by deforming the rivet body and breaking the stem.

Thus, the broken-off stem tail is left between the jaws. Return forwardly of the piston 26 releases the jaws from the stem tail and returns the jaws forwardly.

A passageway 44 exists for the broken-off stem tail to pass rearwardly from between the jaws 38 through the riveting head and out of its rearward end, and into the collecting container 14.

In order to induce the stem tails of set rivets to pass along the passageway 44 and into the container, the passageway is formed as part of an air injector whereby a steam of air is induced to flow rearwardly through the passageway and to entrain any stem tail therein and to convey the stem tail into the container.

The air injector includes a part 50 of the tubular drawbar 32 which projects rearwardly of the piston 26, and a tubular throat member 52. The throat member is elongated and has an enlarged flange 53 at its forward end. The flange 53 abuts the rearward face of the piston 26 and is held in contact therewith by the forward end of the return spring 30 so that the throat member travels with the piston 26. A wide diameter bore 54 extends rearwardly from the flanged end of the throat for a distance somewhat greater than the length of the rearward part 50 of the drawbar. The diameter of the bore is then reduced rearwardly through a tapered transition region 56 to a narrow bore 58 which is coaxial with the bore of the drawbar and extends to the rear end of the throat member.The wide diameter bore 54 receives the rearward part 50 of the drawbar with sufficient clearance to leave an annular passage 62 peripherally of the drawbar. The throat member has a plurality of ports 64 leading from the exterior of the throat member into the annular passage 62.

Compressed air introduced into the cylinder 28 on the rearward side of the piston 26 and externally of the throat member flows through the ports 64 and into the annular passage 62, and then flows rearwardly, through the tapered transition region, into the narrow bore and, via the collecting container 14, to atmosphere. In passing from the wide bore to the narrow bore of the throat, the flow of compressed air induces a secondaryflowof air in a rearward direction through the drawbar 32, and this secon dary airflow entrains any stem tail between the jaws or which has already entered the drawbar, and propels it rearwardly through the drawbar and throat member and out of the rear end of the riveting head.

As previously indicated, it is the purpose of the container 14to catch stem tails issuing from the rear end of the riveting head and thus prevent them from constituting a hazard.

The rear end of the cylinder 28 is substantially closed by a stepped annular gland 70 which is keyed into the rear end of the bore of the cylinder 28.

A manifold 72 is secured to the gland 7Q by an annular nut 74 which threadedly engages the gland.

A rearward externally cylindrical portion 60 of the throat member through which extends the narrow bore 58 projects rearwardly through the gland and can slide longitudinally therein when the piston 26 moves in the cylinder 28. Together, the throat member and the gland constitute a valve for controlling the flow of compressed air to the injector during operation of the tool.

Thus, the compressed air required for operation of the air injector is delivered from a supply by a hose 76 from which it enters the manifold 72 and passes first through a short vestibule 78 and then turns through a right angle into a passage 80 from which it passes through a port 82 formed in the annular gland and which leads into the central bore of the gland in which is received the rearward portion 60 of the throat. When the piston 26 is at the forward end of its stroke, there exists in the gland an annular passage 84 peripherally of the rearward portion 60 of the throat member and which leads forwardly into the cavity of the cylinder 28 through which the piston 26 is slidable.Thus, the compressed air is able to enter the cylinder 28 and thence to pass through the ports 64 into the wide bore 54 of the throat member and thence rearwardly to atmosphere, causing stem tails to be expelled rearwardly as previously explained.

In orderto ensurethatthe maximum pressure is available, at least in the final stage of setting a rivet when the stem tail has to be broken off by the pulling of the tool, the airflow to the air injector is cut off as soon as the piston 26 has moved rearwardly through a short distance.

Thus, the throat member is stepped to provide a forward portion 66 of greater external diameter than that of the rearward portion 60 and such that a slight rearward movement of the piston 26 moving the throat member rearwardly, engages the forward portion 66 in the annular passage 84, thereby cutting off the flow of air into the cylinder 28 and to the injector so that the injector ceases to operate temporarily until the operator releases the trigger at the end of a riveting operation, thereby causing the piston 26 to return forwardly and opening the way for airto flow again to the injector The container 14 has vents 86 for the escape to atmosphere of air coming from the injector, and has an externally screw threaded neck 88 which can be threadedly engaged in an internally screw threaded socket 90 formed at the rearward facing end of the manifold 72.The container can thus be supported on the riveting head in a position to catch the stem tails expelled, and it can easily be removed by unscrewing from the manifold in order, for example, to empty the container. It is in such circumstances that operation of a tool without its container in position can possibly cause injury or mishap.

The tool of this example therefore includes means whereby the air supply to the injector is bled to atmosphere when the container 14 is not properly engaged in an co-operating with the socket of the riveting head so that the air injector becomes disabled and ineffective to expel stem tails from the riveting head.

As best seen in Figures 3 and 4, the manifold 72 provides, at the inner end of the socket, an annular face 92 peripherally of the nut 74. A bleed passage 94 extends substantially in alignment with the hose and vestibule 78, from the vestibule, and opens into the annular face 92 at 95.

Two annular washers 96,98 are held captive by the nut 74. The washer 96 is resiliently deformable sealing washer formed of rubber, and the washer 98 is a rigid supporting washer formed of steel. When the container 14 is not screwed fully into the socket, the washers are able to float lengthwise of the nut between a position in which the washer 96 abuts the face 92, and a position in which the washer 96 is spaced from the face 92 or in very lightly touching contact with the face 92. Then, the sealing washer 96 does not close the opening 95, and compressed air entering the manifold from the normal supply can escape from the bleed passage 94 to atmosphere at a rate of flow sufficient to prevent the operation of the injector.

When the container is screwed home into the socket, as shown in Figure 1,the neck 88 abuts the rigid washer 98 and drives it towards the face 92, and so compresses the sealing washer 96 firmly against the annular face, thus sealing off the opening 95 of the bleed passage. The compressed air is therefore no longer able to escape through the bleed passage but is constrained to seek another path to atmosphere which it can do, provided the piston 26 is forward, by passing through the chamber 28, the ports 64 and onward, through the injector.

Thus, it will be appreciated that it is necessary for the container to be properly engaged in the socket and thus to complement the riveting head in order for the injector to be able to operate to expel a stem tail from the riveting head, since without the container in position the air supply bleeds away before reaching the injector.

Thus, in this embodiment of the invention, the manifold provides a safety valve in which the annular face 92 constitutes a valve seat peripherally of the opening 95 of the bleed passage 94, and the resilient washer 96 constitutes a closure member for the bleed opening 95. In this embodiment, the safety valve, when closed by engagement of the container 14 in the socket, prevents the escape to atmosphere of the air supplied for operation of the injector so that the injector operates to expel stem tails, and when opened by removal of the container 14, disables the injector by allowing escape to atmosphere of the air which otherwise could pass through the injector and cause it to operate to expel stem tails.

Another embodiment of the invention will now be described with reference to Figures 5 and 6, in which there is shown a riveting tool 100 of which most parts are identical to those of the tool of Figure 1 and are indicated by the same reference numerals. The tool 100 has a manifold 110 which differs from that of Figure 1 in that the manifold 110 provides a safety valve 112 which is opened when the container is engaged in the socket of the manifold. The safety valve, when open, allows compressed air to flow to and through the air injector, causing it to operate to expel stem tail. The safety valve is closed when the container is not engaged in the socket, and when so closed positively shuts off the supply of compressed air to the injector.

Thus, the manifold 110 receives a compressed air supply hose 76 which leads into a vestibule 78 from which the air passes into a passage 114 at right angles to the hose, and into a chamber 116. The chamber 116 is formed as a bore which extends into the manifold from the annular face 92 and the opening of which at the annular face is plugged by a valve body 118 secured in the bore. The valve body 118 has a stepped axial bore providing a wide passage 120 which extends into the body from the chamber 116, and a narrow guide bore 121 opening at the annutar face 92.

A port 122 in the body 118 ieads from the wide passage 120 to the port 82 in the gland 70 and thence to the cavity of the cylinder 28.

Associated with the valve body 118 is a valve closure member or jumper 124 having a sealing washer 126 and a push rod 128. The sealing washer is urged by a compression spring 130 in the chamber 116 into sealing engagement with the valve body 118 so as to close the passage 120 from the chamber 116. The push rod 128 extends with substantial clearance through the wide passage 120 and extends slidably through the reduced diameter guide bore 121 in the body, and when the washer 126 is actually in sealing engagement with the body 118 the push rod projects beyond the face 92.

In this embodiment the resiliently deformable washer 96 is omitted, but the rigid steel washer 98 is present. When the container 14 is engaged in the socket, it forces the rigid washer 98 towards the annularface 92 ofthesocket,thewasherfirst engaging the projecting push rod of the jumper 124 and pushing it inwardly of the manifold against the urging of the spring 130. The sealing washer 126 is thereby lifted from the valve body and a passage from the chamber 116 through to the injector is thus opened.

Conversely, when the container 14 is removed from the socket, the spring 130, assisted by the pressure of the compressed air supply, forces the sealing washer of the jumper into sealing engagement with the valve body so that the air supply to the injector is decisively cut off, thereby ensuring that no further stem tails can be entrained until the container is re-fitted.

It will be appreciated that the invention can be embodied in ways other than those specifically described above. Those skilled in the arts will readily appreciate that there are other ways of ensuring that the action of means for expelling stem tails from a riveting tool is disabled when a container intended to catch them safely is removed from its operative position.

Instead of an air operated means, such as the air injector, for expelling stem tails from the riveting head, the means for expelling stem tails could be electromagnetic means, and the means for disabling the expelling means could be an electricai switch operated by separation of the stem tail receiving container from the riveting head.

It will be appreciated that it is not necessary for the receiver to retain the stem expelled from the riveting head as is done by the container 14 of the illustrated embodiments. Thus, instead of the receiver being a substantially closed containerforthe stem tails, the receiver could be a duct, such as a flexible hose arranged to convey the stem tails to a suitable destination which could be, for example, a floor standing bucket or other means for collecting and containing the stem tails.

Claims (8)

1. A riveting tool for setting a breakstem rivet, and comprising a riveting head having means for engaging the stem of the rivet and operative to set the rivet and break off a tail part of the stem, and means for expelling the broken off stem tail from the riveting head, the tool having means separable from the riveting head for receiving a stem tail expelled from the rivet head, wherein the riveting head includes disabling means which is rendered operative when the receiving means is separated from the riveting head, for disabling the means for expelling the stem tail.

2. A riveting tool as claimed in Claim 1, wherein the expelling means is adapted to be operated by a supply of compressed air, and the disabling means comprises valve means arranged to control the supply of compressed air.

3. A riveting tool as claimed in Claim 2, wherein the valve means is operative, when the receiving means is separated from the riveting head, to allow compressed air to bleed away from the supply so as to render the supply of air ineffective to operate the expelling means.

4. A riveting tool as claimed in Claim 3, wherein the valve means comprises a bleed passage leading from the supply and opening at a face of the riveting head, and means for sealing the opening of the passage when the receiving means is engaged with the riveting head, the sealing means being free to move away from the face so as not to seal the opening when the receiving means is removed.

5. A riveting tool as claimed in Claim 4, wherein the bleed passage opens into a socket into which the receiving means can be engaged for receiving stem tails, and the sealing means comprises a resiliently deformable sealing washer arranged to be forced into sealing engagement with the said face by engagement of the receiving means in the socket.

6. A riveting tool as claimed in Claim 2, wherein the valve means comprises sealing means which shuts off the supply of compressed air to the expelling means when the receiving means is sepa rated from the riveting head.

7. A riveting tool as claimed in Claim 6, wherein the valve means comprises a valve body having a passage for air to flow to the expelling means, and a valve closure member upstream of the supply for closing the passage when the receiving means is separated from the riveting head.

8. A riveting tool substantially as hereinbefore described with reference to the accompanying drawings.