IL39631A - Apparatus for setting blind tubular rivets including means for automatically supplying the rivets - Google Patents

Abstract

1397544 Blind riveting AVDEL Ltd 26 May 1972 [28 May 1971] 18178/71 Heading B3U Blind riveting apparatus as described in Specification 1,397,543 is characterized by abutment means 18, 20, a mandrel 12, first and second holding means 26, 28 and 30, 36, each of which is arranged to hold the mandrel at a time when the other is out of engagement with the mandrel, the first holding means 26, 28 being reciprocable in the axial direction of the mandrel between a forward, Fig. 1, and rearward, Fig. 3, location, and movable in a direction transverse to the mandrel axis between a mandrel holding position and a position remote from the mandrel and through a rivet feeding position between said mandrel holding position and said remote position, the first holding means being operable to hold and move the mandrel lengthwise of its axis while moving between the forward position and an intermediate location between the forward and rearward locations, and, in the rivet feeding position, to engage a rivet on the mandrel stem while moving independently of the mandrel between the intermediate and rearward locations, and in the remote position at the rearward location to allow a rivet to move along the mandrel past the first holding means, means, e.g. gas jet 42, being provided for advancing a rivet forwardly along the mandrel from the rearward end thereof and past the first holding means. [GB1397544A]

Description

39631/2 'nan maiep nnaoa nya b 7pnn nnaoan η^οηιυ-ικ npooKb o»yxaK Apparatus for setting blind tubular rivets including means for automatically supplying the rivets AERPAT A.G.

C:37644 39631/2 This invention relates to blind riveting for setting blind tubular rivets of the kind comprising a shank and an enlarged head at one end of the shank, and having a bore extending through the head and shank. Such rivets are well known and are commercially available under the registered Trade Mark ' Chobert 1.

More particularly the invention relates to blind riveting apparatus which is adapted to supply blind tubular rivets to a setting station, and to set the rivets at the setting station.

As far as is relevant to the invention claimed in the present application, the prior art disclosed in French specification No. 2,018,202 comprises blind riveting apparatus having two pairs of mandrel-gripping jaws spaced apart along the mandrel for gripping the mandrel and pulling it to place successive rivets, the two pairs of jaws being opened alternately so that a rivet fed on to the mandrel from the tail end thereof can pass successively through both sets of jaws towards the head of the mandrel.

In this prior art apparatus, the jaws of each pair are movable in a direction transverse to the mandrel axis between a mandrel holding position (in which they grip the mandrel) and a remote position away from the mandrel which they allow a rivet to pass between the jaws. Neither pair of mandrel-gripping jaws performs any rivet feeding function to assist in feeding the rivets towards the head of the mandrel. Also in the prior art machine, both pairs of mandrel-gripping jaws are fixed together for reciprocation in unison in the axial direction of the mandrel, and since at least one pair of jaws is always gripping the mandrel, neither pair of jaws can move independently of the mandrel in the axial direction of the mandrel. By distinction, the first holding means of the present invention moves independently of the mandrel in order to feed rivets along the mandrel. To this end, the first holding means is also movable transversely of the mandrel axis through a rivet feeding position in which it does not grip the mandrel but does engage a rivet to feed it along the mandrel.

According to the invention there is provided blind riveting apparatus comprising abutment means for supporting a rivet in a rivet setting operation, an elongated mandrel having an enlarged head, and a stem extending rearwardly of the head, the mandrel being movable lengthwise of its axis, relative to the abutment means, to pull the enlarged head through a tubular rivet supported by the abutment means, first and second hoi dLng means each of which may be in or out of engagement with the mandrel and each of which is arranged to hold the mandrel at a time when the other of the holding means is out of engagement with the mandrel, the first holding means being reciprocable in the axial direction of the mandrel between a forward and a rearward location, and movable in a direction transverse to the mandrel axis between a mandrel-holding position and a position remote from the mandrel and through a rivet feeding position between said mandrel-holding position and said remote position, the first holding means being operable to hold and to move the mandrel lengthwise of its axis while moving between the said forward location and an intermediate location "between the ■—r forward location and the rearward location, and in the rivet feeding position, to engage a rivet on the mandrel stem while moving independently of the mandrel between the said intermediate location and the rearward location, and, in the remote position at the rearward location to allow a rivet to move along the mandrel past the first holding means, means being provided for advancing rivets forwardly along the mandrel from the rearward end thereof and past the first holding means.

The first holding means may comprise a pair of pulling jaws.

Each pulling jaw may be associated with a cam which constrains the jaw to move between the mandrel-holding position and the said position remote from the mandrel.

Each pulling jaw may be spring biassed to move transversely towards the position remote from the mandrel and may be constrained to move in opposition to the spring bias by the associated cam.

The second holding means may be disposed rearwardly of the holding means.

The means for advancing rivets forwardly from the rear end of the mandrel and past the first holding means may comprise jet means for directing a jet of gas forwardly along the mandrel.

The jet means may be disposed rearwardly of the rear end of the mandrel when the mandrel is in its rearward position.' A preferred embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:- Figures 1 to 4 are schematic views from the front of a ^ blind riveting machine showing the positions of parts of the machine in successive stages of operation; Figure 5 is a schematic side view corresponding to Figure 4; Figure 6 is a schematic side view showing parts of the machine in a further stage of operation; Figure 7 is sectional elevation through part of the machine taken on the line VII - VII of Figure 13 and corresponding generally to the views shown in Figures 1 - 4; Figure 8 is a sectional elevation through part of the machine taken on the line VIII - VIII of Figure 12 and corresponding generally to the views shown in Figures 5 and 6; Figure 9 is a section on the line IX -IX of Figure 8; Figure 10 is a side elevation of a mandrel forming part of the machine; Figure 11 is a schematic diagram illustrating a pneumatic circuit for controlling operation of the machine; Figure 12 is a front elevation of the complete machine; Figure 13 is a side elevation of the complete machine ; Figure 14 is a section on the line XIV - XIV of Figure 8.

The riveting machine of this embodiment is intended for setting blind tubular rivets of the kind comprising a shank and an enlarged head at one end of the shank, and having a bore extending through the head and shank. Such rivets are well known and are commercially available under the registered Trademark ' Chobert'. Such rivets are set by means of a mandrel having a stem on which the rivets are a sliding fit, and an enlarged head at one end of the stem, each rivet being threaded onto the mandrel stem with the tail end of the rivet (i.e. the end of the rivet shank remote from the rivet head) towards the head of the mandrel, and the mandrel is then pulled to draw the mandrel head through the rivet bore, thereby expanding the shank of the rivet. A plurality of rivets may be loaded onto the stem of the mandrel with their tail ends towards the mandrel head, and can then be set by pulling the mandrel to draw the head through the rivets successively.

The machine of this embodiment is adapted to automatically maintain a supply of rivets to a rivet setting station and to set the rivets in a suitable apertured workpiece at the setting station from below the workpiece. Thus, rivets are presented at the setting station head down and tail extending vertically upwards, the workpiece being positioned so that the tail of the rivet projects through an aperture in the workpiece, and the rivet is then set. A further rivet is then automatically presented at the setting station ready for setting.

The riveting machine comprises a riveting head together with means for storing and supplying rivets to the riveting head, and control gear for controlling the operation of the riveting head.

The construction of the riveting head is shown in detail in Figures 7 and 8 but some of its more important parts are illustrated schematically in Figures 1 to 6 in which the relationships of these parts in different stages of operation of the machine can readily be seen.

The riveting head 10 comprises a mandrel 12 having an elongated stem 14 and a head 16 at one end of the stem. The head end of the mandrel is regarded as the forward end, the other end being the rear end of the mandrel. The mandrel is reciprocable along its axis in relation to a pair of nose-jaws 18, 20 which are arranged on opposite sides of the mandrel stem at a position adjacent to the head. The nose-jaws each present a forwardly facing abutment surface 22, 24 adjacent to the mandrel and are resiliently urged towards a closed position in which these abutment surfaces normally co-operate to form an annular abutment peripherally of the mandrel. When the mandrel is moved forwardly, the head is spaced forwardly of the nose-jaws, (i.e. above them in the normal attitude of the riveting head) as shown in Figure 5, and when the mandrel is moved to its rearward position, the head is disposed between the jaws so that the forward end of the mandrel is flush with or even behind the abutment surfaces of the nose-jaws.

The mandrel is reciprocated by means of a pair of pulling jaws 26, 28 situated rearwardly of the nose-jaws.

The pulling jaws are movable between a closed position in which they co-operate to hold the mandrel and an open position in which they are disengaged from the mandrel, and are also reciprocable in the lengthwise direction of the mandrel. The movements of the pulling jaws are rather complex and will be discussed hereinafter: suffice it to say here that, when the mandrel is in its rearward position, the pulling jaws disengage from the mandrel and so do not hold it in the rearward position. However, when the mandrel is at its rearward position it is engaged and held by a detent 30 situated rearwardly of the pulling jaws. The detent 30 comprises a ball 32 which is urged by a compression spring 34 to engage in a peripheral groove 36 formed in the mandrel stem near the rear end of the mandrel.

A pair of rivet locating jaws 38, 40 are disposed on opposite sides of the mandrel axis at a position immediately forward of the detent but generally rearwardly of the rear end of the mandrel when the mandrel is in its forward position. The locating jaws are able to open and close in synchronism with the opening and closing of the pulling jaws.

A rivet locating plunger 58, shown schematically in Figures 5 and 6, is reciprocable at right angles to the mandrel axis to deliver rivets one at a time from the rivet supply means into position between the closed locating jaws when the mandrel is in its forward position. A rivet thus delivered is held rearwardly of the mandrel by the locating jaws with its bore aligned with the mandrel and with the tail end of the rivet towards the nose-jaws.

A jet 42 is arranged on the axis of the mandrel at a position which is to the rear of the rear end of the mandrel when the mandrel is in its rearward position, and is arranged to direct a stream of air or other gas forwardly along the mandrel. The jet is connected through conduit (not shown) to a source of pressurized air or other gas.

A feature v/hich enables the riveting head to operate upwardly (i.e. from below a workpiece as distinct from downwardly with the riveting head above the workpiece or horizontally with the riveting head to one side of a work- piece) is the provision of a latch 44 which is resiliently urged into a position close to or engaging the mandrel and which moves pivotally away from the mandrel to allow rivets to move forwardly along the mandrel past the latch but prevents the rivets from moving rearwardly past the latch under the influence of gravity.

The sequence of operation of the parts so far referred to is as follows :- Referring first to Figure 1, in which the mandrel 12 is in its forward position relative to the nose-jaw 18, 20 and the pulling jaws 26, 28 are in their forward position and gripping the stem 14 of the mandrel and thereby holding the mandrel, it will be seen that the mandrel stem 14 extends through four rivets of which three rivets, indicated by the reference numerals 46, 48, 50, form a column generally to the rear of the nose-jaws and are supported by the pulling jaws 26, 28. The fourth, or leading rivet 52 has passed forwardly of the nose-jaws 18, 20 and is supported against rearward movement by the abutment surfaces 22, 24 of the nose jaws.

It will be noted also that another rivet, referred to as a fed rivet 54, is located between the locating jaws 38, 40 which are in their closed condition and that the rear end of the mandrel is forward of the fed rivet and aligned with the bore of the fed rivet.

In practice, and as shown in Figures 7 and 8, the distance between the pulling jaws, when in their forward position, and the nose jaws is greater than the length of a column of three rivets, and consequently the number of rivets forming the column is appropriate to the actual distance between the pulling jaws and nose-jaws.

In the condition shown in Figure 1, the riveting head is ready to set the leading rivet 52, and in use, a suitably apertured workpiece (not shown) is now brought into position, the head of the mandrel being passed through the aperture in the workpiece and the workpiece is lowered until its lower surface abuts the head of the leading rivet 52 and the shank of the leading rivet extends through the aperture of the workpiece. The riveting head is then actuated to set the rivet.

Actuation of the riveting head causes it to perform automatically a cycle of operations which is completed by the return of the riveting head to the condition shown in Figure : On actuating the riveting head, the pulling jaws 26, 28 move rearwardly while still gripping the mandrel, pulling the mandrel rearwardly until the mandrel head has passed right through the bore of the leading rivet 52 and the forward end of the mandrel has come to lie flush with the abutment surfaces of the nose-jaws. As previously indicated, the passage of the mandrel head through the leading rivet sets the rivet, causing the rivet to firmly engage the workpiece, and disengages the mandrel from the leading rivet.

Simultaneously with the setting of the leading rivet, the rearward movement of the mandrel has caused the rearward end of the stem of the mandrel to pass through the bore of the fed rivet 54 so that the fed rivet is now threaded on the mandrel stem, and the ball 32 of the detent 30 has engaged in the peripheral groove 36 near the rearward end of the mandrel the detent spring 34 having yielded previously to allow the portion of the' stem between the groove and the rear end of the mandrel to pass the detent.

As the pulling jaws move rearwardly, pulling the mandrel, the column of rivets supported by the pulling jaws also moves rearwardly under the influence of gravity until the rearmost rivet 50 of the column abuts the latch 44. The latch prevents further rearward movement of the column of rivets so that they do not follow the further rearward movement of the pulling jaws. , With. the mandrel now in its rearmost position, in which it is held by the engagement of the detent ball 32 in the peripheral groove of the mandrel stem,1 and with the column of rivets 46, 48, -50 supported against further rearward movement by the latch, the pulling jaws now begin progressively to open while continuing to move rearwardly and simultaneously the looating jaws 38, 40 also begin to open. This stage is shown in Figure 2.

The rearward and opening movements of the pulling jaws continue until the pulling jaws reach their rearmost position in which they are fully open and the locating jaws are also .fully opened.

A stream of air or other gas is then delivered through the jet and, on engaging the head of the fed rivet 54, drives the fed rivet forwardly past the pulling jaws until it abuts the rearward side of the latch as shown in Figure 3. The stream of air is sustained to maintain the fed rivet in abutment with the latch and the pulling jaws now begin to move forwardly and to close progressively to a rivet feeding position. On reaching the head of the fed rivet 54, the pulling jaws are closed to an intermediate position in which they are closed sufficiently, to abut the fed rivet but not to grip the mandrel. The pulling jaws continue to move forwardly without gripping the mandrel and in doing so urge the fed rivet 54 forwardly past the latch which yields resiliently to permit the rivet and jaws to pass. This stage of operation is shown in Figures 4 and 5* Thus, when the fed rivet is advanced along the mandrel, it strikes the latch and causes defleotion of the latch. However, the pulling jaws are so shaped that they also will deflect the latch when moving either forwardly or rearwardly past the latch.

The pulling jaws continue to move forwardly and eventually close upon and grip the, mandrel stem at the same position as before, having urged the rivets 46, 48, 50 forward along the mandrel stem by a distance equal to the length of the fed rivet. The closed pulling jaws continue to advance, now carrying forwardly the mandrel, the rivets 46, 48, 50 and the fed rivet 54.

As the pulling jaws move forwardly past the latch 44 they become disengaged from the latch which returns resiliently to the position close to the mandrel stem. At this stage the rivet locating plunger 58 is aotuated to deliver a further rivet 56 from the rivet supply means into j position between the closed locating jaws and outs off the supply of air to the jet 42. The further rivet 56 thus comes eventually to occupy the position formerly occupied by the fed rivet 54 at the beginning of the cycle, and remains there to constitute a fed rivet in the next cycle.

As the pulling jaws continue to move forwardly, the rivet 46 comes into abutment with the resilient nose-jaw3 and urges the nose-jaws to open. This stage is shown in Figure 6, from which it will be appreciated that the pulling aws have not quite reached the forward end of their stroke and the locating plunger 58 is still in the course of delivering the further rivet 56 towards the locating jaws.

As the pulling jaws complete their forward movement, they advance the rivet 46 through the opened nose-jaws and the nose-jaws then resiliently close behind the rivet 46 to provide an annular abutment rearwardly of the head of the rivet 46 which thus assumes the position formerly occupied by the leading rivet 52. Having advanced the rivet 46 to the position of the leading rivet, the pulling jaws and mandrel reach the end of their forward stroke and stop. By this time, the delivery of the further rivet 56 into position between the locating jaws is also complete and the riveting head is again in the condition shown in Figure 1 and ready to commence a further cycle.

Further details of the construction of the machine will now be described with reference to Figure 7 to 14.

In Figures 7 and 8, the condition of the machine is the same as shown in Figure 1, the pulling jaws 26, 28 being in their fully forward position and gripping the mandrel 12.

The riveting head 10 comprises a rectangular frame 60 having horizontal, parallel, upper and lower cross members 62, 64 respectively which are held in spaced relation by right and left vertical members 66, 68 respectively. A rail 70 extends horizontally between the vertical members at a position approximately midway between the upper and lower cross members.

A vertical plate 72 is secured to the lower cross member 64 and the upper cross member 62 and supports means for storing and supplying rivets to the riveting head.

The means for storing and supplying rivets comprises a side blade hopper feeder 74 of conventional construction and a flight 76. The side blade hopper feeder is arranged to contain a supply of tubular rivets and orientates and delivers the rivets to the flight in side by side relationship with their heads uppermost and their shanks depending from the rivet-heads. The flight provides a surface 78 which is downwardly inclined at an angle of about 30° and formed with a longitudinal slot 80 down which the rivets slide under the influence of gravity, the rivet heads being supported by the surface 78 and the rivet shanks depending into the slot 80. Towards the lower end of the flight, the surface 78 curves downwardly through an angle of about 150°. A curved plate 82 serves to support the rivets with their shanks in the groove as they pass down the curved portion of the flight and thereby become inverted with their heads lowermost and supported by the plate, and their shanks upstanding in the groove.

A double acting pneumatic jack 84 for moving the pulling jaws 26, 28 is mounted on the lower cross member 64. The jack comprises a pneumatic cylinder 86, a piston 88 and a piston rod 90. The cylinder 86 is bolted to the underside of the lower cross member with its axis vertical. The piston rod 90 is axially aligned with the cylinder and extends upwardly through an annular seal 92 mounted in a central hole in the lower cross member. The lower end of the piston rod is secured to the piston 88 which sweeps the bore of the cylinder and the pulling jaws 26, 28 are pivotally attached to the piston rod which is bifurcated at its upper end.

Upper and lower ports (not shown) are provided adjacent the upper and lower ends respectively of the cylinder. Admission of air through the lower port drives the piston upwardly, raising the piston rod, and admission of compressed air through the upper port drives the piston downwardly, lowering the piston rod.

The pulling jaws 26, 28 are identical, and each comprises a vertical limb 94, 95 integral at its upper end with a cylindrical housing 96 and at its lower end with an arm 98.

The vertical limos of the two pulling jaws 26, 28 extend through elongate openings 100, 102 in the rail, so that the arms are below the rail and the housings are above the rail. The arm of each pulling jaw extends at right angles to the vertical limb and the housing extends across the other end of the limb and parallel to the arm. The free end portion of the arm of each jaw 26, 28 is offset to provide a single tongue 104. The tongues of the two jaws are each formed with an aperture through which passes a pivot pin 106 by which both the pulling jaws are pivotally attached to the bifurcated upper end of the piston rod, the offset arrangement of the tongues of the arms of the two pulling jaws allowing both pulling jaws to be mounted on the same pivot pin while the vertical limbs and housings lie in a single plane. The vertical limbs 94, 95 are each formed with a longitudinal guide face 108, 110 respectively. The housings of the two pulling jaws are aligned with each other and their adjacent ends are externally tapered at 112. Each housing has a stepped horizontal bore which has a wide portion 114 at the outer end of the housing and which is stepped at 120 to a narrow bore portion 122 which extends through the tapered portion 112 of the housing to that end of the housing which is adjacent to the other jaw. Disposed within the housing of each jaw is a mandrel gripping member 116 and a pressure exerting member 124. The pressure exerting member 124 comprises a cylindrical block 126 which is slidable within the wide bore portion 114 of the housing, and a stem 128 which extends from the block into the narrow bore portion 122. The mandrel gripping member 116 comprises a cylindrical block 118 and three hardened steel fingers, 130, 132 and 134 projecting from the tapered portion 112 of the housing, two of the fingers, 130 and 132, being spaced apart and vertically aligned on one side of the mandrel axis and the other finger 134 being offset to the other side of the mandrel axis and between the other two fingers, the fingers of each jaw interdigitating with the fingers of the other jaw and cooperating to grip the mandrel when the jaws are in their closed position. A plurality of belleville washers 136 are shown disposed between the block 124 and the step of each jaw. The purpose of these washers is merely to facilitate accurate adjustment of the gripping members 116 to enable the fingers to suitably grip the mandrel.

Mounted at the outer end of each of the housings is a cam follower roller. Each of the cam follower rollers 140, 141 is mounted on a shaft 142, 143 respectively for rotation about a horizontal axis transverse to the bore of its jaw housing. Two cam blocks 144, 146 are secured at the inwardly facing sides of the right and left vertical members respectively of the frame by pairs of tension bolts 148, 150 (only one bolt of each pair being shown in Figure 7) which pass through each of the vertical members into threaded engagement with the cam blocks. Paired upper and lower spacing bolts 152, 154 (of which only one of each pair is shown) extend through each of the vertical members in threaded engagement therewith into abutment with the outwardly facing surface of the cam block secured thereto. By suitable adjustment of the tension bolts and space bolts, the distance between the inwardly facing surfaces 156, 158 of the two cam blocks can be adjusted. The inwardly facing surfaces of the two cam blocks 144, 146 constitute opposing cam surfaces against which the cam follower rollers of the pulling jaws run.

Tension springs, 160, 162 are secured at one of their ends to the lower ends of the cam blocks by means of pins 164, 166 and their other ends are attached to pins 168, 170 which are slidable against the guide faces 108, 110 of the vertical limbs of the pulling jaws. The tension springs urge the pulling jaws to pivot outwardly so as to maintain the cam follower rollers in abutment with the cam surfaces 156, 158 of the cam blocks.

The inwardly facing cam surfaces 156, 158 of the cam blocks each provide three distinct cam faces, namely a forward cam face 172, an intermediate cam face 174, and a rearward cam face 176. The forward and rearward cam faces of the two cam blocks are parallel to each other, and as illustrated in Figure 7, the rearward cam faces of the two cam blocks 144, 146. are spaced apart by a distance greater than the distance between the forward cam faces of the two blocks. The intermediate cam face on each block is inclined between the forward and rearward cam faces and the distance between the intermediate faces of the two cam blocks decreases progressively in the upward or forward direction.

With the pulling jaws 26, 28 in their raised or forward position as shown in Figure 7, the cam follower rollers 140, 141 abut the forward cam faces 172 of the cam blocks which are so adjusted that the pulling jaws are held in their fully closed position with the steel fingers of the mandrel-gripping means of the two pulling jaws interdigitating to grip the mandrel between them.

Actuation of the jack 84 to lower the piston rod 90 and move the pulling jaws downwardly or rearwardly, causes the cam follower rollers to traverse the cam faces of the cam blocks in the rearward direction. While the cam follower rollers are traversing the forward cam faces of the cam blocks, the jaws are held in their closed position. When the cam follower rollers traverse the intermediate cam faces of the cam blocks in the rearward direction, they are constrained to follow the profile of the cam block by urging of the tension springs and accordingly, the pulling jaws progressively open as they move rearwardly. When the cam follower rollers reach the rearward cam face of the cam blocks they are in the fully open position and further rearward movement of the pulling jaws with the cam follower rollers traversing the rearward cam faces does not cause them to open to. any greater degree.

Conversely, when the jack is actuated to raise the pulling jaws, the cam follower rollers initially traverse the rearward cam faces of the cam blocks so that the pulling jaws move forwardly in their fully open position until the cam follower rollers encounter the intermediate cam faces of the cam blocks. Thereupon, continued forward movement of the pulling jaws is accompanied by progressive closing of the pulling jaws and finally, when the cam follower rollers reach the forward cam faces of the cam blocks, the pulling jaws move forwardly without further closing.

The upper cross member 62 has a central aperture 178 in λhich is mounted the lower end of a vertical tube 180. At the upper end of the tube is mounted a nosepiece 182.

The nosepiece 182 comprises a tubular body 184, the nose-jaws 18, 20, and a helical compression spring 186. The tubular body 184 is screwed to the upper end of the vertical tube 180. The nose-jaws are of generally semi-cylindrical shape, and co-operate with each other to form substantially a tube peripherally of the mandrel 12. The compression spring 186 abuts an inwardly projecting flange 188 at the forward end of the tubular body, and an outwardly extending flange 190 at the rearward end of the two co-operating nose-jaws, and urges the nose-jaws rearwardly into the tubular body 184 by which the jaws are so constrained that their forward ends are closed together.

Forward movement of the nose-jaws relative to the tubular body, as when the pulling jaws advance a column of rivets into abutment with the nose-jaws (as explained with reference to Figure 6), allows the nose-jaws to move radially outwardly and thus to open and allow the leading rivet of the column to pass between the nose-jaws. Thereafter the compression spring 186 urges the nose-jaws rearwardly into the tubular body so that they close behind the leading rivet and the abutment surfaces 22, 24 of the nose-jaws abut the rearward end of the rivet head.

As will have been appreciated from the previous description, the mandrel 12, has its head 16 above or forwardly of the nose-jaws and the mandrel stem 14 extends rearwardly between the nose- aws, through the vertical tube 180, between the fingers of the two pulling jaws and, in the condition of the machine shown in Figure 7, its rear end is disposed forwardly of the rivet locating jaws 38, 40.

The rivet locating jaws 38, 40 are slidably mounted for lengthwise movement along the upper surface of the rail 70 on opposite sides of the jet 42. The jet 42 is in the form of a vertical bore, opening at the upper surface of the rail 70 and is axially aligned with the mandrel stem.

The locating jaws 38, 40 are each attached to one of the guide pins 168, 170 respectively so that they open and close in conert with the opening and closing movements of the pulling jaws. The rivet locating jaws define, when closed, a cavity 192 which is shaped to accommodate a fed rivet and to hold the rivet with its head lower most and its shank extending upwardly in alignment with the mandrel. The cavity defined by the closed locating jaws has an opening through which a rivet fed by the locating plunger 58 can enter the cavity.

The rivet locating plunger 58 is disposed within a guide channel 192 which extends horizontally and at right angles to the rail 70 between the lower end of the flight 76 and the cavity 192 between the locating jaws.

The rivet locating plunger 58 is reciprocable lengthwise of the guide channel by means of a double acting pneumatic piston-cylinder arrangement 198.

Admission of compressed air into the right hand end of the pneumatic cylinder 198 (as viewed in Figure 8) moves the locating plunger to the left, allowing the lowermost rivet in the flight to enter the guide channel. Subsequent admission of air to the left hand end of the pneumatic cylinder 198 moves the locating plunger to the right, pushing the rivet along the guide channel into position in the cavity 192 where the head of rivet overlies the opening of the jet 42.

The lower end of the vertical bore which forms the jet 42 is closed and intercepted by an air passage 200 v/hich is connected by conduit (not shown) to the air supply. The bore of the' jet 42 is also intercepted by the detent 30. As can be seen in Figure 8, the detent spring 34 is compressed in a bore 202 by means of a retaining screw 204 and urges the detent ball 32 transversely into the bore of jet 42 where it abuts against a stop 206 which prevents the ball falling out of the bore 202 and down the bore of the jet 42.

The latch 44 comprises a vertical bar 208 which is pivotally mounted at its lower end on a pin 210 supported by the rail 70. A blade member 212 is secured to the bar by a screw 214 and provides, at the upper end of the vertical bar, a blade 216 which extends horizontally towards the mandrel stem. The blade member 212 is adjustable on the bar 208 to allow the blade 216 to be adjusted lengthwise of the mandrel. A leaf sprin 218, which is secured to the rail by the retaining screw 204, resiliently urges the latch to pivot about the pin 210 so that the blade normally engages the mandrel stem.

The pneumatic circuit for controlling the operation of the riveting machine will now be described with particular reference to .Figure 11.

The operation of the machine is primarily subject to the operation by a machine operator of a pedal-operated spring-return impulse valve 220. The valve 220 is connected to a source of air under pressure at 222.

When the machine operator depresses the pedal of valve 220 the air supply 222 is connected through the valve to a conduit 224, the valve allowing a pulse of compressed air to pass along the conduit. This pulse initiates performance of a complete cycle of operations by the machine under the logical control of the control circuit.

The pulse is delivered by the conduit 224 to a 4-way 5-port double pilot valve 226. The valve 226 has an inlet port 228 through which it is connected to the main supply of compressed air. A conduit 230 connects an outlet port of the valve 226 to the upper end of the cylinder of the main jack 84, and a conduit 232 connects another outlet port of the valve 226 to the lower end of the cylinder of the jack 84.

In the normal condition of the valve 226, the inlet port 228 is connected through the valve to the conduit 232 so that pressure is maintained in the lower portion of the cylinder of the jack 84 and the piston 88 is in the raised or forward position and the conduit 230 is connected through the valve to a silencer and thence to exhaust so that pressure in the upper end of the cylinder is substantially atmospheric.

When a pulse is delivered along the conduit 224, the conduit 232 is disconnected from the i let port 228 and is connected to a conduit 234 to exhaust at a jet 236. The jet 236 may be arranged to direct air issuing from the jet onto rivets descending the flight 76 in order to assist their passage along the flight. Simultaneously the conduit 230 is connected through the valve 226 to the inlet 228 so that compressed air is delivered to the upper end of the cylinder of jack 84 and causes the piston to descend through the cylinder lowering the piston rod and moving the pulling jaws rearwardly. Descent of the piston in the cylinder of jack 84 sweeps air from the lower end of the cylinder through the conduit 232 via the valve 226 and the conduit 234 to exhaust through the jet 236.

As the pulling jaws descend, they mechanically actuate and hold actuated a 4-way, 5-port pilot return trip valve 238.

In the normal condition of the valve 238, the main air supply is connected via an inlet port 240 through the valve 238 and a conduit 242 to one end of the cylinder of the piston cylinder arrangement 198 (the left hand end as viewed in Figure 8) so that the rivet locating plunger 58 is moved to the right (as shown in Figures 5, 6 and 8) thereby advancing a rivet along the guide channel into the cavity between the locating jaws.

When the valve 238 is actuated by the rearward movement of the pulling jaws, the left hand end of the cylinder 198 is connected via the conduit 242 via the valve 238 to exhaust, and the air supply via port 240 is connected through the valve and a conduit 244 to the right hand end of the cylinder 198 moving the piston therein to withdraw the rivet locating plunger 58 along the guide channel 194 so as to admit a rivet from the flight into the guide channel .

Simultaneously with the delivery of air along conduit 244, air is delivered from the conduit 244 through a branch conduit 246 to actuate a 3-way, 3-port sprung return pilot valve 248. A conduit 250 which leads to the air jet 42 is normally connected through the valve 248 to exhaust but when air is supplied along the conduit 246 to the valve 248 the conduit 250 is connected through the valve 248 to the main air supply via inlet port 252 so that air is delivered via the jet 42 to advance a rivet forwardly along the mandrel when the rivet locating plunger withdraws to admit a further rivet into the guide channel.

Once the valve 238 has been actuated by the rearwardly moving pulling jaws, it remains in the actuated condition while the pulling jaws complete their rearward movement and begin to move forwardly again. When the forwardly moving pulling jaws pass the position at which they previously actuated the trip valve, they disengage from the trip valve allowing it to return to its normal condition under the influence of the pressure of the main air supply delivered via a pilot conduit 254.

Similarly, a pilot conduit 256 connects the conduit 230, via an adjustable pressure regulator 258, to the valve 258, whereby the valve 226 is returned to its normal condition due to an increase of air pressure in the conduit which occurs when the piston of jack 84 reaches the end of its rearward movement. The pressure regulator is adjusted to provide a short delay before returning the valve 226 to its normal condition after the piston of jack 84 reaches the end of its rearward stroke.

An air bleed 260 is provided to enable the pressure in conduit 224 to equalise with the atmosphere after delivery of each pulse along the conduit 224.

Claims (13)

P.197 Gr.B.

1. Blind riveting apparatus, comprising abutment means for supporting a rivet in a rivet setting operation, an elongated mandrel having an enlarged head and a stem extending rearwardly of the head, the mandrel being movable lengthwise of its axis, relative to the abutment means, to pull the enlarged head through a tubular rivet supported by the abutment means, first and second holding means each of which may be in or out of engagement with the mandrel and each of which is arranged to hold the mandrel at a time when the other of the holding means is out of engagement with the mandrel, , the first holding means being reciprocable in the axial direction of the mandrel between a forward and a rearward location, and movable in a direction transverse to the mandrel axis between a mandrel-holding position and a position remote from the mandrel and through a rivet feeding position between said mandrel-holding position and said remote position, the first holding means being operable to hold and to move the mandrel lengthwise of its axis while moving between the said forward location and an intermediate location between the forward location and the rearward location, and, in the rivet feeding position, to engage a rivet on the mandrel stem while moving independently of the mandrel between the said intermediate location and the rearward location, and, in the remote position at the rearward location to allow a rivet to move along the mandrel past the first holding means, means being provided for advancing rivets forwardly along the mandrel from the rearward end thereof and past the first holding means. P.197

2. Blind riveting apparatus as claimed in claim 1, wherein the first holding means comprises a pair of pulling jaws.

3. Blind riveting apparatus as claimed in claim 2, wherein each pulling jaw is associated with a cam which constrains the jaw to move between the mandrel-holding position and the said position remote from the mandrel.

4. Blind riveting apparatus as claimed in claim 3, wherein each pulling jaw is spring biassed to move transversely towards the position remote from the mandrel and is constrained to move in opposition to the spring bias by the associated cam.

5. Blind riveting apparatus as claimed in any preceding claim, wherein the second holding means is disposed rearwardly of the first holding means.

6. Blind riveting apparatus as claimed in any preceding claim, wherein the means for advancing rivets forwardly from the rear end of the mandrel and past the first holding means comprises jet means for directing a jet of gas forwardly along the mandrel.

7. Blind riveting apparatus as claimed in claim 6, wherein the jet means is disposed rearwardly of the rear end of the mandrel when the mandrel is in its rearward position. P.197

8. Blind riveting apparatus as claimed in any preceding claim, comprising means for delivering tubular rivets to and aligning the rivets with the mandrel in a position through which the stem of the mandrel extends when the mandrel is in a rearward position and which is rearwardly of the mandrel when the mandrel is in a forward position.

9. · Blind riveting apparatus as claimed in claim 8, wherein the means for delivering and aligning the tubular rivets is arranged to deliver the rivets to and align them at a position which is forwardly of the second holding means and the means for advancing rivets forwardly from the rear end of the mandrel.

10. Blind riveting apparatus as claimed in either of claims 8 or 9, wherein the means for delivering and aligning rivets comprises locating jaws arranged to open and close in timed relationship to the movements of the mandrel for holding a rivet in alignment with the mandrel, and means for feeding rivets one at a time into position between the locating jaws.

11. Blind riveting apparatus as claimed in any preceding claim, wherein the abutment means comprises co-operating abutment jaws adapted to be opened by a rivet moving forwardly along the mandrel and to resist rearward movement of a rivet positioned forwardly of the abutment jaws. . 39631/2

12. Blind riveting apparatus as claimed in any preceding claim, wherein a latch is provided at a position forwardly of the first holding means and -rearwardly of the abutment means, the latch being adapted to permit rivets to move forwardly along the mandrel past the latch and to prevent rivets moving rearwardly past the latch.

13.' Blind riveting apparatus as claimed in any preceding claim, wherein the second holding means comprises a detent positioned to engage the mandrel only when the mandrel is at or near its. rearward position.