GB1572269A - Jaw assembly for blind riveting apparatus - Google Patents

Description

(54) JAW ASSEMBLY FOR BLIND RIVETING APPARATUS (71) We, AVDEL LIMITED, a British Company of Mundells, Welwyn Garden City, Hertfordshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a jaw assembly for blind riveting apparatus.More particularly, the invention relates to a jaw assembly of the type through which a reusable mandrel passes and which jaw assembly com- prises a plurality of jaws which are resiliently urged into a closed position, and which can be opened against the resilient urging, by the thrust of a rivet being fed along the mandrel from the back of the jaws towards the front thereof, to allow the rivet to pass through from the back to the front thereof, the jaws then being resiliently urged into the closed position in which the front of the jaws provides an abutment for the rivet to be broached by the mandrel.

Such a jaw assembly is hereinafter referred to as "a jaw assembly of the type defined".

Such a jaw assembly is well known in connection with blind riveting systems marketed under the Registered Trademarks "CHO BERT" and "BRIV". Examples of such a jaw assembly, and the riveting apparatus in which it is incorporated, are described in, for example, British patent specifications 642,664 and 1,183,049.

The invention provides a jaw assembly of the type defined, which jaw assembly comprises: a pair of opposed jaws, at least one of the jaws being movabIe from the closed position to the open position by a generally pivoting movement about a position intermediate its forward end and rearward end; a housing which surround at least the rearward part of the jaws; jaw-opening means protruding through an opening in the housing and acting on the jaw rearwardly of the said intermediate position, the application of force to the jaw-opening means causing pivoting movement of the jaw as aforesaid, to open the jaws to allow reloading of a mandrel and a stack of rivets loaded thereon through the jaws from front to back thereof.

When both of the pair of opposed jaws are movable by a generally pivoting move- ment as aforesaid, preferably each jaw has an associated jaw-opening means. Preferably the two jaw-opening means are arranged to that the aforesaid forces required to open the two jaws respectively are opposed to and balance, each other.

A specific embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a longitudinal axial section through part of a riveting gun including a jaw assembly according to the present invention; Figure 2 is a longitudinal axial section, on an enlarged scale, through the jaw assembly; Figure 3 is a cross-section on the doublecranked line 111411 of Figure 2; Figure 4 is similar to Figure 2 but shows the jaws open to permit reloading of a mandrel carrying a stack of rivets; Figure 5 is a partial axial section, at right angles to Figure 4, on the line V-V of Figure 4;; Figure 6 is an exterior elevation of the jaw assembly, taken in the direction of the arrows VI in Figures 2 and 4, showing the jaws closed behind a rivet to be broached by the mandrel.

The riveting apparatus of which part is illustrated in Figure 1 is a pneumatically operated hand-held blind riveting gun of the 'kind used intheaforemenfioned "CHOBERT" (R.T.M.) and "BRIV" (R.T.M.) systems. It comprises an elongated barrel 11 on the front end of which is mounted the jaw assembly 12. Throughout the length of the barrel ex tends a steel mandrel 13 having an enlarged head 14. the mandrel carries a stack of tubu lar rivets 20 preloaded on it. The rear or tail end of the mandrel is releasably clamped in tail jaws (not shown) which are reciprocable longitudinally of the barrel with respect thereto by means of a triple piston and cylin der device (not shown). This is actuated by means of a valve operated by a trigger button and. connected to an air line.In the normal or forward position of the mandrel, as shown in Figures 1 and 6, the mandrel head 14 is sufficiently far in front of the abutment face 21 of the nose jaws 22, 23 of the jaw assembly 12 to accommodate the leading rivet 24 between the abutment 21 and mandrel head 14. When the trigger is pressed by the gun operator, the valve admits compressed air to the piston and cylinder device. This retracts the mandrel head 14 through the tubular rivet 24, thus broaching the rivet. The rivet is prevented from moving rearward by the support of the abutment face 21 against the head of the rivet. When the trigger is released, the mandrel returns forwardly to its original position, under the urging of a spring. As it does so, the next rivet 24a, is pushed through the jaws 22, 23 which open temporarily to allow its passage.The rivet is pushed forwards by the action of a so-called cursor at the rear of the stack of rivets 20, the cursor being operated either mechanically by the reciprocation of the mandrel and barrel, or pneumatically. The jaws 22, 23 close behind the rivet after the latter has passed through them, ready for the next cycle of operation of the tool to broach the next rivet.

The jaw assembly is shown in greater detail in Figures 2 to 6. It comprises a tubular housing 31 and the two jaws 22, 23, The housing consists of a main bed 32, the rear end 33 of which is screwed on to the front end of the barrel 11, and a retaining cap 34 which is screwed over the forward.

end of the body 32. Each jaw 22, 23 is generally half-tubular and is formed at its forward end with an internal lip 35, the for ward face of which provides half of the jaw abutment face 21. Intermediate its length the jaw is formed with a shaped external projection 36, the rearward part 37 of which tapers inwardly and rearwardly. At its inner end the jaw is formed with an external flange 38. The jaw 23 is a mirror image of the jaw 22, and the jaws present between them a cylindrical passage 39 of such a diameter that the enlarged heads of the rivets 20 are an easy running fit therein. At the forward end the bore 30 between the lips 35 is constricted in diameter so that the front abutment face 21 supports a rivet head as previously described. The rear faces of the lips 35 are inclined to facilitate the ad vancing head of a rivet pushing the jaws apart.

The rearward part of the jaws are located inside the housing 32. The forward end of the housing, on the front of the cap 34, has an inwardly extending flange 41 formed with an outwardly opening internal taper 42 which matched the rearward tapers 37 on the jaw projections 36. A coiled compression spring 43 is located inside the forward part of the jaw housing 32 and around the rearward part of the jaws. The spring abuts at its rear end against the rear end flanges 38 on the jaws and at its forward end against the front flange 41 on the housing. Consequently the spring 43 urges the jaws 22, 23 rearwardly into the housing.

The action of the front housing flange taper 42 on the tapered parts 37 on the jaw pro- jections urges the jaws towards each other and into contact i.e. into the closed position.

Each jaw has an inner face which contacts the other jaw. Each inner face comprises a forward part 40 which when the jaws are closed lies substantially along the mandrel axis (i.e. in a plane containing the mandrel axis) and a rearward part 44 which, when the jaws are in the closed position diverges rearward away from the mandrel axis.

The junction between the two inner face parts 40, 44 is at an apex 45.

When an advancing rivet pushed through the jaws from the back to the front of the lips 35, the housing taper 42 constrains the jaws so that they must move slightly forwardly, compressing spring 43 slightly, in order that the front ends of the jaws can move apart to allow the rivet head to pass.

Each jaw also rocks or rolls with a generally pivoting action about the apex 45, so that the rear inner face parts 44 move slightly together, (but not as much as shown in Figure 4). After the rivet head has passed through the lips 35, the spring 43 closes the jaws behind it.

Thus far the action of the jaw assembly is conventional and well known.

When all the stack of rivets 20 preloaded on the mandrel 13 have been broached, the mandrel must be removed from the gun, reloaded with another stack of rivets, and replaced in the gun. The tail jaws are readily unlocked (and re-locked) by means which are well known and form no part of the present invention. Since the mandrel head 14 protrudes beyond the front of the jaws 22, 23 (see Figures 1 and 6) it is easily grasped and the mandrel removed from the gun.

However, in order to replace the reloaded mandrel in the gun it is necessary to open the jaws 22, 23 sufficiently wide to allow the enlarged rivet heads to pass freely be tween the lips 35. This opening of the jaws has previously been achieved by the operator by grasping the jaws and pulling them forwards and apart, whilst at the same time holding the reloaded mandrel in one hand and preventing the stack of rivets from slid ing off it. This can be very difficult and requires considerable experience to carry out successfully.

In the present embodiment of the invention there is provided a jaw-opening member associated with each jaw, the jaw-opening member contacting the jaw rearwardly of the position intermediate its ends about which it executes generally pivoting movement in opening, part of the jaw opening member being accessible from the exterior of the jaw assembly.

Referring to Figures 2 to 6, each jawopening member comprises a square-section plunger 51 (for jaw 22) or 52 (for jaw 23) extending radially of the jaw housing 32 through a square aperture 53 in the main body thereof. The two plungers 51 and 52 are diametrically opposite each other, on a diameter at right-angles to the plane occupied by the inner faces 43 of the jaws.

At its outer end each plunger has a wide smooth button 54, and near its inner end and forwardly extending lug 55 which engages the rear end of its associated jaw 22 or 23 just behind the flange 38.

When the operator wishes to open the jaws 22, 23 fully, he presses the two plungers 51, 52 together, conveniently by means of his thumb and forefinger as indicated in broken lines at 56 in Figure 4. The jaws rock or roll in generally pivoting movements about the positions 45 as well as sliding slightly forwards, until the rearward parts 44 of the inner faces are in contact He opens the front lips 35 of the jaws wide apart, as illustrated in Figure 4. This makes very easy the insertion of the reloaded mandrel 13 and rivets 20 between the jaws, in the direction of arrow R in Figure 4. The rear end of spring 43 does not slip off flange 38 since this flange retains its full diameter at the peripheral zones adjacent the edges of faces 44.

The thrusts on the two plungers are opposite and equal, thus making their operation easy and not likely to unbalance the gun while the operator holds it.

The invention is not restricted to the details of the foregoing example. For instance, it has been found that pressing only one button opens the associated jaw fully and partially opens the other jaw (due to the compressing of spring 43 and frictional drag between the inner faces of the jaws). Thus it would be possible to provide a jaw opening member for only one of the two jaws, although if only one jaw is completely opened the mandrel and rivets being loaded would have to be slightly bent to pass the other jaw. Alternatively, it would be possible to provide a single plunger, or a single button, outside the gun, to open both jaws, by linking the one plunger positively to both jaws.

The invention could of course be applied to riveting apparatus with more than two jaws, e.g. three or four jaws.

WHAT WE CLAIM IS:- 1. A jaw assembly of the type defined, which jaw assembly comprises.

a pair of opiposed jaws, at least one of the jaws being movable from the closed position to the open position by a generally pivoting movement about a position intermediate its forward end and rearward end; a housing which surrounds at least the rearward part of the jaws, and jaw-opening means protruding through an opening in the housing and acting on the jaw rearwardly of the said intermediate position; the application of force to the jaw-opening means causing pivoting movement of the jaw as aforesaid, to open the jaws to allow reloading of a mandrel and a stack of rivets loaded thereon through the jaws from front to back thereof.

2. A jaw assembly as claimed in Claim 1, in which both of the pair of opposed jaws are movable by a generally pivoting movement as aforesaid, and each jaw has an associated jaw-opening means as aforesaid.

3. A jaw assembly as claimed in Claim 2, in which the two jaw-opening means are arranged so that the aforesaid forces required to open the two jaws respectively are opposed to, and balance each other.

4. A jaw assembly substantially as hereinbefore described with reference to, and illustrated in, the accompanying drawings.

5. Blind riveting apparatus incorporating a jaw assembly as claimed in any of the preceding claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. by grasping the jaws and pulling them forwards and apart, whilst at the same time holding the reloaded mandrel in one hand and preventing the stack of rivets from slid ing off it. This can be very difficult and requires considerable experience to carry out successfully. In the present embodiment of the invention there is provided a jaw-opening member associated with each jaw, the jaw-opening member contacting the jaw rearwardly of the position intermediate its ends about which it executes generally pivoting movement in opening, part of the jaw opening member being accessible from the exterior of the jaw assembly. Referring to Figures 2 to 6, each jawopening member comprises a square-section plunger 51 (for jaw 22) or 52 (for jaw 23) extending radially of the jaw housing 32 through a square aperture 53 in the main body thereof. The two plungers 51 and 52 are diametrically opposite each other, on a diameter at right-angles to the plane occupied by the inner faces 43 of the jaws. At its outer end each plunger has a wide smooth button 54, and near its inner end and forwardly extending lug 55 which engages the rear end of its associated jaw 22 or 23 just behind the flange 38. When the operator wishes to open the jaws 22, 23 fully, he presses the two plungers 51, 52 together, conveniently by means of his thumb and forefinger as indicated in broken lines at 56 in Figure 4. The jaws rock or roll in generally pivoting movements about the positions 45 as well as sliding slightly forwards, until the rearward parts 44 of the inner faces are in contact He opens the front lips 35 of the jaws wide apart, as illustrated in Figure 4. This makes very easy the insertion of the reloaded mandrel 13 and rivets 20 between the jaws, in the direction of arrow R in Figure 4. The rear end of spring 43 does not slip off flange 38 since this flange retains its full diameter at the peripheral zones adjacent the edges of faces 44. The thrusts on the two plungers are opposite and equal, thus making their operation easy and not likely to unbalance the gun while the operator holds it. The invention is not restricted to the details of the foregoing example. For instance, it has been found that pressing only one button opens the associated jaw fully and partially opens the other jaw (due to the compressing of spring 43 and frictional drag between the inner faces of the jaws). Thus it would be possible to provide a jaw opening member for only one of the two jaws, although if only one jaw is completely opened the mandrel and rivets being loaded would have to be slightly bent to pass the other jaw. Alternatively, it would be possible to provide a single plunger, or a single button, outside the gun, to open both jaws, by linking the one plunger positively to both jaws. The invention could of course be applied to riveting apparatus with more than two jaws, e.g. three or four jaws. WHAT WE CLAIM IS:-

1. A jaw assembly of the type defined, which jaw assembly comprises.

a pair of opiposed jaws, at least one of the jaws being movable from the closed position to the open position by a generally pivoting movement about a position intermediate its forward end and rearward end; a housing which surrounds at least the rearward part of the jaws, and jaw-opening means protruding through an opening in the housing and acting on the jaw rearwardly of the said intermediate position; the application of force to the jaw-opening means causing pivoting movement of the jaw as aforesaid, to open the jaws to allow reloading of a mandrel and a stack of rivets loaded thereon through the jaws from front to back thereof.

2. A jaw assembly as claimed in Claim 1, in which both of the pair of opposed jaws are movable by a generally pivoting movement as aforesaid, and each jaw has an associated jaw-opening means as aforesaid.

3. A jaw assembly as claimed in Claim 2, in which the two jaw-opening means are arranged so that the aforesaid forces required to open the two jaws respectively are opposed to, and balance each other.

4. A jaw assembly substantially as hereinbefore described with reference to, and illustrated in, the accompanying drawings.

5. Blind riveting apparatus incorporating a jaw assembly as claimed in any of the preceding claims.