Fastener Placement Tools

Abstract

A fastener placement tool (102) has a mandrel (122) capable of sequentially placing a series of captive rivets (124). The tool (102) employs a single electric motor (112) capable of driving the tool into a first cycle for rivet placement or a second cycle for selectively releasing the mandrel (122) from the tool (102) for rivet replenishment. The tool includes a user-operable switch (148) that actually selects whether the tool will operate in the first cycle or the second cycle.

Description

Technical Field

[0001] The present invention relates generally to fastener placing tools and particularly, but not exclusively, to such tools for placing blind side rivets. Background Art

[0002] Fastener placement tools are well known, and those tools used to place so-called blind side rivets are generally used to repeatedly place rivets of a specified length and diameter. For example, such repeated placement can occur in a manufacturing environment such as an assembly line.

[0003] In the case of repeated placement of rivets (or other types of fasteners), it may also be desirable to perform such repeated placement as quickly as possible in order to increase the efficiency of the installation and placement process. Likewise, if it is a manufacturing assembly line environment, then the speed of rivet placement is important. For this purpose, there are known rapid placement tools, such as the one provided by Avdel UK, Ltd. Tools. For example, an example of such a rapid rivet placement tool is shown in GB2,482,162-A. In this prior art disclosure, a rivet box for placement is held in the placement tool so that the rivets can be placed quickly and sequentially.

[0004] Placement tools for rapid rivet placement, such as the tools discussed above, are typically of hydro-pneumatic design. Normally, the motive force for placing the rivet is derived from a pneumatic system that operates using a compressed air source to drive a hydraulic system within the tool to advance and place the rivet.

[0005] Such hydro-pneumatic tools have certain disadvantages: their design is inherently complex because they employ a combination of hydraulic and pneumatic control systems; they tend to be cumbersome because of the need for a source of compressed air supplied to the tool via a hose, which often makes their repeated and prolonged use cumbersome for the operator who must manipulate and hold the tool while placing rivets. Summary of the invention

[0006] It is therefore an object of the present invention to at least reduce the above disadvantages by providing a fastener placing tool which uses an electromechanical system instead of a hydro-pneumatic system to control the operation of the tool. This allows the tool to be more manually dexterous than has heretofore been the case, with the attendant advantage of being usable for longer periods of time for the operator. The use of an electromechanical drive system can also reduce the amount of "down time" of the tool, which is the time when the tool, for example, requires servicing, and during which time the tool cannot be used.

[0007] Rivets placed by rapid placement tools are all pull-through types, such as those disclosed in GB 1,323,873-A. As is well known in the art, these pull-through rivets are blind-side placed fasteners for which the placement operation requires pulling the enlarged head of the mandrel through the body of the rivet (from the blind side of the workpieces to be joined, away from the tool operator, to the operator side). This operation, especially when performed as a sequential rapid placement operation, results in wear of the mandrel, the mandrel head, and the tool jaws that control the operation of the mandrel. This ultimately necessitates the replacement of worn tool components over time.

[0008] For known placement tools that employ hydraulic and pneumatic control systems, replacing worn tool components, particularly the jaws used to grip and control the mandrel, is a lengthy process that typically requires at least partial disassembly of the entire tool. Such disassembly requires particular attention because damage to the hydraulic or pneumatic system may require costly repairs. Therefore, another object of the present invention is to avoid the need for such tool disassembly by employing replaceable elements, such as a replaceable cartridge for the tail jaws that hold and control the mandrel. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which:

[0010] Figure 1 A partial cross-sectional schematic diagram showing a tool according to the present invention;

[0011] Figure 2 Schematically shows Figure 1 An exploded view of the main components of the tool;

[0012] Figure 3 shows a schematic side view of a mandrel for use with the tool of the present invention, the mandrel having mounted thereon a series of captive rivets for placement;

[0013] Figure 4 Show Figure 1 A plan side sectional view of the main components;

[0014] Figure 5 The ball nut 132 is shown. Figure 4 A side sectional view of a bobbin;

[0015] Figure 6a A side partial cross-sectional view showing the drive assembly and nosepiece;

[0016] Figure 6b Shown along Figure 6aA front cross-sectional view of the rotating seat taken along line BB;

[0017] Figure 6c Shown along Figure 6a A cross-section taken along line AA of the embodiment of the present invention, wherein the rotating seat is in a first angle orientation;

[0018] Figure 6d Shown along Figure 6a A cross-section taken along line AA of the embodiment of the present invention, wherein the rotating seat is in a second angular orientation;

[0019] Figure 7 a side cross-sectional view showing the jaws and jaw cartridge holding the mandrel;

[0020] Figure 8 A partial side cross-sectional view showing the drive side of the clutch and its connecting components;

[0021] Figure 9a showing a side view of the clutch mechanism in its engaged state;

[0022] Figure 9b showing a side view of the clutch mechanism in its disengaged state;

[0023] Fig.10a A side cross-sectional view of the head portion of the tool before the rivet placement cycle begins is shown on the left, and a corresponding side view of the distal end of the mandrel is shown on the right;

[0024] Fig.10b a partial cutaway side view showing the clutch and swivel of the tool before the rivet placement cycle begins;

[0025] Fig.10c Shown with Fig.10b perspective cutaway views of the same components;

[0026] Figure 10d to Figure 10g a partial cross-sectional view showing the major components of the tool during a rivet placement cycle of the tool; Fig.10d is the home or starting position where the loop is placed, and Fig.10e , Fig.10f and Figure 10g Each of them shows the mandrel advancing to the right in the figure;

[0027] Fig.11a A sectional view of the jaw box and jaw opener is shown on the left; and a sectional view of the rotary seat is shown on the right; both views are during the beginning of the second cycle of the tool for spindle release;

[0028] Fig.11b Shown with Fig.11a The view corresponding to the view, but the second loop is in progress;

[0029] Figure 11c to Figure 11f a partial cross-sectional view showing the main components of the tool during a second cycle for mandrel change; Fig.11c is the home or starting position of the second cycle, and Fig.11d , Fig.11e and Fig.11f Each of which shows the spindle retracted to the left in the figure;

[0030] Fig.12 A partial exploded view showing the jaw box assembly and its fitting within the tool;

[0031] Fig.13 a flow chart showing the operation of the entire functional tool, and

[0032] Fig.14 Show Fig.10b A perspective view of a wave spring. DETAILED DESCRIPTION

[0033] See first Figure 1 and Figure 2 The fastener insertion tool 102 according to the present invention includes a barrel 104 formed as an axially extending hollow metal cylinder having a distal end and a proximal end, in this example an aluminum cylinder. Figure 1 In the figure, the distal end is on the right side and the proximal end is on the left side. The tool 102 includes a handle 106 that a user can grasp, and an actuation trigger 108 is formed on the handle 106. This means that the proximal end of the barrel 104 is adjacent to the handle 106 of the tool.

[0034] A nose jaw assembly 110 is formed on the distal end of barrel 104, which will be described in detail below. The purpose of the nose jaw assembly is to form a contact point between tool 102 and a workpiece to which the fastener is to be applied and to position the fastener during the fastener placement operation, as will be described below.

[0035] The fastener with which the tool 102 operates is a so-called blind fastener, in this example a rivet 124. Blind fasteners are well known to those skilled in the art and include fasteners that are accessible only on one side of a workpiece and whose placement in the workpiece is actuated from a far side of the workpiece that is not accessible to an operator.

[0036] On the side of the handle 106 opposite the barrel 104 is an electric motor 112. The electric motor is operated by a battery 114, which is attached to the base of the handle 106 and provides motive force to the barrel 104 via a drive assembly 116 to which the motor 112 is operably coupled. Also between the handle 106 and the motor 112 is a jaw assembly, here a removable jaw box 118.

[0037] Mounted on barrel 104 and coupled to drive assembly 116 is a user operable switch 120 which operates to both i) set the axial position of the barrel for either fastener placement or jaw operation, and ii) select the operating mode of the barrel between fastener placement and jaw operation.

[0038] Now also see Figure 3 , which shows a mandrel 122 (in Figure 1 One of the rivets 124 is shown at the distal end of the barrel 104 held by the nose jaw assembly 110. Figure 3 The right side of the mandrel) terminates in an enlarged diameter head 126, as will be appreciated by those skilled in the art of fastener placement. Figure 3 1 (left side) includes an end stop 128, here a mechanical cursor. As the fastener, i.e., rivet 124, is placed, the end stop 128 moves along the mandrel 122 in an indexed step-wise manner, one step for each placement, so as to maintain the rivet at the distal end of the mandrel 122 for placement, as will be described below. The mandrel assembly (i.e., the mandrel and its captive rivet) can be loaded into the hollow barrel by the user of the tool. In order for this to occur, the jaws within the jaw box 118 (described below) need to be in their released or open position to allow the proximal end of the mandrel to be inserted into the jaws.

[0039] Now also see Figure 4 and Figure 5 It can be seen that an outer spiral groove 130 is formed on the barrel 104 along a portion of its axial range, and a rotatable ball nut 132 is mounted on the spiral groove 130. The ball nut 132, which has an internal thread form that matches the spiral groove 130 on the barrel 104, is retained in the drive assembly housing 134 so that the ball nut 132 can only rotate but cannot move in the axial direction. Therefore, the rotation of the ball nut 132 causes the axial movement of the barrel 104, because the barrel can only move along its axis ( Figure 4The rotation of the ball nut 132 is achieved by the operation of the motor 112, which is coupled to the ball nut 132 via a drive shaft 136. As is well known in the art, each end of the drive shaft 136 carries gears 138, 140, which are journaled pinions.

[0040] Between the drive shaft gear 140 and the ball nut 132 is a clutch, in this example a bi-directional clutch 142, which will be described in more detail below with particular reference to FIG. 9. The clutch 142 serves to permit rotational drive to be transmitted from the motor 112 via the drive assembly 116 to the ball nut 132 under normal circumstances until one of two conditions occurs: i) the bobbin reaches the limit of its forward or rearward travel, or ii) the torque applied to the ball nut 132 exceeds a predetermined limit. Since the bobbin can move in one of two directions (axially forward or axially rearward), the clutch is bi-directional.

[0041] At the limit of one end of the spiral groove 130, the proximal end of the barrel 104 is a jaw opener 144. The jaw opener is used to open the jaws held in the jaw box 118 only when the barrel has traveled to the limit of its rearward direction, and only in other circumstances as will be described below. A dead stop 146 is formed at the other end of the spiral groove 130. The dead stop is formed in the barrel surface at the transition portion where the spiral groove 130 meets the body of the barrel 104, and is used to prevent the forward movement of the barrel 104 (i.e., to the right in the figure) from overstroking during the placement of the rivet 124.

[0042] In reference Figure 5 It will be understood from the foregoing that this figure shows only the driven side of the clutch 142.

[0043] Now also referring to FIG. 6, a user-operable switch is formed at the front end of the drive assembly housing 134, in this example, the user-operable switch is a rotatable nose piece 148. The nose piece is axially fixed to the drive assembly housing 134, but can be rotated to select one of the two cycles of the bobbin 104. In one cycle, the forward and backward movement of the bobbin 104 realizes the placement of the rivet and resets it to place the next successive rivet. In the other cycle, the forward and backward movement of the bobbin 104 realizes the release or retention of the mandrel 122 through the claw 150 in the claw box 118. In a preferred embodiment, the rotation of the nose piece 148 to any corresponding position to select the first cycle or the second cycle can also set the predetermined axial position of the bobbin 104 relative to the drive assembly 116. This means that the starting axial position of the bobbin 104 relative to the drive assembly housing 134 can be different between the first cycle and the second cycle of the bobbin. However, in the example shown in the drawings, the barrel 104 has a single starting (or "home") position common to both the first and second cycles. Although not described in detail herein, those skilled in the art will appreciate that there are many ways in which the rotation of the rotary seat 148 can initiate a selection of the two cycles described above. For example, two micro switches provided on the inner surface of the rotary seat 148 can make or break an electrical circuit, which then initiates the program for the appropriate cycle.

[0044] The rotary seat 148 is formed with two sets of protrusions 176 and 178 on the inside. In this example, the protrusions include a pair of protrusions 176 and 178 that are diametrically opposed. Figure 6a As can be most easily seen in the figure, the pairs of protrusions are offset in the axial direction. The first set of protrusions 176 is used to actuate the first cycle of the barrel 104, and the second set of protrusions 178 is used to actuate the second cycle of the barrel 104. The two sets of protrusions 176, 178 are selected here so that the user needs to rotate the rotary seat 148 45° to switch the tool 102 between the first cycle of the barrel or the second cycle of the barrel.

[0045] Now consider Figure 7 , the manner in which the jaws 150 of the jaw box 118 retain and release the mandrel 122 will be described. The mandrel 122 needs to be removed from the barrel periodically, most commonly to restock the mandrel with new rivets 124 for placement. However, the mandrel should be safely retained in the default position so that the user does not inadvertently separate the mandrel 122 from the tool 102. To this end, the "fail-safe" position of the jaws in the jaw box is used to engage with the mandrel 122 to constrain the mandrel within the barrel 104. To achieve this, the jaws 150 are resiliently biased by the compression spring 152 into engagement with the mandrel ( Figure 7 The claw (not shown) engages. Figure 7In the embodiment shown, there are two jaws spaced circumferentially at 180° intervals) that can only travel radially inward or outward within the conical taper 154 of the retaining nut 156. The inner surface 158 of the jaws is serrated to enhance their grip on the spindle.

[0046] Although the jaws 150 themselves can only travel in the radial direction, they are held in a turret 160 that can move in the axial direction. In this way, axial movement of the turret 160 will cause the jaws to move in the radial direction (if the turret 160 is moved toward Figure 7 , the claw moves radially inward; and if the retainer (here the claw turntable 160) moves to Figure 7 The turntable 160 is biased toward Figure 7 The right side of the tapered portion 154 (i.e., toward and engaging the inner wall of the tapered portion 154) causes the claws 150 to tend to be pushed radially inwardly, thereby tending to grasp the spindle 122 inserted therebetween.

[0047] The jaw box 118 includes a spindle end stop 128. Another purpose of the end stop 128 is to ensure that the spindle is positioned in a repeatable known position when the user inserts the spindle 122 into the barrel 104 of the tool before the tool is started. Both the end stop 128 and the spring 152 are held in place (and the spring is applied with a known tension) by an adjustable nut 162. The nut 162, together with the cooperable frontmost portion 164 of the housing, forms the outer shell of the jaw box 118.

[0048] Now also see Figure 8 9, the structure of the clutch 142 mechanism will be described in more detail. When the motor 112 is actuated, the drive shaft 136 rotates, causing the gear 140 to rotate therewith. Since the gear 140 cooperates with the spur gear 166 formed on the outer surface of the clutch housing 168, the clutch 142 also rotates. The rotation of the clutch 142 will cause the ball nut 132 to rotate therewith unless one of two torque conditions occurs.

[0049] The clutch 142 is a two-way clutch, which is formed by two groups of teeth, namely a first group of clutch teeth 170 and a second group of clutch teeth 172, which have a tapered tooth profile. Figure 9a and Figure 9b The two sets of teeth, a first set of clutch teeth 170 on the drive side set of teeth and a second set of clutch teeth 172 on the driven side set of teeth, are biased into cooperative engagement by means of a spring, in this example a compression spring 174 (in Fig.14174), in this example, the compression spring is a wave spring. The tension in the spring 174 is selected in a known manner to ensure that the tooth sets, i.e., the first set of clutch teeth 170, the second set of clutch teeth 172, are engaged only until a predetermined torque exists between them. At this predetermined torque, the first set of clutch teeth 170 (from Figure 9a and Figure 9b As can be seen in FIG. 1 , the first set of clutch teeth 170, which has an axial extension less than that of the second set of clutch teeth 172, is pushed along the ramp formed between the engagement surfaces of the two tooth sets. This ramping movement causes the first set of clutch teeth 170 to move axially (towards) against the tension of the spring 174. Figure 8 9), thereby disengaging the drive to the ball nut 132. Figure 9a and Figure 9b It can be seen that the first set of clutch teeth 170 has a slightly rounded end surface, thereby providing a shallower bevel than the bevel of the second set of clutch teeth 172, thereby ensuring smooth ramping of the first set of clutch teeth 170 on the second set of clutch teeth 172 when the clutch is released. Those skilled in the art will understand that this is not a necessary feature of the clutch 142, but a preferred feature. Moreover, different bevel angles can be shared between the tooth sets, i.e., the first set of clutch teeth 170 and the second set of clutch teeth 172, or even mixed within each tooth set. The purpose of smooth ramping can be achieved by any variation of this principle.

[0050] Release of clutch drive is required in either of two situations (described below): i) when the barrel 104 reaches the limit of its forward or rearward travel. This occurs when the rivet 124 has been placed, or when the barrel is fully retracted to open the jaws 150 (when the dead stop 146 reaches the limit of its rearward travel within the jaw box 118); or ii) when an over-torque condition occurs, such as poor placement of a rivet or an internal drive jam within the tool. In either case, it is important to disconnect the drive from the motor 112 to the ball nut 132 so that damage to the tool mechanism does not occur. Since the barrel operates in both the axial forward and rearward directions, it is necessary for the clutch 142 to be bidirectional.

[0051] Now let's look at the operation of the tool 102 and how those features briefly described above operate together during such operation, also referring to Figures 10(a) to 10(c). As already mentioned above, the barrel 104 can be operated in either of two cycles. The first cycle is used to place the rivet 124 in the workpiece, and the second cycle is used to clamp the jaws 150 onto or release them from the mandrel 122, respectively.

[0052] Considering the first cycle, the bobbin 104 may preferably, but not necessarily, start from the home position. This is the stationary position to which the bobbin 104 will return when not in operation, and is the starting position for any operation. The home position is preferred because, in this example, the axial forward and backward movement of the bobbin 104 is controlled by counting the number of revolutions of the ball nut 132, which in turn determines the linear advancement or retraction of the bobbin 104 (depending on the direction of rotation of the ball nut 132). In this example, the axial range of the bobbin forward movement is different from that of the bobbin backward movement.

[0053] Once the operator sets the angular position of the rotary seat 148 to its appropriate position to select the first cycle (bobbin operation), the operation of the control motor (see also Fig.13 104. The software (the detailed operation of which is not described herein as it is not germane to the present invention) in the software control flow chart in the figure) then sets the motor 112 to rotate in the correct direction to cause rotation of the ball nut 132 so that the bobbin moves in the forward direction (to the right in all figures). Disposed inside the rotary seat 148 is a bobbin stop member 180 which serves as a bobbin advancement stop member and is designed to ensure that the bobbin 104 cannot be advanced too far when the rivet 124 is placed. The bobbin stop member 180 does not rotate with the ball nut 132, but (similar to the bobbin 104) is held against rotation and is only permitted to advance or retract in a linear axial direction. During the forward movement of the barrel 104, if the barrel stop member 180 contacts the inner sleeve 186 of the rotary seat, then further advancement of the barrel 104 will be prevented because the first set of clutch teeth 170 will move along the ramp on the second set of clutch teeth 172, thereby releasing the drive from the ball nut 132 to the barrel 104. However, it should be understood that this situation should not occur under normal circumstances because before this, the rotation counting program has counted the necessary number of revolutions of the ball nut 132 that have occurred and the reversal of the rotation direction of the motor 112 has been achieved. At the limit of the forward movement of the barrel 104, the rivet 124 will have been placed. This rivet placement itself is not described in this article because it is well known to those skilled in the art of blind rivet placement. Those skilled in the art will understand that when placing each fastener according to the present invention, the mandrel rod will not be broken because rapid riveting like this requires the mandrel to remain intact when all fasteners are placed.

[0054] Two bayonet tabs 182, 184 are formed at the front end of the barrel advancement stop member, diametrically opposed to each other. Depending on the rotational orientation of the seat (i.e., the cycle to which it is set) and the degree of axial advancement of the barrel 104, the bayonet tabs 182, 184 selectively engage with the seat tabs 176, 178 (FIG. 6(b)). In the home position (i.e., before the barrel movement in the first cycle begins), the bayonet tabs 182, 184 are located to the left of the seat 148, as best seen in FIG. 10(a), FIG. 10(b) and FIG. 10(d). As also shown in FIG. 10(d), the rivet 124 retained on the mandrel 122 has not yet been advanced, so the farthest rivet is retained in the nose jaw assembly 110. Those skilled in the art will understand the operation of the nose jaw assembly and how the nose jaw assembly functions to place the rivet 124. Since rivet placement itself is not germane to the present invention, it will not be described in any detail herein. However, the present invention is understood to require a working knowledge of the general operation of multiple blind side rivet placements from a mandrel where the rod remains unbroken after rivet placement.

[0055] It can be understood that the rotary seat 148 is mechanically connected to the inner sleeve 186. Therefore, when the rotary seat 148 rotates counterclockwise (such as Figure 6c 11 ), which selects the first cycle. The pair of projections 176 and 178 rotate with the rotary seat 148 to form a passage for the bayonet projections 182 and 184 to move axially forward (to the right in FIG. 11 ). The projection 178 prevents the bayonet projections 182 and 184 from overactuating in the axial rearward direction, thereby creating a mechanical limit. This locks the rotation of the ball nut 132, and then an overload is detected, disengaging the clutch 142. The pair of projections 176 acts as a guide to prevent the tool user from rotating the rotary seat 148 during operation of this first cycle.

[0056] Moreover, it should be understood that when the rotating seat is rotated clockwise, Figure 6d As shown, this actuates the second cycle (clamping or releasing of the jaws 150). The protrusion pair 176 and 178 rotates with the rotary seat 148 to form a channel for the bayonet protrusions 182 and 184 to move axially rearward (or to the left in Figure 11). The protrusion pair 176 prevents the bayonet protrusions 182 and 184 from over-actuating in the axial forward direction, thereby creating a mechanical limit. This locks the rotation of the ball nut 132, and any overload detected will disengage the clutch 142. The protrusion pair 176 acts as a guide to prevent the tool user from rotating the rotary seat 148 during operation of this second cycle.

[0057] Now also refer to Figure 10d to Figure 10g, which shows a rivet placement cycle. As the motor 112 rotates and the ball nut 132 rotates therewith, the bobbin 104 then advances axially to the right of the figure. Moreover, since the bobbin stop member 180 is held against axial movement on the spiral groove 130 of the bobbin 104 but is free to rotate thereabout, the bobbin stop member 180 also advances as the bobbin 104 advances. FIG. 10( e) shows the bobbin having advanced 10 mm to the right compared to FIG. 10( c). It can be seen from FIG. 10( c) that the head 126 of the mandrel 122 has begun to be pulled through the rivet 124 due to the advancing bobbin 104. This is part of the normal rivet placement process.

[0058] Figure 10(f) shows the barrel 104 having been moved 20 mm to the right from its home position. It can be seen that the barrel stop member 180 is further to the right within the rotary seat 148 and the mandrel head 126 has now moved completely through the distal rivet 124. Thus, the rivet has been placed in the workpiece at this stage.

[0059] In normal operation, the count of revolutions of the ball nut 132 indicates that the rivet 124 has been placed and the rotation of the motor 112 should be reversed to return the barrel 104 to its home position. However, if this does not occur for some reason, such as failure to properly place the distal rivet 124, or inaccurate counting of the revolutions of the ball nut 132, the situation shown in FIG. 10(g) may occur. In this figure, it can be seen that maximum forward movement has been reached (here, 25 mm to the right of the barrel home position of FIG. 10(d)). Not only have the bayonet projections 182, 184 contacted their respective seat projections 176 or 178 (thereby preventing further advancement of the barrel 104), but the clutch 142 has been disengaged by the first set of clutch teeth 170 moving along the ramp over the second set of clutch teeth 172, thereby preventing any further drive torque applied to the ball nut 132 by the motor 112.

[0060] according to Fig.13 10( g) occurs (i.e., full forward movement of the bobbin 104 or disengagement of the clutch 142 occurs), the motor reverses its rotation to immediately return the bobbin 104 to its home position of FIG. 10( d).

[0061] Once the barrel 104 returns to the home position of FIG. 10( d ) (and assuming that the previous rivet 124 has been placed and has not blocked the nose jaw assembly 110, e.g., due to misplacement), the next rivet in the series of rivets 124 held on the mandrel 122 can be placed. To begin placing the next sequential rivet, the operator of the tool 102 (with the rotary seat 148 remaining set to the first cycle position) simply depresses the trigger 108, and the first cycle begins again, as described above.

[0062] At some stage, the tool 102 operator will wish to stop placing rivets using the first cycle. This will occur when a series of rivets 124 held on the mandrel 122 have all been placed, or if the size of the rivet to be placed needs to be changed (e.g., to a larger or smaller rivet). This will require the mandrel 122 to be released by the jaws 150 so that a new (or newly rivet-loaded) mandrel can be placed in the tool 102. In order to release and replace the mandrel 122, the rotary seat 148 needs to be rotated to its second position, where the tool operates in a second cycle.

[0063] Once the rotary seat is rotated to the correct orientation for operating the second cycle, the operator actuates the trigger 108, which causes the motor 112 to rotate, thereby causing the ball nut 132 to rotate therewith to move the barrel 104 in its rearward direction (to the left side of all drawings). FIG. 11 (a) shows the home position of the second cycle. In this example, this is the same home position as the first cycle, but this is not necessarily the case. It should be understood that the home position of the first and second cycles may be different, depending on the internal dimensions of the tool and / or the length of the mandrel.

[0064] 11(a), the bayonet projections 182, 184 in the rotary seat 148 are located axially midway between the rotary seat inner sleeve 186 and the stop ring 1881. The stop ring 1881 prevents any further retraction of the tube stop member 180 as an end stop member during its rearward cycle.

[0065] It can be seen in FIG. 11( a) that the jaw opener 144 formed at the proximal end of the spindle 122 is located to the right and outside the confines of the jaw box 118. This axial position of the jaw opener 144 means that the combined force acting on the jaw 150 is the compression force to which the spring 152 is subjected. This combined force causes the jaw 150 to be pushed to the right side of the figure, and thus to be pushed radially inward by the conical tapered portion 154 of the retaining nut 156, thereby clamping the jaw 150 on the proximal end of the spindle 122.

[0066] Referring also to FIG. 11( c ), the home position of the second cycle can be seen in more detail, with the nose jaw assembly 110 also shown. Those skilled in the art will appreciate that during the second cycle, a notable feature of the nose jaw assembly 110 is that it releases the distal end of the mandrel 122 so that the operator can remove the mandrel from the tool by pulling it to the right of the figure. This can also be achieved if the mandrel is supplied as a single unit including the nose jaw assembly 110. An enlarged view of each of the corresponding portions of FIG. 11( c ) shown in FIG. 11( d ) shows the main functional areas of the tool 102 in the home position and at the beginning of the second cycle.

[0067] Figures 11(d) and 11(e) show that the second cycle has caused the barrel 104 to move axially 6 mm in its rearward direction (to the left in the figure) compared to the home position. It can be seen here that when the rotation of the motor 112 has caused the ball nut 132 to rotate therewith, the barrel 104 has moved axially 6 mm rearward, and therefore the jaw opener 144 has moved within the confines of the jaw box 118 and contacted the frontmost side (i.e., the right side) of the movable jaw turret 160.

[0068] As shown in Fig. 11(f), with the barrel 104 moved 10 mm to the left from its home position, continued rearward movement of the barrel 104 causes the compressive force of the spring 152 to be overcome by the torque of the motor 112 applied to the spring 152 via the rotation of the ball nut 132. In this position of the barrel 104 in Fig. 11(f), it can be seen that the jaw opener 144 has moved the jaw turret 160 far enough to the left that the jaws 150 have moved radially outward along the tapered portion 154 to the extent that they are now disengaged from the spindle 122. The operator of the tool 102 can now remove the spindle 122.

[0069] Once the operator has inserted a new mandrel into the tool 102, they can then actuate the trigger 108 again to complete the second cycle. Fig.13 As can be seen from the flow chart of FIG. 1 , this reverses the direction of rotation of the motor 112, and therefore also the direction of rotation of the ball nut 132, in order to move the bobbin 104 axially forward to its home position. As with the first cycle, the second cycle is controlled by counting the number of revolutions of the ball nut 132, whether to release or reset the pawl 150. As with the first cycle, in the event that a control error causes excessive movement (forward or backward) of the bobbin 104, the clutch 142 will be disengaged before an over-torque condition can occur.

[0070] As mentioned above, in this example of the invention, the jaws 150 are part of a replaceable cartridge, namely the jaw cartridge 118. Fig.12102. Such a cartridge is shown in more detail in FIG. 103. Here it can be seen that the output of the motor 112 is a gear 188 which operably engages with the gear 138 when the jaw cartridge 118 is placed in the tool 102 to transmit rotational drive to the drive shaft 136. The advantage of a replaceable cartridge instead of discrete jaws built into the tool 102 is that maintenance becomes a simple operation. For example, if the jaws become worn, all the operator needs to do is operate the latch 190 to release the cartridge from the tool 102, lift the cartridge out of the tool with the aid of the handle 192, and replace the jaw cartridge 118 with a new cartridge.

[0071] Now please see Fig.13 , it can be seen that, as discussed above with reference to the rotation of the rotary seat 148, the user of the tool 102 is able to set the cycle to a first cycle ("set the tool to the PLACING stroke") or a second cycle ("set the tool to the TAIL JAW stroke") depending on the angular orientation of the rotary seat. For example, as described above, the cycle setting is determined by which micro-switch completes the circuit. However, those skilled in the art will appreciate that any suitable manner of achieving the desired tool cycle setting is effective.

[0072] As can be appreciated from the foregoing, during the first cycle (placing successive rivets 124 from the mandrel 122), movement of the jaws 150 is not possible. In other words, the jaws 150 must remain in their clamped (radially inward) position throughout the first cycle. Likewise, during the second cycle (jaw release and re-placement), the rivet mandrel 122 must not be operated in the rivet placement cycle. This means that the first and second cycles are mutually exclusive, and operation of one cycle precludes operation of the other until one cycle is fully completed.

[0073] Those skilled in the art will appreciate from the above that the drive assembly includes all features for obtaining the rotational output of the motor 112 and converting it into the linear axial movement of the bobbin 104. Therefore, although in the above example, the drive assembly includes gears 138, 140 and the drive shaft 136 and ball nut 132 engaged therewith, other components may also be involved in the transmission of the drive. In fact, those skilled in the art will appreciate that alternative means for obtaining the rotational output of the motor and converting it into linear bobbin movement are possible. For example, rack and pinion or timing belt arrangement will also work well.

[0074] In the foregoing, especially with reference to Fig.10b, the biasing of the clutch 142 by a wave spring is an important feature. Those skilled in the art will appreciate that this forward bias (i.e., biasing the clutch 142 to its engaged position under normal circumstances) will be achieved by a conventional helical compression spring. However (also now referring to Fig.14 ), the wave spring 174 is selected to provide significant advantages over conventional coil springs. Specifically, the weight and space savings associated with wave springs and the loss of tension / compression forces are advantages of the present invention. Wave springs also tend to provide a more consistent spring return rate than coil springs. By using multiple separation points and contact points (respectively Fig.14 194 and 196) in order to achieve weight savings, these separation points and contact points provide a greater compression area density than a helical spring providing the same mechanical tension. This also allows space savings, since the tension per linear meter is therefore greater.

[0075] In the above, reference is made to counting the number of revolutions of the ball nut 1332 during tool operation. Those skilled in the art will appreciate that any suitable method for such counting may be employed. For example, a mechanical counter or software embedded in an IC may be equally well employed.

[0076] Features List

[0077] 102 Tools

[0078] 104 Bobbin

[0079] 106 handle

[0080] 108 Trigger

[0081] 110 nose claw assembly

[0082] 112 Electric motor

[0083] 114 Batteries

[0084] 116 drive components

[0085] 118 claw box

[0086] 120 switch

[0087] 122 spindle

[0088] 124 rivets

[0089] 126 spindle head

[0090] 128 spindle end stop

[0091] 130 bobbin outer spiral groove

[0092] 132 ball nut 132

[0093] 134 drive assembly housing

[0094] 136 drive shaft

[0095] 138 Gears

[0096] 140 Gears

[0097] 142 Clutch

[0098] 144 jaw opener

[0099] 146 Dead stop

[0100] 148 Rotary Seat

[0101] 150 boxes of claws

[0102] 152 Compression spring

[0103] 154 tapered tapered portion

[0104] 156 retaining nut

[0105] 158 claw serration part

[0106] 160 claw movable holder

[0107] 162 Adjustable Nut

[0108] 164 Front of the jaw box housing

[0109] 166 Clutch Spur Gear

[0110] 168 Clutch housing

[0111] 170 First set of clutch teeth

[0112] 172 Second set of clutch teeth

[0113] 174 wave spring

[0114] 176 first rotating seat protrusion

[0115] 178 second rotating seat protrusion

[0116] 180 bobbin stopper

[0117] 182 first bobbin stop member bayonet protrusion

[0118] 184 Second bobbin stop member bayonet protrusion

[0119] 186 swivel seat 148 inner sleeve

[0120] 188 Motor output gear

[0121] 190 Box Latch

[0122] 192 Box Handle

Claims

1. A fastener placement tool (102) for sequentially placing a series of fasteners into a workpiece to which the tool is applied, the fasteners being held fixed on an axially extending mandrel (122), the tool comprising: a movable barrel (104) into which the mandrel is insertable and wherein axial movement of the barrel relative to the fastener effects placement of the fastener; a jaw box (118) having a plurality of jaws (150), each of the plurality of jaws being selectively movable under the influence of movement of the bobbin to restrain axial movement of the spindle or to release the spindle from the jaws; an electric motor (112) for providing motive force to selectively move the barrel for i) fastener placement, or ii) jaw movement; a drive assembly (116) that converts rotation of the electric motor into movement of the barrel to selectively: place a fastener or move the jaws; a switch (148) operable by a user of the tool to control selection of the electric motor to move the barrel for i) fastener placement, or ii) jaw movement; A clutch (142) selectively engages or disengages drive from the electric motor to the drive assembly.

2. The fastener placement tool of claim 1, wherein: The movement of the barrel is a first cycle in which the fastener is placed, or a second cycle in which the jaws are moved to constrain or release the mandrel, and both the first cycle and the second cycle include axial forward and backward movement of the barrel.

3. The fastener placement tool of claim 2, wherein: Operation of the switch determines whether the bobbin (104) undergoes the first cycle or the second cycle.

4. The fastener placement tool of claim 2, wherein: In either the first cycle or the second cycle, the clutch (142) is capable of releasing drive from the drive assembly (116) to the bobbin when the bobbin reaches a predetermined limit of movement.

5. The fastener placement tool of claim 3, wherein: In either the first cycle or the second cycle, the clutch (142) is capable of releasing drive from the drive assembly (116) to the bobbin when the bobbin reaches a predetermined limit of movement.

6. The fastener placement tool of claim 1, wherein: The clutch (142) is a bidirectional clutch.

7. The fastener placement tool of claim 1 further comprising a jaw assembly, wherein: The jaw assembly includes the jaw box (118).

8. A fastener placement tool according to any one of the preceding claims, wherein: The drive assembly includes a ball nut (132) disposed between the electric motor (112) and the bobbin, the ball nut (132) converting the rotational output of the electric motor into axial movement of the bobbin.

9. The fastener placement tool of claim 8, wherein: The clutch is between the electric motor and the ball nut (132).

10. The fastener placement tool according to any one of claims 1 to 7, wherein: The barrel (104) includes a proximal end and a distal end, and a jaw opener (144) is formed at the proximal end of the barrel.

11. The fastener placement tool according to any one of claims 1 to 7, wherein: The barrel includes a proximal end and a distal end, with a nose jaw assembly (110) formed at the distal end of the barrel for transferring the fastener from the mandrel to a workpiece.

12. The fastener placement tool of any one of claims 1-7, wherein: The selective movement of the jaws (150) includes radial movement relative to the axial extent of the spindle.

13. The fastener placement tool of any one of claims 1-7, wherein: The selective movement of the jaws is axial movement relative to the spindle.

14. The fastener placement tool of claim 6, wherein: The clutch is biased by a wave spring (174) toward an engaged position of the clutch.

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