EP0812243A1

EP0812243A1 - Riveting device

Info

Publication number: EP0812243A1
Application number: EP96902348A
Authority: EP
Inventors: Joseph Patrick Costello; Raymond Lister Tolver; Philip David Cole; Carl James Luttmer; Brian William Tolver-Banks
Original assignee: World Wide Product Dev Co Ltd
Current assignee: World Wide Product Dev Co Ltd
Priority date: 1995-02-15
Filing date: 1996-02-13
Publication date: 1997-12-17
Also published as: MX9706296A; CN1175916A; CA2213217A1; JPH11505474A; AU4055995A; KR19980702261A; WO1996025258A1; TW346423B

Abstract

A power operated self-drilling rivet setting device wherein an operator held housing contains a motor (27) driving a principal pinion (24); this principal pinion (24) is connected through gear wheel (25) to the cam (16) driving a rivet setting mechanism, the latter as is well known in the Art. The above mechanism is contained within an independently rotatable cylinder (44) which directly rotates the rivet setting means. With the power ON, torque is initially directed to the rivet setting mechanism through gear wheel (25) to tighten the jaws (5) onto the mandrel shank (40), until the minimum torque required to collapse a rivet (39) is more than that required to drill a workpiece, then the gear wheel (25) will stop rotating to become a moon wheel to the drive-pinion (24). Subsequently, the rotary cylinder (44) will rotate and drive the self-drilling rivet. Drilling the workpiece takes place until the rivet is seated. More pressure on the trigger-switch (32) will brake the rotary cylinder (44) transferring torque back through the gear wheel (25) to set a rivet, after which the cam (16) with continued brake pressure from the trigger-switch (32) will return the mechanism through 360° of arc to disgorge the spent mandrel and be ready to receive another.

Description

RIVETING DEVICE

Background of the Invention

Field of the Invention

This invention relates to power operated self-drilling rivet setting tools that drill and set 'pop' type and 'blind' rivets having a mandrel that pulls through a rivet body to upset said rivet body in a workpiece.

Prior Art

There have been several attempts to produce a marketable power tool that will grasp the mandrel of a self-drilling rivet in the tools jaws, drill the workpiece, set the rivet and return the jaws to their original open position to accept the next self-drilling rivet.

These tools fall generally into the classification of hand operated power tools and

examples of hand operated self-drilling rivet setting power tools are illustrated in:

PCT EP92/02861

PCT EP93/01044

PCT EP93/03222

A feature of these tools is the provision of a mechanism requiring a reversing action

of the drive to return the mechanism to its original position; this reversing action creates design problems and the necessary sophistication to overcome them.

However, the unique features of the power tool disclosed herein overcome these disadvantages with a minimum of operating parts, making it light-weight and marketable. Brief Summary of the Invention

The novel tool of this invention is a light-weight power operated self-drilling rivet setting tool that has a minimum operating parts.

It is an object of this invention to provide a self-drilling rivet setting power tool having a one-piece housing containing the drive unit, cam operated mandrel drawing mechanism, the latter enclosed within a rotatable cylinder facilitating the drilling operation of the tool. The housing is adapted to be held by the operator.

A further object of this invention is the provision of a resiliently bias'd ON/OFF trigger-switch to control all the functions of the tools drilling and rivet setting cycle, making it quick and user friendly.

It is a further object of this invention to provide a satisfactory gripping means to the mandrel shank during the drilling operation. This is achieved by the torque-converter action of the tool, which, when a mandrel is inserted in the open jaws position of the tool and the trigger-switch is depressed, initial torque is directed through a worm driven cam mechanism within the rotary cylinder, to draw and tighten the jaws upon the mandrel shank. As pressure increases on the jaws, torque is automatically transferred into rotation of the cylinder body giving liberty to the drilling operation. The mandrel shank now held tightly in the tools jaws.

It is another object of this invention to provide a means to transfer torque from the drilling mode to the drawing mode to set a rivet using the single trigger-switch. This is achieved by providing a brake-band around the rotary cylinder body and controlling it fractionally by further depressing the trigger-switch.

It is still another object of this invention to provide a means to return the mechanism to its jaws open position using the single trigger-switch. This is achieved by maintaining pressure on the trigger-switch until the worm driven cam driving the drawing mechanism to set a rivet, completes 360 degrees of arc.

Yet another object of this invention is to provide "an end of cycle" positioning means for inserting and release of a mandrel shank. This is achieved by providing a spring-loaded locking-ball interfacially situated between the tools jaws-piston and housing; the locking-ball seating in a recessed dimple in the tools jaws-piston when the tool is in the jaws open position, thus preventing over-run after releasing the trigger-switch, as torque is now translated into the rotary component.

A further object of this invention is to provide a means to prevent premature collapsing of the rivet body due to drill-bite, or too much pressure on the trigger before drilling of the workpiece is completed. This is achieved principally by providing a drive- pinion and gear wheel ratio that "ensures that the maximum drive-power needed to complete the drilling operation is less than the minimum drive-power needed to collapse the rivet"; to prevent accidental collapse of a rivet, a spring-loaded locking-ball is provided interfacially situated between the tools jaws-piston and its housing; the locking-ball seating in a recessed slot means in the tools jaws-piston and extending from an "end of cycle" position to a point at which the jaws are satisfactorily tightened upon the mandrel shank. At this point pressure on the spring-loaded locking-ball prevents unwanted torque-conversion during the drilling operation so preventing premature collapsing of the rivet body.

A further object of this invention is to provide a self-drilling mandrel that prevents splaying of a rivet body prior to insertion in a workpiece. This is achieved by providing a tapered portion to the mandrel shank before and into a concave recessed shoulder means at the junction of the mandrel shank and self-drilling head. This allows a suitable rivet body to squeeze in rather than splay out at the rivets interface with the mandrels shoulder part when initial tension is applied to the mandrel shank. The tapered portion of the mandrel shank also doubles as a "break-point" allowing the drill-point head to fall clear preventing corrosion problems associated with the "blind" type rivets after setting has taken place.

Brief Description of the Drawings

Figure 1. is a cross-sectional view of the power operated drilling and rivet setting tool and mandrel of this invention.

Figure 2. is a cross-sectional view of the tools rotary cylinder part at 90° to that shown in Figure 1.

Figure 3. is a cross-sectional view of the brake-band assembly.

Figure 4. shows a plan view of the brake-band control-bar system.

Description of the Preferred Embodiment

Attention is now directed to Figure 1 which illustrates the power operated self-drilling rivet setting tool of this invention as having a one piece housing 35 containing the drive unit 27, the cam operated mandrel drawing mechanism 4 to 16, the latter enclosed within a rotatable cylinder 44 which facilitates the drilling operation of the tool. The housing 35 is

adapted to be held by the operator. Now referring to Figures 1 , 2, 3 & 4 and to better understand the mechanisms of the preferred embodiment of the tool of this invention a step by step description of one complete cycle of the tools working parts, from insertion of a self-drilling rivet, setting of the rivet to the next insertion is detailed.

Starting in the jaws 5 open position of the tool, a mandrel shank 40 of a self-drilling rivet is inserted fully into the respective size nozzle 1, as is well known in the Art. The resiliently bias'd 31 trigger-switch 32 is pulled to activate the ON/OFF switch 28 starting the drive motor 27 driving the principal drive-pinion 24 of the tool; this drive-pinion 24 is extended into a housed bearing centrally situated at one end of a rotary cylinder 44 having also a bearing supporting the other end; this allows the drive-pinion and rotary cylinder to rotate independently of each other.

From this drive-pinion 24 a gear wheel 25, of a ratio in favour of the drilling mode until the rotary cylinder 44 is braked, when said gear wheel 25 drives the rivet setting mechanism though a worm 17 and cog wheel 21 supporting a cam 16 and connecting-rod 15 to the jaws piston 14.

A light pull on the trigger-switch 32 will engage the braking system 19, 20, 22, 23, 30 & 32; whereas, when the trigger-switch 32 is pulled the stirrup-rod 20 rides up the divergence of the brake-band by a canting means of the brake-band holding blocks 19 and an arc scribed by the end bearing 29 of the stirrup-rod 20. This action tightens the brake¬ band 22 around the slipper-ring 23 thereby braking the rotary cylinder 44 and transferring torque to the rivet setting mechanism. This method is used to create less pressure on the bearing parts.

This light braking action of the rotary cylinder may be used to release the "end of cycle" spring-loaded locking-ball 9 from its seat 11 in the jaws-piston 14 as it pulls through its housing 7; this action withdraws the jaws 5 from the spreader-ring 3 at the threaded end 2 of the nozzle 1 and conal pressure from the jaws-piston 14 on jaws 5 engages jaws-teeth 41 upon the mandrel shank 40, as is well known in the Art.

The jaws-teeth 41 are angled to facilitate grip on the mandrel shank during the drilling operation and such that the teeth cause an inward pull on the mandrel shank.

As the jaws pressure increases on the mandrel shank 40 so tightening up for the drilling operation torque will be transferred to the drilling mode as the gear wheel 25 comes to rest.

To prevent premature collapsing of the rivet 39 prior to completion of the drilling operation due to possible torque variations, a spring-loaded locking-ball 9 is inter-facially situated between the jaws-piston 14 and housing 7, with a slot means 10 from the "end of cycle" position to a point before collapsing of a rivet would occur and the natural torque- conversion point dictated by the ratio of the drive-pinion 24 and gear wheel 25; at which point considerably more pressure would have to be applied to the trigger-switch 32 or excessive drill-bite to collapse a rivet prematurely.

The workplace is now drilled and the rivet seated.

At this point more pressure is exerted upon the trigger switch to brake the rotary cylinder 44 and transfer torque through gear wheel 25 to drive the rivet setting mechanism. This gear wheel 25 turns a left-hand threaded worm 17 anti-clockwise to the drilling mode resulting in the cam 16 drawing on the worm side of its pivotal point 18 and the thrust of the worm to its inner-end bushing. The off-set pivotal point of the cam at 18 allows for a straighter pull to the jaws-piston 14 by the connecting-rod 15 during the rivet setting part of the tools cycle, creating less friction and less wear to the working parts.

With the rotary cylinder firmly braked the cam action will continue to draw the jaws- piston and subsequently jaws 5 putting the mandrel shank 40 through the rivet 39 and to upset said rivet in a workpiece; after which further drawing of the jaws-piston will eventuate in snapping off the drill-point head 36 from the mandrel shanks narrow end of the tapered portion 39 and the concave shoulder portion 37 of the drill-point rivet head 36.

Maintaining pressure on the trigger-switch 32 will return the cam 16 to its foremost position, during which time the tool may be withdrawn from the workpiece.

As the cam 16 returns the jaws-piston 14 to its foremost position the torque-converter locking-ball 9 will click into the slot means 10 indicating the tools cycle is almost at its end; this may easily be seen through the out windows at 45.

The trigger-switch 32 may.be released as the "end of cycle" locking-ball clicks into its seating dimple 11 in the jaws-piston 14 ending the cycle.

The jaws will now be in the open position against the spreader-ring 3 and pressure from the spreader-piston 8 due to the spring 12, as is well known in the Art.

Now the spent mandrel may fall free of the tool and a new self-drilling rivet inserted in the nozzle 1.

An ON/OFF adjustment screw 34 is provided.

Claims

CLAIMS :-

1. A power operated self-drilling rivet setting tool synergetically adapted to automatically drill a workplace, place the rivet and pull a mandrel and drill-point head to upset a rivet body in said workplace.

2. A tool as claimed in claim 1 including a one piece housing containing the drive unit, drilling mechanism and drawing mechanism required to set a "pop" type or "blind" rivet in a workpiece, and release the mandrel shank; the housing adapted to be held by the operator.

3. A tool as claimed in either claim 1 or 2 including a single trigger-switch to control all the functions of the tools cycle.

4. A tool as claimed in any preceding claim including an in-built "end of cycle" locating means to control over-ride.

5. A tool as claimed in any preceding claim including an in-built locking means to protect against premature collapsing of a rivet.

6. A tool as claimed in any preceding claim including a self-drilling mandrel having a shape and configuration to prevent premature playing of a rivet prior to completion of the drilling operation when initial tension is applied to the mandrel shank.

7. A tool as claimed in Claim 2 wherein the housing is joined though its centre plans to produce a shape and configuration to the tool that is user friendly.

8. A tool as claimed in Claim 3 wherein the trigger-switch controls the ON/OFF power function and a torque-converter control function of the tool.

9. A tool as claimed in Claim 8 wherein the torque-converter control means is by way of a trigger-switch operated braking means to the drilling mechanism.

10. A tool as claimed in Claim 9 wherein the braking means is by way of a band around a rotary cylinder facilitating the drilling and rivet setting object of the tool.

11. A tool as claimed in Claim 10 wherein the brake-band tension is controlled by a movable stirrup-rod connected at one end to the trigger-switch and scribing a waxing arc there from and slidably attached either side of the convergence of the brake-band into a pair of canted brake-band holding blocks; whereby increasing pressure on the trigger-switch raises said stirrup-rod horizontally to the brake-band against the divergence of said brake-band from its canted holding blocks, tightening the band "around" the rotary cylinder.

12. A tool as claimed in either Claim 10 or 11 wherein the rotary cylinder rotates about its drive shaft but independently so at the one end; the other end supported by a hearing located in the tools housing.

13. A tool as claimed in any one of Claims 10, 11 or 12 wherein the rotary cylinder provides the drilling capability of the tool.

14. A tool as claimed in any one of Claims 10 to 13 wherein the rotary cylinder houses a worm shaft and cog wheel driving a cam drawn connecting-rod to the rivet upsetting mechanism.

15. A tool as claimed in Claim 14 wherein the rivet upsetting mechanism is attached to the fore-part of the rotary cylinder and revolves as one.

16. A tool as claimed in Claim 14 wherein the worm drive-shaft has a fixed gear wheel at its drive end coupled to a drive-pinion from the motor.

17. A tool as claimed in Claim 16 wherein the drive-pinion and gear wheel ratio is such that it ensures that the maximum drive-power needed to complete the drilling operation is less than the minimum drive-power needed to collapse a rivet.

18. A tool as claimed in any one of Claims 3, 9 or 17 wherein brake-band pressure

applied to rotary cylinder directs torque to the rivet setting mechanism through the drive- pinion and gear wheel.

19. A tool as claimed in either Claim 14 or 16 wherein the worm-drive has a left-hand thread and turns in an anti-clockwise direction to the clockwise drilling mode; this draws the cam and connecting-rod on worm side of said cams pivotal point.

20. A tool as claimed in Claim 19 wherein the pivotal point of the cam is offset from the rotary cylinders pivotal point line in a direction opposite the worm-drive and dictates a straighter pull from the cam through its connecting-rod to the jaws-piston of the rivet setting mechanism creating less friction and less wear to the working parts.

21. A tool as claimed in Claim 4 wherein a spring loaded locking-ball is interfacially situated between the jaws-piston and its housing and seating in a recessed dimple in said jaws-piston and its housing and seating in a recessed dimple in said jaws-piston when the tool is in its "end of cycle" position preventing over-run when the trigger-switch is released.

22. A tool as claimed in Claim 5 wherein a spring-loaded locking-ball is interfacially situated between the jaws-piston and its housing and seating in a slot means in the jaws-piston from an "end of cycle" position to a point before collapsing of a rivet would occur - and the natural torque-conversion point dictated by the drive-pinion and gear wheel ratio, and wherein the locking-ball restricts any further movement of the jaws-piston protecting against premature collapsing of a rivet due to drill-bite or too much pressure on the trigger-switch by the operator.

23. A tool as claimed in Claim 6 wherein a self-drilling mandrel having a tapered portion before and into a concave recessed shoulder means at the junction of the mandrel shank and self-drilling head to allow a compatible rivet body to be squeezed in rather than out at its interface with the mandrels shoulder part, when initial tension is applied to the mandrel shank

in the tightening mode.

24. A tool as claimed in either Claim 6 or 23 when the tapered portion of the mandrel shank doubles as a "snap-off" point of the rivet in a workpiece preventing corrosion problems associated with "blind" type rivets.

25. A power operated self-drilling rivet setting tool substantially as herein described with reference to the accompanying drawings.