GB2172233A

GB2172233A - Hand riveter with force limitation

Info

Publication number: GB2172233A
Application number: GB8606574A
Authority: GB
Inventors: Manfred Elflein
Original assignee: Honsel Nieten & Metallwarenfab
Current assignee: Honsel Nieten & Metallwarenfab
Priority date: 1985-03-16
Filing date: 1986-03-17
Publication date: 1986-09-17
Also published as: GB8606574D0; DE3509614A1; GB2172233B; FR2578766A1

Abstract

In a hand riveter comprising two articulated levers (7) for applying an axial force for the performance of the actual riveting operation, and with a rotatable screwthreaded drift (2) for screwing and unscrewing the rivet nut, one of the levers is provided with an overload device (30) to indicate and/or limit the pressure force which can be applied during the riveting operation. Said one lever comprises two pivoted (33) parts (7a,7b), the tip (35) of a driver pin (36) in one part (76) engaging in a recess (34) in the other part (7a). A pre-stressing is applied to pin (36) by an adjustable pressure device (38,41). If a given pressure force is reached, tip (35) slides out of recess (34) and lever parts (7a,7b) disengage. Part (7b) may have a window and scale to view nut (41) position. <IMAGE>

Description

SPECIFICATION Hand riveter with force limitation This invention relates to a hand riveter comprising one or two articulated levers for applying an axial force for performing the actual riveting operation, and comprising a rotatable screwthreaded drift for screwing and unscrewing the rivet nut.

The problem arising in hand riveters of this kind is that a given pressure force is applied.

The pressure force depends on the operating conditions and, in particular, the size of the blind rivet nuts. In pneumatic-hydraulic tools the working pressure can be adjusted to the appropriate operations required. In hand riveters available on the market the operator is responsible for applying the correct working pressure during riveting. Thus the use of hand riveters entails some lack of certainty depending on the reliability of the operator.

The object of the invention, therefore, is to provide a hand riveter which ensures that a given working pressure is applied and which prevents an excessive working pressure from being applied.

To this end, in a hand riveter of the kind referred to hereinbefore, according to the invention a lever is provided with an overload device to indicate and/or limit the pressure force that can be applied during the riveting operation.

According to one advantageous embodiment, the overload device disengages a part of the articulated lever when a given pressure force is reached.

To allow adjustment to different operating conditions, according to another feature of the invention, the magnitude of the pressure force that can be applied by the articulated levers is adjustable.

In one advantageous development of a hand riveter of this kind, an articulated lever is divided into two parts articulated on one another by pivots, the front part of the articulated lever terminating in a projection disposed between a U-shaped part, which receives the same, on the rear part of the articulated lever, the projection on the front part of the articulated lever has a recess, and a driver pin engages in said recess and is disposed in the rear part of the articulated lever, to which pin there is transmitted, by means of a pressure device, a pre-stressing acting in the direction of the recess of the projection.

Advantageously, the pressure device consists of a pneumatic or hydraulic jack, or the pressure device consists of a spring assembly disposed at the rear of the driver pin.

In this case, advantageously, the spring assembly is formed by cup springs disposed in a cavity in the rear part of the articulated lever.

In that case, in an advantageous development of the invention, the cavity has an internal screwthreading and an adjusting nut is adapted to be screwed in and engages the rear end of the spring assembly.

To allow monitoring, a window is provided in the rear part of the articulated lever to give sight of the adjusting screw and a calibrated scale is provided at the window.

In one advantageous embodiment, the front end of the driver pin tapers to a point where it fits in a V-shaped groove in the projection on the front part of the articulated lever and the rear end of the driver pin terminates in a widened foot.

The invention will be explained in detail hereinafter with reference to one exemplified embodiment and the accompanying drawings wherein: Figure 1 is a partial longitudinal section of a hand riveter.

Figure 2 shows an articulated lever of the hand riveter according to Fig. 1 in an exploded view.

Fig. 1 illustrates a hand riveter having an electrical drive for the screwthreaded drift 2.

The latter can be rotated by means of a pull tube attached thereto, or by means of a gear disposed between the articulated levers 7.

In the hand riveter shown in Fig. 1, a screwthreaded drift 2 is provided at the front end in the nozzle 1 and a rivet nut (not shown) can be screwed thereon for use. At the rear end of the nozzle 1 a locknut 3 is provided for the nozzle. A transverse bearing 5 extending on either side of the tool and receiving pivots 6 by means of which two articulated levers 7 are articulated on the tool, is mounted on a bearing bush 4. Two crosslinks 8 extend from the articulated levers 7, to which they are fixed by pivots 9, to the tool housing 10, where they are articulated by means of pivots 11. At the front end of the housing 10 a knurled sleeve 12 is provided for adjusting the tool travel. By means of its screwthreaded head 13 the spindle 14 is connected via a driver 1 5 to an output shaft 16 of an electric motor 17.Spindle 14 is screwed into the rear end of the drift 2, which is disposed inside a guide sleeve 18, and is fixed by a retaining nut 29.

The drive housing part 1 7 surrounding the electric motor is connected to a drive housing part 19 which receives a battery which acts as a power supply and is electrically connected to the electric motor disposed in the part 17. The drive housing 17, 19 jointly enclosing the electric motor and the battery is constructed as a unit and is disposed at the rear end of the housing 10 remote from the tool head 1, 3. To this end, the rear end of the housing has a screwthread 20 on which a locknut 21 is screwed. The locknut has an inwardly projecting flange 22 by means of which it engages behind a shoulder 23 at the junction point between the larger-diameter drive housing part 17 enclosing the electric motor and the lower-diameter drive housing part 19 containing the battery.

As will also be seen from Fig. 1, the straight articulated lever 7 is divided by a joint into a front part 7a and a rear part 7b, which in turn has a handle 25 at its rear end. An overload device is provided at the joint 30 between the front part 7a and the rear part 7b and serves to indicate and/or limit the applied pressure produced during riveting by the compression of the two levers 7.

Referring to Fig. 2, the rear end of the front part 7a of the lever terminates in a projection 31. The front end of the rear part of the lever consists of a U-shaped receiving part 32 in which, in the assembled state, the projection 31 of the front part 7a of the lever fits and is connected by a pivot 33 in the part 32. The projection 31 of the front part 7a of the lever has a V-shaped recess 34 in the form of a groove which the tip 35 of a driver pin 36 engages in the assembled state. Pin 36 terminates at the rear end in a widened foot 37 behind which there is disposed a spring assembly consisting of cup springs 38. The cavity 39 of the rear part 37b of the lever, which contains the spring assembly 38, has an internal screwthreading 40 into which an adjusting nut 41 can be screwed.The springs 38 are thus tensioned and exert a pressure on the foot 37 of the pin 36 in the direction of the projection 31 on part 7a of the lever. Alternatively the pressure can be applied to the pin 36 by other spring means or a pneumatic or hydraulic jack. The adjusting nut 41 enables the required pressure to be produced but this pressure will no longer be adequate when a given force is applied to the levers 7 and enables the pin 36 or the tip 35 to slide out of the groove 34 so that the rear part 7b of the lever disengages from the front part 7a.

This system prevents excessive force being applied by means of the levers 7 or else indicates that a given applied pressure at the nozzle 1 is exceeded. A window may be provided at the rear part 7b of the lever in order, for example, to show the position of the adjusting nut 41 in the rear part 7 of the articulated lever by means of a calibrated scale so that the latter can be used to adjust the force up to the value at which the riveter can operate.

The invention thus provides a hand riveter which without any appreciable expenditure in terms of equipment, and without any additional means occuping additional space, allows an indication of when a predetermined force adjustment is exceeded during riveting and prevents an undesirable force from being applied at the nozzle during riveting.

Claims

1. A hand riveter comprising one or two articulated levers for applying an axial force for performing the actual riveting operation, and comprising a rotatable screwthreaded drift for screwing and unscrewing the rivet nut, characterised in that a lever (7) is provided with an overload device (30) to indicate and/or limit the pressure force that can be applied during the riveting operation.

2. A hand riveter according to claim 1, characterised in that the overload device (30) disengages a part (7b) of the articulated lever when a given pressure force is reached.

3. A hand riveter according to claim 1 or 2, characterised in that the magnitude of the pressure force that can be applied by the articulated levers (7a, 7b) is adjustable.

4. A hand riveter according to any one of claims 1 to 3, characterised in that an articulated lever (7) is divided into two parts (7a, 7b) articulated on one another by pivots (33), the front part (7a) of the articulated lever terminating in a projection (31) disposed between a U-shaped part (32), which receives the same, on the rear part (7b) of the articulated lever, the projection (31) on the front part (7a) of the articulated lever has a recess (34), and a driver pin (35, 36) engages in said recess (34) and is disposed in the rear part (7b) of the articulated lever, to which pin there is transmitted, by means of a pressure device (38, 41), a pre-stressing acting in the direction of the recess (34) of the projection (31).

5. A hand riveter according to claim 4, characterised in that the pressure device consists of a pneumatic or hydraulic jack.

6. A hand riveter according to claim 4, characterised in that the pressure device consists of a spring assembly (38) disposed at the rear of the driver pin (36, 37).

7. A hand riveter according to claim 6, characterised in that the spring assembly is formed by cup springs (38) disposed in a cavity (39) in the rear part (7b) of the articulated lever.

8. A hand riveter according to claim 7, characterised in that the cavity (39) has an internal screwthreading (40) and an adjusting nut (41) is adapted to be screwed in and engages the rear end of the spring assembly (38).

9. A hand riveter according to claim 8, characterised in that a window is provided in the rear part (7b) of the articulated lever to give sight of the adjusting screw (41) and a calibrated scale is provided at the window.

10. A hand riveter according to any one of claims 4 to 9, characterised in that the front end of the driver pin (36) tapers to a point (35) where it fits in a V-shaped groove (34) in the projection (31) on the front part (7a) of the articulated lever and the rear end of the driver pin (36) terminates in a widened foot (37).