EP0922536B1 - Device for placing rivet nuts - Google Patents

Description

The invention relates to a device for setting blind rivet nuts, where the mandrel as far as it will go into the mouthpiece Nut thread is screwed in and then moved axially, so that the thin-walled material of the cut part after evades on the outside and forms a bulge.

With corresponding devices, however, the tractive force applied is not constant throughout the riveting process, rather is for example with two hand levers to be moved towards each other the force applied is greatest towards the end of the movement. However, the greatest force is required at the time when that The material of the cut part begins to open outwards move while with progressive movement an ever less Force is required until the riveting process is terminated must be when the bead is against the wall of the Drill hole to avoid damaging the thread.

The wall thickness in the cut-out part of the blind rivet nut becomes preferably chosen so that the clamping force of the formed Bead is as large as possible to later secure against rotation Act.

Accordingly, the tensile force required for riveting is usually just below the thread load capacity, which makes the concrete Riveting the blind rivet nut with those previously available on the market Riveting tools is complicated.

These are the blind rivet nut each over the thread diameter riveted and limited tractive force so that A sufficient bead forms, but the thread at the end the riveting process is not damaged. This is logical in itself Type of processing or riveting blind rivet nuts fails but because of the small difference between that required for riveting Tensile force and the maximum thread load capacity.

As a consequence, tools with a so-called Stroke. There are also mechanical tools for Smaller thread dimensions known to the operator must rely on his feeling.

When riveting with stroke limitation is the riveting The required path is calculated and the stroke of the tool is limited to this. This procedure is quite complicated as it is only approximate there and blind rivet nuts from different manufacturers can be manufactured with different tolerances.

This method of operation also requires that the blind rivet nut, even though it has a wide tolerance range, with one tool can be riveted in only one and the same material thickness can. Other problems arise from being accurate by the operator care must be taken that the blind rivet nut is always complete screw on the mandrel of the tool as far as it will go, so that the set stroke is not partially empty running.

In practice, this is often due to the rigid stroke limitation insufficient riveting or damage to the thread because, the devices are set more precisely by the specialist, and the Processing is carefully monitored.

Overall, the processing of blind rivet nuts is in contrast technically quite demanding for processing blind rivets, so that the use in small series hardly is worthwhile and to this day there is no noteworthy do-it-yourself market has formed.

A device for setting blind rivet nuts, for example, is off FR 2 354 853 A is known. This works purely mechanically. The of Beginning of the axial movement of the blind rivet nut decreasing tensile force can be applied due to the fact that two Lever arms for operating the device are bent away from each other and with this one depending on the infeed movement of the Lever arm movable actuator cooperates, which Control element receives the mandrel.

Similar devices for setting blind rivet nuts, which are therefore exclusive act mechanically, are from FR 2 343 564 A and EP 0 159 255 A is known.

GB 2 130 514 A describes a device for setting blind rivets, which are provided with rivets tearing off during the riveting process, known. This device brings traction to the formation of a Bead through a thin-walled, cut part on the Blind rivet on, such that one from the beginning of an axial movement decreasing tensile force of the blind rivet is applied. A Press clamp is pressed against a mouthpiece on the blind rivet until it stops attached and then axially shifted so that the thin-walled material of the cut-out part migrates to the outside and forms a bead. In this device is the pneumatic cylinder in a manner known per se as a double-acting cylinder designed and runs against the return stroke after the riveting process a compression spring, which is part of that for the next operation required force is stored. This device is not suitable for setting blind rivet nuts.

The invention has for its object a device for setting of blind nuts, in which the setting of Blind rivet nuts are simple, safe and economical.

The task is solved by a device for setting blind rivet nuts according to the features of claim 1. Further training of the device are described in the subclaims.

The device according to the invention makes it possible to apply a tensile force, that corresponds to the required power. The traction is possibly at the beginning above the thread force, what but causes no problems because of the blind rivet nut shaft initially yields, while at the end of the movement the force decreases is that damage to the thread is no longer possible is. Tools designed in this way can do a great deal Tolerance can be set. Your regulation, for example about a pressure reducer, is very easy, because the specialist Tensile force of a thread is known. In particular, by the invention avoided tools previously available on the market, where the tensile forces do not meet the requirements, by starting from an unfavorable moment at a time where high force is required, comparatively little force is applied while at the end of the movement there is a very cheap power transmission, what exactly should not be the case as this will damage the thread can occur.

The inventive design of the device as a hydropneumatic Tools can make this structurally particularly simple and enables safe and economical setting the blind rivet nuts. The pneumatic cylinder is in the device designed in a manner known per se as a double-acting cylinder. This runs against one on the return stroke after the riveting process Spring, which is a part of that required for the next operation Force is stored.

The invention is described below using an exemplary embodiment described. Only FIG. 5 shows an embodiment according to the Invention. The representation of Figures 1 to 4 relates to Designs that are not covered by the invention.

Figur 1

ein Gerät mit zwei aufeinander zu bewegbaren Hebelarmen, die in einem Querlager angelenkt sind;

Figur 2

eine abgewandelte Ausführungsform, bei der die Hebelarme an dem Gehäuse angelenkt sind;

Figur 3

eine abgewandelte Ausführungsform mit einer Feder zur Druckminderung;

Figur 4

ein hydro-pneumatisches Werkzeug mit einer Druckminderfeder und

Figur 5

eine abgewandelte Ausführungsform - gemäß der Erfindung - mit einem doppelt wirkenden Zylinder mit einer Druckfeder zur Kraftspeicherung.

It shows:

Figure 1

a device with two mutually movable lever arms, which are articulated in a transverse bearing;

Figure 2

a modified embodiment in which the lever arms are hinged to the housing;

Figure 3

a modified embodiment with a spring for pressure reduction;

Figure 4

a hydro-pneumatic tool with a pressure reducing spring and

Figure 5

a modified embodiment - according to the invention - with a double-acting cylinder with a compression spring for energy storage.

Fig. 1 shows a mechanical device consisting of a transverse bearing 1 in which a guide tube 2 is fixed is screwed, which is used to support the housing 3, so that it is axially displaceable against the transverse bearing 1.

With the cross bearing 1 axially fixed, but with free radial play is a mandrel 4, which by the Guide tube 2 protrudes from the housing 3 and there is connected to the mandrel 10. In the housing 3 the mouthpiece 11 is screwed in and over a Knurled nut 12 countered. The cross bearing 1 is with the Housing 3 connected by the lever arms 8 in the transverse bearing 1 be stored with a cross pin 7 and the tabs 6 in Housing 3 with a cross pin 5 and in the lever arm 8 with a cross pin 9 are stored.

When operating the lever arm from position 1 to Position 2 shifts the housing 3 with the mouthpiece 11 against the mandrel 10 with a decreasing Power transmission.

Fig. 2 shows a modified design, the is that the cross bearing 1 with the housing 3rd is connected by the lever arms 8 in the housing 3 with a Cross pin 2, 7, 27 are stored and the tabs 6 in Cross bearing 1 with a cross pin 2, 5, 25 and in the lever arm 8 be stored with a cross pin 2, 9, 29. When pressed lever arm from position 1 to position 2 the housing 3 with the mouthpiece 11 against the Threaded mandrel 10 with a likewise decreasing Power transmission.

Fig. 3 shows a modification in which a mechanical device consists of a transverse bearing 31 in which a guide tube 32 is screwed, which for Storage of the housing 33 is used so that this against the Cross bearing 31 is axially displaceable. During the riveting process cross bearing 31 and housing 33 move away from one another, what with one in between and both connected spring 34 to a constant increase in Resistance leads.

Another design, particularly suitable for hydro-pneumatically driven tools, is in Fig. 4 shown and is the stroke against a increasing force to drive. Any type of spring is suitable or suspension or a design based on the system of the shock absorber. Contrary to the well-known hydro-pneumatic Tools that work with a linear force by a pneumatic cylinder 41, which has a hydraulic piston 42 a corresponding translation executes and hereby drives a hydraulic cylinder 43, the threaded mandrel 44 axially against the mouthpiece 45 moves, the tensile force of the tool during the Stroke reduced by the pneumatic piston 47 against a corresponding spring 46 moves.

The devices shown in Figs. 3 and 4 destroy a force. It is cheaper to have one before Riveting generated spring force to use the force of the tool during the riveting process and during relaxation reduced. Such a solution according to the invention is shown in FIG.

The tractive force of the device can change during the stroke can be reduced by the pneumatic cylinder 41 as double acting cylinder is designed and initially on the return stroke after a riveting process against a compression spring 57 runs and part of the necessary for the next step Force thus saves. This not only does the desired thing degressive traction, but also allows an essential one Improve the performance of the cylinder, thus either has more power or can be designed accordingly smaller can.

The tensile force can also be applied to mechanical tools can be reduced during the stroke by the spring 4 is designed as a compression spring and when opening the tool part of the necessary for the next step Strength stores. This not only does the desired thing degressive traction, but also allows an essential one Improve the performance of the tool, which is more Power generated or designed accordingly smaller can.

To the spring body in all constructions if possible to keep small and at the same time increase traction reduce, the spring can be designed so that when Supportive at the beginning of the riveting process and in the final phase acts as an inhibitor. This is accomplished by one and the same Spring used both as a compression spring and as a tension spring becomes. When the tool returns, it passes over hers relaxed state into a state storing the strength and thus acts as a compression spring. Supported during the riveting process the spring pulls the tension of the Degressive tool, as already described, then as Tension spring to reduce this force even more.

Instead of the springs shown, others can flexible materials are used for spring action.

Instead of a spring force can reduce the Traction also the driving force of the tool, e.g. B. Compressed air during the riveting process.

Oil brakes, shock absorbers, frictional resistances of all kinds all are nevertheless suitable for achieving the same technical effect.

Claims (4)

1. Device for placing blind rivet nuts, which applies a tensional force to the blind rivet nut for formation of a swelling through a thin-walled cut-free portion, such that a tensional force decreasing from the start of an axial movement of the blind rivet nut is applied, whereby a threaded spindle (44) is screwed into the internal thread until it stops against a mouthpiece (45) and is subsequently moved axially, so that the thin-walled material of the cut-free portion moves outwards and forms the swelling, whereby with the device a pneumatic cylinder (41) is designed in known manner as a double-acting cylinder and on the back-stroke following the riveting procedure, moves against a spring force and thereby stores part of the force required for the next working operation, whereby with the hydro-pneumatic device the pneumatic cylinder (41) performs a gearing process via a hydraulic piston (42) and thereby drives a hydraulic cylinder (43) which moves the threaded spindle axially.
2. Device according to Claim 1, whereby with the hydro-pneumatic device, the force allocated to the selected thread may be regulated with a pressure reducer.
3. Device according to Claim 1 or 2, whereby the spring (57) is designed as a compression spring and on opening of the tool, stores part of the force required for the next working operation.
4. Device according to one of the claims 1 to 3, whereby for reducing the tensional force, an electronic control device is provided.

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