DE102006002237A1 - Monitoring process for set bolt joint making involves using reaction force and/or end position of bolt to evaluate and/or influence process - Google Patents

Abstract

The monitoring process for a joint between at least two components (2, 4) driving a set bolt (6) with head (8), shaft (10) and tip (12) at high speed into the two components. The reaction force acting on the components and/or the end position of the bolt is detected and used to evaluate the process and/or the completed joint.

Description

The The present invention relates to a method and an apparatus to monitor a joining process for connecting at least two components by means of a setting bolt.

The so-called pinching is a forming technique joining method, in which a setting bolt by means of a setting device in the form of a bolt gun, a Powder cartridge or the like at high speed in the is driven to be connected components. The bolt set finds in many areas such as steel construction, facade construction, metal construction, shipbuilding and construction industry application. In the present context stands the fastening of metal sheets to profile components, in particular for the motor vehicle industry in the foreground, although the invention is not limited thereto.

fasteners are available in different versions. First, there are the set bolts, colloquially called nails, the components to be joined insoluble connect with each other. On the other hand there are the threaded bolts, the the components to be joined solvable connect with each other.

When Setting tools come in particular so-called bolt pushing tools in question, in which one between a propellant charge and the set bolt arranged piston is used to the set bolt in the joined To collect components. Here one differentiates between the impact piston principle and the piston principle: The impact piston principle is the setting bolt arranged coaxially separated from the thrust piston and he then hits powered by the gases of the ignited cartouche, outdoors Flight on the set bolt on. The thrust piston principle is the thrust piston already before the ignition directly on the set bolt which rests directly on the components to be joined. thrust piston and setting bolts are therefore from the gases of the ignited cartridge accelerated together from a standstill.

The Boltsetting is becoming increasingly widespread in application areas, where a high quality and strength of the set compound are important. The present Invention deals with the problem of optimizing the setting bolt joining process, in particular with regard to the joining of components (sheet metal / profile component) in vehicle construction.

Of the The present invention is based on the object, a method and a device for monitoring a joining process for connecting at least two components by means of a setting bolt to create, improve and ultimately optimize the quality and strength of the connection between the components can be used.

To the solution according to the invention the set-up force acting on the components Reaction force and / or the final position of the setting bolt in the finished Connection recorded and to assess the joining process and / or the connection used. Preferably, the detected reaction force and / or the detected setting bolt end position for controlling / controlling the joining process used.

The The present invention is based on extensive research gained knowledge that the reaction force and set bolt end position fundamental Characteristics are, which a purposeful statement about the during the joining process allow occurring effects. These parameters can therefore for one simple yet reliable monitoring and in particular control / regulation of the joining process are used.

The Invention is further based on the knowledge that the temporal Course of the reaction force during of the joining process an increase to a first maximum, a drop to a minimum and shows a renewed increase to a second maximum. The first Maximum arises when the bolt tip penetrates into the components, the minimum when passing the bolt shank through the components and the second maximum when placing the bolt head on the top Component. These extreme values of the reaction force can, in particular in connection with the set bolt end position, are used as parameters that in particularly simple way of monitoring and control / regulation of the joining process with a view to optimizing the quality and strength of the connection.

A Device according to the invention to perform of the method comprises a force sensor for detecting the reaction force and / or an optical sensor for detecting the setting bolt end position.

Further advantageous embodiments of the invention will become apparent from the claims.

Based The drawings are details and embodiments of the invention explained. It shows:

1 to 4 different process steps when joining two components by means of a setting bolt using a Rondelle in a schematic form;

5 a finished connection between two components by means of a modified setting pin without Rondelle;

6 to 8th a device for monitoring the joining process in different operating states in a schematic form;

9 a graph in which the reaction force is plotted against time;

10 one of the 9 corresponding diagram with two curves for two different values of set energy;

11 a the 4 and 5 corresponding representation of a compound in which it has come to a "punch" of the setting bolt;

12 a diagram in which the set bolt end position and the second maximum of the reaction force is plotted against the set energy;

13 a graph in which the reaction force over time for different positions of a Rondelle is applied to the setting bolt to illustrate the influence of the Rellellenlage on the reaction force and the strength of the compound, and

14 a diagram in which the reaction force over time for a working according to the impact piston principle setting device and a working according to the thrust piston principle setting tool is applied.

The 1 to 4 illustrate the different stages of the process when bolting, ie when connecting two components 2 . 4 by means of a setting bolt 6 from a setting tool (in the 1 to 4 not shown) at high speed in the components 2 . 4 is driven. High speeds are to be understood as firing speeds which are usually between 10 and 100 m / s but may also be greater or smaller.

In the embodiment of 1 to 4 consists of the setting bolt 6 from a bolt head 8th with a central elevation, a cylindrical bolt shank 10 and an ogival pin tip 12 , The set bolt 6 is a roundel 14 assigned.

The 1 to 4 show four stages of the process, before the penetration of the setting bolt 6 ( 1 ), Penetration of the bolt tip 12 ( 2 ), Passage of the bolt shank 10 through the components 2 . 4 ( 3 ) and (indirect) placement of the bolt head 8th on the upper part 2 , As shown, the components are 2 . 4 not pre-punched. When penetrating displaced therefore the setting bolt 6 Material of the components 2 . 4 , Due to the high penetration rate, this leads to a strong increase in temperature and plasticization of the displaced material, which leads to material build-up in the joining area.

The setting bolt 6 For example, consists of steel, and the components 2 . 4 consist for example of aluminum. However, other materials are possible, such as aluminum, magnesium, brass, ceramic and fiber reinforced plastic for the setting bolt 6 and different material combinations for the components 2 . 4 including steel, aluminum and plastic. Particularly advantageous is the joining of components made of magnesium has proven.

It is understood that the 1 to 4 just show an example of the bolt setting. The method for monitoring the joining process to be described below is applicable to virtually every form of bolting.

5 shows an example of another embodiment of a setting bolt 6 ' in which the bolt head 8th' on its underside an annular groove 16 and the bolt shank 10 ' with a surface profiling 18 is provided. The surface profiling 18 , which consists for example of elevations and depressions in the form of coaxial rings or a thread fills in the joining process with plasticized material, whereby the pull-out strength of the compound is increased. We are represented in the joint of the 5 no rondel provided.

It will now be on the 6 to 8th Reference is made, in which different operating states of an embodiment of an inventively designed device for monitoring the joining process is shown.

An only fragmentary indicated setting tool 20 includes a thrust piston 22 and one on the component 2 attachable mouthpiece 24 , The mouthpiece 24 is with breakthroughs 26 provided on the one hand setting bolts 6 on the other hand, to vent the area below the bolt head, which is provided during the joining process for pressure equalization.

The trained as a profile component component 4 is on a support schematically illustrated as a spring-mass system 28 stored. The support 28 is a force sensor 30 assigned to the components caused by the setting force 2 . 4 acting reaction force F _R detected. The force sensor 30 For example, a piezoelectric sensor, but may also be formed in other ways.

In the illustrated embodiment, the force sensor 30 between the support 28 and the component 4 arranged so that the force sensor 30 the reaction force recorded directly. However, the reaction force could also be detected indirectly. This could be achieved, for example, by placing in the mouthpiece 24 a force sensor (not shown) is integrated, which during the joining operation on the mouthpiece 24 detected acting force.

Out this force, which becomes smaller during the setting process, could then be closed to the reaction force.

Above the two components 2 . 4 is an optical sensor 32 arranged, which detects the setting bolt end position. The optical sensor 32 For example, a laser sensor, but may also be designed in other ways.

The setting bolt end position EL is, for example, as a distance between the top of the bolt head 8th respectively. 8th' and the top of the component 2 in the finished compound ( 8th ) Are defined. Preferably, the optical sensor 32 relative to the mouthpiece 24 of the setting device 20 firmly arranged. The top of the component 2 then serves as a reference, so that the optical sensor 32 only the location of the top of the bolt head 8th respectively. 8th' must capture in the finished connection.

Appropriately, occurring during the joining process vibrations of the components 2 . 4 attenuated to high-frequency signal components of the force sensor 30 to filter out the generated reaction force signal. As in the 6 to 8th indicated schematically, is therefore at the bottom of the component 4 a cushioning pad 34 arranged. The force sensor 30 is thus able, during the joining process ( 6 to 8th ) to generate a meaningful reaction force signal, which will be discussed in more detail below.

In the illustrated embodiment, the damping pad 34 between the support 28 and the component 4 arranged. In principle, the damping pad could also be arranged at a different location.

Further, a return spring damping device (not shown) is preferably provided, which damps occurring during the joining process springback vibrations. Such a return spring damping device, for example, from a damping body, between the component 2 and the mouthpiece 24 is arranged exist. Another possibility consists of a resilient mounting of the mouthpiece, the axial Ausgleichsbewegun conditions of the mouthpiece during rebound of the components 2 . 4 against the mouthpiece 24 allows. Another possibility consists of a damping arrangement, for example in the form of two small shock absorbers, in addition to the mouthpiece 24 is arranged and springback movements of the two components 2 . 4 fields.

Such a return spring damping device protects the components involved, in particular the mouthpiece 24 as well as the components to be joined, against damage and wear and contributes to the sound attenuation.

The diagram of 9 shows a typical course of the reaction force F _R over the time t during the joining process (for example, at an exit velocity of the set bolt of 100 m / s). As can be seen, the reaction force signal has a vibration-like course with a first maximum, a minimum and a second maximum. The first maximum arises when penetrating the bolt tip into the components, the minimum in the passage of the bolt shank through the components and the second maximum when placing the bolt head on top of the upper component 2 ,

The present invention is based on the finding that the time profile of the reaction force F _R and in particular the three extreme values allow reliable statements about the joining process as well as the quality and strength of the connection, so that they can be used for monitoring and in particular for influencing the joining process, which will be explained in more detail below.

The diagram of 10 , in which again the reaction force F _R is plotted over time, contains two signal curves obtained in experiments. The component 2 consisted of a sheet metal (material: AlMg 5 Mn), and the component 4 from a hollow profile (material: AlMgSi 0.5). The fixing bolt, which in the 1 to 4 consisted of X-EDNI 16 P8, and the rondelles made of aluminum.

As shown in the diagram, the set energy of the setting bolt was 96 Nm in one case and 46 Nm in the other case. The different values of the set speed and set energy led to significantly different progressions of the reaction force signal:
The connection set with the set energy of 96 Nm produces a pronounced first maximum, a pronounced minimum and a pronounced second maximum, which is greater than the first maximum.

The first maximum occurs when the bolt tip penetrates into the components, whereby the size of the first maximum is a consequence of the high impact velocity or set energy.

The Minimum arises when the setting bolt passes through the two Components. The fact that the minimum is less than zero indicates indicates that the bolt tip the plasticized material in the joining area so strong radially outward accelerates that the bolt shaft partially no contact with Material of the components has.

The second maximum arises when placing the bolt head on the Top of the components. The fact that the second maximum is greater than that first maximum is realize that there is a "punch" of the set bolt has come.

The term "breakdown" is to be understood as a state in which the bolt head penetrates into the upper component and, in particular, a downwardly increasing gap between the bolt shaft and the material of the lower component is produced, as described in US Pat 4 is indicated. Obviously, the force exerted by the bolt head (directly or indirectly via a rondel) and the upper component on the lower component, so large that the otherwise existing compressive stresses are reduced and a clearly visible hole is formed in which the setting bolt tampered with can literally rattle. In addition, the finished compound has a comparatively low strength.

Clear different is the course of the reaction force signal at a set energy of 46 Nm and a correspondingly lower setting speed.

So the first maximum is lower, and the minimum is much larger than at the turn for the greater set energy. This leaves through the slower impact speed and the lower Setting speed during passage of the bolt shank through the explain both components. Obviously, the setting process less material of the components plasticized, so no correspondingly strong pressure relief occurs during passage of the bolt shank.

Furthermore, it can be seen that no pronounced second maximum arises. Rather, there is only a small second maximum, from which the reaction force gradually subsides in a flowing transition. The reason for this course of the reaction force in the region of the second maximum is that the bolt head does not touch the components. Rather, the bolt head is clearly over, and also the bolt tip is not completely pushed through. The setting bolt takes an end position approximately between the in the 2 and 3 shown positions.

In summary let yourself Thus, find that a set power of 96 Nm too big and one Set energy of 46 Nm is too small to be at the given parameters to make a satisfactory connection. This is possible on the course of the reaction force and in particular at the extreme values recognize first maximum, minimum and above all second maximum.

Of the Course of the reaction force and in particular allow the extreme values thus a surveillance and evaluation of the joining process as well as the finished connection. You can in particular to a Control or regulation of the joining process used become.

The unsatisfactory state of the set with the two set energies 96 Nm and 46 Nm connection can also by that of the optical sensor 32 ( 6 to 8th ) are detected set pin end position EL. This results in the set energy of 96 Nm an end position EL, which is less than zero (breakdown), while the set energy of 46 Nm results in an end position, which is significantly greater than zero.

The Set bolt end position can thus also for monitoring and evaluation of the joining process and the finished compound are used. A controller or regulation of the joining process can therefore be dependent also done by the set bolt end position EL.

One Method for controlling the joining process according to the present Invention is for example characterized in that the impact velocity the setting bolt or the setting energy depending on the reaction force and / or the setting bolt end position is specified. A method for Rules of the joining process according to the present Invention, for example, in such a way that the impact velocity the setting bolt or the setting energy depending on the reaction force and / or the setting bolt end position is regulated so that the first Maximum and / or the minimum and / or the second maximum of the reaction force remain within a specified tolerance band.

Based on the diagram of 12 a process monitoring is explained in which the reaction force F _R and the end position EL are used together as monitoring parameters.

In the diagram of 12 is the second maximum of the reaction force curve RKV (curve a), the set screw end position EL (curve b) and the maximum force F _max (curve c) obtained during tensile tests over the set energy W _kin . The diagram was obtained in experiments in which the same set bolts and components as in the trials of the diagram of 10 were used.

As can be seen, the second maximum of the reaction force (curve a) rises above a certain set energy of z. B. 75 Nm leaps and bounds. In this area designated A, it is evident to a breakthrough of the setting bolt (see 11 ).

Below a certain set energy of z. B. 45 Nm, the setting bolt end position increases EL (curve b) jumped. Obviously it comes with this B designated area to no placement of the bolt head.

As determined by means of experiments, the formation of the joining region or the maximum head tensile forces (maximum force F _max ) determined during head tensile tests correlate very well with the setting bolt end position and the second maximum of the reaction force profile. The maximum force F _max (curve c) drops significantly above the upper limit.

Between the lower and upper limit of the set energy in the designated C Area, the curves are reasonably constant, indicating a stable joining process and to conclude an optimal formation of the connection.

In In this area, the head tensile strength (curve c) varies the least, and also the second maximum of the reaction force profile and the Setting bolt end position are relatively constant in this area. properties like optical quality and strength of the connection are largely consistent here, thus a high reproducibility and comparability of the joining process is ensured.

From the diagram of 12 and from the above description it is clear that the second maximum of the reaction force profile RKV and the set bolt end position EL are two quantities that can be used for non-destructive process monitoring with the aim of monitoring the connection quality. The second maximum of the reaction force curve in this case allows a limitation to high energies, while the set bolt end position can be used as a limitation to low energies.

According to one preferred embodiment of Invention is therefore the joining process dependent on of the two characteristics second maximum of the reaction force curve and set screw limit position controlled or regulated.

Based on the diagrams of 13 and 14 Further possibilities for monitoring and evaluating the joining process as well as the connection produced thereby with the aid of the reaction force profile are explained.

In the diagram of 13 , which under the same experimental conditions as the diagrams of 10 and 12 Again, the reaction force is plotted against time for three different initial layers of a rondelle on the set bolt. In the Rondell position Rl = 0, the Rondelle is approximately in the region of the transition between the bolt tip 12 and the bolt shank 10 ( 1 to 4 ), and in the rondelevels Rl = +1 and Rl = -1, the rondel is above or below this transition.

As From the diagram, the initial position of the rondel has a considerable influence on the first maximum of the reaction force. in the unfavorable Case (Rl = -1) that is true Penetration of the bolt tip in the components with the tearing of the Rondelle together, resulting in a correspondingly large reaction force. This in turn has a significant impact on the strength of the connection. So was carried out in the Try the maximum force of the head tensile strength 0.30 kN at Rl = -1, 1.35 kN at Rl = 0 and 1.79 kN at Rl = +1.

Based the course of the reaction force can therefore be the initial position to optimize the rondel on the bolt shank.

In the diagram of 14 Again, the reaction force is plotted over time. The curve a and the curve b were obtained with a setting device operating on the percussion piston principle or with a setting device operating on the thrust piston principle. Incidentally, the experimental conditions were the same as in the experiments described above.

As can be seen, the curve b (thrust piston principle) has no pronounced minimum and not pronounced second maximum. This is due to the lower penetration rate attributed to that too permanent Friction between the bolt shank and the material of the components leads. It is also recognizable that the reaction force and thus the load the components longer ongoing.

The curve a (impact piston principle) has a larger first maximum and in particular a pronounced, significantly lower minimum. The low minimum indicates that as the bolt shank passes through the components, the plasticized material is accelerated radially outwards, resulting in a corresponding pressure relief. The second maximum, the one wich represents characteristic value for the connection quality, in the case of the curve a (percussion piston principle) has a much lower dispersion than in the case of the curve b.

Out leaves these results to conclude that working with a percussion piston principle setting tool across from a working according to the thrust piston principle setting device compounds reproducible with significantly lower deformations and higher strengths can be produced.

The diagram of 14 thus makes it clear that the course of the reaction force can be used to monitor and evaluate the operation of the setting tool.

It will now open again 9 Referenced. In the diagram of this figure, the dashed horizontal line represents the breakdown limit. In order to produce a low-deformation and load-bearing connection, the maximum possible distance between the breakdown limit and the extreme values (first maximum, minimum and second maximum) of the reaction force F _R must be present.

This let yourself achieve that the first maximum, the minimum and the second Maximum possible chosen small become. A reduction of the second maximum can be achieved by a reduction reach the set energy. A lowering of the minimum can be achieved by an increase the impact velocity can be achieved. Also the use from as possible few penetrating interfaces can contribute to this. A reduction of the first maximum can be achieved by increasing the Impact speed, shifting the starting position of one possibly existing rondelle towards the bolt head, in particular by the renunciation of a rondelle, as well as by an increase of the Stiffness of the joining area achieve.

on the other hand let yourself the distance between the breakdown limit and the extreme values the reaction force by increasing the breakdown limit enlarge what For example, by increasing the rigidity of the components, a higher one Impact speed of the setting bolt or by choice of the setting device (percussion piston principle instead of the thrust piston principle).

The Breakdown limit or the distance between the extreme values of Reaction force and the breakdown limit can therefore also for monitoring and in particular be used for controlling / regulating the joining process.

Claims (24)

Method for monitoring a joining process for connecting at least two components ( 2 . 4 ) by means of a setting bolt ( 6 ; 6 ' ), which has a bolt head ( 8th ; 8th' ), a bolt shank ( 10 ; 10 ' ) and a bolt tip ( 12 ) and at high speed in the two components ( 2 . 4 ) is driven in which method during the joining process to the components ( 2 . 4 ) acting reaction force (F _R ) is detected and used to evaluate the joining process and / or the connection. A method according to claim 1, characterized in that the detected reaction force (F _R ) is used to control the joining process (open timing chain). A method according to claim 1, characterized in that the detected reaction force (F _R ) is used to control the joining process (closed loop). Method according to one of the preceding claims, characterized in that the setting energy of the setting bolt ( 6 ; 6 ' ) is influenced as a function of the detected reaction force (F _R ). Method according to one of the preceding claims, characterized in that the time profile of the detected reaction force (F _R ) is determined. Method according to Claim 5, in which the reaction force (F _R ) during the joining process has a first maximum, a second maximum and an intermediate minimum, characterized in that the first maximum and / or the minimum and / or the second maximum are determined and used as characteristic values. A method according to claim 6, characterized in that the joining process is influenced so that the first maximum and / or the minimum and / or the second maximum of the detected reaction force (F _R ) are each within a predetermined tolerance band. Method according to one of the preceding claims, characterized in that the joining process is influenced so that the first maximum and / or the minimum and / or the second maximum of the detected reaction force (F _R ) are as small as possible. Method according to one of the preceding claims, wherein one on the setting bolt ( 6 ) deferred rondels ( 14 ) is used, characterized in that the axial position of the Rondelle ( 14 ) on the setting bolt ( 6 ) depending on the detected reaction force (F _R ) is selected. Method according to one of the preceding claims, characterized in that the reaction force (F _R ) by means of a force sensor ( 30 ) is detected directly or indirectly to generate a reaction force signal. A method according to claim 10, characterized in that the vibrations occurring during the joining process of the components ( 2 . 4 ) are attenuated to filter out high-frequency signal components of the reaction force signal. Method for monitoring a joining process for connecting at least two components ( 2 . 4 ) by means of a setting bolt ( 6 ; 6 ' ), which has a bolt head ( 8th ), a bolt shank ( 10 ) and a bolt tip ( 12 ) and at high speed in the two components ( 2 . 4 ), in particular according to one of the preceding claims, in which method the end position (EL) of the setting bolt ( 6 ; 6 ' ) is detected in the finished connection and used to evaluate the joining process and / or the connection. Method according to claim 12, characterized in that that the detected set pin end position (EL) for controlling the joining process is used (open timing chain). Method according to claim 13 or 14, characterized that the detected setting bolt end position (EL) is used for controlling the joining process becomes (closed loop). Method according to one of claims 12 to 14, characterized in that the setting energy of the setting bolt ( 6 ; 6 ' ) is influenced as a function of the detected setting bolt end position. Method according to one of claims 12 to 15, characterized in that the joining process is influenced so that the bolt head ( 8th ; 8th' ) assumes a zero end position in the finished connection, in which the bolt head ( 8th ; 8th' ) directly or indirectly via a roundel ( 14 ) on the bolt head side component ( 2 ) is applied, without the top of the bolt head side component ( 2 ) is noticeably deformed. Method according to one of claims 1 to 11 in conjunction with one of claims 12 to 16, characterized in that a suitable process for the joining process of the setting energy (W _kin ) and / or the setting speed of the setting bolt ( 6 ; 6 ' ) is determined as a function of the detected reaction force (F _R ) and the detected setting bolt end position. A method according to claim 17, characterized in that a lower limit of said process area in dependence on the detected set screw end position (EL) and an upper limit of said process area in dependence on the detected reaction force (F _R ) are determined. Method according to Claim 18 in conjunction with Claim 67, characterized in that the upper limit of said process range is determined as a function of the second maximum of the detected reaction force (F _R ). Device for carrying out the method according to one of claims 1 to 11 with a setting device ( 20 ) for applying a pulse-shaped setting force on a setting bolt ( 6 ; 6 ' ), a support ( 28 ) for supporting the components to be connected ( 2 . 4 ) and a force sensor ( 30 ) for detecting the setting caused by the setting force on the components ( 2 . 4 ) acting reaction force (F _R ). Apparatus for carrying out the method according to one of claims 12 to 19, in particular according to claim 20, with a setting device ( 20 ) for applying a pulse-shaped setting force on a setting bolt ( 6 ; 6 ' ), a support ( 28 ) for supporting the components to be connected ( 2 . 4 ) and an optical sensor ( 32 ) for detecting the end position (EL) of the setting bolt ( 8th ; 8th' ) in the finished compound. Apparatus according to claim 20 or 21, characterized by a damping pad ( 34 ) on the underside of the bolt head facing away component ( 4 ) for filtering out high-frequency signal components of a reaction force signal. Device according to one of claims 20-22, characterized by a return spring damping device for damping of springback vibrations of the components, ( 2 . 4 ) during the joining process. Device according to one of claims 20 to 23, characterized in that the setting device ( 20 ) a on the bolt head side component ( 2 ) attachable mouthpiece ( 24 ), with openings ( 26 ) for venting the area below the bolt head ( 8th ; 8th' ) is provided during the joining process.