WO2008155107A2

WO2008155107A2 - Adhesive bond

Info

Publication number: WO2008155107A2
Application number: PCT/EP2008/004899
Authority: WO
Inventors: Markus Emert; Thorsten Hillesheim; Jürgen Schonlau; Bernhard Kirsch; Burkhard Kremmling; Ralf Grohn; Ralf Holder; Axel MÜLLER
Original assignee: Thomas Magnete Gmbh
Priority date: 2007-06-18
Filing date: 2008-06-18
Publication date: 2008-12-24
Also published as: DE202008005171U1; WO2008155107A3; DE102007028503B3

Abstract

The invention relates to an adhesive bond between a first part (4) and a second part (5). The first part (4) is connected to the second part (5) by means of an adhesive that can be detached by being thermally activated. In order to obtain an adhesive bond that reliably joins two parts and can be reliably detached, the adhesive is thermally activated by feeding electric power thereto.

Description

adhesive bond

The invention relates to an adhesive connection between a first part and a second part, wherein the first part is connected by an adhesive to the second part, wherein the adhesive is releasable by a thermal activation.

In modern motor vehicles safety systems or safety devices are state of the art, with which, for example, flaps or doors are kept locked. Electrical or mechanical actuation of such safety devices allows these flaps or doors to be opened. The safety function is limited to preventing unauthorized or unintentional opening of the flaps or doors. In this case, there are no separate requirements for the switching time when deactivating the locking function.

Critical safety devices include those for occupant and pedestrian protection that require mechanical actuation to activate in a very short time. Such safety devices include in particular tensioning devices for safety belts, rollover protection bars in cabriolet vehicles, engine hood displays for the protection of pedestrians and adjusting devices for car seats and headrests. When performing an actuating movement of such safety devices various systems are known. In most cases coil springs are used, which are biased by a suitable holding device. Such a holding device is inhibited by a system of levers and pawls in its movement. Here, a lever can be moved via an electrically activated actuator. In the deactivated state, when the safety device is held under pretension, the actuator is pressed by the lever into a defined end stop and thus inhibits the movement or actuation of the safety system. To trigger the safety device of the actuator is electric activates and then executes a small adjustment movement with a small force and a relatively large way to actuate the locking lever. The lifting system translates the force and reduces the stroke of the actuator, thereby releasing the coil spring so that it can move while breaking its bias.

As actuators for the above-described safety device usually pyrotechnic actuators are used. Alternatively, the use of lifting magnet is known. Regardless of the type of actuator, the above safety device suffers from the disadvantage that the lever system is complicated. To undercut the very large holding forces of the coil spring, a large lever ratio is required. Since the known actuators are limited in the length of their travel, the locking lever with the coil spring is only on a very small contact surface in engagement. In addition, a high rigidity is required for the lever system to prevent a connection or a clearance. The above aspects lead to a complex design of the lever system, which are associated with cost disadvantages and also a critical operational safety.

For the mechanical connection of two components, a so-called pyrotechnic securing element is known on the market, which consists of two with a locking ring firmly interconnected items. If necessary, the two components can be quickly released from each other by an electrically triggered pressure pulse. Through the locking ring both the holding force and the separation force can be adjusted application-related. The use of such a pyrotechnic fuse element is e.g. in the case of door hinge pins, in order to be able to separate doors wedged after an accident, or hood joints, in order to be able to set up an engine hood after an accident.

Adhesive bonds are known in practice which connect two parts, the adhesive being released by thermal activation as a result of a temperature change. increase is solvable. Melting adhesives dissolve when heated, releasing their associated parts. This is also the case, for example, with a solder joint in which the solder connects two parts. A disadvantage of such adhesive bonds that they are not suitable for holding parts to be separated of a security system, since the activation takes a long time and is poorly timed reproducible.

US Re 34,238 shows an apparatus for holding a biased safety system configured as a fuel cap. The fuel cap consists of a main body, which is threaded on one

The pipe socket can be screwed on. In the end face of the tank cap a sealing body forming plate is provided which has a circumferential flange and which is held in the closed position under the bias of a spring which is supported against a collar of the main body. The spring is supported on two legs, which are fixed by a plate on the sealing body and protrude from this in the pipe. The legs are folded down at the end with their projecting into the tube area and form a hook-shaped receptacle for the one end of the spring. The legs are formed of two halves, which are connected to each other via a fusible element. In a conventional overpressure, the sealing body can be lifted a small distance from the main body under tension of the spring and allows escape of the pressurized gas. If the temperature exceeds a preset value, the fusible element melts, the lower halves carrying the spring fall off, and under the gas pressure, the sealing member can be lifted without having to overcome the bias of the spring.

DE 77 12 696 LM shows a safety valve for a gas line, in which in the case of overheating the normally open passage is closed by disengagement of the valve disk against the valve seat forming an annular surface. The valve plate is biased by the spring, which is supported against a corresponding abutment. The spring is penetrated by a valve stem, which is fixed to the valve disc. In a circumferential groove of Valve tappet engages a bimetallic strip, which secures the valve disc against disengagement under the bias of the spring. The bimetallic strip moves out of the circumferential groove when a certain temperature is exceeded and releases the valve disk.

No. 5,788,212 A shows a through-valve which biases a closing member in the opening direction under the bias of a spring, wherein a plunger engages in a circumferential groove of the sealing body and is prevented from disengaging by a thermally activatable disengaging mechanism. The thermally activatable release mechanism comprises an element of one

Shape memory alloy, which shrinks as the temperature increases so that the plunger can be pushed away from the circumferential groove and the passage is released under the bias of the spring.

US 4 176 718 A shows a device for holding a prestressed safety system, here: a sprinkler system in which the opening of a sprinkler nozzle is closed by a cover. The lid is in this case positively held by a part in position by one end of the part bears against the lid and the other end of the part against an abutment. A bracket is held between two legs, which are connected to each other via a fusible element. Upon melting of the fusible element, the bracket is disengaged and allows the part to disengage from its closed position and thereby release the lid.

No. 5,695,306 A describes a connecting device with which two components are connected to one another. The separation of the two components takes place without the use of pyrotechnic means and melting of a fusible material. For this purpose, the device has a housing in which a prestressed compression spring presses by means of a displaceably guided in a hollow piston on a connecting element which extends in the form of a punch through the first component slidably through and is bolted to the underlying second component. In a starting point state, the piston is in the hollow chamber in an upper stop position, wherein the hollow chamber is filled below the piston with the fusible material. The fusible material is initially in a solid state, whereby the piston is forcibly held in the upper stop position. In a targeted heating of the meltable material decreases its viscosity, so that the material flows through flow channels past the piston in an upper region of the hollow chamber. As a result, the piston can move within the hollow chamber due to the bias of the compression spring down and presses the connecting element down. In this case, the second component is then separated from the first component. The device has a complicated and costly construction and is not suitable for time-critical Sichereits- functions, since the melting of the fusible material takes too much time.

It is the object of the invention to provide an adhesive joint, which reliably connects two parts, and in which the connection is reliably solvable.

This object is achieved by an adhesive bond with the features of claim 1. Advantageous developments of the invention are defined in the dependent claims.

The adhesive joint of the present invention is releasable by supplying electric power similar to a pyrotechnic igniter, and quickly and surely releases the bonded parts from each other. The separation of the parts does not require the destruction of one of the parts, can be triggered remotely, is similar to a common adhesive used and can not be misappropriated.

Such an adhesive bond is particularly suitable for use in a device for holding a prestressed safety system, in which a first and a second part hold the safety system against a bias, and first and second part with a adhesive bond according to the invention are releasably held. The solution of the adhesive bond then takes place by supplying electrical energy. Almost explosive, the solution, and thus the release of the security system. An independent unlocking of the security system is reliably prevented, and allows easy operation of the safety system in a very short response time.

An inventively equipped preferred device is used to hold a biased security system and thus prevents the self-unlocking of this security system, and includes

Hook element as a first part and a base member connected to the hook member by an adhesive connection as a second part, which is engageable in a default state with a part of the safety system, thereby biasing the safety system, wherein the part of the safety system, with the the hook element is in its initial state in engagement, can be moved or actuated by a thermal activation of the adhesive bond.

The device according to the invention serves to provide a security system, e.g. a coil spring to hold reliably under bias.

The thermal activation of the connection, which is suitably converted into heat by the supply of heat and / or electrical energy, ensures that either the hook element is disengaged from the part of the safety system or at least allows movement of this part of the safety system so that the bias of the safety system can degrade to its activation. As a result of the stored energy of the safety system or its bias voltage is moved by the movement of the part of the safety system, a mechanical system or the like, and thereby performs the safety function. The inventively equipped device can be used in connection with safety systems of active hoods for pedestrian protection, rollover protection in convertible vehicles, headrests for Occupant protection, belt tensioners or locking systems can be used for the proactive occupant protection of vehicles.

In an advantageous embodiment, the hook element is elongated and arranged with its longitudinal axis substantially parallel to the security system. This has the advantage that the hook element takes up little space or installation space. In addition, even a slight movement of the hook element away from the safety system is sufficient to disengage from the part of the safety system. Conveniently, the hook member may be at one end in engagement with the part of the security system.

The device according to the invention comprises a base element with which the hook element is connected in its initial position, wherein the connection between the hook element and the base element can be released by the thermal activation. After the hook element and base element have detached from each other, the part of the safety system can move to perform the safety function. In order to ensure a low installation dimension, the base element can be elongated in the same way as the hook element, with the longitudinal axis of the base element being substantially aligned with the longitudinal axis of the hook element.

According to a preferred development, the hook element and the base element can each have a toothed section, which sections ensure a positive connection of hook element and base element. If the base element and / or the hook element are at least partially made of a memory metal or a bimetal, these elements can move away from each other in a thermal activation, thereby canceling the positive connection of the toothed portions. For example, if the base member is disposed on the hook member side opposite to the safety system, it may suffice to make only the base member of a memory metal or a bimetal so that the base member deformed by the thermal activation to the outside away from the hook member and thereby the positive connection of the toothed portions is released. Once the interlocking connection between the hook element and the base element is released, the hook element can no longer oppose the force of the biasing of the safety system, so that as a result the part of the safety system can move to execute the safety function. Thus, it is not mandatory for the movement of this part of the security system that the hook element is disengaged therefrom. The only prerequisite for this is a release of the hook element of the base element.

According to the invention it is provided that the first part and the second part are glued together. To release the first part of the second part of the adhesive can be specifically weakened or softened. For this purpose, a metal wire with high resistivity may be provided at the connection point between the hook element and the base element, which converts supplied electrical energy into Joule heat, thereby melting the adhesive and correspondingly releasing the adhesive bond between the hook element and the base element.

In an advantageous embodiment of the invention may be provided on the contact surface between the first part and the second part of a substance which decomposes with the addition of heat energy. Such a substance is also known as "blasting powder" or as black powder. The decomposition of this explosive powder is highly exothermic and destroys the adhesive bond, separating the first part and the second part. The use of such an explosive powder allows very short response times to separate the first part of the second part and thus to unlock the safety system within a very short time, so that a corresponding execution of the safety function is ensured. Conveniently, such a blasting powder may be mixed into the adhesive, are glued together with the first part and second part. For generating a predetermined activation heat or energy For example, at the contact surface between the hook element and the base element, a metal wire with high resistivity may be provided which converts supplied electric energy into Joule heat and thereby causes decomposition of the explosive powder, so that the first part and the second part are affected by this exothermic reaction of the explosive powder be separated from each other. The use of such an explosive powder allows a very short response time to release the safety system. The use of the explosive powder is possible not only in a gluing of the first part and the second part, but also in the variant of a positive connection in which toothed sections are respectively formed on the second part and on the first part.

It is alternatively possible to mix other substances in the adhesive. According to a preferred embodiment, an agent is selected as the substance, which with a bonding component of the

Adhesive reacts upon activation by applying a voltage and / or thermal activation and thus dissolves the adhesive. For this purpose, in particular an exothermic, self-sustaining reaction is expedient, as this self-maintains after initiation of the reaction and propagates advantageously explosively, and also causes the desired thermal activation. In this way, it is also possible to trigger in atmospheres which do not sufficiently contain free oxygen for combustion, e.g. under protective gas such as nitrogen or in liquid media such as water.

With appropriate selection of adhesive and substance, it may be sufficient to apply a voltage for the activation, which triggers an ignition, without providing an electrical conductor in the form of a metal wire.

Preferably, the first part and the second part have surface areas that together define a guide, for example, in that the first part is guided on the second part. At these surface areas, or on spaced therefrom surface portions, the first and second part are provided with the adhesive bond, so that after loosening the Adhesive joint the relative mobility is established. Thus, according to a first preferred embodiment, the first part may be a rail, and the second part may be a slider guided in the rail. According to a second preferred embodiment, the first part is a pin part, and the second part is a part of the eye receiving the pin member. According to a third preferred embodiment, the first part is a ball part of a ball joint, and the second part is a pan part receiving the ball part. According to a fourth preferred embodiment, the first part is designed as a prestressed leaf spring spring member, and the second part of an abutment for the spring member, wherein the spring member can deliver the stored bias by activation. According to a fifth preferred embodiment, the first part is a plate body, for example a glass pane, and the second part is a frame, which can be released from the frame by activation of the plate body, for example as an emergency exit in vehicles. According to a sixth preferred embodiment, the first part and the second part are cores of a mold, which are split to be removable from the cast mold despite undercuts. According to a seventh preferred embodiment, the first part and the second part are plates of a capacitor whose dielectric is the adhesive, and whose dielectric is changeable by activation of the adhesive. According to an eighth preferred embodiment, the first part is a vessel and the second part is a closure part of the vessel. Further advantageous applications are toys or joke articles. Finally, the invention can be used in all safety systems, in particular pyrotechnic, which are electrically triggered, such as deployable roll bars and vehicle flaps, or for airbags, especially when a short response time is required.

In principle, any adhesive bond from the prior art can be designed according to the invention, in order to facilitate disassembly and sorting in the event of subsequent disposal. The time from activation to dissolution of the adhesive bond is expediently less than 1 second, preferably less than 100 milliseconds. The thermal activation can be assisted by the supply of external thermal energy. In any case, the thermal activation also takes place by supplying electrical energy, for example to the above-mentioned metal wire with high resistivity, which electrical energy is then converted into Joule heat in this metal wire.

Expediently, an electrical voltage ignites a substance mixed into the adhesive bond, with the resulting reaction, which may be exothermic, lifting the adhesive bond. This allows the

Bonded connection can be canceled without external temperature increase, for example in response to an electrical command or a sensor signal. In this case, the ignition advantageously takes place in the manner of a blasting of the substance, so that the adhesive bond can be canceled with an extremely short response time.

It may be provided in addition to the adhesive connection, an additional connection of the first with the second part, for example, a looping with a wire that melts or destroyed upon supply of electrical energy, or an electrically actuated latch member. If two connections are provided, they can be triggered simultaneously with the same control command. Alternatively, these are triggered by different criteria, for example, once temperature and once applying an electrical voltage, so that the risk of accidental release is reduced.

A method for producing a releasable connection or for quickly releasing a connection between two holding parts, in particular base part and hook element, in which the two holding parts are joined together by an adhesive connection, is characterized in that the application of an electrical voltage to the adhesive joint this picks. If two different types of connection can advantageously be canceled by an applied voltage, a particularly secure connection is created. Advantageously, can be checked at any time in an adhesive connection, which is provided with electrical contacts for canceling the adhesive bond, whether the compound has stock, for example by measuring the resistance. This can be queried at any time for a safety-relevant component, whether it is ready for operation. For this purpose, the same wiring can be used, which is also intended for the supply of electrical energy.

The abovementioned embodiments of the device together lead to the following further advantages:

- No special tools are needed to change the safety system once it has been triggered;

- For activation of the hook element only a minimum thermal or electrical energy consumption is required; - The control of the hook element can be done using airbag control units;

- Activation of the hook element is not possible by electrostatic charges;

- No vibration-sensitive power reduction lever systems are required to keep the safety system under tension;

- The device of the invention is easily adaptable to existing space, since it requires only a small installation space itself;

- Minimal weight due to small number of components, at least only a single component in the form of the hook element; - No toxic or polluting emissions;

- No explosion noise, minimal risk of fire, no danger of explosion; and

- Inexpensive design possible.

A method according to the invention for producing a releasable adhesive bond between a first part and a second part, in which the adhesive bond comprises an adhesive, is characterized in that the adhesive is mixed with a substance that dissolves the adhesive when energy is applied and breaks the connection. The energy is supplied as electrical energy, for example as ignition current, which leads to a conversion of the substance with dissolution of the adhesive.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically below with reference to preferred embodiments in the drawings and will be described in detail with reference to the drawings.

As an explosive adhesive, a composition according to the invention is defined, which is mixed from an adhesive and a substance, wherein the adhesive may be both a one-component adhesive and a two-component adhesive. The substance is selected to mechanically or chemically decompose on activation, in particular by the supply of electrical energy, in the mixed state, at least after curing or bonding of the adhesive, that the adhesive property is so canceled or at least reduced that bonded parts can be easily separated, or the composite is completely lifted. The decomposition can occur as a consequence of the temperature due to the reaction of the substance, for example in the case of a hotmelt adhesive, or by mechanical breakage of the structures of the adhesive. Preferably, however, a component constituting the solidification or cohesion of the adhesive is consumed in the reaction of the substance, thereby destroying the adhesive in its chemical composition.

The adhesive is suitably selected from the group of physically setting adhesives or chemically curing adhesives. For a chemically curing two-component adhesive off Binder and hardener, the substance can react after activation with one of the two components and thus cancel the adhesive bond. Particularly preferred are organic adhesives such as acrylate adhesives and epoxy adhesives, and silicones and silane-crosslinking polymer adhesives.

For the supply of electrical energy expediently a firing arrangement is provided, which preferably initiates an ignition current by applying a DC voltage to the substance or to the metallic conductor. The ignition arrangement is provided with a switch.

Fig. 1 shows a simplified principle side view of a first

Embodiment of an apparatus in connection with a safety system in the form of a biased coil spring, in which the adhesive bond of the invention is used.

FIG. 2 shows a side view of the device of FIG. 1. FIG.

FIG. 3 shows a perspective view of the device of FIGS. 1 and 2, respectively. FIG.

FIG. 4 is a partially cutaway front view of the device of FIG. 3. FIG. 5 is a front view of the device of FIG. 3.

FIG. 6 shows a rear view of the device of FIG. 3. FIG.

Fig. 7 shows a simplified side view of a second

Embodiment of a device in which the adhesive bond of the invention is used. 8 shows a longitudinal cross-sectional view through a hook element or a base element from FIG. 7.

Fig. 1 shows a simplified principle side view of a device 1 in conjunction with a security system 2 in the form of a biased coil spring. The coil spring 2 is inserted into a socket 3 and projects with its upper end out of the socket 3. The device 1 comprises a hook element 4 and a base element 5, which are detachably connected to each other via a connection point 6. The basic element 5 has a hook 7 at its end opposite the connection point 6. In the same way, the hook element 4 has a hook 8 at its end opposite the connection point 6. In Fig. 2, the device 1 is shown in a side view. The base member 5 is hooked with its hook 7 in a retaining flange 9, which is provided externally on the bushing 3 in the bottom region thereof. The hook element 4 is hooked with its hook 8 at an upper lateral edge 2a of the coil spring 2.

In an initial position of the device 1 or the hook element 4, the hook element 4 is connected to the base element 5. The length of the device 1 is adapted to a length of the coil spring 2, when this is compressed under bias and inserted into the bushing 3, adjusted, so that the device 1 in hinged at the upper end of the coil spring 2 hook member 4, the coil spring 2 reliably keeps under tension. In Fig. 1, the force is indicated by an arrow F, which is exerted by the bias of the coil spring 2 on the device 1 and in particular the connection point 6 between hook element 4 and base element 5. By a thermal activation of the connection point 6 between the hook element 4 and the base element 5, the connection between the hook element 4 and base element 5 is released so that thereafter the coil spring 2 can relax in the direction of the force F upwards. The coil spring 2 is actuated in this movement upwards (not shown) mechanical system with which a safety function is performed, for example, in connection with active hoods for pedestrian protection, rollover protection in convertibles, headrests for occupant protection and / or belt tensioner or Locking systems for the proactive occupant protection of vehicles.

The device 1 can be used not only in a safety system 2 in the form of a helical spring, but also in similar safety systems, which in a deactivated initial state under bias are set. These include the example! Gas piston, magnetic piston or the like.

Hereinafter, with reference to FIGS. 3 to 6, an adhesive connection of the hook member 4 and the base member 5 and their release from each other by a thermal activation will be explained in detail.

In Fig. 3, the device 1 is shown in a perspective view. In the area of the connection point 6, the base element 5 has a connection section 10 which extends substantially at right angles to the longitudinal axis of the base element 5. The base element 5 can be made of a thermoplastic, for example a polyamide 66. On one surface of the connection section 10, two tracks 11 are applied in the form of metal tongues, which may be made of brass or coated copper, for example. These metal tongues 11 are embedded in the connecting portion 10, so that their surface is substantially flush with a surface of the connecting portion 10. In the plan view of Fig. 4 it can be seen that the respective upper ends of the metal tongues are connected by a metal wire 12. This metal wire 12 is made of a high resistivity metal, for example, constantan or a metal having similar properties. The metal wire 12 is embedded in a meander-shaped recess of the connecting portion 10 and therefore likewise terminates substantially flush with the surface of the connecting portion 10. For simplicity, in Fig. 4, the hook element 4 is transparent and shown only in its outlines, so that the underlying metal wire 12 and the upper ends of the metal tongues 11 can be seen. The connecting portion 10 of the base member 5 thus forms for the metal tongues 11 and the metal wire 12, a support member on which these elements are mounted. In Fig. 5, the device 1 is seen in a front, and shown in Fig. 6 in a rear view.

The hook element 4 is glued with its end opposite the hook 8 on the connecting portion 10, namely exactly in the region of the metal Wire 12 (Figure 4). Thus, the hook element 4 and the base member 5 are non-positively connected. In the adhesive, which adheres the hook member 4 to the base member 5, a substance which decomposes with the addition of heat energy is mixed. Such a substance is also known by the term "blasting powder" or black powder. The perspective view according to FIG. 3 or a front view shown in FIG. 5 represent the device 1 in an initial state in which the hook element 4 is adhesively bonded to the connecting section 10 of the base element 5. This bond is to tensile force acting in the longitudinal direction of the hook element or base element claimable, so that the device 1 is able to hold the coil spring 2 in the biased position as shown in FIG.

If a voltage is applied to the metal tongues 11, a defined Joule heat is generated by the current flowing through the metal wire 12, which specifically heats the connecting portion 10 in the region of the metal wire 12. With this heating, a predetermined activation energy for the blasting powder is exceeded, so that the blasting powder is ignited and thereby the hook element 4 is "blown away" from the base element 5. After this release of the hook member 4 of the base member 5, the hook member 4 is no longer able to oppose the force exerted by the coil spring 2 force a counter force so that the coil spring 2 can move in the direction of the force F shown in FIG.

After triggering the coil spring 2, this can be moved back into its biased position without much effort and in particular without special tools by being pushed back into the socket 3 and then by hooking a new device in the retaining flange 9 and at the upper side edge of the coil spring 2 is held under bias. It is understood that in the new device 1, the hook member 4 is connected in its initial state as explained above with the base member 5 to initiate the force exerted by the coil spring 2 downward force in the retaining flange 9 and compensate. In Fig. 7, a further embodiment of the device 1 is shown in principle simplified. Here, the hook element and the base member at the connection point 6 each have a toothed portion 13 which are in the initial state with each other. The initial state of the device 1 is shown in Fig. 7 with solid solid lines. Due to the positive connection of hook element 4 and base element 5, it is possible to keep the coil spring 2 in the position shown in Fig. 1 under bias, since a sliding of hook element 4 and base member 5 is prevented in the longitudinal direction from each other.

For example, when the base member 5 is made of a memory metal or a bimetal, detachment of the hook member 4 from the base member 5 can be achieved by thermally activating the joint 6 between the hook member and the base member 5. As a result of this thermal activation, the base element 5 deforms outwardly in the direction of the arrow a and away from the hook element 4, which is indicated in FIG. 7 by dashed lines. In this outward deformation, the toothed portions 13 of the hook member 4 and the base member 5 are disengaged, so that the hook member 4 can not oppose counterforce after this release of the force F exerted by the coil spring 2. Thus, the coil spring 2 can move upward in the direction of the force F as shown in Fig. 1, to trigger the safety function.

In the embodiment of FIG. 7, the toothed portions 13 of the hook member 4 and the base member 5 are glued together, so there is an adhesive bond. By using an explosive powder blended in the adhesive, hook member 4 and base member 5 can be released from each other very quickly by igniting the blasting powder. The activation energy required for the ignition can either be supplied by a sufficient thermal energy from the outside, or alternatively by applying a voltage to a metal wire, which is additionally provided in the region of the toothed areas. The functioning of such Metal wire is explained with reference to Fig. 4 and therefore not described again to avoid repetition.

FIG. 8 shows a section of the base element 5 of the embodiment of FIG. 7 in a longitudinal cross-sectional view. The reference numeral 5a, the side of the base member 5 is referred to, which faces the hook member 4. The reference numeral 5b denotes an outer side of the base element 5, which is opposite to the hook element 4. The base element comprises on its outer side 5b a plating 14, which is firmly connected to a base body 15 of the base element 5. Of the

Base body can be made of a plastic as in the embodiment of FIGS. 1-6, or consist of a metal. In any case, the cladding 14 has a smaller coefficient of thermal expansion than the main body 15 of the base element 5 and was dressed at low temperatures. As a result, the plating 14 deforms outwardly upon heating due to the bimetallic effect, forcibly deforming the base body 15 as well. As a result, when the plating is heated, the base member 5 as a whole deforms in a direction away from the hook member 4, as indicated by dashed lines in FIG.

The base member 5 may also be made of a metal exhibiting an austenitic / martensitic twinning crystal transition above a service temperature and having been cooled below the phase transition temperature using a bending stress. Such a treatment is known as "training", wherein such metal is then referred to as memory metal. After heating to a temperature above the phase transition temperature then spreads the base member 5 in a predetermined direction, ie in the direction of the arrow a of Fig. 7. Thus, if the base member 5 is made of a bimetal or a memory metal is through its Heating, a deformation as shown in Fig. 7 shown by dashed lines, so that thereby the hook element 4 is released from the base member 5. The hook element 4 may have the same structure as the base element 5 according to FIG. 8 with respect to plating or production from a bimetal, with the difference that the plating is then provided on a side of the hook element 4 opposite the base element 5. This has the consequence that the hook element 4 deforms due to the thermal activation, namely away from the base element 5. The effect in relation to the connection point 6 is then the same: the toothed portions 13 of hook element 4 and base element 5 are disengaged , so that these two elements 4, 5 are detached from each other. As a result, the helical spring 2 is movable with its upper side edge 2a in the direction of the force F (FIG. 1).

The invention has been explained above with reference to an embodiment in which the first part as a hook element and the second part as

Base member is formed, and the adhesive connection is provided on flat portions and prevents axial movement. It will be understood that the adhesive bond may also fix other mutually movable mating couples, such as a pivot in the associated hinge eye, a piston in a cylinder, a door to a frame, and others. When the adhesive bond is removed, the mobility or separation of the first part and the second part is achieved.

Appropriate applications for the adhesive bond according to the invention can be found in all security systems, also where emergency exits are to be released by remote release, as well as transport security of sensitive parts, or for releasable attachment of parts that should not be weakened by perforations. For example, a crash box can be glued to a vehicle and simply replaced after a crash. Also, for example, ceramic tiles could be quickly replaced when needed by a vehicle. Other uses of such a composite are also possible: For example, a scaffold could be connected to a façade through the adhesive bond without holes in the façade must be drilled, or a cargo, such as containers, could be secured by the adhesive bond against slipping, for example, each other or against a cargo deck.

Claims

1. Adhesive bond between a first part (4) and a second part (5), wherein the first part (4) is connected by an adhesive to the second part (5), wherein the adhesive is releasable by a thermal activation, characterized characterized in that the thermal activation takes place by supplying electrical energy into the adhesive.

2. Adhesive joint according to claim 1, characterized in that at the contact surface between the first part (4) and the second part (5), a substance which decomposes with the addition of heat energy, is provided.

3. adhesive bond according to claim 2, characterized in that the substance is mixed in the adhesive.

4. Adhesive joint according to claim 2 or 3, wherein at the contact surface between the first part (4) and the second part (5) a metal wire (12) is provided with high resistivity, the converted electrical energy into Joule heat and thereby causes a decomposition of the substance, so that the adhesive bond between the first part (4) and the second part (5) is released.

5. Adhesive bond according to one of claims 1 to 4, wherein the thermal activation takes place by supplying electrical energy, which in a high electrical resistance (12) in electrical conductors

Joule heat is converted.

6. adhesive bond according to one of claims 1 to 5, characterized in that at a connection point (6) between the first part (4) and the second part (5) a metal wire (12) is provided with high resistivity, the supplied electrical Converts energy into Joule heat so that the adhesive melts and the adhesive bond between the first part (4) and the second part (5) is released.

7. Adhesive bond according to one of claims 1 to 5, characterized in that when wiring an electrical voltage is applied to the adhesive, and that a substance mixed into the adhesive carries out a self-sustaining reaction, which leads to a repeal of the adhesive bond.

8. adhesive bond according to claim 7, characterized in that the substance reacts after connection with a component of the adhesive.

9. adhesive bond according to one of claims 1 to 8, characterized in that the second part is biased relative to the first part, and that the release of the adhesive bond is supported by the bias of the second part.

10. Adhesive connection according to one of claims 1 to 9, characterized in that the first part is designed as a base element (5), that the second part as a with the base element (5) connected hook element (4) is formed, both to a A device for holding a prestressed safety system (2), which is held by the hook element (4) under bias, and wherein the part (2a) of the safety system, with which the

Hook element (4) is in its initial state engaged by the release of the connection is movable.

11. Adhesive joint according to claim 10 ₁ in which the hook element (4) elongated and with its longitudinal axis substantially parallel to the security system (2) is arranged.

12. Adhesive joint according to claim 10 or 11, wherein the base element (5) is elongated and whose longitudinal axis is aligned with the longitudinal axis of the hook element (4).

13. Adhesive connection according to one of claims 10 to 12, wherein the hook element (4) and the base element (5) each have a toothed portion (13), which portions a positive connection of hook element (4) and base element (5) in the initial state guarantee.

14. Adhesive joint according to claim 13, wherein the base element (5) and / or the hook element (4) are at least partially made of a memory metal or a bimetal, so that these elements move away from each other during thermal activation and thereby the positive connection the toothed sections

(13) is repealed.

15. Adhesive connection according to one of claims 1 to 9, characterized in that the first part and the second part together define a guide.

16. Adhesive connection according to one of claims 1 to 9, characterized in that the first part and the second part together define a joint.

17. Adhesive composite of a first part (4) and a second part (5), which are held together by a releasable adhesive bond according to one of claims 1 to 16.

18. A method for producing a releasable adhesive bond between a first part (1) and a second part (2), wherein the adhesive bond comprises an adhesive, characterized in that in the adhesive, a substance is mixed, which dissolves the adhesive upon the supply of energy and the connection picks up.

19. The method according to claim 18, characterized in that the energy via a conductor as an electrical ignition current in the mixture

Adhesive and the substance is introduced.

20. Use of a mixed in an adhesive ignitable substance for releasably connecting two parts (4, 5).