EP2826598A1 - Pressing tool with a mechanically acting pressing force limiter - Google Patents

Abstract

The invention relates to a pressing tool (1), which is preferably designed as pressing tongs. According to the invention, the pressing tool has a mechanical pressing force limiting device (63). The pressing force limiting device (63) restricts the pressing force which can be brought about with the pressing tool (1) to a predetermined set pressing force independently of a magnitude of a pressing stroke. The pressing tool according to the invention finds particular use for clamps (3), which are mounted by means of plastic deformation.

Description

The invention relates to a pressing tool for pressing a workpiece. For example, the pressing of the workpiece for frictional or tight connection of components, in particular a nozzle with a pipe or a hose, a sleeve with a shaft o. Ä. (Under some circumstances, a plastically pressed clamp), use, wherein during compression of the Workpiece a plastic deformation of the same can take place. Furthermore, the invention relates to a manually operated pressing tongs and a new use of a special pressing tool or a pressing tongs.

The pressing tool can be any tool by means of which a pressing or "crimping" of any workpiece takes place. An exemplary possible application of the invention is a crimping pliers used for hose clamps of a particular type. Hose clamps are known in which the clamping force is generated via a worm drive actuated by means of a worm screw, the tightening torque of the worm screw predetermining the clamping force. By way of derogation, the clamping force for the particular type of hose clamps can not be brought about by such a worm drive but by means of a plastic deformation produced by a pressing tongs according to the invention. This type of hose clamps is used, for example, in the automotive sector, for example for fixing an axle collar on an axle shaft via a plastically deformed hose clamp. The clamping force in this case determines a sealing force between the sleeve and the axle shaft and a holding force or fixing force. Another field of application of such hose clamps is, for example, the "white goods" with all products in which a hose must be clamped onto a nozzle to produce a sealing effect.

STATE OF THE ART

Usually, the maximum pressing force during pressing of a workpiece by means of a pressing tool by the applied operating force, for example, manually applied to the hand lever of a pressing tongs applied hand forces or the force of an actuator in a pressing machine. The extent of pressing a workpiece by means of a manually operated pressing tongs is thus dependent on the skills and a reproducible, sensitive operation of the user on the hands. By contrast, the reproducible pressing of a workpiece with a predetermined set pressing force by means of an actuator of a pressing machine requires the use of sensors for detecting the pressing force during the pressing stroke and / or a control or regulation of the actuation by the actuator.

DE 42 41 971 C1 discloses a hydraulic pressing tool in which the hydraulic pressure used to actuate the pressing tool is monitored by means of a pressure sensor. Upon reaching a predetermined limit value, a drive motor for a pump, which generates the hydraulic pressure, switched off, whereby ultimately the pressing force of the pressing tool is specified. Alternatively, in the hydraulic supply circuit and a pressure relief or pressure relief valve may be present, which limits the hydraulic pressure and thus the pressing force.

DE 101 40 270 B4 discloses a manually operated crimping tool for pressing a plurality of notches on the circumference of a contact element. The pressing tongs have a pressing stroke limiting device, which is designed as an adjusting screw on which a drive element comes into contact with reaching the adjustable desired pressing stroke. In the manually operated pressing tongs a compulsory locking mechanism is used. In order to allow that the desired pressing stroke is also set so small that with actuation of the actuating element on the adjusting screw the actuating stroke, which is required to open the Zwangsgesperres has not yet reached hits DE 101 40 270 B4 to provide the drive mechanism with an elasticity, which is referred to here as a force-displacement compensating element and as a block consists of a compressible plastic material. An actuation of the hand lever beyond the actuating stroke, for which the drive element comes to rest on the adjusting screw, thus leading to an increasing elastic deformation of the force-displacement compensating element, until the required operating stroke is achieved to release the Zwangsgesperres. In the case of ideal workpieces, in particular without tolerance and Manufacturing inaccuracies of the geometry, and ideal exact insertion of the workpieces in a press tool correlates the adjustable pressing stroke according to DE 101 40 270 B4 with a predetermined desired pressing force. For real workpieces with tolerances and manufacturing inaccuracies as well as imperfections as well as not exactly inserting the workpiece into the pressing tool, the pressing stroke predetermined by the adjusting screw leads to pressing forces varying from pressing process to pressing process.

OBJECT OF THE INVENTION

The object of the present invention is to optimize a pressing tool or a pressing tongs for pressing a workpiece in such a way that defined pressing conditions are present at the end of the pressing stroke, whereby the process reliability can be increased.

SOLUTION

The object of the invention is achieved with the features of the independent claims. Further preferred embodiments according to the invention can be found in the dependent claims.

DESCRIPTION OF THE INVENTION

• Handelt es sich bei dem zu verpressenden Werkstück um ein Kontaktelement, beispielsweise eine Verbindung zwischen einem Stecker und einem Leiter, führt die vorgegebene Soll-Presskraft am Ende des Pressvorgangs zu der Gewährleistung der gewünschten Kontaktierung, wobei auch Beschädigungen von Stecker oder Leiter infolge von zu großen Presskräften vermieden sein können. Andererseits kann eine definierte mechanische Verbindung zwischen Stecker und Leiter herbeigeführt werden, wodurch beispielsweise vermieden werden kann, dass sich im Betrieb des Werkstücks nach Beendigung des Pressvorgangs der Stecker von dem Leiter löst.
• Bei einem Werkstück in Form einer Verbindung von Schläuchen, Stutzen, Steckern, Anschlüssen und/oder Schellen führt die definierte Soll-Presskraft am Ende des Pressvorgangs dazu, dass eine zuverlässige mechanische Verbindung geschaffen ist. Soll die mechanische Verbindung gleichzeitig die Dichtigkeit gewährleisten, trägt die definierte Soll-Presskraft am Ende des Pressvorgangs auch zu einer hohen Zuverlässigkeit der Abdichtung bei.

The invention proposes a pressing tool, by means of which regardless of any manufacturing tolerances or imperfections of the workpiece and inaccuracies in the contact of the workpiece with the pressing tool or when inserting the workpiece in the tool or regardless of the size and type of the workpiece and thus of The size of a pressing stroke at the end of the pressing stroke a pressing force is brought about, which corresponds as exactly as possible to a predetermined target pressing force. This has the following advantages, for example:

• If the workpiece to be compacted is a contact element, for example a connection between a plug and a conductor, the predetermined desired pressing force at the end of the pressing operation leads to ensuring the desired contacting, whereby damage to the plug or conductor as a result of too large pressing forces can be avoided. On the other hand, a defined mechanical connection between plug and conductor can be brought about, for example, whereby it can be avoided that the plug is released from the conductor during operation of the workpiece after completion of the pressing operation.
• In the case of a workpiece in the form of a connection of hoses, nozzles, plugs, connections and / or clamps, the defined nominal pressing force at the end of the pressing operation results in a reliable mechanical connection being created. If the mechanical connection at the same time to ensure the tightness, the defined target pressing force at the end of the pressing process also contributes to a high reliability of the seal.

According to the invention, a pressing force limiting device is used in the pressing tool. This is (different from DE 42 41 971 C1 not designed as a pressure sensor with electrical or hydraulic control or as a pressure relief valve, but) designed as a mechanical pressing force limiting device, whereby a high reliability (while avoiding non-mechanical measures such as electrical sensors and / or hydraulic, pneumatic or electrical control devices) can be ensured. The mechanical pressing force limiting device limits the pressing force which can be brought about with the pressing tool to a predetermined set pressing force. In the context of the invention, this limitation to the predetermined desired pressing force is independent of a size of a pressing stroke, ie not as a pressing stroke limiting device. This will be explained by the following non-limiting example:

Is in the pressing tongs according to DE 101 40 270 B4 at the same setting of the adjusting screw for a first pressing a first workpiece with a first geometry and for a second pressing a second workpiece with a second geometry, which is greater than the first geometry, inserted, so ensures the pressing tongs according to DE 101 40 270 B4 in that the same pressing stroke has to be run through for both pressing operations. This has the consequence necessarily that for the second workpiece a deformation takes place to a greater extent, which usually causes greater pressing forces at the end of the press stroke. In other words, a desired pressing force for different pressing strokes is achieved for this pressing tongs, for example for the first workpiece at the end of the pressing stroke and for the second workpiece already before the end of the pressing stroke. Thus here is the pressing force not limited to a predetermined set pressing force, regardless of a size of the press stroke. In contrast, the mechanical pressing force limiting device according to the invention limits the desired pressing force regardless of the size of the pressing stroke, which may mean that the desired pressing force is independent of a geometry and any tolerances of the workpiece and regardless of the respective positioning and alignment of the workpiece in the tool can be ensured.

It is entirely possible that with the completion of the pressing process and the limitation of the pressing force by the mechanical pressing force limiting device by a controller, an actuator or the user to initiate further steps to move the pressing tool back to the starting position, which for example at a position with open pressing jaws can act. For a particular proposal of the invention, the pressing tool has a return device. The return device automatically moves the pressing tool back to an initial position upon reaching the predetermined threshold value (and activation of the pressing force limiting device). While basically any embodiments of the restoring device are possible, this is preferably a mechanical restoring device, which can use, for example, an energy stored in a spring during the pressing stroke. For a pressing tool in this embodiment, under certain circumstances results in a particularly simple handling or actuation, for which after completion of the press stroke and activation of the pressing force limiting device automatically moves to the starting position, which then can take place a removal of the workpiece from the pressing tool.

It is possible that the pressing tool has a fixed predetermined desired pressing force. In a further embodiment of the invention, the desired pressing force is adjustable. This allows a fine adjustment of the working range of the pressing tool done. It is also possible that the pressing tool is made multifunctional by the adjustability of the predetermined desired pressing force, by this for pressing different workpieces, which require different predetermined set pressing forces, (possibly also with the use of different dies held on the tool) can be used.

• die Abstützung der Pressbacke über eine nicht vorgespannte Feder, so dass sich mit Erhöhung der Presskraft kontinuierlich die Pressbacke unter Beaufschlagung der Feder bewegen kann, oder
• die Abstützung der Pressbacke an der Feder mit Vorspannung derselben, womit sich die Pressbacke mit Erhöhung der Presskraft erst bewegt, wenn die Vorspannkraft der Feder überwunden ist.

For the specific embodiment of the mechanical pressing force limiting device, there are many possibilities, which are not disclosed in the present patent application Embodiments are limited. For an embodiment according to the invention, the pressing tool has a pressing jaw, which is supported by a spring. During the pressing stroke, the pressing jaw can thus be moved under the action of the spring or "yield" in the pressing direction. In this case, the pressing force limiting device is activated in a motion-controlled manner by the pressing jaw (or a component moved with it) supported by the spring. In this case, embodiments are included in which the pressing jaw is supported directly or indirectly using further components moved with the pressing jaw via the spring. It is possible here

• the support of the pressing jaw over a non-preloaded spring, so that can move continuously with increasing the pressing force, the pressing jaw under the action of the spring, or
• the support of the pressing jaw on the spring with bias thereof, whereby the pressing jaw moves with increasing the pressing force only when the biasing force of the spring is overcome.

In a further embodiment of the invention, the setting of the desired pressing force on the setting of a game. The size of the game is dependent on the movement of the pressing jaw or a component moved with the pressing jaw during the pressing process. The activation of the pressing force limiting device takes place with complete closing of the game, whereby an activation connection, a mechanical contact o. Ä. Is created, which has the activation of the pressing force-limiting device result. To name just one example, the contact or the activation connection can generate contact forces, which cause a release of a Zwangsgesperres and / or a return movement of the pressing tool in a starting position.

In a further embodiment of the invention, a drive connection is present in the pressing tool. This drive connection can be achieved by activating the pressing force limiting device, so that no further drive is possible and thus no further increase in the pressing force beyond the set pressing force is possible. It is also possible that by activating the pressing force limiting device, the drive connection is blocked.

In a further embodiment of the invention, the supported via the spring pressing jaw or a moving with this device is equipped with a display unit. The display unit is visible from the outside. By means of the display unit, the extent of the movement of the supported via the spring pressing jaw and thus the pressing force can be displayed, whereby a further increase in process reliability can be done and the user additional monitoring options are provided. The display unit is preferably formed mechanically, wherein a display element can be mechanically coupled to the resiliently supported pressing jaw.

For a particular proposal of the invention, the display unit is multifunctional in that it not only displays the pressing force, but also serves to adjust the predetermined target pressing force and the display of the set predetermined set pressing force. It is advantageous if the display unit is coupled or connected to a component which is moved both with the movement of the pressing jaw with increasing the pressing force and is moved in the course of setting the target pressing force.

The present pressing tool can be any drive mechanism, such as a scissor-type drive, a drive according to DE 101 40 270 B4 with pull tabs, a toggle drive u. Ä., Own, wherein the movement of the pressing jaws can also be translational or can be done by means of a pivoting movement. In a particular embodiment of the invention, the pressing tool has a drive mechanism by means of which several pressing stages can be executed before reaching the predetermined desired pressing force. During the several pressing stages, actuating members, for example hand levers, pass through the same stroke several times, which ultimately ensures a large total stroke, which results from the sum of the strokes in the individual several pressing stages. In this way, the conflict of objectives of a compact embodiment of the pressing tool on the one hand and the enabling of small actuating forces, which require a large translation, can be resolved.

In a further embodiment of the invention, a Zwangsgesperre is present, which only allows a return to the starting position of the pressing tool when the pressing force limiting device is activated or a predetermined or set movement of the supported via the spring pressing jaw is done. Thus, the Zwangsgesperre ensures that a once achieved press position is maintained even if a Actuating force is at least temporarily eliminated. Faulty operations in which the pressing stroke has not gone so far that the pressing force-limiting device has been activated, can be avoided by using the Zwangsgesperres.

In principle, it is possible that the Zwangsgesperre is unlocked after or at the time at which the pressing force limiting device is activated. In a preferred embodiment of the invention, however, the unlocking of Zwangsgesperres before the press force limiting device is activated.

As mentioned above, the pressing tool according to the invention may be a pressing tool of any desired configuration. Also for an embodiment of the pressing tool as a pressing machine with an electric, pneumatic or hydraulic actuator may advantageously be used, the mechanical pressing force limiting device. For a solution to the problem underlying the invention but a manually operated pressing tongs as a pressing tool, as has been previously described, formed. In this pressing tongs, the pressing force limiting means ensures that the pressing force can not become larger than the target pressing force, regardless of the operation by the user and the manual force applied by the users.

The pressing tool according to the invention or the manually operated pressing tongs can be used for the compression of any workpieces. For a further proposal of the invention finds a press shop of the type described above or a manually operated pressing tongs of the type described above use for pressing a (pipe) clamp, which is mounted with a plastic pressing the clamp, for example by the clamp on a hose or a pipe is pressed, which in turn is to be pressed against the outer surface of a nozzle arranged in the interior, a pipe end or a shaft o. Ä. Preferably, the crimping tool is designed as a so-called ear clamp.

Advantageous developments of the invention will become apparent from the claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the description are merely exemplary and can take effect alternatively or cumulatively, without the advantages having to be achieved by embodiments according to the invention. Without thereby the subject of attached As regards the disclosure content of the original application documents and the patent, the following applies: Further features can be taken from the drawings-in particular the illustrated geometries and the relative dimensions of several components relative to one another and their relative arrangement and operative connection. The combination of features of different embodiments of the invention or of features of different claims is also possible deviating from the chosen relationships of the claims and is hereby stimulated. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, in the claims listed features for further embodiments of the invention can be omitted.

The features mentioned in the patent claims and the description are to be understood in terms of their number that exactly this number or a greater number than the said number is present, without requiring an explicit use of the adverb "at least". For example, when talking about an element, it should be understood that there is exactly one element, two elements or more elements. These features may be supplemented by other features or be the only characteristics that make up the product in question.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1

zeigt einen relevanten Teil eines Presswerkzeugs in einer geschnittenen Seitenansicht.

Fig. 2

zeigt das Presswerkzeug gemäß Fig. 1 am Ende einer ersten Pressstufe.

Fig. 3

zeigt das Presswerkzeug gemäß Fig. 1 und 2 zu Beginn einer zweiten Pressstufe.

Fig. 4

zeigt das Presswerkzeug gemäß Fig. 1 bis 3 zum Zeitpunkt des Aktivierens der Presskraft-Begrenzungseinrichtung.

Fig. 5

zeigt die automatische Rückstellung des Presswerkzeugs gemäß Fig. 1 bis 4 in Richtung der Ausgangsstellung nach Aktivieren der Presskraft-Begrenzungseinrichtung, wobei ein Sperrelement eine Führung in einer gelösten Stellung hält.

Fig. 6

zeigt das Presswerkzeug gemäß Fig. 1 bis 5 nach Aktivieren der PresskraftBegrenzungseinrichtung, wobei die Führung von dem Sperrelement wieder freigegeben worden ist und eine Vorschubeinheit als Bestandteil des Antriebsmechanismus wieder in Eingriff gebracht worden ist.

Fig. 7

zeigt das Presswerkzeug gemäß Fig. 1 bis 6 in einer Explosionsdarstellung.

In the following the invention will be further explained and described with reference to preferred embodiments shown in the figures.

Fig. 1

shows a relevant part of a pressing tool in a sectional side view.

Fig. 2

shows the pressing tool according to Fig. 1 at the end of a first pressing stage.

Fig. 3

shows the pressing tool according to Fig. 1 and 2 at the beginning of a second pressing stage.

Fig. 4

shows the pressing tool according to Fig. 1 to 3 at the time of activating the pressing force limiting means.

Fig. 5

shows the automatic recovery of the pressing tool according to Fig. 1 to 4 in the direction of the initial position after activating the pressing force limiting device, wherein a blocking element holds a guide in a released position.

Fig. 6

shows the pressing tool according to Fig. 1 to 5 after activating the pressing force limiting device, wherein the guide has been released from the locking element and a feed unit has been re-engaged as part of the drive mechanism.

Fig. 7

shows the pressing tool according to Fig. 1 to 6 in an exploded view.

DESCRIPTION OF THE FIGURES

The Fig. 1 to 6 show the relevant part of a pressing tool 1 in different operating positions during the pressing process and the return to a starting position. In Fig. 7 the pressing tool 1 is shown in exploded view. The pressing tool 1 is a manually operated pressing tongs 2.

The crimping tool 2 is used for crimping and plastically deforming a (pipe) clamp 3, for example, to connect two radially inwardly arranged from this components frictionally and / or positively and mechanically permanently with each other and / or seal against each other. It is possible that the clamp 3 is used for attaching an axle cuff on a shaft.

The pressing tongs 2 is manually operated by hand lever 4, 5, wherein in the in Fig. 1 to 6 shown section of the pressing tongs 2 only the hand lever 4 can be seen. The hand lever 4 is pivotally mounted about a bearing pin 6 formed by a pivot bearing 7 relative to a housing 8 or pliers head. By contrast, the hand lever 5 is rigidly connected to the housing 8. The pressing of a workpiece 9, here the clamp 3 with further components arranged therein, takes place between two pressing jaws 10, 11, which are spaced apart from each other, formed by bearing pins 12, 13 pivot bearing 14, 15th from the starting position according to Fig. 1 are pivotable in a closed position and back to the starting position. The bearing pins 12, 13 are fixed relative to the housing 8. Upon actuation of the hand lever 4, 5, without a workpiece 9 is received between the pressing jaws 10, 11, the pressing jaw 11 moves relative to the housing 8, while the pressing jaw 10 does not move relative to the housing 8. A resilient support of the pressing jaw 10 via a spring 16 relative to the housing 8 only comes into effect when 9 pressing forces are exerted on the pressing jaws 10, 11 during a pressing operation as a result of a clamped between the pressing jaws 10, 11 workpiece.

The hand lever 4 is L-shaped, wherein in the free end region of the much longer leg, the manual operation is performed by the user. The pivot bearing 7 is arranged in the connecting region of the two legs of the L. The free end portion of the shorter leg of the L carries a bearing pin 17, which is pivoted about the pivot bearing 7 with the hand lever 4. The bearing pin 17 forms a pivot bearing 18 for an end region of a pull tab 19. In the other end region of the pull tab 19, a pivot bearing 21 is formed with a bearing pin 20, via which the pull tab 19 is hinged to a feed unit 22.

The feed unit 22 has a guide 23, which is designed here as a pivot bar and in Fig. 1 on the bottom has a sliding or guide surface 24. The guide 23 is supported via a bearing pin 25 to form a pivot bearing 26 pivotally relative to the housing. About a spring 27, the guide 23 in Fig. 1 counteracted about the pivot bearing 26 counterclockwise. A housing 28 of the feed unit 22 is guided on the guide surface 24 of the guide 23 via rollers 29, 30. Furthermore, the feed unit 22 has a feed lever 31, which by means of a bearing pin 32 with the formation of a pivot bearing 33 relative to the housing 28 of the feed unit 22 is pivotable. The feed lever 31 is in this case in Fig. 1 clockwise acted upon by a spring 34.

Opposite the housing 8 is in Fig. 1 slidably guided in the horizontal direction, a feed rod 35. The feed lever 31 and the feed rod 35 are interacting with locking teeth 36, 37, wherein the locking teeth 36 of the feed lever 31 is formed in the region of the abutting on the feed rod 35 end face, while the locking teeth 37 of the feed rod 35 in the contact area on the top of the same is. The locking teeth 36. 37 are pressed together by the spring 34 and the spring 27. The locking teeth 36, 37 are formed such that at pressure forces in the feed lever 31 as a result of movement of the feed unit 22 in Fig. 1 to the right (ie in the direction of the pressing jaw 11) the toothing 36 of the feed lever 31 as a result of the acting positive engagement, the feed rod 35 entrains. By contrast, the engagement of the locking teeth 36, 37 no tensile forces transmitted to the feed lever 31 - but slides on a movement of the feed unit 22 of the pressing jaw 11 away the locking teeth 36 ratchet-like along the locking teeth 37, so that the feed rod 35 is not taken.

In which the pressing jaw 11 facing end portion of the feed rod 35 is hinged to this via a formed with a bearing pin 38 pivot bearing 39, a thrust pocket 40 which is hinged in the end of the feed rod 35 end portion via a bearing pin 60 on the pressing jaw 11. The effective direction of the push rod 40, which results from the connecting axis of the bearing bolt formed with the pivot bearing 61 and the pivot bearing 39 extends eccentrically to the pivot bearing 14 of the pressing jaw 11, so that a thrust force in the push rod 40 applies a closing moment on the pressing jaw 11.

Apart from the locking teeth 37, the feed rod 35 has a further toothing 41, in which a locking element 42 engages with a tooth or a toothing. The blocking element 42 is guided vertically to the guide direction of the feed rod 35 and acted upon by a spring 43 in the direction of the toothing 41 of the feed rod 35. The feed rod 35 is in Fig. 1 via a spring 44, in particular a tension spring, acted upon by the pressing jaw 11 away. The feed rod 35 can be in Fig. 1 in the direction of the press jaw 11 ratchet-like move relative to the locking element 42, while for movement of the feed rod 35 in the opposite direction due to the positive engagement of the locking element 42 in the teeth 41, the movement of the feed rod 35 is blocked. With the teeth 41 and the blocking element 42, a Zwangsgesperre 45 is formed. The teeth 36, 37 on the one hand and the Zwangsgesperre 35 thus block a movement of the feed rod 35 in mutually opposite directions.

The pressing jaw 10 is (integrally formed for the illustrated embodiment) of a cranked or L-shaped lever 46 in the region of the much shorter leg of the L, wherein the pivot bearing 14 in the region of the crank or the connecting portion the leg of the L is arranged. In the press jaw 10 facing away from the end portion of the lever 46 is supported by the spring 16 on the housing 8, which can be done without or with bias of the spring 16. With increasing pressing force on the pressing jaw 10 (and for prestressed spring 16 only when exceeding a predetermined by the bias threshold force) pivots the lever 46 in Fig. 1 counterclockwise about the pivot bearing 14 relative to the housing 8, which corresponds to an opening movement of the pressing jaw 10. Here, this opening movement of the pressing jaw 10 is smaller or much smaller than the corresponding closing movement of the other pressing jaw eleventh

The lever 46 carries, in particular adjacent to the end region, which interacts with the spring 16, an adjusting screw 47 or a Einstellpin which or which is oriented tangentially to the pivot axis of the pivot bearing 14. An actuation and display unit 49 is pressed against the front of the adjusting screw 47 arranged inside the pressing tongs 2 via a spring 48 supported on the housing 8. For the illustrated embodiment, the actuation and display unit 49 is L-shaped with a shorter leg 50 which abuts the end face of the adjusting screw 47, and a longer leg 51 which has a bore in the region of which a guide parallel to the adjusting screw 47 is carried by a housing 8 carried by the guide rod formed.

Furthermore, an activating element 54 is rotatably mounted relative to the housing 8 by means of a pivot bearing 53 formed with a bearing pin 52. The activation element 54 has approximately in a 3 o'clock position via a projection 55 and in a 12 o'clock position via a projection 56. The projection 55 engages in the in Fig. 1 At the projection 56, the guide 23 is supported in such a way that the projection 56 obstructs a pivoting of the guide 23 of the feed rod 35 away. A spring 66 acts on the activation element 54 in Fig. 1 in the clockwise direction and in the direction of the explained blocking a movement of the guide 23, which is oriented away from the feed rod 35. Between an extension of the activation element 54, which is arranged approximately in the 9 o'clock position, and the underside of the leg 50 of the actuation and display unit 49 is in the starting position according to Fig. 1 a game 59 formed.

The function of the pressing tongs 2 will be described below with reference to the different operating positions Fig. 1 to 6 explains:

In the starting position according to Fig. 1 the hand lever 4, 5 are open and between the pressing jaws 10, 11, the workpiece 9 is inserted, which is still undeformed at this time.

Starting from the starting position according to Fig. 1 pivoted the hand lever 4 in a first pressing stage in the direction of the hand lever 5 by applying actuation forces by the user, this pivoting leads to a movement of the bearing pin 17 on a circular path around the pivot bearing 7. The pull tab 19 converts this movement in a translational movement of the Feed unit 22 in Fig. 1 in the direction of the pressing jaw 11, which is guided by the guide 23. Here, under pressure of the feed lever 31 to pressure on the bearing pin 32, the feed lever 31, the locking teeth 36 and the locking teeth 37, a thrust force applied to the feed rod 35. This thrust is in turn transmitted via the bearing pin 38, the push rod 40 and the bearing pin 60 on the die 11, whereby under deformation of the workpiece 9, a closing movement of the dies 10, 11 takes place. Fig. 2 shows the end position of the hand lever 4 with completion of the first pressing stage, for which the hand lever 4 is oriented parallel to the hand lever 5, wherein Fig. 2 the hand lever 4 is covered by the other components.

It can be seen in Fig. 2 in that, as a result of the pressing forces acting on the pressing jaw 10, a slight pivoting of the lever 46 takes place under the action of the spring 16. This pivoting of the lever 46 has the consequence that the game 59 has become smaller or even eliminated altogether, so that the leg 50 comes to rest on the extension 58.

In order to enable a further pressing stage, then the hand lever 4 is then pivoted back away from the user of the hand lever 5, until the in Fig. 3 shown position of the hand lever 4 is reached. In this case, ratchet-like sliding of the feed lever 31 with its locking teeth 36 via the locking teeth 37 of the feed rod 35 so that the feed unit 22 can be moved back to the left and away from the pressing jaw 11 without the feed rod 35 is taken. The reached at the end of the first pressing stage position of the feed rod 35 is hereby secured by the Zwangsgesperre 45. Preferably, the tooth spacing of the toothing 41 of the forced locking mechanism 45 corresponds to the extent of movement of the feed rod 35, which can be brought about with the stroke of the hand lever 4 in the first pressing stage. Based on the operating position according to Fig. 3 can then be carried out the second pressing stage, in which first any game 59, which is left after the first pressing stage, is overcome, which is analogous to the description during the first pressing step. If the game 59 overcome, a further movement of the hand lever 4, 5 leads to a further increase in the pressing force on the pressing jaw 10 and a further pivoting of the lever 46. This movement of the lever 46 takes over the adjusting screw 47, the actuating and display unit 49 (counter to its application by the spring 48) with. The actuation and display unit 49 in turn takes over the extension 58 with the activation element 54. The pivoting of the activation element 54 in the counterclockwise direction caused thereby has, as in FIG Fig. 4 can be seen, first the consequence that the extension 55, the locking element 42 from the teeth 41 (counteracting the action of the spring 43) lifts, which basically due to the action of the spring 44 and the acting pressing forces movement of the feed rod 35 of the press jaw 11 could be done away. However, act via the locking teeth 37, 36 still generated by the hand levers 4, 5 feed forces, which continue the pressing force is maintained at the pressing jaws 10, 11. At the same time or with a further increase in the pressing force but the projection 56 out of contact with the guide 23, which has the consequence that, in particular caused by acting on the locking teeth 37 compressive force the guide 23 and hereby the entire feed unit 22 to the pivot bearing 26th can pivot away from the feed rod 35 ( Fig. 4 ). Since the movement of the feed lever 31 is limited in the direction of the feed rod 35 by a stop 62 formed by a pin, comes with the pivoting of the feed unit 22, the locking teeth 36 of the feed lever 31 out of engagement with the locking teeth 37 of the feed rod 35. This entails that the feed rod 35 is moved due to the pressing forces on the pressing jaws 10, 11 and the spring 44 in the opening direction and away from the pressing jaw 11, which is accompanied by an opening movement of the pressing jaws 10, 11. In order to avoid that prior to the complete opening of the pressing jaws 10, 11 again pivoting back of the feed unit 22 takes place and hereby engage the locking teeth 36, 37 again, a blocking element 64 (shown in phantom in the figures) is pushed under the guide 23, which the Guide 23 (and thus the feed unit 22) at a distance from the feed rod 35 holds, so that the locking teeth 36, 37 do not interact with each other ( Fig. 5 ). For the illustrated embodiment, the blocking element 64 is displaceably guided relative to the housing 8 and supported by a spring, not shown here so that the blocking element 64 is acted upon in the direction of the feed unit 22. The movement of the feed rod 35 of the pressing jaw 11 away is caused by the spring 44. Upon reaching the starting position, ie open pressing jaws 10, 11, an extension or an end face of the feed rod 35 comes to rest on a shoulder or an end face of the locking member 64. Here, the stiffness of the spring 44, over which the feed rod 35 is retracted, greater than the rigidity of the not shown Spring, which acts on the blocking element 64 in the direction of the guide 23 blocking position. This has the consequence that with approach to the starting position, the feed rod 35, the blocking element 64 entrains, which in accordance with Fig. 6 the support or blockage of the return movement of the guide 23 and the feed unit 22 is eliminated. This in turn has the consequence that in the initial position, the guide 23 and the feed unit 22 can pivot back again, which is in particular caused by the spring 27, which again the operative connection between the locking teeth 36, 37 can be brought about ( Fig. 6 ). Now, the hand lever 4 can be pivoted outwards again, whereby the feed lever 31 rides like a ratchet with its locking teeth 36 along the locking teeth 37. This is the in Fig. 1 restored initial position shown.

With the lever 46, the spring 16, the adjusting screw 47, the actuating and display unit 49, the activation element 54 and its interaction via the projection 55 with the blocking element 42, the projection 56 with the guide 23 and the extension 58 with the actuating and display unit 49, a pressing force limiting means 63 is formed. This is activated at the moment in which the guide 23 fixing effect of the projection 56 is removed and the locking teeth 36, 37 are disengaged and the locking element 42 is lifted out of the toothing 41. With this activation, no further increase in a pressing force can take place - on the contrary, the pressing tongs 2 automatically return (at least partially) to the initial position Fig. 1 with open pressing jaws 10, 11 back.

About the size of the game 59, the spring stiffness of the spring 16 and the lever ratios to the lever 46 can be specified for which pressing force the pressing force limiting device 63 is activated. This maximum pressing force, which is also referred to as desired pressing force, can thus be adjusted by changing the screwing of the adjusting screw 47, whereby the game 59 increases or decreases. With the screwing of the adjusting screw 47, the actuating and display unit 49 moves. This can have a pointer, not shown in the figures, which is visible from the outside of the pressing tongs 2. It is possible that in the area of the pointer, the housing 8 has a scale. By changing the screwing of the adjusting screw 47, the pointer moves along the scale, whereby the size of the game 59 and thus the size of the target pressing force for which the pressing force limiting device 63 is activated, is visible from the outside and also a setting process of the adjusting screw 47 can be visually monitored by the operator.

A return device 65, which automatically moves the pressing tool at least partially back to an initial position upon reaching the predetermined pressing force, is formed with the spring 44. If a temporary blockage of the return movement of the feed unit 22 is required, the return device 65 is also formed with the blocking element 64 and the associated spring.

LIST OF REFERENCE NUMBERS

1

press tool

2

crimping pliers

3

clamp

4

hand lever

5

hand lever

6

bearing bolt

7

pivot bearing

8th

casing

9

workpiece

10

pressing jaw

11

pressing jaw

12

bearing bolt

13

bearing bolt

14

pivot bearing

15

pivot bearing

16

feather

17

bearing bolt

18

pivot bearing

19

pull tab

20

bearing bolt

21

pivot bearing

22

feed unit

23

guide

24

guide surface

25

bearing bolt

26

pivot bearing

27

feather

28

casing

29

role

30

role

31

feed lever

32

bearing bolt

33

pivot bearing

34

feather

35

stinger

36

locking teeth

37

locking teeth

38

bearing bolt

39

pivot bearing

40

pushrod

41

gearing

42

blocking element

43

feather

44

feather

45

Zwangsgesperre

46

lever

47

adjustment

48

feather

49

Actuator and display unit

50

leg

51

leg

52

bearing bolt

53

pivot bearing

54

energizer

55

head Start

56

head Start

57

recess

58

extension

59

game

60

bearing bolt

61

pivot bearing

62

attack

63

Pressing force-limiting device

64

blocking element

65

Reset device

66

feather

Claims (13)

Pressing tool (1) for pressing a workpiece, characterized in that a mechanical pressing force limiting device (63) is provided which limits the pressing force with the pressing tool (1) independently of a magnitude of a pressing stroke to a predetermined desired pressing force. Press tool (1) according to claim 1, characterized in that a restoring device (65) is present, which automatically moves the pressing tool (1) back to an initial position upon reaching the predetermined threshold value. Pressing tool (1) according to claim 1 or 2, characterized in that the predetermined desired pressing force is adjustable. Pressing tool (1) according to one of the preceding claims, characterized in that a) the pressing tool (1) has a spring (16) supported pressing jaw (10) and b) the pressing force limiting device (63) is activated in a motion-controlled manner by means of the pressing jaw (10) supported by the spring (16) or by a component moved therewith. Press tool (1) according to claim 4 when appended to claim 3, characterized in that the setting of the desired pressing force via the setting of a game (59), the size of the movement of the pressing jaw (10) or one with the pressing jaw (10 Moving device is dependent, with the closure of the game (59), the pressing force limiting device (63) is activated. Pressing tool (1) according to claim 4 or 5, characterized in that a drive connection is present, which can be released or blocked by activating the pressing force-limiting means (63). Pressing tool according to one of the preceding claims, characterized in that the pressing jaw (10) supported by the spring or a component moved with the latter is equipped with a mechanical display unit (49) which is visible from the outside and the extent of movement of the spring via the spring (16) supported pressing jaw (10) and thus the pressing force indicates. Press tool (1) according to claim 7, characterized in that the mechanical display unit (49) displays both the pressing force and the setting of the predetermined desired pressing force. Pressing tool (1) according to one of the preceding claims, characterized in that the pressing tool (1) has a drive mechanism by means of which a plurality of pressing stages can be executed before reaching the predetermined desired pressing force. Crimping tool (1) according to any one of the preceding claims, characterized in that a Zwangsgesperre is present, which only allows a return to the starting position when the pressing force limiting means (63) is activated or a predetermined or set movement of the spring ( 16) supported pressing jaw (10) is done. Crimping tool (1) according to claim 10, characterized in that the Zwangsgesperre is unlocked at a pressing force which is smaller than the desired pressing force for which the pressing force limiting means (63) is activated. Manually operated pressing tongs (2) in the form of a pressing tool (1) according to one of the preceding claims. Use of a pressing tool (1) according to one of claims 1 to 11 or a manually operated pressing tongs (2) according to claim 12 for pressing a clamp (3), which is mounted with a plastic pressing.

Images