WO2007076955A2

WO2007076955A2 - Pliers

Info

Publication number: WO2007076955A2
Application number: PCT/EP2006/012377
Authority: WO
Inventors: Christian Knoll; Philipp BÖHMEL; Otmar Karle
Original assignee: Wiha Werkzeuge Gmbh
Priority date: 2005-12-22
Filing date: 2006-12-21
Publication date: 2007-07-12
Also published as: WO2007076955A3; WO2007076955A8

Abstract

The invention relates to a pair of pliers comprising: two parts (3, 5), each of which having a gripping jaw (9, 13) provided with a gripping surface; an articulation (7) that pivotally connects the two parts (3, 5); and handle elements (17, 19) that are associated with the parts (3, 5). The pliers are characterised in that at least one of the opposing gripping surfaces is curved, i.e. is convex with respect to a central axis M of the gripping jaws (9, 13).

Description

tongs

description

The invention relates to a pair of pliers with two pliers parts and associated gripping elements. The pliers parts each have a gripping jaw with a gripping surface, which serve the detection of objects. The pliers are pivotally connected together by a hinge.

Pliers of the type mentioned here are known. The pliers parts can perform a pivoting movement and be moved to a first function tion position in which the pliers is open. In an opposite pivoting movement, the gripping jaws of the pliers parts are moved toward each other and take a second functional position in which touch the grip surface having a gripping jaws or capture an object. Between the gripping surfaces is thus a V-shaped area. It becomes clear that an object caught by the forceps merely makes line contact with the gripping surfaces, unless it is accidentally V-shaped in turn. The load in the line-shaped contact areas is relatively high, so that damage may occur to the surface of the object. Moreover, the holding forces are in many cases not sufficient due to the linear contact.

The object of the invention is therefore to provide a pair of pliers which does not have this disadvantage. To solve this problem, a pair of pliers is proposed which has the features mentioned in claim 1. The pliers include two pliers parts with gripping jaws having gripping surfaces with which objects can be detected. The forceps are characterized in that at least one of the mutually facing gripping surfaces, which come into contact with an object to be detected, is arcuate. It is here provided that the gripping surface is convex with respect to a central axis of the gripping jaws, that is curved in the direction of the central axis. This geometry of the gripping surfaces ensures a virtually parallel gripping of objects.

In a further preferred embodiment, the gripping surfaces on partial surfaces, which are separated by depressions. These can run in the longitudinal and / or transverse direction of the pliers parts. The partial surfaces ensure that the forceps can not slip off so easily when detecting objects. Also a direction independent holding of objects is guaranteed.

Further embodiments emerge from the subclaims.

The invention will be explained in more detail below with reference to the drawing. Show it:

Figure 1 is a schematic diagram of a pair of pliers in a first

Functional position;

Figure 2 is a schematic diagram of the pliers of Figure 1 in a second functional position; Figures 3 and 4, the front part of the pliers shown in Figures 1 and 2 with detected objects of different sizes;

Figures 5 and 6 the front part of a pair of pliers according to Figures 1 and 2 with modified pliers parts that detect objects of different sizes;

Figure 7 is a section through the joint of the pliers along a first plane passing through the joint and

8 shows a section around a twisted with respect to Figure 7

Level through the joint.

The pliers 1 shown in FIG. 1 have a first pliers part 3 and a second pliers part 5. The pliers parts 3 and 5 are connected to each other via a hinge 7.

The first pliers part 3 has a first gripping jaw 9 and a holding arm 11. The second pliers part 5 has a second gripping jaw 13 and a driver 15.

From Figure 1 it can be seen that the support arm 11 of the first jaw 9 is opposite and that the driver 15 of the second jaw 13 is opposite and that the joint 7 between the ends of the pliers parts 3 and 5 is arranged.

The pliers 1 also have a first gripping element 17 and a second gripping element 19, wherein the first gripping element 17 is rigidly connected to the holding arm 11 and thus to the first pliers part 3. that is. The second handle member 19 is in contrast pivotally connected to the second pliers part 5, here with the hinge 7 remote from the end of the driver 15.

Figure 1 shows the pliers 1 in a first functional position, namely in the open state. The two pliers parts 3 and 5 are thus spread substantially V-shaped, and the gripping elements 17 and 19 are at a distance from each other.

The handle elements 17 and 19 shown in Figure 1 are cut open. Therefore, it can be seen that the pliers 1 comprises a coupling element 21, which is mounted pivotably on the one hand on the first pliers part 3 or on the first gripping element 17 and on the other hand on the second gripping element 19. It is provided that the articulation point 23 is arranged in the connection region of the upper end 25 of the coupling element 21 with the first pliers part 3 and the first gripping element 17 at a distance from the axis of rotation 27 of the joint 7. Accordingly, it is provided that the articulation point 29 is arranged between the lower end 31 of the coupling element 21 and the second grip element 19 at a distance to the articulation point 33 between the end 7 remote from the joint 7 end 35 of the driver 15 and the second Griffelernent 19th

FIG. 1 shows a first imaginary connecting line V1, which intersects the axis of rotation 27 of the joint 7 and the articulation point 33, and also a second connecting line V2, which connects the articulation point 23 between the coupling element 21 and the first pliers part 3 and the first gripping element 17 and the pivot point 29 at the lower end 31 of the coupling element 21 cuts. In addition, FIG. 1 shows a third connecting line V3, which axis 27 of the joint 7 and the pivot point 23 intersects, finally, a connecting line V4, which intersects the pivot point 33 at the end 35 of the driver 15 and the pivot point 29 at the lower end 31 of the coupling element 21. It is clear that the connecting lines V1 and V2 are substantially parallel to each other, as are the connecting lines V3 and V4. Overall, these connecting lines describe a parallelogram. This makes it clear that a so-called parallelogram joint is created here, which connects the two gripping elements 17 and 19 with each other.

FIG. 1 also shows that an imaginary central axis M1 of the two clamp parts 3 and 5 with an imaginary center axis M2 of the grip elements 17, 19 encloses an angle α of approximately 135 °. The pliers parts 3 and 5 are thus angled relative to the gripping area of the pliers 1 formed by the gripping elements 17 and 19, which substantially improves their handleability. The illustration according to FIG. 1 clearly shows that the cranked pliers parts 3 and 5 are arranged quite differently than in the case of conventional flat pliers. This is an essential aspect that allows fatigue-free working with the pliers shown here.

The pliers 1 also has a spring element 37, which develops a biasing force, due to which the pliers 1 is urged into a first functional position, namely in the open position shown here in Figure 1. In the exemplary embodiment illustrated here, the spring element 37 acts, on the one hand, on the first grip element 17 and, on the other hand, on the coupling element 21 so that a force directed to the left in FIG. 1 is built up, which moves the second grip element 19 to the left away from the first grip element 17. urges, whereby the pliers 3 and 5 are opened. By the force of the spring element 37, the coupling element 21 is pivoted to reach the open position about the pivot point 23 in a clockwise direction. The force also causes the driver 15 of the first pliers part 3 is pivoted clockwise about the axis of rotation 27 of the joint 7, so that the first gripping jaw 9 pivots upward and thus away from the second gripping jaw 13 in a clockwise direction.

As a result of the connection of the two gripping elements 17 and 19 in the manner of a parallelogram joint, the second gripping element 19 is displaced virtually parallel to the first gripping element 17 to the left. Unlike conventional pliers so between the handle members 17 and 19 no expanding, V-shaped gap is formed. Rather, a user can take the first handle member 17 in the hand, wherein the outside of the handle member 17 comes to rest in the interior of the hand and the four fingers surround the second handle member 19. When closing the pliers, the four fingers can already act in the open functional position, the second handle member 19 with a force and thus build up a high gripping and clamping force. It is achieved here by about 25% improved force application of the hand forces.

The two gripping elements 17 and 19 are practically in the manner of a pistol grip in the user's hand, while the pliers parts 3 and 5 point forwards in the direction of a working field or an object to be detected.

It is readily apparent that by the angled position of the pliers parts 3 and 5 relative to the handle elements 17 and 19 a very ergonomic working position is ensured and that by the parallel displacement of the two gripping elements 17 and 19 to each other when closing the pliers 1 evenly large clamping forces can be built, this even in the open state of the pliers. 1

The pliers 1 also has a locking element 39, which here starts from the coupling element 21 and is arranged on the side facing away from the driver 15 of the coupling element 21. When closing the pliers 1, the coupling element 21 pivots about the pivot point 23 in the counterclockwise direction and thus takes the locking element 39, until it engages in a locking element 41. This has an operating button 43 accessible from above, which is displaceable to the rear, in this case to the right, so that a latching lug 45 of the latching element 41 engages in a latching recess 47 of the locking element 39. The latching element 41 may be spring-loaded and urged into its locking position, so compared to the position shown in Figure 1 to the right.

Figure 2 shows the pliers 1 in a second functional position, namely closed, wherein the Zängenteüc 3 and 5, more precisely their first gripping jaw 9 and second gripping jaw 13 abut each other. The same parts are provided with the same reference numerals, so that reference is made in the description of Figure 1 in order to avoid repetition.

When the forceps 1 are closed, forces are exerted on the second grip element 19 from the left, so that forces are applied in the direction of the first grip element 19. element 17 is relocated. In this case, the coupling element 21 rotates about the pivot point 23 in the counterclockwise direction.

During a pivoting movement of the coupling element 21, the driver 15 of the second pliers part pivots counterclockwise, whereby the second gripping jaw 13 is displaced in the direction of the first gripping jaw 9.

When closing the pliers, the second handle member 19, as I said, displaced substantially parallel to the first handle member 17, while also slightly moved up, because the distance between the imaginary third connecting line V3 and the imaginary connecting line V4 is smaller. It can be seen here that the central axis M1 between the jaws 13 and 15 practically coincides with the connecting line V3.

In the considerations given here, it was assumed that when the pliers 1 are closed, the first gripping element 17 remains practically unflexed, in particular in order to be able to define the movement of the parts assigned to the pliers 1. However, it is clear that a relative movement between the two gripping elements 17 and 19 leads to each other for closing the pliers 1. regardless of which of the two gripping elements 17, 19 is held or displaced, or whether both gripping elements are moved towards each other.

Figure 3 shows the front part of the pliers 1, namely the first pliers part 3 and the second first pliers part 5. The same parts are provided with the same reference numerals, so in so far as reference is made to the description of Figures 1 and 2 in order to avoid repetition. From the enlarged view of the pliers parts 3 and 5 it is clear that their gripping jaws 9 and 13 have gripping surfaces 49 and 51, which face each other. In the exemplary embodiment shown here, the gripping surfaces 49, 51 are formed in an arcuate manner, that is to say they are arched in the direction of a central axis M, that is to say they are of convex design. The gripping surfaces 49 and 51 are formed symmetrically with respect to the central axis M, so that in the following only the design of the lower gripping surface 49 of the gripping jaw 9 is discussed.

The gripping surface 49 has an imaginary envelope, but, as can be seen in FIG. 3, in the exemplary embodiment illustrated here, is subdivided into individual partial surfaces whose width, seen in the longitudinal direction of the gripping jaw 9, can be chosen differently. In the exemplary embodiment illustrated here, the partial areas 49, 49 'etc. are separated from one another by recesses 53, which in this case run parallel to one another and perpendicular to the image plane of FIG.

The rectilinear depressions 53 form part surfaces 49, 49 ', etc., which extend over the width of the gripping surface of 43 measured perpendicular to the image plane of FIG. 3 and are substantially rectangular in shape.

It is very well conceivable to provide depressions running in the longitudinal direction of the gripping jaw 9 in order to form partial surfaces. Preferably, partial surfaces are formed, which are separated from one another by recesses, which extend on the one hand transversely to the longitudinal extension of the gripping jaw 9 to the other in the longitudinal direction thereof. Such a grid of depressions makes rectangular Partial surfaces formed whose length is less than the length of the gripping jaw 9 measured length of the gripping surface 49 and whose width is smaller than the width of the perpendicular to the image plane of Figure 3 measured width of the gripping surface 49th

It is readily apparent that the depressions can also extend at an angle to the longitudinal or transverse extent of the gripping jaw 9 and thus delimit partial surfaces which are, for example, diamond-shaped. Thus, rectangular, square or diamond-shaped partial surfaces can be formed by selecting the course of the depressions accordingly.

Instead of the straight-line course explained here and the uniform arrangement of the depressions, irregular depressions can also be selected in order to form any desired partial areas.

The depth and the cross section of the depressions can be adapted to the desired gripping behavior of the forceps 1.

FIG. 3 shows an article 55 which is held between the pliers parts 3 and 5. This is a relatively thin object, the Zangeteile 3 and 5, and the associated gripping surfaces 49 and 51 are therefore located at a relatively small distance from each other.

It can be seen from the magnification of FIG. 3 that the arched gripping surfaces 49 and 51 engage the upper and lower side surfaces of the article 55 with an area located near the front end 57 of the gripper 1. The number of the upper and lower surfaces of the article 55 touching partial surfaces depends on the curvature of the gripping surfaces 49 and 51, which is chosen here relatively low, to detect objects relatively well.

FIG. 4 again shows the front part of the pliers 1, namely the gripping jaws 9 and 13 of the pliers parts 3 and 5, which are connected to one another via the hinge 7.

The same parts are provided with the same reference numerals, so that reference can be made to the description of Figure 3. The only difference with respect to Figure 3 is that the object 55 'detected by the forceps 1 is thicker than the object 55 shown in Figure 3.

In order to be able to grasp the object 55 ', the pliers 1 are opened further, the gripping surfaces 49 and 51 thus being at a greater distance from one another. In the illustrated here, the opening angle of the two pliers parts 3 and 5, the upper and lower sides of the article 55 'of other areas of the gripping surfaces 49 and 51 are detected: It is clear here that the front end 57 nearest partial surfaces of the gripping surfaces 49 and 51 do not touch the object 55 '. This is rather detected by a region of the gripping surfaces 49 and 51, which are arranged at a distance from the front end 57 of the forceps 1.

The joint 7 has a hinge pin 35 which runs perpendicular to the image plane of FIG. 1 and which has a central passage hole 37 here. The hinge pin 35 passes through through holes in the first and second pliers parts 3 and 5 and connects them articulated with each other. By a preferably established splashed plastic ring in the joint 7, the hinge pin 35 is fixed in the joint 7, so that it can not fall out of the through holes. At the same time it is ensured in a suitable manner that the plastic ring on the one hand reduces the friction between the hinge pin 35 and the pliers parts 3 and 5, on the other hand between the pliers parts 3 and 5 with each other.

The attached to the support arm 11, not shown here grip element is preferably molded. It is particularly advantageous if at the same time the plastic ring in the joint 7 is injected during injection molding of the handle member. In this case, different plastic materials for the ring and / or for the grip element can be used and / or the plastic ring and the grip elements in the so-called two-component injection molding process can be realized.

The grip element 19 is attached to the driver 15 and to the coupling element 21 at the articulation points 29 and 33.

The pliers parts 3 and 5 are preferably made of metal, in particular by way of the MIM process, the so-called metal-molding injection process or metal powder injection molding process.

From the comparison of Figures 3 and 4 it is clear that so thin objects, such as the object 55 shown in Figure 3, with the front end 57 of the forceps adjacent areas of the gripping surfaces 49 and 51 are held. The thicker the article, the more the contact areas between the top and bottom of the article and the gripping surfaces 49 and 51 migrate inwards and thus lie at a distance from the front end. of pliers 1. This is clear from Figure 4: There, the top and bottom of the object 55 'is not touched by the front portions of the gripping surfaces 49 and 51, but by areas which are at a distance from the front end 57.

This gripping behavior of the forceps 1 is based exclusively on the fact that at least one of the gripping surfaces 49, 51 here both curved gripping surfaces are formed curved. For this purpose alone, the formation of partial surfaces is not required.

But if at least on one side, in the embodiment shown here on both sides, partial surfaces formed, for example, the partial surfaces 49 ', 49 ", etc., increases the grip of the gripping surfaces 49, 51 of the forceps 1, so that objects can be detected non-slip. The holding forces can be specifically influenced by providing depressions in the gripping surfaces 49, 51, which are either transverse to the longitudinal extent of the gripping jaws 9, 13 in the direction of the longitudinal extension of the gripping jaws 9, 13 and / or at a desired angle thereto Finally, it is also possible to choose any depression contours in order to specifically influence the grip of the forceps 1 and to build up direction-independent adhesive forces.

Preferably, the pliers parts 3 and 5, at least the gripping jaws 9 and 13 are produced by means of the MIM technique, that is, in the so-called metal injection molding technique, which is also referred to as metal powder injection molding. In this manufacturing method, the pliers parts 3 and 5 or the gripping jaws 9 and 13 are produced by means of a shaping process, in which the gripping surfaces 49 and 51 and their contours are also smoothed out. teres can be realized. It is thus possible to form the gripping surfaces 49 and 51 only curved, with these bulge in the direction of the central axis M, or produce part surfaces which are separated from each other by recesses. Since the course of the depressions is realized by a molding process, virtually any contours can be generated, which would be much more expensive in a chip-making production of the jaws 9 and 13.

From the explanations of the gripping behavior of the forceps 1 is clearly lent that this is based solely on the particular configuration of the gripping surfaces 49 and 51, which may be formed continuously flat or may be provided with recesses to produce partial surfaces.

Due to the curvature of the gripping surfaces 49, 51 it is achieved that thin objects 55, as shown in FIG. 3, are detected in a planar manner, namely with the region of the gripping surfaces 49 and 51 which lies close to the front end 57 of the forceps 1.

Thicker articles, for example articles 55 ', as illustrated in Figure ₄ are detected with a portion of the gripping surfaces 49, 51 which is located at a distance from the front end 57 of the tongs. 1

From the explanations on the grasping behavior of the forceps 1, it is also clear that the objects, which may be more or less thick, are grasped by the gripping jaws 9 and 13 independently of how the forceps parts 3 and 5 continue beyond the articulation 7 and how the gripping elements 17 and 19 are formed. So it is very possible to realize pliers that are the usual ones Handles, as they are provided for example in flat-nose pliers and the like, so that just do not have parallelogram hinge, as shown in Figures 1 and 2.

FIGS. 5 and 6 show the front part of a pair of pliers 1 with modified pliers parts 3 and 5. The same reference numbers are used for the same and functionally identical parts, reference is made to the description of the preceding figures to avoid repetition.

The pliers parts 3 and 5 have gripping jaws 9 and 13 with gripping surfaces 49 and 51, which lie opposite each other and here detect a small object 55. By "small" herein is meant an article that has a relatively small thickness, and therefore the tong parts 3 and 5 are relatively close together in detecting the article 55.

The pliers shown in FIG. 5 are simplified compared to those explained with reference to FIGS. 1 to 4: the first gripping surface 49 is flat, that is, it is not curved. The opposite gripping surface 51 of the second pliers part 5 is curved in the broadest sense. It has three partial surfaces 51, 51 "and 51 '", wherein the number of partial surfaces can be adapted to different applications.

The partial surfaces are formed in a plane and close to each other, so that in each case forms a vertex. The gripping surface 51 is thus formed as a polygon.

It can be seen from FIG. 5 that the partial surface 51 'closest to the front end 57 of the forceps 1 is connected to the upper side of the tongs 1'. object 55 includes an acute angle, so this does not touch. The lying at a distance from the front end 57 central part surface 55 'lies flat on the top of the article 55 at. Finally, the face 51 'farthest from the front end 57' again includes an acute angle with the top of the article 55, the space formed here opening in the opposite direction as that between the first face 51 'and the top the article 55 is included.

Since the object 55 rests with its underside flat on the newly formed gripping surface 49, this is particularly well maintained between the pliers parts 3 and 5. Nevertheless, the pliers 1 is very well suited to detect objects of different thickness.

This can be seen from Figure 6, which shows the front end of the pliers 1, which is shown in Figure 5. The same parts are provided here with the same reference numerals, so reference is made to the previous description in so far.

The object 55 'detected here is thicker than that shown in FIG. The pliers parts 3 and 5 thus have a greater distance in order to be able to detect this object 55 'at all.

It can be seen here that the object 55 'in turn rests flat on the lower gripping surface 49 of the first pliers part 3. Of the gripping surface 51, the region of the gripping surface 51, which is furthest away from the front end 55, lies on the partial surface 51 '"on the upper side of the object 55', so that, too, between the pliers parts 3 and 5 or the zugehöri- gene gripping jaws 9 and 13 held. In the illustrations according to FIGS. 5 and 6, the detected objects are those which are rectangular in side view. They differ in that they have different thickness. This also applies to the objects 55 and 55 'shown in FIGS. 3 and 4.

The difference between the embodiment of the forceps 1 and the first embodiment shown in FIGS. 5 and 6 is that only one gripping surface is arched, and in the process the partial surfaces 51 ', 51 ", 51'" of the upper partial surface 51 polygon-like contiguous and here is waived any recesses.

After the explanations of the gripping surfaces 49 and 51 of the pliers parts 3 and 5, it should be pointed out here that one of the gripping surfaces can also be concave relative to the central axis M of the gripping jaws 9 and 13. It is particularly preferred that the opposite gripping surface 51 is further formed convex relative to the median plane M. In such an embodiment, a defined three-point system can be realized on objects that are grasped by the gripping surfaces 49 and 51. This makes it possible to achieve a particularly secure and non-tilting grip.

With reference to the following figures 7 and 8, the structure of the joint 7 between the pliers parts 3 and 5 is explained in detail:

FIG. 7 shows the region of the joint 7 in cross section, which runs along the line AA shown in FIG. Visible here are the first pliers part 3 and the second pliers part 5. Here is the first pliers part 3 with a through hole 153 and the second Pliers part 5 is provided with a passage opening 155. The two openings 153, 155 are aligned with each other and receive the main body 157 of a hinge pin 159, which is provided with a collar 161. This prevents the hinge pin 159 can slide through the first and / or second passage opening 155 or 153.

The main body 157 has on its outer side an annular groove 163, while on the inside of the through holes 153 and 155 at least one recess, preferably also an annular groove 165 is provided, wherein a portion of the annular groove of the first through hole 153 in the first pliers part 3 and a second region may be associated with the second passage opening 155 of the second pliers part 5. It is crucial that the annular groove 163 on the outside of the hinge pin 159 and the annular groove 165 in the region of the first and second passage opening 153, 155 at least partially at the same height, measured in the direction of the central axis 167 of the hinge pin 159. In this way, in the area of the joint 7 an inner annular space 169 created in which a ring 171, preferably made of plastic is provided. Preferably, the ring 171 is injected. For this purpose, at least one outwardly open, with the annular space 169 in connection standing access channel 173 is provided in the region of the joint 7, can be injected through the plastic in the annulus 169. It is also conceivable to provide a plurality of access channels to press plastic over several areas in the annulus 169.

The ring 171 reduces the friction of the parts moving relative to one another in the region of the joint 7. From FIG. 7 it can be seen that the annular space 169 also extends radially outwards relative to the central axis 167, ie has a diameter which is greater than that of the through openings 153 and 155. As a result, the first pliers part 3 only touches the second pliers part 5 outside the plastic ring 171 realized here ,

The joint 7 described here can be produced in a very simple manner: the two pliers parts 3 and 5 are placed on one another in such a way that the passage openings 153 and 155 in the pliers parts 3 and 5 are aligned. It can then be the hinge pin 159 inserted into the through holes 153 and 155 until it rests with its collar 161 on the outside of one of the pliers parts. Here, the hinge pin 159 is inserted by way of example from below into the passage openings 153, 155, so that the collar 161 rests on the outside of the second pliers part 5.

Subsequently, a plastic compound can be injected via the at least one access channel 173 to realize a ring 171 having a cylindrical portion which extends over a certain height - measured in the direction of the central axis 167 -. The height here is about one third of the common thickness of the two Zangβnteüe 3 and 5. The ring 171 also has a radially outwardly extending, rather plate-shaped portion which is disposed in the contact region between the first pliers part 3 and the second pliers part 5, and in a plane on which the central axis 167 is vertical. In this way, the contact surface of the two pliers parts 3 and 5 in the region of the joint 7 is reduced. Overall, therefore, reduces the ring 171, the friction between the two pliers parts 3 and 5 with each other and the friction of these two pliers parts relative to the hinge pin 159th

After all, the joint 7 can be produced inexpensively in a simple manner. The parts associated with the joint 7, the pliers parts 3 and 5, are connected to each other by the hinge pin 159. The hinge pin is secured in the through holes 153 and 155 by the injected ring 171 against falling out. The joint is characterized by the fact that the friction of the parts connected together in the region of the joint is reduced to a minimum.

It is clear from the explanations regarding FIG. 7 that the configuration of the ring 171 can be adapted in a wide frame to the forces prevailing in the joint 7. It is thus possible to provide a higher cylindrical section measured in the direction of the central axis 167 than shown here. It is also conceivable to change the extent of the ring 171 measured perpendicularly to the center axis 167 in order to provide a more or less large copper surface in the area of contact between the first and second tong parts 3, 5, which reduces the friction forces in the region of the joint 7 serves.

Incidentally, the friction can also be influenced, in particular reduced, by the selection of special plastic materials.

The two pliers parts 3 and 5 are preferably made of metal. Particularly preferred in the manufacture of the so-called MIM technique is the metal injection molding technique, also known as metal powder injection molding technique. In the manufacture of the pliers 1 3 and 5 handle members 17 and 19 are attached to the pliers parts. Preferably, a fixed handle member 17 is attached to one of the pliers parts, here to the first pliers part 3, which can therefore perform no pivoting movement relative to the pliers part 3.

Particularly preferred in the manufacture of the forceps 1 is a method in which the first grip element 17 is integrally formed on the first forceps part 3, preferably injection-molded.

In a further step, the first pliers part 3 can now be connected to the second pliers part 5 by passing the hinge pins 159 through the through openings 153 and 155 after the pliers parts 3 and 5 have been joined together. To complete the joint 7, the ring 171 is then injected.

It can be seen here that the two pliers parts 3 and 5 can also be assembled beforehand and the hinge pin 159 can be inserted, and then the first gripping element is attached to the first pliers part 3, preferably injection-molded. Particularly preferred is a production method in which the first gripping element is integrally formed on the first pliers part 3 in one process step. in particular molded, and the ring 171 is injected into the region of the joint 7.

In this case, adapted to the different loads of the handle member and the ring 71 different plastic materials can be used and the molding of the handle member and the injection of the ring 171 can be realized in the so-called two-component injection molding. It becomes clear that, of course Also, the same plastic materials for the handle member and the ring 171 are used.

In a further step, the parallelogram joint is then completed by the coupling element 21 is inserted, this is preferably mounted pivotably in the region of a passage opening on the first pliers part 3. The other end 31 of the coupling member 21 is then pivotally connected to the second handle member 19. At a distance from this, the second grip element 19 is connected to the end 35 of the driver 15.

Furthermore, the spring element 37 and the latching element 41 are used, before then the first handle element 17 is completed, in particular by placing a lid or a second half-shell. Accordingly, the second handle member 19 is completed by an associated part.

For the gripping elements 17 and 19, a material is preferably used, which is particularly handy to prevent slipping when handling the pliers 1. The material must be hard enough to absorb the forces that occur when using the pliers 1 and to be able to forward them to the pliers parts 3 and 5.

It is also conceivable to provide the gripping elements 17 and 19 with regions of different plastics, that is to say to use softer materials in the contact area of the hand and fingers in order to increase the ease of use. Again, it is quite possible to use different plastic materials in the manufacture of the handle elements 17 and 19 and to process by two-component injection molding. The use of plastic material for the gripping elements 17 and 19 is particularly advantageous because even when using metal in the manufacture of the pliers parts 3 and 5, the user is insulated from them and the risk of being electrocuted when handling the pliers 1 on a minimum is reduced.

FIG. 8 shows the joint 7 between the two tong parts 3 and 5 in a sectional view, the section extending along the line BB shown in FIG. 1 and lying in an imaginary plane in which the central axis 167 of the hinge pin 159 is also located lies. The same parts are provided with the same reference numerals, so reference is made to the description of the preceding figures, in particular to Figure 4.

Also in Figure 8, the two pliers parts 3 and 5 of the pliers 1 are greatly enlarged in cross section along the line BB shown in Figure 1 reproduced. The passage opening 153 in the first pliers part 3 and the passage opening 155 in the second pliers part 5 are in alignment with one another and receive the hinge pin 159, which is arranged here so that it rests on the second pliers part 5 with its collar 161 protruding radially beyond the peripheral surface thereof. so through the two Durchgangsoffnungsn 153 and 155 can not slip through. As already explained with reference to Figure 7, the main body 157 of the hinge pin 159 is provided on its outer side with an annular groove 163, while the inside of the through holes 153 and 155 has a recess, so that the annular groove 165 is given, in which a plastic compound is injected. This results in a ring 171, which engages on the one hand in the annular groove 163 in the main body 157 of the hinge pin 59 and on the other hand in the recesses in the through holes 153 and 155, so that so in the Zangenteilen 3 and 5 are available. The ring 171 thus engages in the two pliers parts 3 and 5 and in the hinge pin 159 so that it can no longer be pushed out of the through openings 153 and 155 in the direction of its central axis 167. The two pliers parts 3 and 5 are thus secured by the ring 171.

In addition, it is provided that the pliers parts 3 and 5 are coupled together by a bayonet-type connection 175. This is realized by introducing into one of the two gripper parts, here in the second gripper part 5, a groove 177 extending over a circular arc. It can extend over the thickness of the second pliers part 5. The groove 177 is provided with a projection 179 at least in a region of its circular-arc extension which projects radially outward into the groove with respect to the center axis 167 of the hinge pin 159.

To realize the bayonet-type connection 175, the other pliers part, in this case the first pliers part 3, has a projection 181 extending parallel to the central axis 167, which on its side facing away from the main body of the pliers part 3 comprises a section projecting radially inwardly in the direction of the central axis 167 acting as abutment 183.

The length of the projection 181 and the thickness of the abutment 183 are selected so that the radially inwardly projecting abutment 183 engages in a functional position of the connection 175 under the projection 179, so that the two pliers parts 3 and 5 are locked together. In order to create a connection 175 of the type discussed here, at least one groove 177 and at least one projection 181 are provided, which projects into the groove 177. It is preferably provided that two point-symmetrical grooves 177 are provided in one of the gripper parts, here in the second gripper part 5, which are curved in a circular arc. Correspondingly, two projections 181 are provided on the other part, in this case on the first pliers part 3, which likewise have a circular arc shape.

The on the first pliers part 3 facing side of the groove 177 is formed in a range - measured perpendicular to the central axis 167 - so wide that the abutment 183 of the first pliers part 3 can be introduced there. This serving as a receiving portion portion of the groove 177 is arranged so that the projection 181 can engage with the abutment 183 in the receiving portion of the groove 177 when the two pliers parts 3 and 5 are superposed in their maximum open functional position. When the two pliers parts 3 and 5 are then slightly pivoted into their closed position, the abutment 183 engages under the radially outwardly projecting projection 179 of the groove 177, so that the projection 81 of the first pliers part 3 securely held in the groove 177 of the second pliers part 5 becomes.

It is preferably provided that, when the two pliers parts 3 and 5 are in their fully closed position, ie when the pliers 1 is closed, the abutment 183 completely under the projection 179 comes to rest and the two pliers parts 3 and 5 optimally through the connection 175 are held together. If the pliers parts 3 and 5 of the pliers 1 opened a little, they will be in the region of the connection 175 through the largely held together over the abutment 183 projection 179. This results in an excellent stability of the connecting portion of the pliers parts 3 and 5 in the joint 7, while the pliers 1 is used.

Only in the maximum open state of the pliers 1, the two pliers parts 3 and 5 are held together exclusively by the ring 171 made of plastic. Since the pliers are not used in this position, the user thereby no disadvantages. The circular arc-shaped abutment 183 engages under the projection 179 as soon as the pliers 1 is slightly closed and possibly used for work. In particular, however, if the forceps is opened only over a certain range and may also have to apply high forces, the abutment 183 engages far below the projection 179, so that the joint 7 is very stable by the bayonet-type connection 175 and can absorb high forces.

The joint 7 of the forceps 1 is characterized in that it is particularly low friction, because in the interior of a plastic ring 71 is provided. This extends over the contact area between the two Zangenieiien 3 and 5 and the Geienkbüizβπ 59 of the joint 7, but also over a range of the contact surface between the Zangenteilen 3 and 5. In particular, in the selection of suitable plastics, which are preferably processed by injection molding friction forces can be reduced to a minimum. This helps to minimize the forces required in handling the forceps 1. In the production of the pliers 1 as far as possible resorted to plastic injection molding process, wherein at least the production of the first handle member 17 and the ring 71 in a common process step is possible, even if for the two plastic parts different plastic materials are used, the different load cases in the grip area and in the area of the joint 7 are adapted. In this case, two-component injection molding can be used.

Two-component injection molding can be used not only in the more or less simultaneous production of handle elements and the ring 71, but also in the production of the handle elements themselves, which may include plastics of different properties. On the one hand, hard plastics are used which can intercept the forces which occur during the use of the forceps 1 and can also have a reinforcing core of metal. On the other hand, plastics are used which prevent the user from slipping off the grip elements 17 and 19, and which also have inherent elasticity in order to reduce the stresses on the user's skin when the forceps 1 are used.

Claims

claims

1. pliers with

two gripping jaws (3, 5) each having a gripping jaw (9, 13) provided with a gripping surface,

- One of the pliers (3.5) pivotally connecting

Joint (7) and with

- the pliers parts (3,5) associated with handle elements (17,19),

characterized in that

- At least one of the mutually facing gripping surfaces (17,19) arcuate, namely

with respect to a central axis M of the jaws (9,13) are convex.

2. Pliers according to claim 1, characterized in that the at least one gripping surface (49,51) has partial surfaces (49 ', 49 ").

3. Pliers according to claim 2, characterized in that the partial surfaces are separated by transverse to the longitudinal extent of the associated pliers part recesses (53).

4. Pliers according to claim 2 or 3, characterized in that the partial surfaces are separated by extending in the longitudinal direction of the associated Zange gente part wells.

5. Pliers according to one of the preceding claims 2 to 4, characterized in that the partial surfaces are separated by extending at an angle to the longitudinal extent of the associated pliers part recesses.

6. Pliers according to one of the preceding claims 2 to 5, characterized in that the gripping surfaces have rectangular, square and / or diamond-shaped partial surfaces.

7. Pliers according to one of the preceding claims, characterized in that the gripping surfaces (49,51) are identical.

8. joint for a pair of pliers (1) with two pliers parts (3,5), in particular for a pliers (1) according to one of claims 1 to 7, characterized by a hinge pin (159) and an injected ring (171).

9. Joint according to claim 8, characterized in that the pliers parts (3,5) each have a hinge pin (159) of the joint receiving through hole (153,155).

10. Joint according to claim 8 or 9, characterized in that the inside of at least one of the passage openings (153,155) at least one recess preferably have an annular groove (165).

11. Joint according to one of claims 8 to 10, characterized in that the outer side of the hinge pin (159) has an annular groove (163).

12. Joint according to one of the preceding claims 8 to 11, characterized in that the central axis (167) of the through holes (153,155) and the hinge pin (159) coincide, and that the at least one depression or the annular groove (165) the inside of the passage openings (153,155) and the annular groove (163) on the outside of the hinge pin (159) - seen in the direction of the central axis (167) - at least partially at a height, so that an annular space (169) for the ring (171) is formed.

13. Joint according to claim 12, characterized in that an at least outwardly open access channel (173) leads to the annular space (169).