CH712544A2 - Torque tool, especially a screwdriver or a wrench. - Google Patents

Abstract

The present invention relates to a dynamometric tool, in particular a wrench or a screwdriver, for example a watchmaker's screwdriver. The key comprises first and second coaxial teeth (1, 2), arranged so as to be able to engage frontally one in the other. The teeth of said first and second teeth (1, 2) have faces inclined with respect to an axial plane, and said faces comprise helical contact surfaces. Thanks to the arrangement of the contact surfaces of the teeth, the triggering of the key is very reliably activated when the tightening torque is reached. The variation between the forces measured during successive triggers is small. On the other hand, the wear of the teeth is reduced, which makes it possible to maintain high precision during a prolonged period of use.

Description

TECHNICAL FIELD [0001] The present invention relates to a dynamometric tool, in particular a screwdriver or a torque wrench. In one embodiment, the torque tool is a watchmaker's screwdriver.

State of the art and problems at the origin of the invention [0002] Screwdrivers and torque wrenches are used in many technical fields to control the tightening torque of nuts and screws so that they are mounted optimally . These keys can be classified into two main groups. In release keys, the key contains a mechanism that prevents a screw or nut from being tightened with a torque greater than the predefined and desired torque. On the other hand, the direct-reading keys display the current value, but do not necessarily contain a trigger mechanism. It should also be mentioned that trigger wrenches can be fixed or adjustable.

[0003] Torque tools are disclosed, for example, in US Pat. No. 7,272,999, US Pat. No. 7,487,700, US 2007/0281 274 and still US 2009/0 025 851.

The present invention relates more particularly to dynamometric tools trigger. To determine the reliability of such a tool, one can conduct a series of measurements and record the precise value of the tightening torque during a trip. It can then be observed that the screwdrivers currently found on the market have a greater or lesser variability between the desired tightening torque (fixed or set) and the measured trip torque. The present inventor has in particular made measurements in the field of watchmaker's screwdrivers. An object of the present invention is to reduce the variability between the desired torque and the actual tightening torque observed when using the key repeatedly.

Another object of the invention is to reduce the wear of the gears which are generally used in the trigger mechanism of the torque wrenches. The present inventor has found that the wear due to repetitive and / or prolonged use of the key causes a discrepancy between the adjusted tightening torque and that actually observed at the time of release. This divergence usually increases over time due to wear. SUMMARY OF THE INVENTION [0006] The present inventor has implemented a dynamometric tool comprising a triggering and / or uncoupling device comprising two toothed wheels and / or two teeth. Generally, the wheels or teeth are coaxial and arranged so as to be able to engage frontally. Surprisingly, thanks to the shape and / or the contact surfaces of the teeth of these teeth, it is possible to reduce the wear due to a repetitive use of the key and to reduce the variability between the torque value of desired tightening and that which is observed.

In one aspect, the invention relates to a torque tool selected from the wrenches and screwdrivers, the tool comprising: - first and second coaxial teeth, arranged to be able to engage frontally one in the other when using the tool; an engagement structure or a connection structure making it possible to make the tool integral with said engagement structure, said engagement structure being intended to be brought into contact with a screw, a bolt, and / or a nut when the use of the tool, to allow the transmission of a torque to said screw, said bolt and / or said nut by said torque tool; a gripping structure intended to be held in the hand of a user or by a robotic arm and making it possible to apply the said moment of rotation; a flexible and / or flexible structure, connected to said first toothing so as to exert a determined force on said first toothing and to allow a displacement of said first toothing when said first toothing is subjected to a force in the direction opposite to said determined force and when said force in the opposite direction exceeds the value of the determined force.

In one aspect, the invention relates to a torque tool selected from the wrenches and screwdrivers, the tool comprising: - first and second coaxial teeth, arranged to be able to engage frontally one in the other when using the tool; an engagement structure and / or a connection member making it possible to make the tool integral with said engagement structure, said engagement structure being intended to be brought into contact with a screw, a bolt, and / or a nut during use of the tool, to allow the transmission of a torque to said screw, said bolt and / or said nut by said torque tool; a gripping structure, intended to be held in the hand of a user or by a robotic arm and for applying said torque; a flexible and / or flexible structure, connected to said first toothing so as to exert a determined force on said first toothing and to allow a displacement of said first toothing when said first toothing is subjected to a force in the direction opposite to said determined force and when said force in the opposite direction exceeds the value of the determined force; characterized in that a tooth of said first toothing has first and second faces, arranged to be in contact with first and second faces, respectively, of a tooth of said second toothing, when the tool is in the rest position , in that said first and second faces comprise surfaces inclined with respect to an axial plane, and in that said first faces and / or said second faces comprise twisted contact surfaces.

DESCRIPTION OF THE DRAWINGS The characteristics and advantages of the invention will appear more clearly on reading the description of a preferred embodiment, given solely by way of example, in no way limiting, with reference to the schematic figures in FIG. which:

Fig. 1 shows a torque tool in the form of a watchmaker's key according to an embodiment of the invention.

Fig. 2 shows elevational views of various embodiments of coaxial teeth that can be used to make a torque tool according to an embodiment of the invention. The teeth shown in panels A, B, C are distinguished at the angle between the two contact faces of the teeth and the horizontal (the transverse plane). These angles determine, in combination with an elastic element, the values of the tightening torque and / or loosening of the dynamometric tool.

Fig. 3 shows the teeth described with respect to FIG. 2 in black and white.

Fig. 4 shows the teeth of FIGS. 2 and 3 in a front gear position, as is the case when the tool with the teeth is in a rest position or in a position of use when the tightening torque is below the value of tripping or uncoupling.

Fig. 5 is a top view and in perspective of a first gear of the dynamometric tool according to one embodiment of the invention.

Fig. 6 is a perspective view enlarging a tooth of the toothing shown in FIG. 5.

Fig. 7 is a front view of the teeth according to one embodiment of the invention.

Fig. 8 is an enlargement of an extract of FIG. 6, showing a front view of a tooth of a toothing of the tool according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] The present invention relates to a dynamometric tool chosen from the wrenches and the screwdrivers. In a preferred embodiment, the tool is a watchmaker's screwdriver. In a preferred embodiment, the tool is a key or a trigger screwdriver.

By way of example, FIG. 1 shows a watchmaker's screwdriver 10 according to an embodiment of the invention. The screwdriver 10 has a longitudinal shape and has an outer sleeve 5 having a substantially tubular member. The tabular element 5 is closed towards its first end (or its upper end) by a bearing head 31, made in the form of a ferrule inserted in the sleeve 5. To its opposite end, shown at the bottom in FIG. 1, the screwdriver includes a connection structure 4.

The outer sleeve 5 functions as a gripping structure, because it is intended to be held in the hand of a user or by a robotic arm. The sleeve makes it possible to grasp the tool and to apply the said moment of rotation. The user can hold the sleeve 5 by his fingers and apply a torque by rotating the screwdriver axially, about its longitudinal axis.

The connection structure 4 and arranged to allow to make the screwdriver 10 secured to an engagement structure (not shown). By "engagement structure" is meant any structure having a shape adapted to a particular type of screw or nut, for example screws with a split head, Philips cruciform, Pozidriv cruciform, Torx,

Tri-Wing, with hollow pan, for example. In the case of a torque wrench, the engagement structure is adapted to a nut, for example, to a hex nut, square nut, to mention a few.

The engagement structure may be disposed at the end of a rod, the opposite end of which is adapted to be received by the connection structure 4. The connection structure comprises a housing 34 for the structure of commitment. For these purposes, the connection structure 4 may include an opening 32 adapted to receive the rod of the engagement structure. The lateral hole 33 is threaded and makes it possible to fix said rod with a screw inserted through the opening 33. In one embodiment, the rod may have a non-circular section, for example square or hexagonal, so that to be locked in rotation in the connection structure 4.

The elements that allow the screwdriver to perform its dynamometer function are preferably inside the tool, for example in the space provided in the tube of the outer sleeve 5. The screwdriver 10 comprises in particular a trigger or uncoupling device 30, which comprises two toothed wheels 41, 42, whose teeth 1,2, are arranged to be able to mesh one into the other.

Before discussing the triggering device, it should be noted that, in the embodiment shown, the first and second gears 41, 42 are coaxial and arranged so as to be coupled frontally one in the other through their first and second teeth 1,2, respectively. This type of coupling makes it possible to place the wheels in a minimal space. The teeth of these wheels are oriented on a circle in axial direction, allowing a front gear of the first and second gears. This type of frontal gear is also known from the "Hirth toothing".

The first and second gears 41, 42 may themselves be in the form of hollow cylinders and / or tubes, housed axially in the housing provided by the outer sleeve 5. The first and second gears can, for example, be visualized as a tube whose one end is crenellated, said end of the tube thus forming a toothing. The first and second teeth 1, 2, in particular the characteristics of the teeth, will be described in detail further below.

In the screwdriver shown in FIG. 1, the second gear 42 is axially below the first gear 41. The second gear 42 thus functions as an axially lower stop for the first gear 41 and holds it in its housing in the sleeve 5.

In the triggering device shown, the first gear 41 is integral in rotation relative to the sleeve 5, but it can move axially in the sleeve 5, guided by the latter, at least along a predefined distance . The outer sleeve 5 and the first wheel 41 are locked in rotation by conjugated grooves / ribs.

For example, the first gear 41 may comprise, on its outer cylindrical surface, longitudinal grooves, in the axial direction, arranged to receive longitudinal ribs, disposed on the inner surface of the sleeve 5, or vice versa.

On the other hand, the second gear 42 is rotatably connected to the connection structure 4. In the embodiment shown, the connection structure 4 comprises a rod 36, on which the second tabular wheel 42 is fitted and rotatably secured by ribs / conjugate grooves. As the second toothed wheel 42 is not made integral in rotation with the sleeve 5, it, as well as the connection structure 4 of which it is integral in rotation, can rotate with respect to the outer sleeve 5.

While the assembly formed by the connection structure 4 and the second gear 42 can, in principle, rotate relative to the sleeve 5, this assembly is blocked in the axial direction. On the other hand, the first gear wheel can move axially, but is locked in rotation relative to the sleeve 5.

The triggering device also comprises the spring 6, which is held in compression between the screw 37 on the one hand and the first gear wheel 41 on the other. One end of the spring 6, the lower end according to the fig. 1, notably rests on a bearing surface 38, disposed at the opposite end of the first toothing 1 on the tube comprising said first gear 41.

The screw 37, which contains the bearing surface for the upper end of the spring 6, is inserted and retained in the sleeve 5, the latter having a thread to receive said screw 37. The screw 37 is accessible from the upper opening of the screwdriver, following the removal of the ferrule 31, the latter functioning as a closure cap of the outer sleeve 5.

The tightening torque of a dynamometric tool corresponds to a determined or predefined value. When the torque applied by a user reaches or exceeds said determined value, the moment of rotation is no longer transmitted to the screw, due to the triggering of the triggering device, more precisely due to a disconnection of the first and second teeth 1,2.

Those skilled in the art will understand that in a torque screwdriver as shown in FIG. 1, the value of the tightening torque is determined in part by the force exerted by the spring 6 in the axial direction on the first gear 41, the latter being thus forced into the front coupling position with the second gear 42. D ' on the other hand, the value of the tightening torque is determined by the geometry of the contact surfaces of the first and second teeth, as will be described later below.

When a user tightens a screw with the screwdriver 10, a torque is transmitted from the sleeve, held in the hand of the user, through the toothed wheels 41,42 and geared to the connecting member 4, and the connection member to the engagement structure and finally to the screw. On the other hand, when the torque applied by the user exceeds the tightening torque, the second wheel 42 moves in rotation relative to the first gear 41, pushing the latter in the axial direction against the force of the spring 6. This rotational movement between the first and second gears 41,42 characterizes the trigger. When the applied torque exceeds the value of the tightening torque, said torque is no longer transmitted to the screw due to the uncoupling, that is to say the relative rotation between the gears 41,42.

As mentioned above, the trip keys can be fixed or adjustable. According to a preferred embodiment of the invention, the torque of the dynamometric tool is adjustable. In the case of the screwdriver shown in FIG. 1, the adjustment can be made by screwing and unscrewing the screw 37, which determines the axial position of the screw 37 in the sleeve 5. As the screw contains the support for the spring 6, this position of support determines the compression level of the spring 6 and therefore the force exerted by the latter in the axial direction, holding the two gears in the coupling position. The more the spring is compressed, the larger the torque value of the screwdriver.

It should also be mentioned that the screwdriver shown in FIG. 1 comprises a connection member 4, to make the screwdriver 10 secured to the engagement structure (not shown). As indicated, the engagement structure comprises the part whose shape and / or geometry makes it possible to apply a rotational moment to a screw or a nut and thus to drive the screw or the nut in rotation so as to tighten and / or loosen. For example, in a flat-head screwdriver, the engagement structure corresponds to the flat end that is inserted into the head of a slotted head screw.

In the embodiment shown in FIG. 1, the engagement structure can be removed and replaced, for example depending on the screw to be tightened, or when the engagement structure is damaged. In this case, the same screwdriver 10 can be used to clamp different types of specifications or screws of different sizes, using the appropriate engagement structure.

In an alternative embodiment of the invention, the engagement structure is integral with the screwdriver and can not be replaced. In this case, the second gear can be directly integral in rotation with the engagement structure. In other words, the connection member 4 and the engagement structure can be made in one piece.

The present inventor has found that the accuracy and reliability of a torque tool depend on the geometry of the teeth of said first and second teeth 1,2, and in particular the geometry, shape and / or arrangement of the contact surfaces. teeth.

The geometry of the teeth according to the preferred embodiments will be discussed in more detail with reference to FIGS. 2-8.

Figs. 2 and 3 show three examples of pairs of frontal and axial teeth A, B and C which are distinguished from each other at the shape and / or the profile of the teeth of the teeth. As an illustration, the teeth are shown apart. In fig. 4, the first and second teeth 1,2 are intermeshed in one another, as is the case when the tool 10 is at rest or when the tool is used to tighten a screw or a nut, and the applied torque is less than the value of the tightening torque.

FIG. 5 is a front view in perspective and from above of a toothing 1, according to one embodiment of the invention. We can see the axial orientation of the teeth 14, arranged at the end of a tube 13. The tube 13 comprising the toothing 1 forms a toothed wheel 41. An annular rim 25 is disposed inside the toothing 1 at the end of the tube 13.

In the case of the second gear 42, which also contains a flange 25 ', this flange may serve as a bearing surface, for example to retain the gear 42. As can be seen in FIG. 1, the connecting member 4 comprises, on its rod 36, an annular bulge 43. This bulge rests on the annular flange 25, thus blocking the second gear 42 axially, preventing a displacement of the wheel upwards. Towards its lower end, the second gear 42 rests on an annular edge 44 arranged in the housing of the outer sleeve 5. Thus, the second gear 42 can not move axially.

FIG. 6 is the extract A of FIG. 5, showing in more detail a tooth 14 of the first toothing 1. Each tooth has first and second faces or surfaces 11,12, which are in contact with the complementary faces 11 ', 12' (not shown) of the teeth of the second toothing 2, when the latter is in gear with the first toothing 1. It should be noted that the first and second teeth 1, 2, are preferably identical, to allow optimal gearing. In other words, the teeth of the first toothing 1 preferably have the same geometry as the teeth of the second toothing 2, at least as regards the contact surfaces, and / or the elements which allow the coupling of the teeth. gear wheels.

In the present description, the terms "face" and "surface" are used interchangeably to designate the first and second faces 11,12 of a tooth 14. The term "flank" is also known to designate a zone contacting the tooth of a toothed wheel with another tooth.

In the present description, the prime sign (') is used to refer to a corresponding structural element of the second toothing. For example, "the first contact surface 11 of a tooth of the first toothing 1 is in contact with the first contact surface 11 'of the second toothing 2". The structural elements of the second toothing 2 are generally not shown in the drawings, and therefore the corresponding reference numbers (11 ', 12', 25 ') do not appear there.

In a radial direction, perpendicular to the general axis of the gears 41, 42, each tooth 14 is preferably defined by the inner and outer surfaces 21,22. A first contact surface 11 is thus delimited, radially, by the inner and outer surfaces. The outer and inner edges 16 and 17 preferably constitute or demarcate this limitation. In the axial direction, the first contact surface 11 is delimited by the top 15 of the tooth. Downwards, the first contact surface 11 may be delimited by a recess 23, which separates and / or connects the teeth 14 of a toothing.

Similarly, the second contact surface 12, located opposite the first contact surface 11 of the same tooth 14, is delimited radially by the inner and outer surfaces 21, 22, and axial direction upwards from the top 15, and downwards by a hollow 23 which separates the teeth from the toothing.

In one embodiment, the tooth 14, 14 'of a toothing comprises a top 15 connecting said first and second faces 11, 12, 11', 12 'of a tooth, said vertex 15 being rounded or flattened , preferably rounded. In the case of a flattened top, the tip of the tooth is flat and may have a surface parallel to the transverse plane.

In one embodiment, the surface of the contact face 11, 11 'is greater than the surface of said second face contact face 12,12'.

When the first and second teeth 1,2 are coupled, the first contact surfaces 11 of the teeth 14 of the first toothing 1 are in contact with the first contact surfaces 11 'of the second toothing 2. Similarly, the second contact surfaces 12 of the teeth of the second toothing 2 are in contact with the second contact surfaces 12 'of the first toothing 1. When the first gear 41 rotates relative to the second gear 42, the teeth slide on their respective first or second contact surfaces 11,11 ', 12, 12', in the direction of rotation, as shown in FIG. 7.

As can be seen in FIGS. 5 and 6, the contact surfaces 11, 12 are not flat. In one embodiment, at least the first or the second contact surface 11, 12, is not flat, preferably the two contact surfaces of a tooth and / or teeth of a toothing 1, 2 are not flat.

According to a preferred embodiment of the invention, at least one of the two contact surfaces of a tooth of the toothing is helical and / or twisted. The slightly helical and / or twisted surface is shown in FIGS. 5, 6 and again in FIG. 7, in which the arrangement of the first contact surface 11 is recognizable.

It should be noted, at this stage, that the toothed wheel of the invention does not have or not necessarily a helical toothing. In the state of the art, the helicoidal teeth comprise teeth whose shape generator is a helical line of the same axis as the axis of rotation, sometimes recalling the threading of a screw. In this case, these are teeth in which the teeth are essentially oriented in the radial direction and not in the axial direction as is the case according to one embodiment of the present invention. Unlike the helical teeth of the state of the art, the toothing of the present invention is preferably a toothing for a front coupling in the axial direction, and the contact faces 11, 11 'of the teeth are slightly helical.

The first helical contact surface 11, 11 'is arranged to allow the teeth to remain in close contact on the contact surface when one of the toothed wheels rotates relative to the other. The helical surface has the effect of reducing shear due to rotation, because the surfaces remain parallel, and / or remain complementary during rotation.

At this stage it should be noted that, during a rotation of a toothed wheel relative to the other, one of the two wheels performs at the same time a movement in the axial direction, to allow said rotation when the tightening torque is exceeded. When the contact surfaces between two adjacent teeth are flat, as is the case in known torque screwdrivers, the combination of the two relative movements, the rotation and the concomitant axial displacement, generates friction forces locally very high, for example between a point of the contact surface 11 of a first tooth and a point on the vertex 15 'of the other tooth, on which the first tooth slides.

According to the invention, a greater part of the surfaces of two intermeshing teeth preferably remains in contact during rotation, and consequently the friction performed by one tooth in rotation on the contact surface of the other tooth on which it slides, is distributed over a larger area and is therefore more regular. For this reason, wear resulting from high friction on some points or edges of the teeth of the state of the art is reduced.

Thanks to the arrangement of the contact surfaces of the teeth according to the invention, the triggering of the key is activated very reliably when the tightening torque is reached. The variation between the forces measured during successive triggers is small. On the other hand, the wear of the teeth is reduced, which makes it possible to maintain high precision during a prolonged period of use.

In one embodiment of the invention, one of the two contact surfaces of a tooth, for example the second contact surface 12, 12 ', is flat.

A flat surface is chosen, for example, when the contact surface is essentially vertical, that is to say in the plane both radial and axial. Such a plane preferably extends along the axis of central rotation 20 (Figures 2 and 5). In this case, the tool 10 has the dynamometric characteristic in a direction of rotation, for example in the tightening direction, but is not dynamometric in the other direction, typically loosening. In many torque tools, a tightening torque applies only to tightening, but not to loosening. This is the case when there is no reason to fear damage to the parts concerned when loosening.

According to a preferred embodiment, the tightening torque is the torque determined in the direction of the watch, and the loosening torque refers to the torque in the opposite direction.

In another embodiment, the dynamometric tool of the invention comprises a specific and / or limiting tightening torque and a specific and / or limited loosening torque. In this case, neither of the two contact surfaces 11, 12 of a tooth is vertical / axial, i.e. neither of the two contact surfaces can be aligned in an axial-radial plane. This is a preferred embodiment, shown in the drawings.

In the case of the preferred embodiment, the first and second contact surfaces 11, 12 of a tooth 14 are inclined with respect to the transverse plane and also with respect to the axial-radial plane. However, according to a preferred embodiment, the tightening torque is different from the loosening torque. Preferably, the loosening torque is higher than the tightening torque. For this reason, the angle of inclination of the first contact surface 11 is different from the angle of inclination of the second contact surface 12.

In the embodiment shown in FIGS. 5-7, the first contact surface 11 is less inclined, relative to the transverse plane, than the second contact surface 12. The limit torque defined by the second surface 12, combined with the characteristics of the spring 6, will be higher than the limiting torque associated with the first contact surface 11. If it is considered that the first surface 11 defines (together with the spring 6) the tightening torque and the second surface 12, the loosening torque, it becomes clear that the toothed wheel shown in fig. 5 corresponds to the first toothed wheel 41 of the torque screwdriver shown in FIG. 1. FIG. 5 shows the first gear 41 in the opposite position with respect to its position in the screwdriver of FIG. 1. In figs. 7-8, the first gear 41 is shown in the same orientation as in FIG. 1.

A consequence of the helical and / or twisted shape of the first contact surface 11, and preferably also of the second contact surface 12, is that the angle between the contact surface and the transverse plane (horizontal in the drawings) does not correspond to a fixed angle value. In order to illustrate the nature of the angles of the contact surfaces, FIG. 8 shows the corresponding lines on which lie the edges of the contact surfaces 11, 12.

FIG. 8 shows a tooth 14 in front view and / or in elevation from the outside in the radial direction. The tooth 14 is thus visualized in two dimensions, corresponding to a projection of the tooth 14 on an axial plane or a longitudinal and tangential plane, perpendicular to the radial axis of the observer. In this view, the curve and / or the inflection of the inner and outer edges 16-19, coming from the circular section of the toothed wheel, is not visible because of the perspective. In other words, the curvature is eliminated by the choice of the position of the observer of the two-dimensional projection of the tooth 14. In this view, the outer edges 16, 18 and inner 17, 19 of the first and second / or second surface 11, 12 each comprise straight lines and / or segments of a straight line. According to the invention, preferably a part of the aforementioned edges appears as the segment of a line in a view corresponding to that of FIG. 8.

The characteristics of the edges 16-19 described below, for example in terms of angles α, β, λ, δ, apply to the perspective of the tooth 14 according to FIG. 8.

In one embodiment of the invention, for the skilled person observing a tooth 14 in front view, in elevation as shown in FIG. 8, at least a portion of the outer edge 16 and / or at least a portion of the inner edge 17 of the first contact surface 11 is a segment of a line and / or a line.

In one embodiment of the invention, for the skilled person observing a tooth 14 in front view, in elevation as shown in FIG. 8, at least a portion of the outer edge 18 and / or at least a portion of the inner edge 19 of the second contact surface 11 is a segment of a straight line and / or a straight line.

In one embodiment of the invention, the outer edge 16 of said first surface 11, 11 'of said tooth is longer than an inner stop 17 of said first surface 11, 11'. This also applies when said edges are observed in projection as illustrated in FIG. 8.

In one embodiment, the outer edge 18 of said second surface 12, 12 'of said tooth is longer than an inner stop 19 of said second surface 12, 12'. This also applies when said edges are observed in projection as illustrated in FIG. 8.

Claims (10)

As mentioned in lafig. 8, the outer edge 16 of the first contact surface 11 appears as the segment of a line whose intersection with the transverse plane 26 defines the angle a. The inner stop 17 is on a straight line shown in dashed lines in FIG. 8, which encloses the angle β with respect to the transverse plane 26. Preferably, the inner and outer edges 16, 17 of the first contact surface 11 are not parallels. Preferably, the inner and outer edges 18, 19 of the second contact surface 12 are not parallels. In the illustrated embodiment, the second contact surface is also helical. For this reason, the outer edge 18 and the transverse plane form between them the angle γ. The angle δ is formed between the inner stop 19 and the transverse plane. In the context of this description, the angle formed between the first contact surface 11 and the transverse plane 26 is considered to be (α + β) / 2. By analogy, the (enclosed) angle formed between the second contact surface 12 and the transverse plane 26 is considered to be (γ + δ) / 2. According to one embodiment of the invention, 90 °> a> 5 ° and 90 °> β> 5 °. Preferably 60 ° to> 10 ° and 65 °> β> 15 °, more preferably 55 °> to> 20 ° and 60 °> β> 25 °. According to one embodiment of the invention, 90 °> γ> 10 ° and 90 °> δ> 10 °. Preferably 70 °> γ> 15 ° and 75 °> δ> 20 °, still preferably 65 °> γ> 20 ° and 70 °> δ> 25 °. According to one embodiment, γ> a; and γ, a Φ 0, that is to say, γ and a are both, independently of one another, different from 0. According to one embodiment, δ> β; and δ, β φ 0. [0074] According to one embodiment, (γ + δ)> (α + β). According to one embodiment, α, β> 15 ° (that is to say that each of the two angles is, independently of one another, greater than 15 °), preferably> 20 ° and more preferably> 25 °, even> 30 °. In one embodiment, α + x = γ, x being from 5 ° to 40 °, preferably from 7 ° to 30 °, more preferably from 10 ° to 25 °. In one embodiment, β + γ = δ, y being from 5 ° to 40 °, preferably from 7 ° to 30 °, more preferably from 10 ° to 25 °. In a preferred embodiment, 15 °> (β-α)> 0, preferably 10 °> (β-α)> 0, and even more preferably 6 °> (β-α)> 0. [ In one embodiment, 15 °> (δ-γ)> 0, preferably 10 °> (δ-γ)> 0, and even more preferably 6 °> (δ-γ)> 0. In one embodiment, the angle α between the outer edge 16 of said first surface 11, 11 'and a plane 26 perpendicular to the axial direction, is smaller than the angle β between the inner edge 17 of said first surface 11, 11 'and said perpendicular plane 26. [0081] In one embodiment, an angle γ between the outer edge 18 of said second surface 12, 12' and a plane 26 perpendicular to the axial direction, is less than the angle δ between the inner edge 17 of said second surface 12, 12 'and said perpendicular axis 26. [0082] As the skilled person will understand, the difference between the angles α and β is the result (and or the expression) of the helical surface of the first contact surface 11. Likewise, the difference between the angles γ and δ is the result of the helical surface of the second contact surface 11. [0083] a person skilled in the art will be able to choose the angles α, β, γ, δ independently so as to obtain a particular desired result, for example a particular tightening and / or loosening torque, adapted to the application of the dynamometric tool. claims A torque tool (10) comprising: - first and second coaxial teeth (1,2) arranged so as to be able to engage frontally with each other when using the tool (10) ; - an engagement structure (3) and / or a connecting member (4) for making the tool (10) integral with said engagement structure (3), said engagement structure (3) being intended for be brought into contact with a screw, a bolt, and / or a nut during the use of the tool, in order to allow the transmission of a torque to said screw, said bolt and / or said nut by said torque tool; - A gripping structure (5), intended to be held in the hand of a user or by a robotic arm and for applying said torque; a flexible and / or flexible structure (6), connected to said first toothing (1) so as to exert a determined force on said first toothing (1) and to allow a displacement of said first toothing (1) when said first toothing is subjected to a force in a direction opposite to said determined force and when said force in opposite direction exceeds said determined force; characterized in that - a tooth (14) of said first toothing (1) has first and second faces (11, 12) arranged to be in contact with first and second faces (11 ', 12'), respectively , a tooth (14 ') of said second toothing (12) when the tool is in the rest position, in that said first and / or second faces (11, 12, 11', 12 ') comprise surfaces inclined relative to an axial plane, and in that said first faces (11, 11 ') and / or said second faces (12, 12') comprise helical contact surfaces. 2. The tool (1) according to claim 1, characterized in that said tooth (14, 14 ') comprises a crown (15) connecting said first and second faces (11, 12, 11', 12) of a tooth, said apex (15) being rounded or flattened, preferably rounded. 3. The tool (10) according to any one of the preceding claims, characterized in that, in an elevational view showing the tooth in two dimensions, at least a portion of an outer edge (16) of said first surface (11, 11 ') of said tooth, and / or at least a portion of an inner ridge (17) of said first surface (11, 11'), is a segment of a straight line. 4. The tool (10) according to any one of the preceding claims, characterized in that an outer stop (16) of said first surface (11, 11 ') of said tooth is longer than an inner stop ( 17) of said first surface (11, 111). The tool (10) according to any one of the preceding claims, characterized in that an angle (a) between the outer edge (16) of said first surface (11, 11 ') and a plane (26) ) perpendicular to the axial direction, is smaller than the angle (β) between the inner edge (17) of said first surface (11, 11 ') and said perpendicular plane (26). The tool (10) according to any one of the preceding claims, characterized in that an angle (γ) between the outer edge (16) of said second surface (12, 12 ') and an axis (20) ) perpendicular to the axial direction, is smaller than the angle (δ) between the inner edge (17) of said second surface (12, 12 ') and said perpendicular axis (20). The tool (10) according to any one of the preceding claims, characterized in that said first and second contact surfaces (11, 12) are inclined with respect to an axial plane. 8. The tool (10) according to any preceding claim, said tool being selected from the wrenches and screwdrivers. 9. The tool (10) according to any one of the preceding claims, said tool being a screwdriver. 10. The tool (10) according to any one of the preceding claims, said tool being a watchmaker's screwdriver.