EP1954447A1

EP1954447A1 - Angle-head screwdriving tool incorporating a torque sensor mounted on the output shaft, and corresponding transmission module

Info

Publication number: EP1954447A1
Application number: EP06830243A
Authority: EP
Inventors: Nicolas Le Du; Jean-Clair Leme; Benoît ALLENOU
Original assignee: Georges Renault SAS
Current assignee: Georges Renault SAS
Priority date: 2005-12-01
Filing date: 2006-11-30
Publication date: 2008-08-13
Anticipated expiration: 2026-11-30
Also published as: JP5184368B2; FR2894172A1; EP1954447B1; FR2894172B1; JP2009517234A; US20100269646A1; WO2007063106A1

Abstract

The subject of the invention is a screwdriving tool comprising: - a drive shaft; - an angle head (5) comprising an output shaft (51) whose axis of rotation (511) is approximately orthogonal to the axis of said drive shaft (4); - transmission means connecting said drive shaft (4) to said output shaft (51); - and at least one torque sensor built into said output shaft (51); said tool being characterized in that said transmission means comprise at least one intermediate gear (6) whose axis is approximately parallel to said output shaft (51) and which engages with a gear (512) designed to turn said output shaft (51), and at least one bevel coupling (2) connecting, directly or indirectly, said drive shaft (4) to said intermediate gear or gears (6).

Description

Angle head screwing tool, including a torque sensor mounted on the output shaft, and corresponding transmission module.

The field of the invention is that of the tooling. More specifically, the invention relates to industrial tools, and more particularly the tools provided to exert a screwing with a determined torque.

In the field of the invention, the screwing tools are widely used in the industrial sector, the tools are fixed (which includes tools mounted on machines or manipulators) or portable.

These tools can integrate electric or pneumatic motor means according to the envisaged applications.

According to a widespread implementation of these tools, they are connected by appropriate connectors to an electronic controller (in the form of a cabinet) for programming a large number of operating cycles (for example 250 cycles), each cycle can be composed of 20 phases of operation.

These cycles can be programmed directly from a keyboard that includes the electronic box or by associated programming software (the box or boxes are then connected to the programming system by a network type field, Ethernet or other). These systems make it possible to ensure traceability of the operations performed by the tool, for example by ensuring the recording of results such as the final tightening torque, the final tightening angle, the date and time of the operations or else the representative curves of the quality (good or bad, according to predetermined parameters) of the screwing done. The tool itself may also include means for indicating the quality of screwing, for example by providing a report "Good / Bad" viewable using LEDs.

It will be understood that systems of this type make it possible to carry out a wide range of parameter setting and control operations. According to another known technique, the tool is connected to the electrical sector of way to power a control electronics integrated into the tool. In this case, the tool has a small display and some buttons.

It is understood that, in one or the other of the technologies described above, the data concerning the tightening torque are essential to order the tools correctly and to be able to follow up on the screwing results.

Indeed, the data on the tightening torque are used many times, to ensure of course the quality of the assembly to be made by screwing, but also to allow traceability of operations and to perform a statistical processing of data of Tightening.

Currently, the torque sensors implemented in the screwdrivers are constituted by strain gauges (generally mounted in bridge).

As illustrated in FIG. 1, these strain gauges are mounted on a support consisting of a cylindrical element 1 whose torsional deformation is measured by means of the gauges, this deformation being translated into a measurement of the tightening torque.

Conventionally, this cylindrical element is associated with a reduction gear with epicyclic train whose structure is recalled hereinafter. A single stage epicyclic reduction comprises:

- a tube with an inner ring called reduction ring;

- one or more satellite gears; a satellite carrier; a solar. A screwdriver such as that illustrated in Figure 1, in which the torque sensor is integrated on the reduction ring, corresponds to the most common technique for measuring the torque screw.

According to this technique, the movement of the reduction ring is then transmitted to the output shaft via a bevel gear 2. However, depending on the state of wear or lubrication of this gear, there is produces at this level a loss of torque which generates a drift between the torque measured on the ring and the torque applied to the screw to be tightened.

This leads users of this type of tool to perform frequent and expensive checks on these tools. According to another known technique, illustrated in FIG. 2, the measurement of the tightening torque of a screwdriver is obtained by means of a torque sensor 3 integrated on the output shaft of the angle head, outlet of conical coupling 2.

Moreover, according to this technique, the technology of the torque sensor is of the type using: strain gauges stuck on the output shaft; an electronic circuit embedded on the output shaft; a rotating transformer.

The rotating transformer supplies the onboard circuit with a voltage which, once rectified, feeds the strain gage bridge, which itself produces an output signal in the form of a voltage which is converted into a frequency signal by the onboard circuit and then recovered via the rotating transformer.

This type of sensor is described in the patent document published under the number DE-I 980 4695.

This solution makes it possible to measure the torque actually applied to the screw insofar as there is no disturbing element between the screw and the sensor.

In addition, the sensor technology used in this solution eliminates the problems of wear and signal continuity conventionally encountered with rotating collectors (because of the use of brushes in rotating contact with the collector tracks, generating friction necessarily causing wear of the brushes).

On the other hand, the presence of this sensor at the exit of the angle head has the disadvantage of significantly increasing the height of the head and, consequently, of reducing the accessibility of the tool in narrow areas. In general, when designing a screwdriver angle head, we seek the best compromise including between the following parameters: reliability, particularly with regard to the torque actually applied to the screw relative to the measured torque. Torque losses can indeed occur because of the wear of the conical coupling, its performance then varies according to the wear. However, an uncertainty exists as to the state of wear of the conical coupling of the screwdriver, this uncertainty being mitigated in practice by daily checks (the prediction and / or the automatic compensation of the level of wear does not exist currently); accuracy of measurement of the tightening torque; durability of the screwdriver.

The invention particularly aims to overcome the disadvantages of the prior art. More specifically, the invention aims to provide an angle screwdriver that is more reliable than existing solutions, particularly in that it allows to measure the torque actually applied to a screw.

Another object of the invention is to provide such a screwdriver which offers a satisfactory and durable level of precision in the measurement of the torque. The invention also aims to provide such a screwdriver which avoids causing a significant increase in the height of the angle head.

Another object of the invention is to provide such a screwdriver which can be manufactured more easily than conventional screwdrivers, especially in that it can be manufactured with a minimum of logistical constraints, by using production centers and / or or remote skills.

Yet another object of the invention is to provide such a screwdriver that allows to consider significant gains in terms of maintenance.

Yet another object of the invention is to provide such a screwdriver which is simple in design and easy to implement. These objectives, as well as others that will appear later are achieved thanks to the invention which relates to a screwing tool comprising: a motor shaft; an angle head comprising an output shaft whose axis of rotation is substantially orthogonal to the axis of said motor shaft; transmission means connecting said motor shaft to said output shaft; at least one torque sensor integrated on said output shaft; characterized in that said transmission means comprise at least one intermediate gear with an axis substantially parallel to said output shaft and cooperating with a gear for driving in rotation an output shaft, and at least one conical coupling connecting, directly or indirectly, said motor shaft and said one or more intermediate gears.

In this way, a screwdriver according to the invention makes it possible to integrate a torque sensor on the output shaft to precisely measure (the sensor being placed closer to the screw) the torque actually applied to the screw, while retaining a head height comparable to the standard tool described in the state of the art (in which the torque sensor is mounted on the reduction ring).

In addition, such a screwdriver avoids the implementation of a conical coupling directly in the corner head, this type of implementation inducing disadvantages in terms of durability (in addition to its size).

The invention thus proposes a design of angle head more durable than existing solutions, this by the implementation of a drive of the output shaft via parallel gears, rather than by a conical coupling. . In fact, parallel gears are simpler to manufacture, control and adjust. In addition, they provide a more homogenous tooth contact and a larger contact area. This results in a durability superior to that of a conical coupling.

At the same time, the conical coupling placed at the output of the motor shaft turns faster but is subject to a significantly lower torque than when it is placed in the corner head. It is therefore less subject to wear and / or breakage.

According to an advantageous solution, said transmission means comprise a parallel intermediate gear train whose axes are parallel to said output shaft.

It is thus easy to adapt the reduction between the motor shaft and the output shaft, this by the choice of gears.

It is recalled that a reduction is intended to increase the final torque with respect to the engine torque, and, consequently, to reduce the tool output speed of rotation relative to that of the motor axis. The reduction ratio is thus determined as a function of the screw cut that one wishes to achieve and the available engine torque.

In addition, the presence and length of the gear train makes it possible to more widely deport the size of the conical coupling relative to the angle head, which ensures good accessibility of the tool in small spaces.

According to an advantageous characteristic, said transmission means are mounted within a detachable module of a member incorporating said torque sensor. According to another advantageous characteristic, said transmission means are mounted within a detachable module of a body. integrating said motor shaft and motor means.

According to one or other of these characteristics, preferably according to a combination thereof, a screwdriver of modular design is obtained in which the three main constituents of the tool (motor, reduction and sensor) can be manufactured independently and combined. at the end of the assembly by a few screws.

Such a design makes it possible to separate the different technological components and allows their realization in separate production centers. In addition, the benefits for maintenance are obvious, the components defective which can be changed quickly.

Preferably, said transmission means are associated with sealed ball bearings.

Such a module is therefore waterproof and can be perfectly independent of the engine block and / or torque sensor torque module.

According to an advantageous solution, said torque sensor comprises at least one strain gauge bonded to said output shaft.

Preferably, said torque sensor comprises an electronic circuit embedded on said output shaft. According to another characteristic, said torque sensor comprises a rotating transformer.

According to a preferred solution, said gear is guided in an upper portion of said angle head by at least one ball bearing on either side of the toothing of said gear. Advantageously, said output shaft is guided in a lower portion of said corner head by at least one bearing with two rows of balls.

According to a particularly advantageous embodiment, said gear is guided in an upper part of said angle head by at least one ball bearing on either side of the toothing of said gear, said output shaft being guided in one part. bottom of said corner head by at least one bearing with two rows of balls.

Preferably, said one or more guide bearings of said gear are sealed bearings. In this way, the risk of possible grease leakage from the gear train and / or the gear coupled to the output shaft towards the sensor is avoided (which limits the risk of disturbances of the measurement).

Advantageously, said member comprises a housing, said tool comprising stop means for diffusing into said housing axial stresses exerted on said output shaft. The invention also relates to a transmission module intended to be integrated in a screwdriver comprising: a motor shaft; an angle head comprising an output shaft whose axis of rotation is substantially orthogonal to the axis of said motor shaft; transmission means connecting said motor shaft to said output shaft; at least one torque sensor integrated on said output shaft, characterized in that it integrates said transmission means, these comprising at least one intermediate gear whose axis is intended to extend parallel to said output shaft and intended to cooperate with a gear carried by said output shaft, and at least one conical coupling intended to connect, directly or indirectly, said motor shaft and said one or more gears. Other characteristics and advantages of the invention will emerge more clearly on reading the following description of a preferred embodiment of the invention, given by way of illustrative and nonlimiting example, and the appended drawings among which: Figure 1 is a longitudinal sectional view of a screwdriver head tool according to a first embodiment of the prior art;

- Figure 2 is a longitudinal sectional view of an angle head screwing tool according to a second embodiment of the prior art; Figure 3 is a longitudinal torque view of a preferred embodiment of the invention; FIG. 4 is a view of the invention according to the embodiment illustrated in FIG. 3, showing the mounting in separable modules of the tool; Figures 5 and 6 are views of a screwing tool according to the invention, respectively from above and in longitudinal section; - Figure 7 is another view of a screwing tool according to the invention; showing the separate transmission and sensor modules; - Figure 8 is a top view of the sensor module. With reference to FIG. 3, the invention applies to a screwing tool comprising a motor shaft 4 and an angle head 5 whose output shaft 51 has an axis of rotation 511 substantially orthogonal to the axis of rotation. the motor shaft 4.

The motor shaft 4 and the output shaft 5 are connected in rotation by transmission means.

According to the principle of the invention, these transmission means comprise a conical coupling 2 connecting the drive shaft 4 directly or indirectly with an intermediate gear whose axis of rotation is parallel to the axis of rotation of the output shaft. , this intermediate gear cooperating with the output shaft via another gear carried by the output shaft. It is understood that in this way, the conical coupling is brought closer to the engine block incorporating the shaft. This conical coupling is, in other words, provided in the vicinity of the end of the motor shaft (or is carried by this end) so that the bulk of it is not detrimental to the accessibility of the angle head in small spaces. In other words, the conical coupling is remote from the angle head, one or more parallel axis gears to the output shaft being interposed between the output shaft and the conical coupling.

According to the embodiment of the invention illustrated in FIG. 3, the conical coupling 2 is mounted at one end of the drive shaft 4 (here constituted by a main body 41 and an extension 42), and a parallel gear train 6 is mounted between the conical coupling 2 and a gear 512 for rotating the output shaft 51.

It will be understood that the screwing tool thus constituted comprises a reduction chain coupling the motor and the output shaft and that this reduction chain has the conical coupling as input member. The exercising couple on the elements of the growing chain while approaching the output shaft, the positioning of the conical coupling directly at the output of the motor shaft makes it possible to reduce as much as possible the torque supported by the conical coupling. The tool uses a torque sensor technology described above with reference to the state of the art (that is to say of the type described in the document published under the number DE-I 980 4695). It is recalled that such a sensor comprises:

strain gauges bonded to the output shaft; an on-board electronic circuit on the output shaft; a rotating transformer.

A torque sensor of another technology may, however, be implemented according to another possible embodiment.

With reference to FIG. 4, the torque sensor is designed as an independent module 7 fixed by two screws to a transmission module 8 of the tool.

The shaft of this sensor comprises male splines for transmitting the torque, these splines being intended to fit into the gear with parallel teeth 512 (FIG. 3) allowing the transmission of the torque. This gear 512 is itself driven by a gear train with parallel teeth, as mentioned above.

This arrangement makes it possible to maintain a head height comparable to the standard tool, and is much more compact than the tool illustrated in FIG.

The reduction therefore comprises gear 6 forming a reduction whose ratio is adapted to the level of torque that it is desired to reach as output tool.

The gears 6 and the conical coupling 2, are integrated in the module 8, itself separable from the engine block 40 as will be explained in more detail later. Note that the extension 42 of the motor axis is integrated in the module 8, the latter having an end intended to be housed in the end of the main body 4 of the motor shaft so as to make the main body and the extension solidarity in rotation. This module 8 is equipped with sealed ball bearings to contain the grease necessary for the lubrication of the gears. This module 8 is also waterproof and independent.

Fixing the module on the engine block 40 is achieved by three screws 9 distributed at 120 ° and inclined by 15 ° relative to the motor axis (a higher number of screws can of course be considered). This arrangement makes it possible to reduce the external dimensions of this fastener, and allows easy assembly and disassembly, requiring no special wrench or high tightening torque or gluing, assuming the use of a hot-air tool heater. at the time of disassembly.

Figures 5 to 8 illustrate an alternative embodiment of a screwing tool according to the invention. As it appears in FIGS. 6 and 7, the output gear 512 is supported on either side of its toothing (5122) by two ball bearings 52, completely taking up the transmission stresses exerted on the gear 512, these stresses being generated by the intermediate gear train 6. Therefore, the gear 512 does not transmit any bending force to the output shaft (any bending forces on the output shaft being of a nature to disrupt the torque measurement) via the female splines 5121 (of the gear 512) and the male splines 513.

Note that the presence of two ball bearings 52 (instead of one) avoids a cantilever mounting gear 512, thereby avoiding a "ball" effect that would be present in the case of a unique bearing. In other words, this mounting of a bearing on either side of the gear 512 improves the stiffness of the guide (being distant from one another) and ensures a homogeneous distribution of the stresses on the bearings , while registering in a small footprint. Such an assembly thus limits the forces transmitted to the output shaft by the gear 512 to the single screwing torque.

The output shaft is supported at its lower part by a ball bearing which can alternatively be a rigid ball bearing (as in FIG. 3) or a double row of ball bearings 53 (FIG. 7). Preferably, this bearing is a double-row ball bearing which makes it possible to fully recover the bending forces generated by the outlet bushing on the drive square 514 and thus eliminate external disturbances on the sensor, which would not be the case with a bearing with an oblique contact.

According to another characteristic, stop means 531, 532 are provided for diffusing into the housing 70 of the sensor module axial stresses exerted from outside on the square. This avoids transmitting these forces to the active part of the sensor.

These means comprise, according to the present embodiment, a locking ring 531 is mounted in a groove on the shaft 51, this ring bearing against the inner ring of the bearing 53. In parallel, a second ring stop 532 is mounted in a groove formed inside the housing 70, this ring bearing against the outer ring of the bearing 53.

In addition, it is noted that the ball bearings 52 are sealed. There is no possible grease leakage from the gear train 6 and / or the gear 512 to the sensor (which limits the risk of disturbances in the measurement).

In the same way, it is expected that the bearing 53 is sealed, thus avoiding any rising of external fluid to the sensor.

The technology of supply of the gauge bridge 72 and the onboard electronic circuit 74 and signal recovery is based on the use of a rotary transformer 73. There is therefore no wear of brushes possible. As indicated above, the sensor module 7 is designed as an independent module and fixed by two screws 71 to the rest of the tool. This results in obvious advantages for manufacture and maintenance, the sensor module and its internal organs thus being easily accessible and / or replaceable. More specifically, the module 7 comprises a housing 70 having two wings 701 delimiting between them a concave shape for receiving the correspondingly shaped end 81 of the transmission module. These wings 701 provide a seat on the transmission module, and contribute to ensuring the stability of the attachment of the sensor module on the transmission module in the event of lateral or longitudinal impact.

It is noted that moreover the holes 711 for receiving the fastening screws 71 are substantially centered with respect to the length L of the casing 70 of the module, contributing, with the general shape of the casing, to the stability of the attachment of the sensor module to the transmission module. Moreover, the power supply of the sensor module and the recovery of the frequency signal is achieved by only two wires that do not require special electromagnetic protection, in view of the sensor technology used. These two son pass through a duct formed in the thickness of the transmission module casing for reasons of mechanical protection. The wires are connected to a power supply and a frequency signal processing module, both present in the handle of the tool.

Claims

1. Screwing tool comprising: - a motor shaft (4); an angle head (5) comprising an output shaft (51) whose axis of rotation (511) is substantially orthogonal to the axis of said motor shaft

(4); transmission means connecting said driving shaft (4) to said output shaft (51); at least one torque sensor integrated on said output shaft (51), characterized in that said transmission means comprise at least one intermediate gear (6) of axis substantially parallel to said output shaft (51) and cooperating with a gearing (512) for rotating said output shaft (51), and at least one conical coupling (2) connecting, directly or indirectly, said drive shaft (4) and said at least one intermediate gear (6).

2. Screwing tool according to claim 1 characterized in that said transmission means comprise a parallel intermediate gear train (6) whose axes are parallel to said output shaft (51).

3. Screwing tool according to one of claims 1 and 2, characterized in that said transmission means are mounted within a module (8) detachable to a member (7) incorporating said torque sensor.

4. Screwing tool according to one of claims 1 to 3, characterized in that said transmission means are mounted within a module (8) detachable a body (40) incorporating said drive shaft (4) and motor means.

5. Screwing tool according to one of claims 3 and 4, characterized in that said transmission means are associated with sealed ball bearings.

6. Screwing tool according to any one of claims 1 to 5, characterized in that said torque sensor comprises at least one strain gauge bonded to said output shaft.

7. Screwing tool according to any one of claims 1 to 6, characterized in that said torque sensor comprises an electronic circuit embedded on said output shaft.

8. Screwing tool according to any one of claims 1 to 7, characterized in that said torque sensor comprises a rotating transformer.

9. Screwing tool according to any one of claims 1 to 8, characterized in that said gear (512) is guided in an upper part of said corner head by at least one ball bearing (52) on the other hand. other of the toothing (5122) of said gear (512).

Screwing tool according to any one of claims 1 to 9, characterized in that said output shaft (51) is guided in a lower part of said corner head by at least one bearing (53) with two rows. of balls.

11. Screwing tool according to claims 9 and 10, said gear (512) is guided in an upper portion of said corner head by at least one ball bearing (52) on either side of the toothing (5122 ) of said gear

(512), said output shaft (51) being guided in a lower part of said corner head by at least one bearing with two rows of balls.

12. Screwing tool according to any one of claims 9 to 11, characterized in that said one or more guide bearings of said gear (512) are sealed bearings.

13 screwing tool according to claims 3 and 10, characterized in that said member (7) comprises a housing (70), said tool comprising stop means (531), (532) for diffusing into said housing (70). ) axial stresses exerted on said output shaft (51). 14. Transmission module intended to be integrated into a screwdriver comprising: a motor shaft (4); an angle head (5) comprising an output shaft (51) whose axis of rotation is substantially orthogonal to the axis of said motor shaft (4); - Transmission means connecting said drive shaft (4) to said output shaft (51); at least one torque sensor integrated on said output shaft (51); characterized in that it integrates said transmission means, the latter comprising at least one intermediate gear (6) whose axis is intended to extend parallel to said output shaft (51) and intended to cooperate with a gear ( 512) carried by said output shaft (51), and at least one conical coupling (2) for connecting, directly or indirectly, said drive shaft (4) and said one or more intermediate gears (6).