EP0904899A2

EP0904899A2 - Tool for screwing/unscrewing nuts provided with toothing on their external surface

Info

Publication number: EP0904899A2
Application number: EP19980203056
Authority: EP
Inventors: Andrea Peroni
Original assignee: Cazzaniga SpA
Current assignee: Watts Industries Italia SRL
Priority date: 1997-09-24
Filing date: 1998-09-12
Publication date: 1999-03-31
Also published as: ITMI972155A1; IT1295054B1

Abstract

Tool for screwing/unscrewing nuts (30) provided with toothing (31) on their external surface, which comprises an operating part (10) and a part (20) for engaging with said nut (30), said engaging part essentially consisting of two arms (24) which are associated with corresponding means (26) for operating said arms so as to close them in the radial direction onto the nut (30) and means (23;123;223) for engagement with and rotational operation of the nut (30) in both directions for screwing/unscrewing thereof.

Description

The present invention relates to a tool for screwing/unscrewing nuts provided with a radial toothing on their external surface.
It is known in the technical sector relating to the connection of pipes to threaded connections of hydraulic equipment and the like that there exists the need to screw onto the threading of the said connection the locking nut of the union which provides the sealed connection between the two parts.
It is also known that tightening of the nut of the union cannot be performed by means of power-driven tightening tools, of the screwing and similar type, since access to the nut with the tool is possible only in a radial direction and not in the axial direction which is prevented by the presence of the pipe, on the one hand, and the connection itself, on the other hand.
An Italian patent application in the name of the same Applicant describes a locking nut provided with a radial toothing formed on its external surface and suitable for radial engagement with a corresponding tightening tool. The technical problem which is posed, therefore, is that of providing a manual or power-driven tool, of the screwing/unscrewing type, suitable for engagement in the radial direction with locking nuts for connection elements of parts to be joined together in frontal and/or perpendicular directions such as, for example, those of the unions for the sealed connection of pipes with threaded connections of hydraulic, pneumatic and similar equipment.
Within the scope of this problem a further requirement is that the tool should be easy and inexpensive to manufacture, consisting of a small number of parts, that it should be easily accessible for any maintenance operations and that it should have small overall dimensions so as to facilitate storage, transportation and use by the user also in difficult conditions.
These technical problems are solved according to the present invention by a tool for screwing/unscrewing nuts provided with toothing on their external surface, which comprises an operating part and a part for engaging with said nut, said engaging part essentially consisting of two arms which are associated with corresponding means for operating said arms so as to close them in the radial direction onto the nut and means for engagement with and rotational operation of the nut in both directions for screwing/unscrewing thereof.
Further details may be obtained from the following description of a non-limiting example of embodiment of the invention provided with reference to the accompanying drawings, in which:

Figure 1 shows a partially sectioned front view of a first example of embodiment of the tool according to the invention;
Figure 2 shows a partially sectioned side view of the tool according to Fig. 1;
Figs. 3a-3d show the sequence for gripping and screwing, by means of the tool according to the invention, a nut with an external toothing;
Figure 4 shows a first alternative example of embodiment of the tool according to the invention; and
Figure 5 shows a second alternative example of embodiment of the tool according to the invention.

As illustrated in Figs. 1 and 2, the tool according to the invention comprises a substantially cylindrical body 10 forming the handle of the tool itself and a part 20 for engagement with/operation of the nut 30 to be screwed/unscrewed.
The handle 10 has, housed inside it, a motor 11 for operation of a shaft 11a projecting axially from the body 10, which motor is provided with on/off switching means 12 and means 13 for adjusting its speed of rotation.
Said means for switching it on comprise a switch 12 acting, with a translatory movement, against the thrusting action of a spring 12a which is coaxial with the shaft 11 and which has the function of preventing random and unintentional displacement of the switch with consequent unwanted switching-on of the motor.
Said switch forms a single body with the external cylindrical casing of the screwing device, thus producing the axial movement of the latter as will be further explained below.
The motor may be provided with a mixed power supply from the mains and a rechargeable battery which is known per se and therefore not illustrated.
The part 20 for engaging with and operating the nut 30 comprises a first bevel gearwheel 21a which is mounted on the free end of the shaft 11a and is designed to engage with/operate a corresponding second bevel gearwheel 21b mounted on a pin 21c substantially perpendicular to the axis of the motor shaft 11a.
On the same pin 21c there is also mounted a pinion 22 which is designed to engage with and operate two toothed wheels 23 respectively mounted on corresponding pins 23a, on each of which a shaped arm 24 rotating on the associated pin 23a is also mounted.
As shown, the two arms 24 are arranged symmetrically with respect to the longitudinal axis of the tool and shaped so as to form grippers which are kept in the closed condition by a spring 26 arranged between the two arms 25. In the example shown the spring 26 is positioned at the end of the arms 25 opposite to the gripping end, relative to the pin 23a, and is therefore a compression spring which pushes against the arms so as to keep them normally rotated in the closed condition.
The arms 24 are locked in their working position, engaged with the nut 30, by means of displacement, in the axial direction, of the cylindrical switch 12 which, moving forwards as a result of closing of the starting contact of the motor, comes into abutment against the inner end of the arms 25, preventing the opening rotational movement thereof and thus ensuring a stable grip on the nut.
However, it is obviously within the competence of a person skilled in the art to envisage equivalent variations in the arrangement of the spring and its action, provided that the operation described above is maintained.
Each arm 24 also carries idle rollers 25 on associated pins 25a, which are designed to engage with a corresponding annular seat 32 in the nut 30 so as to allow correct engagement between the parts and facilitate the displacement of the tool in the axial direction together with and in unison with the nut 30 during screwing/unscrewing thereof, as will be further explained below with reference to the description of operation of the tool.
The part 20 engaging with the nut 30, finally, is completed by a protection and safety cover 26' which encloses all the moving parts and leaves exposed only the parts of the arms 24 which are intended to engage with the nut 30.
As illustrated in sequence in Fig. 3, which shows in schematic form a hydraulic union of the known type comprising a plurality of inlets/outlets provided with a locking nut 30, the operating mode of the tool is as follows:

keeping the actuating motor 11 switched off, the gripping arms 24 are moved towards the nut 30 (Fig. 3a);
exerting a pressure on the tool in the axial direction causes widening of the arms 24 and their engagement, in the radial direction, with the nut 30 so that the arms 24 are inserted into the corresponding annular seat 32 of the nut 30 and the toothed wheels 23 mesh with the external toothing 31 of the nut (Figs. 3b,3c);
at this point the motor is actuated by means of the switch 12, causing screwing/unscrewing of the nut 30 of the union, by means of the action of the tool which is able to operate with constant characteristics also during displacement of the nut in the axial direction due to screwing/unscrewing thereof on the threading of the fixed connection, owing to engagement of the rollers 25 of the arms 24 with the annular seat 32 of the nut 30.

It is therefore obvious how the tool according to the invention allows perfect and functional engagement, in the radial direction, with a nut provided with external toothing and how operation of the tool allows screwing/unscrewing of the nut also in the case of frontal and/or perpendicular joining together of parts which prevent the use of normal power-driven tools, frontal access of the latter to the nut not being permitted.
In addition to this, use of the screwing device according to the invention also allows rapid and secure tightening of the nuts since the tool may be calibrated so as to provide a predetermined tightening torque which produces the desired engagement, but without causing damage to the individual parts, damage which is particularly serious in the case, for example, of connections of the hydraulic type where even a small deformation of a component may be the cause of leakages from the union.
Many variations of the individual parts which make up the tool may be introduced without departing from the protective scope of the present patent.
For example, it is envisaged (Fig. 4) that the toothed wheels 23 may be replaced by rubber-lined rollers 123 which allow screwing/unscrewing of nuts which do not have the said toothing 31.
In a further embodiment, an endless belt pulley 223 with a double toothing is provided on the toothed wheels 23 so that the internal toothing receives movement from the toothed wheels themselves and the external toothing transmits the movement to the nut 30.

Claims

Tool for screwing/unscrewing nuts (30) provided with toothing (31) on their external surface, which comprises an operating part (10) and a part (20) for engaging with said nut (30), characterized in that said engaging part (20) essentially consists of two arms (24) which are associated with corresponding means (26) for operating said arms so as to close them in the radial direction onto the nut (30) and means (23;123;223) for engagement with and rotational operation of the nut (30) in both directions for screwing/unscrewing thereof.
Tool according to Claim 1, characterized in that said arms (24) are arranged symmetrically with respect to the longitudinal axis of the tool so as to form grippers which can be clamped onto the nut (30).
Tool according to Claim 1, characterized in that said arms (24) rotate about an associated support pin (23a) fixed to the tool.
Tool according to Claim 1, characterized in that said means for clamping the arms (24) onto the nut (30) are resilient means (26).
Tool according to Claims 1 and 4, characterized in that said resilient means consist of a compression spring arranged between the arms themselves.
Tool according to Claim 1, characterized in that it comprises means (12) for locking the arms (24) upon start-up of the motor of the tool.
Tool according to Claim 6, characterized in that said means (12) for locking the arms (24) consist of a cylindrical casing integral with the switch for switching the motor on/off and movable axially therewith.
Tool according to Claim 1, characterized in that said arms (24) carry rollers (25) designed to engage with an associated annular seat (32) in the nut (30).
Tool according to Claim 1, characterized in that said means (23;123;223) for rotational operation of the nut (30) are coaxially mounted on each fixed pin (23a) supporting the arms.
Tool according to Claim 1, characterized in that said means for rotational operation of the nut (30) consist of a pair of toothed wheels (23).
Tool according to Claims 1 and 7, characterized in that said means for rotational operation of the nut (30) consist of a pair of toothed wheels (23), the part of which engaging with the nut consists of a rubberized covering (123).
Tool according to Claim 1, characterized in that said means for operational rotation of the nut (30) consist of a pair of toothed wheels (23), the part of which engaging with the nut consists of a toothed belt (223) with a double toothing for receiving/transmitting the movement.
Tool according to Claim 1, characterized in that said part (10) for generating the movement for operation of the nut (30) comprises at least one pinion (22) for operation and synchronization of the toothed wheels (23) associated with a bevel gearwheel (21a,21b) for transmission of the movement from the shaft (11a) of a motor (11) to the pinion (22) itself.
Tool according to Claim 1, characterized in that said shaft of the motor (11) is arranged in a direction substantially parallel to the longitudinal axis of the tool.
Tool according to Claim 1, characterized in that the fixed pins (21c,23a) supporting the gearwheels (22,23) for transmission of the movement to the nut (30) are substantially perpendicular to the motor shaft (11a).
Tool according to Claim 1, characterized in that the motor (11) is of the variable-speed type.
Tool according to Claims 1 and 14, characterized in that means (13) for adjusting the speed of rotation of the motor are provided.
Tool according to Claim 1, characterized in that it comprises means (12) for switching the motor (11) on/off, which are associated with a safety device (12a).
Tool according to Claims 1 and 18, characterized in that said safety device consists of a resilient element (12a) coaxial with the motor shaft (11a) and acting against said on/off switching means (12).