WO2012114361A1

WO2012114361A1 - Hydraulic spanner

Info

Publication number: WO2012114361A1
Application number: PCT/IT2011/000153
Authority: WO
Inventors: Silvio GIACOMETTI
Original assignee: SCS Concept Italia SRL
Current assignee: SCS Concept Italia SRL
Priority date: 2011-02-25
Filing date: 2011-05-16
Publication date: 2012-08-30
Anticipated expiration: 2013-08-25
Also published as: ITMI20110286A1

Abstract

A hydraulic spanner for tightening threaded connection elements, comprising a fixed body (1), a movable body (2) having a screwing head (3), a hydraulic mechanism able to rotate said movable body with respect to said fixed body in a screwing direction, characterized in that said spanner comprises a torque transducer (8) directly applied to said movable body. Preferably the spanner comprises a gauge (15) for measuring the screwing angle.

Description

TITLE

"HYDRAULIC SPANNER"

DESCRIPTION

The present invention relates to a hydraulically operated spanner for the tightening of screws, bolts and suchlike. Hydraulically operated means operation with an appropriate pressurised liquid, in particular oil.

To tighten connection elements such as screws, bolts, nuts and suchlike, with high tightening torque, hydraulic spanner systems are used, in which a piston driven by oil pressure acts on a screwing head. A mechanism of an appropriate type, for example, a ratchet mechanism, allows the piston to drag, in a rotary manner, the head in the screwing direction (or unscrewing direction if the possibility of reversing the rotation is envisaged) and allows the return of the piston to the opposite position, relieving the pressure and acting on a suitable valve system, and allowing the piston to carry out, under the action of pressure, a new stroke in the screwing direction, until the operation is complete. The pressurised oil is supplied by a pump, appropriately connected, by means of the said valve system, to the cylinder piston. This type of spanner, and the control system therefor, are in themselves commonly known and need no further description.

As in the case of mechanical-type torque spanners, hydraulically operated spanners can also be employed in the field of industrial assembly when it is necessary to ensure precise tightening of the connection elements. The torque is commonly limited by controlling the oil pressure supplied by the pump, for example, reading it on a manometer; automatic pressure limiting devices may also be envisaged, to stop the process when appropriate. For each spanner there exists a commonly known correlation between the pressure reached in the cylinder and the torque transmitted to the connection element. Also for reasons of space, the manometer is generally located on the pump, upstream of the piping for connection with the cylinder. The above mentioned system has the advantage of notable simplicity and eliminates the need to apply torque transducers between the screwing head and the connection element, which is sometimes impossible or difficult because of the overall dimensions and operating conditions, which may be uncomfortable for the operator. However, the reliability and precision which this system allows are not entirely satisfactory. In fact, unexpected friction or jamming can occur at any point of the transmission between the piston and the screwing head; even if the pressure in the cylinder reaches predetermined level, the torque effectively transmitted to the connection element may be, therefore, lower than expected, or even zero. Problems may also occur in oil supply pipelines or in the valve system, therefore the pump delivery pressure, which is usually what is read or utilised by the control system, is not the pressure effectively reached in the cylinder. Given the potential hazards arising from inadequate tightening operations, a more reliable verification of the tightening torque transmitted to the connection element would be desirable, without recourse to equipment to be placed between the spanner and the element and without rendering operations more complex for the operator.

Furthermore, the effective transmission of the tightening torque to the element does not exclude the possibility of the latter jamming because of seizure, machining defects or assembly errors, without the tightening being carried out in an effective manner. It would therefore be desirable to allow immediate and reliable recognition of this condition, also in this case, without leading to greater complexity of equipment or operation.

The aforesaid problems can now be overcome by means of a hydraulic spanner for tightening threaded connection elements, comprising a fixed body, a movable body having a screwing head, a hydraulic mechanism able to rotate said movable body with respect to said fixed body in a screwing direction, characterized in that said spanner comprises a torque transducer directly applied to said movable body.

Torque transducer means any device for measuring the torque transmitted through the movable body to which said transducer is applied by generating an electrical or other type of signal designed to be used by an appropriate detecting device, for example, a display or alarm device, a calculation unit or other similar devices.

According to a preferred aspect of the invention, said movable body has a first end which features said screwing head and a second end opposite the first having a structure for connection of said transducer with an external detection device.

Preferably, said transducer is contained within the fixed body, and can be applied to the movable body, which preferably features a cylindrical portion in correspondence with said portion.

According to a further preferred aspect, said transducer comprises one or more electrical resistance strain gauges, preferably four.

The movable body may, according to a further aspect of the invention, comprise one or more channels therein, to allow the passage of connectors between said transducer and said structure. According to a preferred aspect of the invention, the spanner also comprises a gauge for measuring the angle of rotation of said movable body with respect to said fixed body.

The invention will now be better illustrated by means of the description of a preferred embodiment, provided in the form of a non-limiting example, with the help of the accompanying drawings, in which:

figure 1 represents, schematically, a hydraulic spanner in accordance with the present invention from a perspective view;

figure 2 represents, schematically, a section view according to a plane passing through an axis of symmetry of the movable body of the spanner according to the present invention.

With reference to the figures, the spanner according to the present invention comprises a fixed body 1, in which a movable body 2, shaped substantially like a shaft, is appropriately seated and designed to rotate, under the action of a hydraulic mechanism, around its own axis. The movable body 2 features a screwing head with an appropriate section 3, for example square, hexagonal or other, a head which can be shaped with a form corresponding to the bolt or nut head for which the spanner is intended, or may be designed for use with appropriate adapters for other forms of screw or nut. The head may, if desired, also be interchangeable. According to a possible embodiment, the movable body may feature a portion 4 with longitudinal grooves designed to engage with an appropriate socket 5, into which the said embodiment is inserted, rotationally integral therewith; in turn, the socket 5 can be grooved externally to engage with a ratchet mechanism contained in an appropriate lever, operated by a movable piston in a hydraulic cylinder machined directly onto the fixed body 1. Alternative embodiments can also be designed, for example with the movable body operated directly by a lever and ratchet mechanism. The movable body 2 can be secured, in an axial direction, within the fixed body, in an appropriate manner. For example, said movable body can be fixed, by means of bolts or flanges or circlips, to the socket 5, or bushings, bearings or other means may be envisaged. As usual, there are channels for connection to the cylinder with connections 6 for valves and supply pumps and oil flow; a adjustable support system 7 can be envisaged. Regarding the aspects described so far, the spanner can be achieved in a similar way to the commonly known technique, with all variations possible depending on needs.

The spanner according to the present invention comprises a torque transducer 8 applied in an appropriate manner to said movable body. For instance said spanner may comprise one or more (preferably four) electrical resistance strain gauges applied to said movable body. According to a preferred aspect, said strain gauges are applied to the exterior of a portion 9 of the movable body designed for this application: for example, said portion can have a smooth external surface, without teeth, designed to engage with the hydraulic mechanism, if present, and a diameter which may be smaller than the portions designed for engagement with the mechanism so as to leave sufficient space between the movable body and the other spanner structures, for example the socket stated above, if present. The strain gauges can be applied and connected, in an appropriate manner known to technicians in the field, to measure the torque transmitted by a shaft, which may be the movable body, according to a preferred embodiment.

Preferably, said portion suitable for application of the transducer is contained within the fixed body. This allows to the transducer to be integrated with the spanner, without increasing the overall dimensions thereof.

According to a possible embodiment, the movable body features, on the opposite end to the screwing head, a structure for connection of the transducer to a data detection and/or processing device. For example, the structure may comprise a sleeve 10 of insulating material, for example a plastic material which bears, on the surface thereof, annular contacts 11, arranged in an essentially reciprocally parallel fashion on the external surface of the sleeve, in order to allow contact between the movable body and a manifold during rotation. For example, the manifold 12 may feature a series of brushes 13, one per contact, said brushes being equipped with springs or another appropriately mounted system to promote contact. The manifold can be, according to a possible aspect of the invention, mounted on a support 14, preferably shaped like a box, fixed to the spanner, to the fixed body for example, by means of appropriately provided slots and screws. The box can, according to a possible aspect of the invention, hold the ends of the movable body.

To connect the transducer to the end opposite the screwing head, appropriate measures may be envisaged, for example, channels can be machined into the movable body for the passage of conductors, for example, insulated electrical wires. According to a possible aspect, a channel 16 can be machined along the axis of the movable body, connected to the surface thereof, in correspondence with the transducer and the connection structure, by radial holes.

According to a preferred aspect of the invention, the spanner also comprises a gauge 15 for measuring the screwing angle, capable of detecting the rotation of the movable body. According to a preferred aspect, said gauge can be fixed to said support. The gauge can be of a known type, mechanical, optical or otherwise, and fitted in an appropriate manner. For example, said gauge may feature a shaft 17, whose rotation is designed to detect, which can be inserted, according to a preferred aspect, directly into the open end of the channel 16. To transmit the rotation from a movable body to the shaft, grooves and corresponding projections may be envisaged on both parts, or a grub screw in a through hole in the movable body, or another means. The presence of the gauge allows the screwing angle to be detected in relation to the torque developed, which allows possible jamming or anomalies to be detected, which would not be detectable by simply measuring the torque. The use of a transducer, in accordance with the present invention, allows a valid use in association with the gauge, because of the precision thereof. In fact, the detection of the torque by measuring the oil pressure, according to the commonly known technique, is not sufficiently precise and is subject to delays due to the inertia of the system, which would not allow good results in the association between the two sets of data.

The manifold and the gauge can be connected to a logic unit (not shown) for the detection, signalling and/or processing of data, designed to show the data measured or processed and/or to emit signals, either of a visual nature, for example by means of a display unit or signal lights, or audio signals, related to the completed tightening or the occurrence of anomalies.

Claims

1. A hydraulic spanner for tightening threaded connection elements, comprising a fixed body (1), a movable body (2) having a screwing head (3), a hydraulic mechanism able to rotate said movable body with respect to said fixed body in a screwing direction, characterized in that Laid spanner comprises a torque transducer (8) directly applied to said movable body.

2. According to a preferred aspect of the invention, said movable body has a first end which features said screwing head and a second end opposite the first having a structure for connection of said transducer with an external detection device.

3. The hydraulic spanner according to any of the previous claims, wherein said transducer is contained in the fixed body itself.

4. The hydraulic spanner according to any of the revious' claims, wherein said transducer is applied to the movable body, in !correspondence with! a cylindrical portion thereof.

5. According to a further preferred aspect, wherein said electrical resistance strain gauges,

6. The hydraulic spanner according to any of the previous claims, wherein said movable body comprises one or more channels (14) inside, in order to permit the passage of connectors between said transducer and said structure.

7. The hydraulic spanner according to claim 2, wherein at the jopposite end of said movable body_with_respeclj to the screwing head, there is ja box (14) applied, comprising a nanifold (12) for connecting said connection structure to a logical unit.

8. The hydraulic spanner according to claims 2 and 7, wherein said structure comprises a sleeve of insulating material having annular contacts (11) and said I m—anif—old ' is a brush I manifold I.

9. The hydraulic spanner according to any of the previous claims, comprising a !gaugej (15) able to [neasure! the rotation angle of the movable body.

10. The hydraulic spanner according to claim 11, wherein said Igaugej has a shaft, inserted into a channel (16) machined along the axis of said movable body and rotationally integral jtherewith!.