Field of application

The present invention relates to a particular handle of a manual screwdriver inside which there is a pre-calibrated torque device, which can be used to tighten a plurality of screws of several dimensions: this is done by using particular shafts, which are appropriately machined and/or shaped, each for an appropriate technical characteristic of the screw to be tightened, in order to work correctly and safely on said screw. In practice, the invention is a new multifunction pre-calibrated dynamometric device, which is capable of cooperating with various shafts (each having an end suitable for the corresponding screw head), provided with suitable contoured machining on the part that is inserted within said handle. The shaft couples with the corresponding dynamometric devices, in order to determine a total rotation-contrasting torque (screwing moment) and an opposite torque (opposite loosening-unscrewing moment), which are suitable for the technical and geometric characteristics of the screws. Said device is particularly suitable to ensure correct manual tightening of screws, for example in fixing the inserts of tools and mills for chip-forming machining.

Background art hi the background art, various kinds of simple or complex screwdriver for manual use are known. Their manual use by operators does not ensure reliably the tightening torque, since each person has a different strength in his or her hands. This is disadvantageous if one needs to ensure with certainty a screw tightening torque. In particular, this assurance is required for greater work safety in the case of tightenings of the technical type of the plates of tools on mills or other chip-forming and material cutting devices. Good tightening of the locking screws of the tool inserts, particularly on milling machines, which work at a high peripheral speed, in fact avoids severe injury to the operators of machine tools. The inconstant and insufficient tightening of said plates, performed by different operators with traditional screwdrivers, has in fact been all too often the cause of severe workplace accidents.

Currently, in order to avoid these drawbacks, series of torque screwdrivers, each calibrated for a specific pattern and size of the screw, are known and commercially available. Other screwdrivers have a mechanical device with springs, which is built into the handle in order to adjust the calibration of the screwing torque, but use a single shaft and a single tightening tip.

This leads to the use of a large series of screwdrivers which are mutually different due to the various characteristics and sizes of the screws, entailing a considerable investment cost for the company.

In order to overcome the cost problem, other screwdrivers are known which have, in the handle, the torque adjustment device, on which the extensions of the shaft that bear the patterns that correspond to the screws are inserted. In this case, the number of screwdrivers or of the extensions connected to the handle is reduced, but the operator is forced to provide a specific adjustment as the characteristics of the screw vary. This makes it more complicated to use the tool and does not prevent errors in calibration by the operator, who must be truly an expert in the field. In view of the various drawbacks of currently known tools, the aim of the present invention is to overcome them both from an economic standpoint and from the point of view of assurance of the torque calibration of the tool.

Summary of the invention

The aim of the present invention is to provide a handle of the universal type containing a pre-calibrated torque device of the multiple type, which is suitable to cooperate in coordination with a series of different shafts (machined in a particular manner), each provided with the pattern of a different screw. Said handle has multiple pre-calibrated screwing torques, which differ as the characteristics of the shafts inserted in it very, without the burden of calibration by the operator. This provides a tool which is safe and usable by any operator.

Therefore, the present invention entails:

- providing a single handle with a pre-calibrated multiple torque device inside it, said device being suitable to work with multiple different and interchangeable screwing shafts;

- providing a torque device constituted by multiple transverse elements which are tensioned, arranged side by side and provided with a central coupling seat in order to adapt to the shafts inserted longitudinally with respect to the handle;

- providing shafts in which the opposite side, with respect to the pattern of the screw, is contoured and machined in a particular manner so as to couple with one or more of the pre- calibrated tensioned transverse elements of the handle;

- providing shafts with patterns for screws of various types and sizes, featuring in particular, for example, the patterns T6, T7, T8, T9, TlO, Tl 5, T20 and others;

- providing a single set, which comprises a series of shafts with various patterns for screws and a single grip handle provided with a multiple pre-calibrated tensioning device which couples with said various shafts;

- providing a device which allows rapid replacement of the various shafts in relation to the patterns of the screw heads, ensuring at the same time a corresponding and suitable screwing

torque tension and an unscrewing (loosening) torque tension in which the contrast torque is higher than the preceding one.

Essence of the invention

The aim of the invention is achieved, according to the characteristics of the main claim and/or of any other claim stated in the present patent description, by providing a manual screwdriver handle a with multiple pre-calibrated torque device, suitable for tightening a series of screws of various sizes, which cooperates in coordination with various shafts provided for this purpose, which are particularly contoured and machined in order to ensure a different screwing torque for each type of shaft suitable to work on the head of the screw to be tightened.

The tool with the handle comprising the device is applied in the field of the interchangeability of plates made of hard and/or sintered metals on multiple tools such as milling machines and the like, which require, for obvious safety, an assurance of the tightening and locking torque of said plates on the central containment body.

The present invention consists of the mutual coordination and cooperation of the handle with a series of different shafts (suitable for various screw types), of the single type (with a pattern at one end) or of the double type (with two different patterns on the two ends), which are contoured and machined in a particular manner in the part for coupling with the containment handle. Said shafts can be easily replaced and are interchangeable by longitudinal extraction with respect to the axis of the handle and subsequent insertion of another shaft, or of an identical shaft, within said handle.

First of all, the handle or handgrip is provided internally with a mechanical torque device of the multiple type, i.e., a set of tensioned elements which lie transversely to the longitudinal axis of the handle and are coaxial and parallel, each element being provided with an identical central meeting seat. Each transverse element is subject to a tension which is provided by means of one (or more) elastic springs or other equivalent means (for example rubber, compressed air, et cetera), which acts on a ball which couples with a corresponding seat shaped like a spherical dome, which is provided on the central element for coupling with the shaft, or other equivalent means suitable for the purpose (for example a clutch system, ratcheting elements, et cetera), calibrated beforehand in order to provide resistance to the rotation of said central seat. This provides a torque which contrasts the rotation of the seat for coupling with the shaft of the screwdriver. If the contrast torque applied to the individual central coupling seat during the screwing action, the rotation force applied to the shaft, is exceeded, the handle rotates freely about its own axis and therefore does not apply a stronger tightening action to the screw, since the maximum torque calibrated beforehand according to the standards provided for that type of screw has been reached.

Furthermore, the present invention allows to have, during unscrewing or loosening, a pre-calibrated torque which is higher than the screwing torque; this is achieved by means of a tangential inclination of the tensioning device (elastic spring and sliding ball) with respect to the perpendicularity of the center of rotation of the rotating central body (the tensioning devices lie on a plane which is perpendicular to the axis of the shaft). Each rotating central body can be subjected simultaneously to the tension of one or more pre-calibrated tensioning devices.

As mentioned, the torque device is of the multiple type, i.e., it has a plurality of elements arranged side by side, each tensioned in a pre-calibrated manner, having an identical and/or different force. In this regard, attention is drawn to the core of the invention: the shaft of the screwdriver in fact has a male coupling seat which is more or less extensive, so as to affect one or more tensioned central female elements, thus providing a different contrast torque during screwing for each shaft and a higher opposite torque during unscrewing. Said shafts are machined in various manners on the part that is inserted in the handle, so as to cooperate by coupling with at least one or more tensioned elements, thus obtaining a specific performance in relation to the type of impression of said screwdriver.

A single multiple tensioning device can be used with various shafts having different technical, mechanical and geometric performance, of the single type (with one pattern at one end) or of the double type (with two different patterns at the two ends).

The geometric shape of the seat for coupling between the rotating central (female) pre- calibrated tensioning element and the cross-section of the corresponding (male) shaft may be any (for example triangular, square, pentagonal, hexagonal, et cetera) and/or may use other known mechanical techniques (for example, a tab and a corresponding contoured receptacle) for coupling the two mutually cooperating elements.

Each pre-calibrated tensioning radial element contained in the handle or handgrip is mutually independent, so that each one contributes to its own torque action, which is added to the- actions of the other adjacent tensioned elements.

Furthermore, the shaft of the screwdriver can be of the monolithic type, i.e., with a contoured insertion shank within the handle and a tip equipped in a fixed manner so as to work on certain screws, of the single or double type, or can also be of the complex modular type, in which only the shank, appropriately shaped for insertion in the handle, is provided with a tip which is interchangeable in relation to the geometric shape of the pattern of the screw on which it is to act.

The present invention, in addition to being particularly suitable in the tightening of screws in the field of multiple-plate tools, by safely ensuring an ideal locking torque in relation to the type of screw, can also be used in other fields of precision mechanics, aeronautical

mechanics, space mechanics and sanitary mechanics (orthopedics, et cetera), which require high performance of the manual tool, capable of ensuring with certainty a, pre-calibrated tightening torque for screwing the screws and/or a higher torque during unscrewing.

Description of the drawings

These and other characteristics of the present invention will become better apparent, by way of preferred but non-limiting example, in the four accompanying drawings, wherein:

Figure 1 is a partial longitudinal sectional side view of the handle of the pre-calibrated torque screwdriver with a shaft inserted and ready for use;

Figure 2 is a side view of seven shafts of a screwdriver of the single type, illustrating the contoured portions for coupling and the taper of the part for insertion within the handle of the screwdriver;

Figure 3 is a side view of four shafts of a screwdriver of the double type with two different patterns at the end, with a shank which is specifically shaped for different torque performance;

Figure 4 is a partial longitudinal sectional side view of the body of the screwdriver, the handle containing multiple sectors which are tensioned in a pre-calibrated manner and are arranged side by side and radially with respect to the central axis of the handle;

Figure 5 is a side view, by way of example, of the screw-type closure end of the handle;

Figure 6 is a transverse sectional view of an element with pre-calibrated tensioning, which is positioned so that said ball returns to the shaft both the pre-calibrated force and the total unscrewing force, with six elastic spring devices which act simultaneously with the respective balls on the central rotating part;

Figure 7 is a front view of the central coupling element, which can rotate between the body of the handle and the shaft, illustrating the central coupling seat of the hexagonal type, and six recesses shaped like a spherical dome on the outer surface:

Figure 8 is a side view of the element of the preceding figure;

Figure 9 is an exploded front view of the three elements that constitute the system for assembling the pre-calibrated tensioning device, which will push the ball against the body of the rotary central element;

Figure 10 is a partial longitudinal sectional view of a screwdriver handle which uses another multiple system for tensioning pre-calibration arranged side by side, with the interposition of Belleville springs (cup shaped springs) or equivalent means between one element and the other, the illustrated device being of the ratcheting type;

Figure 11 is a three-way view of the rotating snap-acting element with the central hexagonal seat for coupling with the shaft, provided with a male set of teeth;

Figure 12 is a three-way view of the element that can be fixed to the handle, with a female set of teeth which couples with the element of Figure 11 ;

Figure 13 is a three-way view of a Belleville spring (cup shaped spring) or equivalent means, which will be fitted in pairs between a rotating element and a laterally adjacent fixed element in order to determine the force related to skipping the set of teeth.

According to the invention, and in accordance with a first embodiment, the screwdriver handle (1) with pre-calibrated torque device is suitable for tightening series of screws of various sizes by using suitable and interchangeable shafts (2), of the single type, which are machined in a particular manner, with coupling seats (2.1 - 2.2 - 2.3 - 2.4 - 2.5 - 2.6 - 2.7) and/or (2.8) of the double type, with two different patterns at their ends, which are inserted longitudinally in the handle and are coupled with at least one of said tensioning devices.

The invention relates to a handle (1) which has internally a plurality of devices arranged side by side, which are perpendicular and transverse with respect to the longitudinal axis of the handle (in this case, nine devices are shown, but they may be present in any number), for pre- calibrated tensioning, composed of a peripheral screw (8), an elastic spring (9), and a pusher ball (10). The ball acts on the rotating central element (11) and more precisely on the peripheral recesses (13), while the central part has a female shape (12), as a seat for coupling with the shank of the shaft (2), which in this case is shown with a hexagonal shape but may assume any geometric shape. The seat for the sliding of the ball (10) and the respective tensioning direction are inclined with respect to the rotation axis of the rotating central body (11). This is done to adjust and calibrate the correct force that determines the safe torque during screwing. Furthermore, said inclination produces a greater force in the case of reverse rotation or unscrewing. In this manner, the same screwdriver can be used for calibrated dynamic tightening which acts on the screw and for the loosening or unscrewing of the screw, with a torque which is greater than the screwing torque. One or more peripheral tension elements can act on each individual rotating central element (11), producing a total torque with respect to the central axis; six are shown here, but they may be present in any number, having the same or different calibrations in relation to the performance to be obtained. The handle (1) has a terminal closure screw cap (1.1), while at the front the hole for the longitudinal insertion of the shaft (2) (2.8) is provided with a simple locking device, which acts at right angles and radially with respect to said longitudinal axis (for example an external screw 7, an elastic spring 6, and a ball 5 which couples with the seat 4 provided externally and radially on the shaft, or another suitable equivalent device).

The shafts of the screwdriver, of the single type (2) or of the double type (2.8), are mutually different and interchangeable, since each has a different tip pattern suitable for the

corresponding head of the screw to be tightened or loosened, and each shaft is provided with a particular machining or shaping on the shank which is more or less extensive (3), providing a taper which has a cylindrical cross-section in order to avoid interfering with the coupling seat of the rotating element (11). The shanks of the shafts are inserted within the handle and are positioned in a locked manner (4) by means of the retention device (5, 6, 7). The surfaces with a coupling cross-section (2.1 - 2.2 - 2.3 - 2.4 - 2.5 - 2.6 - 2.7), by entering the handle, couple with one or more of the tensioned elements, thus producing for each one a very specific rotation- contrasting torque. By imparting a torsion force of the handle (1) which exceeds the total calibration torsion force of the devices involved in the shaft-device coupling, the rotating central body (11) rotates about itself and therefore said handle rotates freely (about itself). This confirms that the preset screwing torque for that specific screw has been reached. The reverse rotation of the handle of the screwdriver instead has a torque which is higher than the specific calibrated screwing torque, thus avoiding the need to replace the screwdriver during unscrewing. Said different screwing torque with respect to the unscrewing torque is determined indeed by the inclination of the force calibration device with respect to the rotating central body (11).

A similar device for preset multiple tensioning on the handle (20) is furthermore described which cooperates in coordination with multiple different screwdriver shafts (2) and (2.8), which can be inserted longitudinally with respect to the axis of said handle. The pre- calibrated tensioning occurs in a different manner with respect to the preceding example, in which tensioning occurred on a plane which is perpendicular to the longitudinal rotation axis, with different elastic springs (9) and balls (10) with an adjustment screw (8), whereas in this specific example the tensioning is determined by Belleville springs (cup shaped springs) (16) with a large central hole (21) or other equivalent means, which are arranged coaxially with respect to the longitudinal axis of the handle and the axis for the insertion of the shafts of the screwdrivers (2) (2.8), which in pairs act on the ring (15) which is fixed to the handle (20), with female teeth (18) and a central hole (19), and to the rotating disk (14), with male teeth (17), which matches the female central coupling seat (12) (which is hexagonal, like the seat of the shaft of the screwdriver). Said devices (14, 15) are arranged side by side and coaxial, are spaced (22) in pairs, and are enclosed in the handle with an end cap (23), each acting according to a pre- calibration determined by the force of the torque of the Belleville springs (16) with the central hole (21), which are arranged mutually opposite. Said springs, by acting on the rotating element (14) with a given force, entail a torque which contrasts the rotation of the handle until the tooth of each tensioning device is skipped (longitudinal displacement controlled by the Belleville springs). When the preset screwing contrast force is exceeded, the handle rotates freely.

The invention is of course not limited to the examples of embodiment described above,

starting from which it is possible to provide other embodiments and other solutions, and the details of execution may vary in any case without thereby abandoning the essence of the invention as stated and claimed hereafter.