Chuck with locking system

This is a chuck for equipping a rotary machine, comprising a body intended to be fixed to a drive shaft of the machine, in which there are mounted several jaws which slide in bores converging forward and which each have an outwardly facing threaded part, a sleeve being pivotably mounted on the body and having an interior wall which collaborates with a nut itself engaged with the threaded exterior part of the jaws. The body comprises, in its region covered by the nut, a peripheral set of teeth and the nut bears locking means which are intended to engage in the set of teeth of the body when the chuck is in the tightened position, and which are intended to be activated by the sleeve. The sleeve has an angular relative movement with respect to the locking means between an unlocked position in which the sleeve turns the nut and a locked position in which the chuck is in its tightened position.

BACKGROUND OF THE INVENTION

The subject of the present invention is a chuck to equip a rotary machine.

More specifically, the present invention relates to a chuck intended to equip a drill.

Chucks generally encountered comprise a body intended to be fixed to a drive shaft of the machine, in which there are mounted several jaws which slide in bores converging forward and which each have an outwardly facing threaded part, a sleeve being pivotably mounted on the body and having an interior wall which collaborates with a nut itself engaged with the threaded exterior part of the jaws.

DESCRIPTION OF THE PRIOR ART

An example of such a chuck is described in particular in document EP-618 029 in the name of the Applicant Company.

Chucks of the aforesaid type have the advantage of allowing a tool to be clamped without the need to use a key, while at the same time avoiding unwanted opening of the chuck during, in particular, hammer-drilling. Even though these chucks are entirely satisfactory as far as their operation is concerned, they do have the disadvantage of containing a great many constituent parts. They are therefore of high cost and require several assembly operations.

SUMMARY OF THE INVENTION

It is a particular object of the present invention to overcome the aforesaid disadvantages by providing a chuck in which the number of constituent parts is lower in order to simplify the assembly of this chuck.

To this end, according to embodiments of the invention, the chuck of the aforesaid type is essentially one wherein the body comprises, in its region covered by the nut, a peripheral set of teeth and the nut bears a locking mechanism which is intended to engage in the set of teeth of the body when the chuck is in the tightened position, and which are intended to be activated by the sleeve, and wherein the sleeve has an angular relative movement with respect to the locking mechanism between an unlocked position in which the sleeve turns the nut and a locked position in which the chuck is in its tightened position.

Thus, by virtue of these measures, the chuck has a locking mechanism that is mounted directly on the nut and is operated by the sleeve itself manipulated directly by the operator.

Advantageously, the locking mechanism comprises at least one first spring leaf which is mounted angularly fixedly on the nut and which has a free end projecting through an opening made in the nut so that when the chuck is in the tightened position it reaches the set of teeth of the body.

In a preferred embodiment, the locking mechanism comprises at least one second spring leaf which has a free end equipped with a relief which collaborates, in the unlocked and locked positions of the sleeve respectively, with a first depression and with a second depression which are formed in this sleeve.

Still as a preference, the first and second spring leaves are secured to a ring borne by the nut and prevented from rotating on this nut by means of at least two tabs which enter complementary parts formed in the nut.

As a preference, the sleeve comprises at least one hollowed-out part in which the free end of the first spring leaf is housed, when the sleeve is in the unlocked position, so as to disengage this free end from the set of teeth of the body.

Still as a preference, the sleeve comprises at least two fingers which collaborate with at least two notches formed on the nut, the notches being centered on the axis of the chuck and being longer than the fingers of the sleeve, this length being considered in the direction of the circular arc over which these notches extend.

Advantageously, the difference in length between the notches of the nut and the fingers of the sleeve is tailored so that when the sleeve is in the unlocked position, the fingers are in abutment against one of the faces of the notches and the relief of the second spring leaf is in the first depression, and so that when the sleeve is in the locked position the fingers are in abutment against the other of the faces of the notches and the relief of the second spring leaf is in the second depression.

As an alternative, the tabs of the ring extend radially and the complementary parts formed in the nut comprise at least two notches.

In another alternative form, the tabs of the ring each comprise a base extending transversely with respect to the plane of the ring and two bends which extend from the base and more or less toward the outside of the ring, the bases and the bends nesting elastically in the notches of the nut into which notches the fingers of the sleeve penetrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The chuck1depicted in the figures comprises a body2of cylindrical overall shape having a posterial wall3into which there opens a tapped hole4which is intended to allow the chuck to be secured to a threaded shaft of a rotary machine (not depicted in the figures).

The body2is symmetric about a longitudinal axis X—X and extends between the posterior wall3and a front part5in which there is also formed a cylindrical hole in which a tool such as a drill bit is to be received.

Formed in the body2are three bores8of axis Y—Y which forms an acute angle with respect to the longitudinal axis X—X of the body2. These bores each serve to guide a jaw9and converge toward the front part5of the body2, so that the forward movement of the jaws results in the jaws moving closer together to allow a tool (not depicted) to be clamped.

Furthermore, the exterior part of the jaws9has, in a way known per se, a screw thread10which collaborates with a tapped nut12to cause the jaws to move in one direction or the other in the bores8, depending on the direction in which the nut12is turned.

The nut12is formed of a front cylindrical portion13and of a rear cylindrical portion14which are both of the same inside diameter, the outside diameter of the rear portion14being greater than the outside diameter of the front portion13. The nut12also has a front face15and a rear face16both belonging to a plane roughly transversal to the axis X—X of the body2. The meeting point of the front13and rear14portions defines a surface17parallel to the front15and rear16faces.

As shown more particularly inFIG. 2, the body2has a flange18against which the nut12comes into abutment at the rear along its rear face16. This nut12is axially immobilized forward by a circlip19. To make it easier for the nut12to rotate on the body2, a washer20and a ring fitted with ball bearing balls21are interposed between the rear face16of the nut12and the flange18.

The chuck1also has a sleeve25produced, for example, in synthetic material and mounted to pivot in rotation on the body2about the axis X—X. This sleeve25has an interior wall26which collaborates with the nut12to turn this nut. The sleeve25extends roughly along the entire length of the body2between the posterior wall3and the front part5. This sleeve is axially immobilized on the body2by means of a clip fitting27, situated in the front part. To make it easier for an operator to manipulate, the sleeve25externally has knurling28.

According to one feature of the invention, the body2comprises, in the region covered by the nut12, a peripheral set of teeth30which extends toward the outside of the chuck and parallel to the axis X—X of the body2.

According to another essential feature of the present invention, the nut12bears locking mechanism35which is intended to be engaged in the set of teeth30of the body2when the chuck is in the tightened position, and which is intended to be actuated by the sleeve25. This sleeve has an angular relative movement with respect to the locking mechanism35between a first position or unlocked position (FIGS. 3 and 4) in which the sleeve25turns the nut12and a second position or locked position (FIGS. 5 and 6) in which the chuck is in its tightened position.

As shown more particularly inFIGS. 3 and 5, the nut12preferably has three notches37distributed at uniform angles and which open toward the outside of the nut while at the same time being centered on the axis X—X of the chuck.

The interior wall26of the sleeve25preferably has three fingers38projecting toward the inside of the chuck. The notches37formed in the nut12are longer than the fingers38of the sleeve25, the length being considered in the direction of the circular arc along which the notches37extend. These notches37are laterally delimited by two faces40and41directed more or less radially.

The relative angular movement of the sleeve25is thus limited by the fingers38coming into abutment against the radial face40of the notches37, in the unlocked position (FIG. 3), and against the opposite radial face41of the notches37when the sleeve is in the locked position (FIG. 5).

The locking mechanism35comprises a ring45from which extends a first spring leaf46and a second spring leaf47. The ring45is mounted so that it rotates as one with the nut12and is fixed to the latter by means of three tabs50which enter complementary parts formed in the nut12. As a preference, the ring45is pressed against the surface17of the nut12.

In the first embodiment, the three tabs50extend radially toward the inside of the ring45and the complementary parts formed in the nut12comprise the three notches37into which the fingers38of the sleeve25also penetrate. Of course, as an alternative, the three tabs50could be housed in notches separate from the notches37.

As shown more particularly inFIGS. 4 and 6, the first spring leaf46and the second spring leaf47extend away from one another, above the rear part14of the nut12, being situated on a circular arc centered on the axis X—X. The first spring leaf46has a free end56which is curved toward the center of the chuck, projecting through a transverse recess55formed in the nut12in order, when the chuck1is in the tightened position, to reach the set of teeth30of the body2.

The second spring leaf47has a second end57which has a relief58facing toward the outside of the chuck to collaborate, when the sleeve25is in the locked and unlocked position respectively, with a first depression60and with a second depression61which are formed in the interior wall26of the sleeve25.

Furthermore, the sleeve25comprises, in its interior wall26, a hollowed-out part63ending in a ramp64and in which the free end56of the first spring leaf46is housed, when the sleeve25is in the unlocked position, so as to disengage the free end56from the set of teeth30of the body2, as is depicted inFIG. 4.

It will also be understood that the difference in length between the notches37of the nut12and the fingers38of the sleeve25is tailored so that when the sleeve is in the unlocked position, as depicted inFIGS. 3 and 4, the fingers38are in abutment against the radial face40of the notches37while the relief58of the second spring leaf47is housed in the first depression60, whereas when the sleeve25is in the locked position as depicted inFIGS. 5 and 6, the fingers38of the sleeve are in abutment in the other radial face41of the notches37while the relief58of the second spring leaf57is housed in the second depression61of the sleeves25.

As a preference, as is depicted inFIG. 1, the ring45also has another spring leaf identical to the first spring leaf46and situated diametrically opposite this spring leaf46. Thus, the presence of two spring leaves46offset by 180° makes it possible to be sure that at least one of the free ends of these leaves will collaborate with the set of teeth30of the nut, without the risk of facing an interruption of the set of teeth that is due to the bores for the jaws.

It will thus be understood that, in the unlocked position, as depicted inFIGS. 3 and 4, the sleeve25turns the nut12. In this configuration, the free end56does not collaborate with the set of teeth30of the body2which means that the jaws9are turned freely under the action of the sleeve25.

By contrast, when the chuck is in the tightened position, that is to say when the jaws are in contact with the tool inserted into the chuck, the resistance of the nut12to being turned by the sleeve25increases. The sleeve25then turns with respect to the assembly consisting of the nut12and of the spring leaves46and47. This relative rotation is limited by the difference in length between the fingers38of the sleeve25and the notches37of the nut12. The fingers38then come into abutment against the radial faces41of the notches37while the relief58, borne by the second spring leaf47, is disengaged, through a bending effect, from the first depression60to become lodged in the second depression61. At the same time, the free ends56of the first spring leaves46are deflected toward the inside of the chuck so that these free ends collaborate with the set of teeth30borne by the body2. The tightening of the chuck can then continue as far as the maximum torque that the operator can apply with a ratcheting effect of the spring leaves46on the set of teeth30of the body2which is audible to the operator. Collaboration between the free ends56and the set of teeth30prevent any unwanted unlocking by the vibrations caused during hammer-drilling.

When there is a desire to remove the tool from the chuck again, all that is required is for the sleeve25to be turned from its locked position to its unlocked position. The sleeve25is then turned in the opposite direction to the previous direction, thus causing the relief58to move toward the first depression60and the free ends56of the first spring leaves46to disengage from the set of teeth30. The fingers38of the sleeve25once again come into abutment against the first radial face40of the notches37borne by the nut12. Any additional rotation of the sleeve25turns the nut12and therefore loosens the jaws.

The second embodiment depicted inFIGS. 7 to 9differs from the first embodiment solely in the shape of the tabs50that immobilize the ring45on the nut12. The tabs50now have a base65which extends roughly transversely with respect to the plane of the ring45, and two bends66and67which extend from the base65toward the exterior of the ring45. The base65and the bends66and67are a shape that complements that of the notches37formed in the nut12. The fingers38of the sleeve25are therefore now in contact with the bends66and67, the fingers38being shorter than the height of the bends.

The way in which the assembly works is the same as that described with reference to the first embodiment.

Of course, the invention is not restricted to the examples described hereinabove, and various modifications can be made to it without departing from the scope of the present invention.