Locking drill chuck

A locking drill chuck comprises a chuck body, a plurality of jaws, a nut, a nut jacket, a front sleeve, and a rear sleeve, wherein the chuck body has an axial hole at its rear end for engaging with a driving shaft of a driving means, and the rear sleeve close fits with the outer circumference of the rear end of the chuck body, the jaws are separately fitted in a plurality of corresponding inclined holes equally departed away from each other in the chuck body, the nut engages with the jaws, the locking drill chuck further comprises a locking sleeve provided between the front sleeve and the rear sleeve, and a locking assembly provided between the nut and a stop plane of the chuck body, the locking assembly comprises a locking cap, rolling members, and a locking plate, wherein the locking plate has a plurality of helical grooves with helix angle in an end plane thereof, the rolling members are received in the helical grooves, the locking cap has resilient tabs securing the locking plate together with the plurality of rolling members, and the locking sleeve securely connected to the locking plate. The locking drill chuck in accordance with the present invention is reasonable in structures, easy for assembly, steady in performance, and labor saving, convenient and reliable in operating.

This application claims the benefit of the Chinese patent application No. 03138814.0 filed on Jul. 15, 2003, which is hereby incorporated by reference.

1. Technical Field

The present invention relates to a drill chuck device, in particular, a locking drill chuck.

2. Background Art

A conventional drill chuck comprises a chuck body, a plurality of (for example, three) jaws, a nut, an exterior sleeve comprising a front sleeve and a rear sleeve, etc., and further comprises a bearing and a bearing spacer in the case of manual locking drill chuck for reducing friction. The rear sleeve and the bearing spacer are close fitted to the chuck body, respectively. The three jaws are separately mounted in three corresponding inclined holes equally parted from each other in the chuck body. The nut is deposited in a nut slot of the chuck body, and forms a screw drive mechanism associated with the screw thread of the jaws. The nut also has a nut jacket around and closely fitted therewith. Around the nut jacket is the front sleeve that has keys in its inner wall and in the nut jacket there are recesses corresponding to the keys, such that the front sleeve can be interconnected with the nut jacket via the keys. For preventing the front sleeve from axial shifting, a buffer is close fitted in the front end of the chuck body.

In the use, one may manually rotate the front sleeve, in turn the front sleeve drives the nut jacket and the nut, and then the nut drives the jaws move forward and backward in the inclined hole of the chuck body, so that the three jaws are splayed or closed for complete the loosening and clamping of a drill tool.

However, there are some disadvantages in the prior art that the drill chuck tends to be loosening due to vibration and impact during operation, these results in that the work efficiency is badly influenced and the safety property is poor. With the broadly increasing application of the drill chuck, the request to the product in its working reliability becomes higher and higher. However, the prior art drill chuck is distinctly insufficient in performance of clamping and loosening.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a locking drill chuck with a reasonable structure, secure locking power and high efficiency in torque transmitting, such that it is light and convenient in operating and reliable in clamping and locking.

The locking drill chuck in accordance with the present invention comprises a chuck body, a plurality of jaws, a nut, a nut jacket, a front sleeve, and a rear sleeve, wherein the chuck body has an axial hole at its rear end for engaging with a driving shaft of a driving means, and the rear sleeve close fits with the outer circumference of the rear end of the chuck body, the jaws are separately fitted in a plurality of corresponding inclined holes equally departed away from each other in the chuck body, the nut engages with the jaws, the locking drill chuck further comprises a locking sleeve provided between the front sleeve and the rear sleeve; and a locking assembly provided between the nut and a stop plane of the chuck body, the locking assembly comprises a locking cap, rolling members, and a locking plate, wherein the locking plate has a plurality of helical grooves with helix angle in an end plane thereof, the rolling members is received in the helical grooves, the locking cap has resilient tabs securing the locking plate together with the plurality of rolling members, and the locking sleeve securely connected to the locking plate.

Each of the helical grooves comprises a section λ1where the helix angle is not equal to 0 and a section λ2where the helix angle is equal to 0.

The locking sleeve has connecting tenons on its inner circumference, and the locking plate has recesses in a lower portion of its outer circumference, the tenons and the recesses are fitted together with zero clearance.

The locking sleeve has a plurality of tenons on a central portion of its outer circumference, and the front sleeve has a plurality of recesses with a width larger than that of the tenons for receiving the tenons.

The drill chuck further comprises a resilient interlock, which is shaped in an opening ring with a plurality of projections, the locking sleeve has a plurality of interlocking notches below the tenons, and the front sleeve has a plurality of axial interlocking slots for receiving the corresponding projections of the resilient interlock passed through the interlocking notches of the locking sleeve, so that the locking sleeve is positioned and guided in the front sleeve.

The drill chuck further comprises a driving sleeve deposited between the front sleeve, and the nut and the nut jacket, the driving sleeve has a plurality of resilient pawls around its outer circumference and has a plurality of driving key at its upper end, the front sleeve has a plurality of fitted slot in its inner circumference for receiving the resilient pawls, and the nut has a plurality of recesses at its lower end, so that the front sleeve drives the driving sleeve and thereby the nut to transmit torque.

The locking plate has a plurality of locking flumes in the lower portion of its outer circumference, and correspondingly the locking cap has a plurality of resilient tabs, the resilient tabs may fit in and move along the locking flumes.

The drill chuck further comprises a baffle ring rotatablely mounted between the lower ends of the front sleeve and the chuck body to prevent the sleeve from axial shifting with respect to the chuck body.

The baffle ring has an circumferential opening, and having a skirt close fitted thereto, thereby the baffle ring may fit in an annular groove formed in a lower portion of the chuck body, and resist against a rabbet at the lower end of the front sleeve.

Thanks to the above-mentioned structures, the drill chuck according to the present invention possesses a secondary locking function with particular methods for imputing torque and locking by an interlocking mechanism in addition to the first screw locking function between the nut and jaws, and further provides an new structure where the front sleeve is connected to the chuck body to prevent the front sleeve from shifting away. So the drill chuck according to the present invention is reasonable in structures, easy for assembly, steady in performance, and labor saving, convenient and reliable in operating.

DESCRIPTION OF PREFERRED EMBODIMENTS

As shown inFIG. 1, the present invention relates to a locking drill chuck, which comprises a chuck body1, a plurality of (for example, three) jaws4, a nut3, a front sleeve6, a rear sleeve2, and a bearing12. The chuck body1has an axial hole at its rear end for engaging with a driving shaft of a driving means, and the rear sleeve2close fits with the outer circumference of the rear end of chuck body1. The three jaws4are separately mounted in three corresponding inclined holes equally departed away from each other in the chuck body1. The nut3engages with the jaws4in the inclined holes of the chuck body and the outer circumference of the nut3is connected and secured to the front sleeve6. There is a nut jacket9between the front sleeve6and the nut3. The preceding components, structures and connecting relationship are all prior art and the detailed description will be omitted.

What the present invention is characterized in is that there arc a locking sleeve11provided between the front sleeve6and the rear sleeve2around the chuck body1, and a elastic locking assembly comprising a locking cap15, a plurality of rolling bodies, such as steel ball14, and a locking plate13between the stop plane of chuck body1and the nut3.

As shown inFIGS. 2A,2B,2C, and2D, in upper end plane of the locking plate13there are a plurality of grooves131with helix angle. There is a rolling body provided in each of the helical grooves131, such as a steel ball14. Each of the grooves131in the end plane of the locking plate comprises two sections, i.e. λ1and λ2. Both sections λ1and sections λ2in all the grooves131have the same helix angle, respectively. That is, for the sections λ1or sections λ2, it may be regarded as a plurality of groove sections axially duplicated in a same level plane by one groove section taken from a complete helicoids. Alternatively, the curved surface may also be duplicated in other end planes being pressed shown inFIG. 1, i.e., the pressed end plane of the locking cap, the chuck body or the nut.

The locking plate13has a plurality of locking flumes132at a lower portion of its outer circumference for connecting with the locking cap15, and the locking plate13has a plurality of recesses133for connecting with the locking sleeve11, such that an elastic locking assembly is formed. The locking sleeve11in accordance with the present invention may be a separate middle sleeve or may be connected with the front sleeve6to become an attached sleeve interlocked.

As shown inFIGS. 4A and 4B, the locking cap15has a plurality of resilient tabs151which may move along and be positioned in the locking flume132at the lower end of the outer circumference of the locking plate13. The steel balls14are placed in the helical grooves131in the end plane of the locking plate13. The locking plate13and the steel balls14are interlocked together by the resilient tabs151of the locking cap15.

The locking sleeve11is connected to the recesses of the locking plate13.FIG. 3is a schematic view of structures of a locking sleeve11. As shown inFIGS. 3A,3B, and3C, the locking sleeve11has tenons111for connecting to the corresponding recesses133at a lower portion of the outer circumference of the locking plate13.

The locking sleeve11and the locking plate13are connected together through tenons111and recesses133. The locking sleeve11also has a plurality of tenons112at the middle part of its outer circumference and has opening interlocking notches113below the tenons112. A resilient interlock10is provided in the locking sleeve11. The resilient interlock10an opening and a plurality of projection101that correspond to and pass through the interlocking notches113of the locking sleeve11. And meanwhile, as shown inFIGS. 6A and 6B, the front sleeve6has a plurality of circumferential recesses61in its inner circumference with a width larger than that of the tenons112of the locking sleeve11for receiving the tenons112, thus there is a big gap provided between the laterals of the tenons112and the recesses61. The front sleeve6also has a plurality of axial interlocking slots63for receiving the corresponding projections101of the resilient interlock10passed through the interlocking notches113of the locking sleeve11.

Thus, the locking sleeve11is positioned and guided in the front sleeve6by the interlocking notches113, the interlocking slots63, and the projection101fitted together, and one side of each tenon112of the locking sleeve11abuts one side of the each recess61of the front sleeve6, thereby a synchronous movement and detachment of the front sleeve6and the locking sleeve11are achieved.

A driving sleeve8is further deposited between the front sleeve6and the nut3, the nut jacket9in accordance with the present invention. As shown inFIG. 5, the driving sleeve8has a plurality of driving keys81inserted into a plurality of recesses (not shown) at a lower part of the nut3with a small gap, and the three resilient pawls82in the outer circumference of the driving sleeve8fits with the fitted slots62of the front sleeve6for transmitting the torque to the nut3, thereby the nut3can drive the jaws4to clamp firmly. When the imputed torque reaches a value range predetermined, the three resilient pawls82disengage from the fitted slots62of the front sleeve6automatically, and the nut3will not rotate any more. Thereafter, the transmitting path of the torque is changed so that the front sleeve6accomplishes the force imputes through the locking sleeve11.

As to the positioning of the front sleeve6, as shown inFIG. 1, there is a baffle ring5rotatablely mounted in an annular groove formed in a front portion of the chuck body1. The baffle ring5resists against a rabbet at the lower end of the front sleeve6and has a skirt7close fitted thereto. The baffle ring5has a circumferential opening, so that the front sleeve6may rotate freely relative to the chuck body1and meanwhile prevent itself from being shifted axially.

Next, the operation of the present invention will be described as following.

As shown inFIG. 1, when an exterior force is applied to the front sleeve6, the front sleeve6rotates and drives the driving sleeve8and furthers the nut3, and in turn makes the jaws4to move forward. Thereby the front ends of the jaws4approach the drill tool to be clamped, and meanwhile the resilient interlock10is driven by the front sleeve6and rotates synchronistically with the locking assembly. When the front ends of the jaws move against an outer surface of the drill tool to be clamped, the torque imputed increases so that the drill tool is clamped.

At the same time, the resilient interlock10disengages from the interlocking slot63of the front sleeve6, and locking cap15ceases rotating owing to the increasing friction between the locking cap15and a stop plane of the chuck body1. If the imputed torque reaches a certain range of value, the three resilient pawls82of the driving sleeve8will disengage from the fitted slot62of the front sleeve6, such that the nut3doesn't rotate any longer. After the front sleeve6has passed solely a certain angle corresponding to the foregoing big gap provided between the laterals of the tenons112and the recesses61, the circumferential recesses61in the inner circumference of the front sleeve6come into contact at their another side with the tenon112in the central portion of the outer circumference of the locking sleeve11, and drives the locking plate13to rotate. At this time the locking cap15keeps on unmoving owing to being pressed, which results in the rolling members, such as a steel balls14, to roll in an opposite direction along the helical grooves131in the end plane of the locking plate13from the site of λ1in the helical grooves where the helix angle is not equal to 0 to a horizontal section, i.e. the site of λ2in the helical grooves where the helix angle is equal to 0 so as to be in a state of locking. In the meanwhile, the three resilient tabs151of the locking cap15slide into another locking flume132of the locking plate13.

During this operation, in aspect of principal, the locking assembly acts as a further locking nut for a secondary securing and locking function in addition to the locking function of screw thread between the nut8and jaws4, when the working screw threads between the jaw4and nut3possess a powerful axial deformation differed from that in the prior art, which prevents the nut3from any tendency of rotation, thereby the reliable clamping and locking is reached.

Contrarily, in order to loosen the locking drill chuck, it is only required to rotate the front sleeve6in an opposite direction, and then the front sleeve6drives the locking sleeve11and further the locking plate13and disengages the locking flumes132of the locking plate13from the three resilient tabs151of the locking cap15. At the same time, the steel balls14move from the site of sections λ2of the helical grooves131where the helix angle is equal to 0 to the site of sections λ1where the helix angle is not equal to 0, so that the three resilient tabs151of the locking cap15slide in an reverse direction into another locking flumes132of the locking plate13, thereby the axial powerful deformation of fitted screw thread of the jaws4and the nut3is released. Then the nut3is rotated by way of the engagements of the three resilient pawls82of the driving sleeve8and the fitted slots62of the front sleeve6, and the drill tool is loosened.