GB2189723A

GB2189723A - Tool gripping chuck

Info

Publication number: GB2189723A
Application number: GB08707185A
Authority: GB
Inventors: Teruaki Komatsu; Kunihiko Tatsu; Kiyoshi Kobayashi
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1986-04-28
Filing date: 1987-03-25
Publication date: 1987-11-04
Anticipated expiration: 2007-03-25
Also published as: JPS62255075A; GB2189723B; KR920009833B1; KR870009822A; JPH0780127B2; GB8707185D0; HK43991A

Abstract

A tool gripping chuck comprises a generally cylindrical shaft (31) having a tapered face (33), a hand grip (36) coupled to an axial end of the shaft, a rotary ring (38) mounted shiftably about the shaft with needle rollers (45) received in wedge-like grooves (44) in the inner wall face of the rotary ring interposed between said ring and the shaft (31), and a tool gripping assembly coupled to the other end of the shaft and actuated by rotating the ring (38). The needle rollers (45) within the wedge-like grooves (44) act to lock the rotary ring (38) into a non-rotatable state with rotation of the shaft in a direction of tightening the wedge-like grooves (44) against the rollers (45) on the tapered face (33) of the shaft (31), and an axial shift of the rotary ring (38) away from the tapered face (33) must be made to release the shaft from the non-rotatable state in order to allow a tool (59) to be freed from the tool gripping assembly. <IMAGE>

Description

SPECIFICATION Tool gripping chuck This invention relates to a chuckfor gripping such a tool as a drilling bit, screwdriver bit or the like.

The tool gripping chuck of the type referred to is used in electric tools and the like, and is useful in dismountably mounting the tool for being driven by a power source incorporated in the electric tool.

An example of a known tool gripping chuck of the kind referred to will be the one disclosed in, for example, U.S. Patent No. 4,275,893 to S.G. Bilanceri, in which an enlarged head of a chuck body is screwed axially into a sleeve to be axially shiftable therein, the enlarged head is provided in its forward end with an opening having an internally tapered surface, a plurality of tapered grip rollers are provided in the opening to be resiliently supported by springs so that the grip rollers can abut outwardly againstthe tapered surface of the opening or inwardly against each other in parallel relationship depending on forward or backward movement of the chuck body which decreases or increases gaps between the respective grip rollers.Accordingly, in this tool gripping chuck, axial rotation of eitherthe sleeve orthe chuck body causes the relative position of both members to be changed to vary the gaps between the grip rollers to allowtools of different diameters to be mounted and dismounted.

In Bilanceri, the rotational direction of the chuck in operating state of same is made to be the same as that of the sleeve at the time of tightening the tool so that the chuck allows such operation astotighten a screwwith a screwdriver bit to be smoothly performed, whereas a reverse directional rotation of the chuckfor loosening the bit is always effective to have the sleeve rotated in the direction of increasing the gaps between the grip rollers, so as to cause the gripped tool dismounted even when not intended.

Such disadvantageous rotation of the sleeve may also happen to arise when the user erroneously grips the sleeve during the operation of the chuck, and this known chuck has been able to be used only in one rotating direction.

A primary aim of the present invention is, therefore, to provide a tool gripping chuckwhich can preventtool gripping members from being caused to loosen the gripping either in reverse directionally rotating operation of the chuck or in an event when the user erroneously grips a rotatable member a rotation of which has a relationship to the gripping members.

According to the present invention, the above aim is realized by providing a tool gripping chuck which comprises a shaft driven by a power source to axially rotate, a handle grip fixed to ofthe shaft, a rotary ring rotatably mounted about the shaft, tool gripping members radially shiftable relative to one another with rotation of the rotary ring relative to the shaft, means for locking the rotation of the rotary ring with respect to the shaft, and means for releasing the locking means.

With such an arrangement, the tool gripping chuck according to the present invention can eliminate any unnecessary relative rotation between the rotary ring and the shaft by the locking means to prevent thetool gripping membersfrom being shifted to loosen the gripping so long as the releasing means is not operated.

Other aims and advantages of the present invention shall be made clear in thefollowing description of the invention detailed with reference to a preferred embodiment shown in the drawings, in which: Figure 1 is a sectional view, partly in a side view, of an electric tool which employs a tool gripping chuck according to the present invention; Figure2 is an enlarged sectional view, partly in a side view, of the chuck of the present invention used in the electrictool of Figure 1; Figure 3 is an exploded perspective view of the chuck of Figure 2; Figure 4 is a perspective view as assembled of the chuck of Figure 2; Figure 5is a diagram for explaining the operation of the chuck of Figure 2 fortightening the tool gripping members; and Figure 6 is a diagram for explaining the operation of the chuck of Figure 2 for loosening the tool gripping members.

While the present invention shall now be described with reference to the preferred embodiment shown in the drawings, it should be understood that the intention is not to limitthe invention onlyto the particular embodiment shown but rather to cover all alterations, modifications and equivalent arrangements possible within the scope of appended claims.

Referring to Figures 1 to 6, there is shown such an electric tool as a screwdriver 10which employs atool holding chuck according to the present invention.

The electric screwdriver 10 comprises a housing 12 in which a reversible motor 11 is housed. Provided to the housing 12 on one axial end side of the motor 11 are a power source section 13, and a downward extendedgrip part 14 having acontrol partlsfora switch section 16 included in the housing, and on the other output axial end side of the motor 11 is a power transmission 17 which includes two stage planetary gear mechanisms to perform rotational speed reduction and torque adjustment. Thus, the transmission 17 includes a first sun gear 20 which is mounted on an output shaft of the motor 11 and forms a part of first one of the two stage planatary gear mechanisms.The first sun gear 20 is provided to be in mesh with a plurality of first planetary gears 22 within a gear case 21 which is enclosed in the housing 12. The first planetary gears 22 are carried by a carrier 24 provided within an internal gear 23 to be meshed with the internal gear 23 to be freely rotatable within the gear case 21. The carrier 24 is integrally provided with a second sun gear 25 which in turn is meshed with a second planetary gear 26 engaged to the internal gear 23. The second sun gear 25 is carried on a carrier 28 made integral with an output shaft 27 journalled in the housing 12.

With such electric screwdriver 10 as above, an actuation of the switch section 16 allows power to be suitably supplied from the power source section 13 to the motor 11 so that an output of the motor 11 provided after being subjected at the power transmission 17 to the rotational speed reduction and torque adjustment, i.e., an outputadjustment,to the output shaft 27 operatively associated with a unique tool gripping chuck 30 according to the present invention, to which chuck 30 the output is transmitted.

The tool gripping chuck 30 includes a generally cylindrical, metallic shaft 31 directly coupled to a forward projected end of the output shaft 27 ofthe electric tool, which shaft31 is provided with inner peripheral threads 32 formed in its forward part, with atapered outerface33 gradually decreased in diameter from a middle part to a rearward part, and with a rear end part 34 of a differently configured cross section.This rear end part34 of the shaft 31 is provided to fittingly receive the output shaft 27 of the powertransmission 17 and to be pressingly inserted into an axial opening 35 of a ring-shaped handle grip 36,the opening 35 corresponding in shape to the differently sectioned rear end part34. The handle grip 36 is also provided on its outer peripheral wall with finger engaging grooves, and in its forward end wall with an annular recess 37 in which a coil spring 39 is housed as disposed between the recess 37 and a rotary ring 38 mounted on the shaft 31 to push the rotary ring 38 forward.

The rotary ring 38 comprises a body part 40 made of a synthetic resin in a cylindrical shape having on outer peripheral wall finger engaging grooves, and a ring-shaped metallic lock part 41 to be fittingly inserted into a rearward end ofthe body part 40. The lock part 41 is provided on its outer peripheral wall with axially extended grooves 42which are mutually spaced in circumferential direction so that,when inward projections 43 provided on rearward inner peripheral wall ofthe body part 40 are engaged in the grooves 42 of the lock part41, the body part40 can be coupled to the lock part 41 in the circumferential direction (see Figure 5).Underthis condition, the projections 43 are locked to forward end wall ofthe lock part 41 and thus can provide an axial interlocking to the lock part 41. The lock part 41 is also provided in its inner peripheral wall with axially extended grooves 44 which are spaced from each other in circumferential direction and are made shallower in one circumferential direction (see Figure 6). When the lock part 41 inserted in the body part 40 is mounted on the shaft 31 therefore, the grooves 44 define, together with the outer peripheral wall of the shaft 31 orthetapered face 33, spaces in which a plurality of needle rollers 45 are accommodated (Figures 5 and 6).Accordingly, the needle rollers 45 are arranged as mutually spaced circumferentially along the outer peripheral wall of the shaft 31. Provided on the inner peripheral wall at the forward end of the body part 40 of the rotary ring 38 is an inward projection 46 (Figure 3) which is engaged in one of notches 48 provided in rearward end edge of a hollow and forwardly tapered bush 47 surrounding a flanged forward end part of the shaft 31 so thatthe rotary ring 38 can be interlinked to the bush 47 for rotation therewith and also can shift in its axial direction. The bush 47 is axially opened at forward tip end.A ring member 49 and a washer 50 made of preferably an ethylene fluoride material are disposed between the flanged forward end of the shaft 31 and the needle rollers 45 to surround the central part ofthe shaft 31.

Screwedly engaged to the inner peripheral female threads 32 at forward part of the shaft 31 within the bush 47 is a floating screw member 52 which has outer peripheral male threads 51 and engaging notches 53 provided in forward end edge. Mounted on the forward end of the shaft 31 having the floating screw member 52 screwedly inserted therein is a guide block 54 which has a generally truncated cone contour and a rearward end edge of which is positioned between the body part 40 and the bush 47, and the flanged forward end of the shaft 31, ring 49 and washer 50. In the illustrated embodiment, a plurality of radial projections 55 are formed on rearward end part of the g u i de block 54 to be engaged in other notches 48 than the one in which the projection 46 of the body part 40 is engaged.The guide block 54 is provided with a plurality of slits 56 into which gripping nails 57 are engaged, which nails 57 are respectively formed to have an outerface similarinshapetotheguide blocle 54 end a lug 58to be engaged to edges of the slit 56 so that, when mounted to the guide block 54, the gripping nails 57 are made parallel at their inner edges opposing each other so asto be able to grip such a tool 59 inserted into a gap between the gripping nails 57 as a drilling pin, a screwdriver bit or the like. Engaging rearward ends 60 ofthe respective gripping nails 57 are engaged in the notches 53 made in the forward end edge of the floating screw member 52.

Explanation will be briefly made with reference to an example of assembling the tool holding chuck 30 according to the present invention. The ring 49 and washer 50 are first mounted on the shaft31 with the washer 50 engaged with the flange part of the shaft 31, the body part 40 is fitted on the lock part 41 with the inward projection 43 of the former engaged in one of the peripheral grooves 42 of the lock part 41 to be integrally coupled to each other to form the rotary ring 38, which ring 38 is then mounted onto the shaft 31 with the needle rollers 45 inserted into the spaces defined bythe inner peripheral grooves 44 of the lock part 41 and the tapered face 33 of the shaft 31. Next, the coil spring 39 is disposed between the rotary ring 38 and the handle grip 36, and the handle grip 36 is fixedly mounted to the differently sectioned rear end part 34 of the shaft 31 as aligned atthe axial opening 35 with the end part 34 of the shaft 31. As a result, the washer 50, ring member 49 rotary ring 38, needle rollers 45 and spring 39 are held on the periphery of the shaft 31. Now, the floating screw member 52 is fitted into the shaft 31 with the outer peripheral threads 51 meshed with the inner peripheral threads 32 ofthe shaft31 to be coupled to the shaft 31 ,the gripping nails 57 are inserted into the respective slits 56 of the guide block 54 and the assembly ofthe guide block 54 and nails 57 is inserted into the bush 47. Atthis stage, the gripping nails 57 project attheir tip ends from the forward tip end opening ofthe bush 47, and the radial projections 55 of the guide block 54 are engaged in the notches 48 in the rearward end edge of the bush 47. Further, the bush 47 having therein the foregoing assembly is mounted onto the forward end part of the shaft31 so that one of the notches 48 receives the inward projection 46 of the body part 40 of the rotary ring 38, whereupon the assembling is completed.It should be appreciated that, in the thus assembled chuck30, an axial rotation of the shaft 31 receiving the rotational driving force of the motor 11 interlocks the floating screw member 52 coupled to the shaft 31, guide block 54 coupled to the floating screw member 52 and the gripping nails 57 engaged to the guide block 54 and held attheir lugs 58 between the guide block 54 and the bush 47.

The operation of the tool gripping chuck 30 according to the present invention shall now be explained. When it is desired to mount the tool 59 in the tool gripping chuck 30 ofthe present invention, the tool 59 is inserted into the gap between the gripping nails 57 in the opening of the bush 47 positioned attheforward end of the chuck 30. Under this condition, the user holds the handle grip 36 in his one hand and turns the body part 40 of the rotary ring 38 with the other hand, in a direction shown by an arrow x in Figure 5.This causes a relative rotation of the shaft 31 and rotary ring 38toeach other so that the bush 47 coupled to the body part 40 of the rotary ring 38 and the assetnbly of the guide block 54 and gripping nails 57 coupled to the bush 47 render the floating screw member 52 coupled to the gripping nails 57 to be rotated relative to the shaft31 and to be projected from the shaft 31.

Simultaneously with this projecting operation, the gripping nails 57 of the assembly are also projected forwardly and moved to approach each other to narrow the axial spacing between their opposing parallel edges because the inner peripheral guide wall of the bush 47 is tapered, wherebythetool 59 can be firmly held by the gripping nails 57.

When it is desired to drive a screw S into a wall W as shown in Figure 1, the motor 11 of the electric screwdriver 10 arranged in this case to provide a normal rotational output in a direction shown byan arrowx'in Figures is actuated, and the shaft 31 is rotated relative to the rotary ring 38 so as to render the floating screw mem ber 52 to be projected forward, that is, to tighten the gripping nails 58 against the tool 59. As a resu it, even when,for example, the user unintentionally grips the rotary ring 38 during operation of the screwdriver 10, the tool 59 will be firmly continuously held by the gripping nails57,to preventthetool 59 from being dismounted.

On the other hand, in loosening the screw S, the motor 11 ofthe screwdriver 10 is reversely rotated and the shaft 31 is rotated in a direction shown by an arrow ytin Figure 6, upon which the rotary ring 38 is rotated in a direction of retreating the floating screw member 52 into the shaft 31. However, so long as the grooves 44 in the lock part 41 for receiving the needle rollers 45 are so formed as to be gradually narrower toward the rotational direction ofthe rotary ring 38, i.e., in the reverse rotational direction y'of the shaft 31 opposite to a normal direction shown by an arrow yin Figures 5 and 6,the grooves 44 and needle rollers 45 cooperate to perform such a locking operation as a wedging action.Therefore, even in loosening the screw S, the tool 59 can be effectively prevented from being undesirably dismounted because of the reliable prevention ofthefloating screw member 52 from being retreated.

Furthermore, even when,for example, the user unintentionallygripsthe rotary ring 38 during the operation of the electric screwdriver, the tool 59 can be reliably kept as held because the locking operation is continuously performed.

In dismounting the tool 59 from the chuck 30, further, the rotary ring 38 is initially shifted in its rearward axial direction toward the handle grip 36 against the resiliency of the spring 39, prior to the rotation of the rotary ring 38, since the locking operation between the grooves 44 and the needle rollers 45 is restricting the rotation in the ydirection.

This axial shiftofthe rotary ring 38 renders the spaces for the needle rollers 45 to be expanded rearward along the tapered face 33 of the shaft31, and the needle rollers 45 are made shiftable to release the locking operation between the grooves 44 and the needle rollers 45. Accordingly, the user rotates the rotary ring 38 in they direction of Figures Sand 6while axially shifting the rotary ring 38 toward the handle grip 36, and an operation opposite to the foregoing mounting operation ofthetool 59 can be carried out, with the gripping nails 58 put in their loosened state of allowing the tool 59 dismounted.

While in the foregoing the rotary ring 38 has been referred to as being rotated in tightening the tool 59, it may be possible that the rotary ring 38 is manually held stationary and the motor 11 is actuated to normally rotate to cause the shaft 31 rotated in the direction x'of Figure 5 to realize the firm holding operation ofthetool 59, whereas, in releasing the tightening forceforthetool 59,the motor 11 is reversely rotated to cause the shaft 31 rotated in the y'direction of Figure 6 while the user keeps the rotary ring 38 shifted rearward toward the handle grip 36, to achieve a quick releasing operation ofthe tool 59.

It will be readily understood by those skilled in the art that, in the foregoing arrangement, the needle rollers4sandgrooves44madeto begradually shallower in the reverse rotational direction of the shaft 31 areforming a locking means, such as a one-way clutch or a so-called silent ratchet, and that the rotary ring 38 retreatable and the tapered face 33 of the shaft 31 functioning to gradually expand the needle-roller accommodating spaces rearward are forming means for releasing the locking means.

Claims

1. Atool gripping chuck comprising a shaft driven by a power source to axially rotate, a handle grip fixed to said shaft, a rotary ring rotatably mounted about the shaft, tool gripping members radially shiftable relative to one another with rotation of said rotary ring with respectto the shaft, means for locking said rotation of the rotary ring relative to the shaft, and means for releasing said locking means.

2. A chuck according to claim 1, wherein said locking means comprises needle rollers disposed between said shaft and said rotary ring and grooves provided gradually shallower in one relative rotational direction between the shaft and rotary ring to define spaces respectively for accommodating each of said needle rollers, for locking said relative rotation in one direction of the rotary ring with respect to the shaft.

3. A check according to claim 2, wherein said handle grip is fixed to an axially rearward end of said shaft, said rotary ring is provided to be shiftable in axiallyforward and rearward directions of the shaft, said gripping members being shifted to approach one anotherfortightening a tool being gripped when said rotary ring takes a position of being shifted in said forward direction where said locking means is made effective, whereras the gripping members are shifted in a tool releasing direction when the rotary ring takes said rearward shifted position where said releasing means is made effective.

4. A chuck according to claim 3, wherein said means for releasing said locking means comprises meansforcausing said rotary ring shifted in said rearward direction and a tapered surface provided to said shaftto be inclined downward in said rearward direction of the rotary ring to enlarge said needle roller accommodating spaces, for allowing said relative rotation between the shaft and the rotary ring to be made in said one direction.

5. A chuck according to claim 4, wherein said meansforshifting said rotary ring in said forward direction is a spring load.

6. A chuck according to claim 2, wherein said rotary ring comprises a cylindrical body part made of synthetic resin and a cylindrical lock part made of a metallic material to be housed in said body partfor interlocking engagement therewith, said lock part being provided in inner peripheral wall with said grooves forming said locking means.

7. Atool gripping chuck substantially as described herein with reference to the drawings.