GB2065001A - A drill chuck - Google Patents

Abstract

A drill chuck comprises an internally screw threaded cylindrical actuating sleeve 1, within which is a holding body 2 grinding jaws 9 which are operatively connected to a member 11 screw threadedly engaging the sleeve 1 and movable axially during rotation of the sleeve to advance or withdraw the jaws. On the front face of the member are formed three radially extending lipped cavities 14 and the jaws 9 at their rear extremities have recesses 10 which allow them to engage in the three said cavities 14. <IMAGE>

Description

SPECIFICATION Drill chuck The present invention relates to a drill chuck.

Drill chucks for drilling machines of the type comprising three jaws for gripping, which jaws are fitted inside a cylindrical sleeve which contains all the components of the chuck, have been known for many years. The three said jaws project through the front end of the chuck and can be advanced or withdrawn simultaneously to close and open their front extremities which are the gripping ends, the chuck being operated by means of a conical toothed key which engages with the front edge of the aforementioned sleeve which is suitably provided with conical teeth which mate with the conical teeth of the key, such that turning the key in one direction or the other causes the key to rotate in one direction or the other and this movement is transmitted in turn to the components contained therein resulting final ly in the advance or the withdrawel of the three jaws.

There exists a variety of mechanisms forming part of the known chucks for transmitting the rotary movement of the sleeve to the jaws thus causing them to be advanced or withdrawn. However, it can be stated that the majority of known devices employ jaws provided with rack type teeth on the boss section engaging with a concave thread such as for example the internal screw thread of a ring or crown wheel which is one of the inner components of the sleeve.

This type of known design as described has major manufacturing disadvantages which result in in creased costs of manufacture. In particular the cutting of the rack on the boss of the jaws is in itself a costly operation insofar as the said jaws have to be machined in a manner in which the necessary high precision, according to the specialists in the matter, calls for considerable care. Furthermore in the manufacture of high quality chucks this precision is only attainable by means of a grinding operation which may decrease the margin of tolerances.

Undoubtedly these operations cost time and money.

In addition, it is also a disadvantage in the aforementioned known chucks that the assembly procedures require the internally threaded ring which operates on the bosses of the respective jaws has to be split.

The improved chuck of the present invention offers a solution to these two problems.

This is achieved by a fundamental modification of the inner structure of the chuck as compared to currently known devices. Following on from the said 'structural innovations the relationship between the internal components making up the chuck is also novel.

The present invention provides a drill chuck comprising a cylindrical sleeve having a screw thread on its inside surface, a holding body fitted within the cylindrical sleeve and hold therewithin against movement relative thereto in the axial direction, a plurality of gripping jaws guided by the holding body, and a one piece withdrawal compo nent which is externally screw threaded for cooperation with the screw thread of the cylindrical sleeve and which is operatively connected to the gripping jaws, the arrangement being such that relative rotation of the cylindrical sleeve and the withdrawal component causes the component to move axially within the cylindrical sleeve thereby to advance or withdraw the jaws for gripping purposes.

It is already known in the prior-art that the front extremities of the three jaws which form the gripping ends project through the front end of the drill chuck. To allow this the jaw may preferably pass through the inside of the holding body, which for this purpose has therein three longitudinal guiding holes with their entry extremities in three respective positions equidistant from the surface of its central zone and converging at the other extremities into a single common opening. According to the characteristics of the device object of this invention the advance and withdrawal of the three jaws is caused by the advance or withdrawal of the previously described annular withdrawal component, the latter being in engagement with the said three jaws.

Further, in order to advance or withdraw the annular withdrawal component the sleeve into which the component is threaded has to be rotated relative thereto. In the embodiment hereinafter described the annular withdrawal component cannot itself rotate relative to the holding body, being in engagement with the jaws which are only capable of moving in a longitudinal direction relative to the holding body, hence the said annular component can also only move in a longitudinal direction. To complete the explanation of the operation of this novel chuck it is sufficient to add that the rotation of the sleeve is caused as in the majority of known chucks, that is it can generally be operated by manually turning the sleeve of the chuck causing the jaws to move without undue resistance.To tighten or to release the jaws use is made of an auxillary tool in the form of a key with conical teeth which can pivot in a suitable hole which is provided in the projecting front end of the holding body and engages with conical teeth provided for that purpose in the front edge of the sleeve.

The invention will be further described by way of example with reference to the accompanying drawings in which: Figure 1, is an exploded view in perspective in which are shown the various components of a drill chuck according to the invention; Figure 2, is a plan view looking into the rear face of the drill chuck of Figure 1; Figure 3, is a cross section along the line Ill - Ill of Figure 2, being a longitudinal section in which can be seen the internal layout of the chuck; Figure 4, is a detail through the line IV - IV of Figure 1.

As may be seen from the drawings, the chuck is a cylindrical sleeve 1, in the interior of which is fitted a holding body 2, having a circumferential intermediate flange 3, which rests against the inside face of a corresponding internal flange 4, at the front opening 5 of the sleeve 1. The holding body is held in place by means of a retention ring 6, which slots into a suitable circular groove 7, on the body. The flange 2 being positioned between the flange 3 and the ring 6. The distance between the flange 3, and the retention ring 6, is greater than the thickness of the flange 4, thus allowing the holding body 2, to rotate freely around its longitudinal axis.

Jaws 9 are slidingly located in the channels 17.

The central zone 8 of the body of each of the jaws 9 is entirely cylindrical and also the jaws are provided at their rear ends with recesses 10.

The advance/withdrawal component 11, is in one single piece and has on its front edge 12, three equally spaced narrow mouthed cavities 13. The withdrawal component has a screw thread on the outer surface 15, which enables it to be screwed into the cylindrical sleeve 1, which has a corresponding screwthread 16 on its inner surface.

The three jaws 9, are connected to the annular withdrawal component 11 by inserting the rear ends of the said jaws 9, into the cavities 13. The recesses 10, allow the jaw to slot into the narrow mouths 14 of the cavities 13, engaging about the lips of the cavities, so as to be slidable radially. Figure 4 shows the movement required to carry out this assembly and details of this combined unit.

The assembly composed of the annular withdrawal component 11 and the three jaws 9 remains assembled without possibility of separation once the said jaws 9, have been inserted into the three longitudinal holes 17, of the holding body 2. The said three longitudinal holes 17 converge into a single opening 18, common to all three and through which protrude the forward gripping extremities 19, of the jaws 9.

The assembly made up of the three jaws 9, the annularwithdrawal component 11 and the holding body 2 is held within the cylindrical sleeve 1. A cover 20 then closes the rear end of the said cylindrical sleeve 1, leaving at the centre a circular opening 21 which allows access to the rear extremity 22, of the holding body 2; this rear extremity 22 being adapted for connection with the motor spindle of a drilling machine to which the drill chuck is to be fitted. As in the prior art the connection is made by means of the screw thread 23.

Figure 3 shows, by means of the double arrow F2, the two possible directions of movement, longitudinally, of the annular withdrawal component 1 1 ; according to the direction of the movement, the front gripping extremities 19 of the jaws 9 either open or close as they slide in the converging guiding holes 17.

The front edge of the cylindrical sleeve 1, is provided with conical teeth 24to which a considerable effort can be applied with the use of chuck key, (not shown in the drawings), which said key has corresponding conical teeth. The hole 25 of the holding body 2, serves for the purpose of inserting the said key in accordance with well known existing practice.

Rotation of the sleeve 1 relative to the holding body 2 causes the withdrawal component 11 to move forwards and backwards within the cylinder 1, thereby advancing or withdrawing the jaws 9 in the channels 17. The withdrawal component 11 being prevented from rotating relative to the holding body 2 by the jaws 9.

Claims (9)

1. A drill chuck comprising a cylindrical sleeve having a screw thread on its inside surface, a holding body fitted within the cylindrical sleeve and held therewithin against movement relative thereto in the axial direction, a plurality of gripping jaws guided by the holding body, and a one piece withdrawal component which is externally screw threaded for cooperation with the screw thread of the cylindrical sleeve and which is operatively connected to the gripping jaws, the arrangement being such that relative rotation of the cylindrical sleeve and the withdrawal component causes the withdrawal component to move axially within the cylindrical sleeve thereby to advance or withdraw the jaws for gripping purposes.

2. A drill chuck as claimed in claim 1 wherein a gripping jaw has a cylindrical central portion.

3. A drill chuck as claimed in claim 1 or 2, wherein the gripping jaws are guided in holes provided in the holding body, which holes converge in the forward direction thereby to cause ends of the jaws to converge as the jaws are moved forward by the withdrawal component.

4. A drill chuck as claimed in claim 1,2, or 3, wherein the withdrawal component is annular.

5. A drill chuck as claimed in any preceding claim, wherein each gripping jaw is connected at an end thereof to the withdrawal component by means which allow movement of the said end radially of the withdrawal component.

6. A drill chuck as claimed in claim 5, wherein each said means comprises a radial channel provided in a face of the withdrawal component, the channel having a lip at the top thereof, and a groove provided proximally of the end of each jaw, thereby to interlock the end of the jaw into the channel and to allow said radial movement.

7. A drill chuck as claimed in any preceding claim, having a cover at a rear end thereof and conical teeth provided on the forward end of the sleeve for cooperation with a chuck key.

8. A drill chuck substantially as hereinbefore described with reference to the accompanying drawings.

9. The features hereinbefore disclosed, other or their equivalents, in any novel combination.