GB2336805A

GB2336805A - A hand machine tool chuck

Info

Publication number: GB2336805A
Application number: GB9909174A
Authority: GB
Inventors: Raymond Brantschen
Original assignee: Scintilla AG
Current assignee: Scintilla AG
Priority date: 1998-04-30
Filing date: 1999-04-21
Publication date: 1999-11-03
Anticipated expiration: 2019-04-21
Also published as: DE19819530A1; GB2336805B; CH693736A5; GB9909174D0

Abstract

A hand machine tool comprises a drive member 14 on which is mounted a sleeve 21 by means of a thread (Fig. 5, 261 and 262; Fig. 7, 27), the sleeve 21 being non-rotatably attached to a disc 22 which has an aperture (Fig. 8, 30) for the insertion of the shank of a tool 19. A torsion spring 23 attached to the sleeve 21 and the drive member 14 acts to rotate the sleeve 21 and disc 22 to thereby clamp retaining ribs 192 and 193 of a tool shaft 19 between a flat clamping surface of the disc 22 and the drive member 14. The chuck is opened by manually rotating the sleeve 21 against the action of the torsion spring 23 and locked in the open state by means of a spring loaded ejector (Fig. 4, 35) which is axially moveable along the drive member 14. The chuck is unlocked and closes when a tool 19 is inserted into the opening. The tool 19 may be a saw blade.

Description

2336805 1 Hand tool machine The invention proceeds firom a hand tool

machine of the type defined in the preamble of claim 1.

With such a hand tool machine, tool changing is possible very rapidly and with a one-hand operation. When the quick-action chuck does not contain a tool, the tool ejector automatically holds the quick-action chuck open so that a new tool may be introduced without any prior manipulation of the quickaction chuck and without the use of auxiliary devices. As a result ' of insertion of the tool shank into the quick-action chuck the tool ejector is displaced counter to the action of an ejection spring and hence releases the quick-action chuck for automatic locking of the tool. As soon as the tool ejector has been moved out of its blocking position, the tensed torsion spring rotates the clamping sleeve with clamping disc and the tool is clamped firmly between drive element and clamping disc. When the tool is to be changed, the clamping sleeve has to be rotated manually counter to the action of the torsion spring. As a result, the tool is released and the tool ejector, which is loaded by the ejection spring, pushes the tool out of the chuck and finally moves back into its blocking position, in which the quick-action chuck is held open.

To realize such a quick-action chuck for a hand-held electric jig saw, it has already been proposed to fix the clamping disc provided with a slot-type opening on a cap, which is held rotatably on an annular flange at the free end of a hoHow-cylindrical lifting rod forming the drive element. The structural unit of cap and clamping disc is enclosed by a collar and connected non-rotatably to the latter. The torsion spring acts on the one hand upon the collar and on the other hand upon the lifting rod. The clamping disc at its disc face directed towards the Efting rod end carries two ramps which, upon rotation of the collar with structural unit comprising cap and clamping disc, run onto the bottom edge of the clamping 2 straps of the saw blade and hence brace the saw blade, which is supported against the end face of the lifting rod, against the lifting rod end. For centring the saw blade, the annular lifting rod end is provided with a diametrical V- shaped groove, into which the clamping straps of the saw blade shank are pressed. The tool ejector, which is simultaneously used to hold the quick-action chuck open, is guided inside the lifting rod in vertical grooves in the rod inner wall so that it is locked against rotation. On the bottom end of the tool ejector a pair of limbs is formed 'm such a way that the limbs in the open position of the quick- action chuck are aligned with arresting holes Mi the clamping disc and under the action of an ejection spring engage at one end into said arresting holes and hence prevent the clampffig disc from being rotated by the tensed torsion spring.

The hand tool machine according to the invention having the features of claim 1 has the advantage that the quick-action chuck, for achieving the same advantageous functionality, is of a much simpler constructional design and is therefore less expensive to manufacture. By virtue of the steep-lead- angle thread provided according to the invention between drive element and clainpm'g sleeve there are fewer structural parts, thereby reducing manufacturing and assembly costs, and also the clamping disc as a result of dispensing with the two diametrically disposed ramps is very much easier to manufacture. The lower number of structural parts makes it possible to achieve a more compact design of the quick-action chuck.

Advantageous developments and improvements of the hand tool machine indicated in claim 1 are possible by virtue of the measures outlined in the further claims.

There follows a detailed description of an embodiment of the invention which is illustrated in the drawings. The drawings show:

Figure 1 a diagrammatic side view of a hand-held electric jig saw; 3 Figure 2 an enlarged, part-sectional view of the cutout II in Figure 1).

2.3 Figure 3 a part-sectional view in the direction of arrow III in Figure Figure 4 a perspective, partially cut-open view of a lifting rod with quick-action chuck of the hand-held Jig saw in Figure 1.

Figure 5 a perspective view of the lifting rod end of the lifting rod in Figure 4; Figure 6 an inverted plan view of the lifting rod end in Figure 5-, Figure 7 a perspective, partially cut-open view of a clamping sleeve of the quick-action chuck in Figure 4; Figure 8 a plan view of the clamping sleeve 'm Figure 7; and Figure 9 a perspective view of a tool ejector in the quick-action chuck according to Figure 4.

The hand-held jig saw, which is shown in side view in Figure 1 as an example of a general hand tool machine, comprises a machine housing 10, on which is formed a handle 11 for guiding the hand-held jig saw, which is placed by means of a supporting plate 12 onto the workplece to be sawn. A button 13 for switching the hand-held jig saw on and off projects from the underside of the handle 11 and cooperates with an electrical switch disposed in the circuit of an electric motor. The electric motor, which is not shown here and is accommodated in the machine housing 10, via a gear sets a lifting rod 14 into reciprocating motion. The lifting rod 14 is supported Mi the machine housing 10 in a top and bottom sleeve bearing, the bottom sleeve bearing 15 being visible in Figures 2 and 3, and passes through a recess 16 'm the machine housing 10 out of the latter so that the free lifting rod end outside of the machine housing 10 is freely accessible.

The recess 16 is sealed by means of a sealing ring 17 to prevent the entry of dust and the like.

4 The lifting rod 14 at its end projecting out of the machine housing carries a quick-action chuck 18 for the exchangeable clamping of a saw blade 19. The saw blade 19 held in the quick-action chuck 18 is supported during operation of the hand-held jig saw by its saw blade back 191 against a supporting roller 20, which is supported on the machine housing. For clamping into the quick-action chuck 18, the saw blade 19 carries two clamping straps 192, 193 which project transversely from the saw blade shank 194. In Figs. 2 and 3, the maximum stroke which the liffing rod 14 effects when driven by the electric motor is indicated by illustrating the quick-action chuck 18 in the one end-of- stroke position by solid lines and Mi the other end-of-stroke position by dash- dot lines.

As is evident from Figure 4, the lifting rod 14 is composed of a flat part 141 and a hollow round part 142, which are firmly connected to one another.

An oval gate 143 formed in the flat part 1,41 is used for the engagement of an eccentric pin of an eccentric drive in the gear, which converts the motion of rotation of the electric motor into a lifting motion of the lifting rod 14. The flat part 141 is guided in the top sleeve bearing and the hollow round part 142 in the bottom sleeve bearing 15, each in an.axially displaceable manner.

The quick-action chuck 18 seated on the free end of the round part 142 is designed in such a way that the saw blade 19 may be introduced into the quick-action chuck 18 without any need for additional manipulation or devices and after its introduction is automatically locked. For removal of the saw blade 19, the quick-action chuck 18 is operated by one hand, the saw blade 19 being ejected and the quickaction chuck 18 being held in open position so that a new saw blade may be introduced at any time without previously having to operate the quick- action chuck 18. For said purpose, the quick-action chuck 18 in particular comprises a pot-shaped clamping sleeve 21, which has a clamping disc 22 fg the pot base, as well as a torsion spring 23 which is supported at one end against the lifting rod 14 and at the other end against the clamping sleeve 21 and, to said end, has its one spring end inserted into a radial bore 24 'm the lifting rod 14 (Figure 5) and its other end inserted into a slot 25 in the clamping sleeve 21 (Figure 7). The clamping sleeve 21 is supported rotatably on the end of the lifting rod 14, for which purpose a partial thread 26 is formed on the lifting rod end and two diametrically disposed cams 27 project radially from the sleeve inner wall of the clamping sleeve 2 1. The partial thread 26 is a double thread and comprises two diametrical thread portions 261 and 262, which extend in each case only ove r part of one half of the circumference of the lifting rod end, Mi the embodainent over 130' (Figure 3). The partial thread 26 is cut Mi a thickened portion 28 formed on the lifting rod end. The two cams 27, which are disposed on the clamping sleeve 21 and of which only the one cam is visible in Figure 7, are disposed at an identical axial distance from the clamping disc 22. In each case, one cam 27 cooperates with one of the two threaded portions 261, 262 in the manner of a threaded connection. For turning the clamping sleeve 21 on the partial thread 26, a handle piece 29 is formed on the outside of the clamping sleeve 21 (Figure 8).

For receiving the saw blade shank 194 in the quick-action chuck 18, the clamping disc 22 has a centrally disposed, slot-like insertion opening 30, the slot width of which is greater than the shank thickness of the thickest saw blade 19 to be used in the quick-action chuck 18. Formed immediately adjacent to the insertion opening 30 are two segment-like recesses 31, 32 which verge into the insertion opening 30, the recesses 31, 32 being formed point- symmetrically relative to the axis of the clampmig sleeve 2 1. The recesses 3 1, 32 cooperate with arresting lugs 33, 34 of an ejector 35 (Figure 9), which may engage positively into the recesses 31, 32 and hence lock the clampmg sleeve 21 against rotation.

As Figure 4 reveals, the cylindrical ejector 35 is guided Mi an axially displaceable and non-rotatable manner inside the hollow round part 142 of the lifting rod 14 and applied by means of an ejection spring 36, which is supported against the end face 351 of the ejector 35 and against the end of the flat part 141 6 projecting into the round part 142, by two stops 337, 38, which are formed at the other end face 352 next to the arresting lugs 33, 34, against counterpart stops 39 (Figure 7) of the clamping disc 22. In Figure 7, of the two counterpart stops 39 only the one counterpart stop 39 is visible. A diametrical axial slot 40 is introduced from the end face 352 into the ejector 35 and has a slot width which is greater than the shank thickness of the thickest saw blade to be used Mi the quick-action chuck 18. Formed in the base of the axial slot 18 is an identical V shaped groove 4 1. A V-shaped groove 42 is mitroduced into the free annular end face of the lifting rod 14 and/or of the hollow round part 142 and/or into the thickened portion 28 of the round part 142 (Figure 5).

To assemble the quick-action chuck 18, the torsion spring 23 is first placed onto the round part 142 and then the round part 142 is connected, e.g. by soldering, welding or the like, to the flat part 14 1. Then, ejection spring 3 6 and ejector 35 are inserted into the round part 142 and the clamping sleeve 21 fitted onto the round part end. The torsion spring 23 is inserted by one end into the radial bore 24 'm the round part 142 and by the other end into the slot 25 in the clampffig sleeve 21 and the clamping sleeve 21 is turned onto the partial thread 26.

The qwick-action chuck 18 is then ready to operate.

The flinction of the quick-action chuck 18 during operation of the hand-held jig saw is as follows:

As a result of introducing the saw blade shank 194 of a saw blade 19 into the slot-like insertion opening 30 in the clamping disc 22 of the clamping sleeve 2 1, the ejector 35 is displaced counter to the action of the ejection spring 36 until it comes to lie above the rear face 221 of the clamping disc 22 directed towards the lifting rod end and so the arresting lugs 33, 34 are lifted out of the recesses 3 1, '32 in the clamping disc 22. At said point, the tensed torsion spring 23 is brought to bear and rotates the clamping sleeve 2 1. In said case, the clamping sleeve 21 with its two cams 27 winds up on the partial thread 26 and 7 clamps the saw blade 19 via the latter's clamping straps 192, 193 fiffaly between the clamping disc 22 and the V-shaped groove 42 in the lifting rod 14. The flat rear face 221 of the clamping disc 22 is in said case supported against the bottom edges of the two clamping straps 192, 193 of the saw blade 19 and presses the top edges of the clamping straps 192, 193 into the V-shaped groove 42 (Figure 2). At the same time, under the action of the ejection spring 3)6 the ejector 35 is also pressed with its V-shaped groove 41 onto the end face of the saw blade shank 194 accommodated in the axial slot 40. with the result that the shank end is also additionally centred.

When the saw blade 19 is to be changed, the clamping sleeve 21 has to be rotated counter to the action of the torsion spring 23) by means of the handle piece 29. In said case, the clamping sleeve 21 moves downwards on the partial thread 26 and releases the saw blade 19. As soon as the clamping straps 192, 19-3) leave the rear face 221 of the clamping disc 22 and engage into the insertion opening 30, the saw blade 19 is ejected by the ejector 35 loaded by the ejection spring 36. At the same time, the arresting lugs 33, 34 of the ejector 35 engage positively into the recesses 31, 32 in.the clamping disc 22. and the ejector 35 is applied by its stops 37, 38 against the counterpart stops 39. When the handle piece 29 is then released, the clamping sleeve 21 is arrested and is incapable of. being rotated back by the tensed torsion spring 23. In the absence of a saw blade 19, therefore, the quick- action chuck 18 is permanently open and a new saw blade 19 may be inserted at any time in the previously described manner into the insertion opening 30 without previously having to effect any manual manipulation of the clamping sleeve 2 1.

8

Claims

1. Hand tool machine having a drive element (14) for a tool (19), which drive element is drivable by an electric motor and hollow-cylindrical at least at its free end, and having, seated on the free end of the drive element (14), a quick action chuck (18) for clamping the tool (19) which has clamping straps (192, 193) projecting transversely from the tool shank (194), which quiick-action chuck comprises a clamping disc (22) having an insertion opening (30) for the tool shank (194), a clamping sleeve (2 1) which is non-rotatably connected to the clamping disc (22) and held rotatably on the free end of the drive element (14) and which through rotation braces the tool (19) between the drive element end and the clamping disc (22), a torsion spring (23) acting on the one hand upon the drive element (14) and on the other hand upon the clamping sleeve (21), and a tool ejector (35) which is non-rotatably guided in the drive element end and at the same time, in the open state of the quick-action chuck (18), locks the clamping sleeve (21) with clamping disc (22) against rotation by the tensed torsion spring (23) and cancels the locking by its axial displacement, which sets in upon insertion of the tool shank (194) into the insertion opening (30), characterized in that the rear face (221) of the clamping disc (22) directed towards the free end of the drive element (14) takes the form of a flat clamping face cooperating with the clamping straps and the rotational connection between the drive element end and the clamping sleeve (2 1) is effected by means of a steep-lead-angle thread (26), which is designed in such a way that upon the rotation of the clamp Mig sleeve (2 1) effected by the torsion spring (23), a sufficient axial displacement of the clamping disc (22) for bracing the tool is achieved.

9 2. Machine according to claim 1, characterized in that the steep-lead angle thread is formed by a partial thread (26) on the drive element end and by two diametrical cams (27) on the clamping sleeve (2 1).

Machine according to claim 2, characterized in that the partial thread (26) is a double thread comprising two diametrical thread portions (261, 262), which extend 'm each case only over part of one half of the circumference of the drive element end, preferably over an angle at circumference of 130', and that the earns (27) are disposed at an identical axial distance from the clamping disc (22).

4. Machine according to one of claims 1 - 3, characterized in that the clamping disc (22) is an integral part of the pot-shaped clamping sleeve (21) and is formed by the pot base of the clamping sleeve (2 1).

5. Machine according to one of claims 1 - 4, characterized 'm that the clamping sleeve (21) carries a handle piece (29) projecting from the sleeve lateral surface for manually rotating the clamping sleeve (2 1) counter to the action of the torsion spring (23).

6. Machine according to one of claims 1 - 5, characterized in that the clamping disc (22) has at least one arresting recess (31, 32), into which an arresting lug (33, 34) disposed on the end face (352) of the ejector (35) positively engages, that the tool ejector (35) has a central recess (40) opening out at said end face (352) for positively receiving the tool shank (194) and that an ejection spring 25 (36) supported between the drive element (14) and the tool ejector (35) presses the base of the recess (40) against the end face of the tool shank and, in the absence of a tool (19), presses the end face (352) of the tool ejector (35) against the clamping face (22 1) of the clamping disc (22), in each case with frictional engagement.

is 7. Machine according to one of claims 1 - 6, characterized 'm that the drive element is a lifting rod (14) and the tool is a saw blade (19), that the insertion opening (30) in the clamping disc (22) is rectangular and that a diametrical, V-shaped (42) groove is introduced into the annular free end face of the lifting rod (14) for supporting the clamping straps (192, 193) of the saw blade shank (194) against the lifting rod (14).

8. Machine according to claim 6 and 7, characterized in that the central recess in the tool ejector (35) takes the form of a diametrical axial slot (40) having a slot width which is greater than the shank thickness of the saw blade (19), and that a V-shaped groove (4 1) is introduced Mi the base of the axial slot.

9. Machine according to claim 7 or 8, characterized Mi that provided in the clamping disc (22) are two segment-like arresting recesses (3 1, 3 2), which are disposed on either side of the rectangular insertion opening (30), preferably point-symmetrically relative to the axis of the clamping disc (22), and verge into the insertion opening (30).

10. Machine according to one of claims 7 - 9, characterized in that the lifting rod (14) is of a two-part construction comprising a drive-side flat part (14 1) and a hollow-cylm"drical round part (142) which carries the quick-action chuck 25 (18).

11. A hand machine tool substantially as herein described with reference to the accompanying drawings.