GB2276118A

GB2276118A - Small machine tool

Info

Publication number: GB2276118A
Application number: GB9404204A
Authority: GB
Inventors: Joachim Schadow; Axel Werner; Manfred Ebinger; Radoslav Grujic
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1993-03-05
Filing date: 1994-03-04
Publication date: 1994-09-21
Anticipated expiration: 2014-03-04
Also published as: FR2702168A1; DE4306787C2; GB2276118B; IT1273370B; ITMI940387A0; ITMI940387A1; DE4306787A1; GB9404204D0

Description

2276118 Power operated sword saw

Prior art

The invention proceeds from a power operated sword saw according to the preamble of claim 1.

A sword saw of said type is known from EP 267 312. The term, sword saw, was chosen because - in a similar manner to chain saws - a plate called a sword supports the reciprocating saw blades at their rear side. The assumption suggested by said term, that with such a saw an infeed cut using the saw point is also possible, is incorrect. The known sword saw may be used, more like a sabre, for cuts perpendicular to the longitudinal axis of the saw blades but not in a longitudinal direction of the saw blades. Furthermore, for the known saw, there are no known means of limiting the cutting depth or adjusting the mitre angle like there are, for example, for the compass saw device according to US 3,823, 473. For said reason, the, as such, advantageous sword saw lags behind the known, earlier compass saw device in terms of versatility. For instance, precise 900 cutting edges are not reliably achievable.

Advantages of the invention In contrast. the solution according to the invention having the characterizing features of claim 1 has the advantage that both the infeed depth or cutting depth and the part-lengths of the saw blades to be used at any one time are preselectably adjustable. Uneven wear of the saw blades may therefore be avoided in that part-lengths thereof may be used successively 1 and so become uniformly worn, this being controllable by means of a scale on the sword.

The stop according to claim 6 has the advantage that it is light, so that it does not impede ease of handling of the sword saw or the like, and may moreover be quickly fitted, so as to be releasable and adjustable into precise angular positions, on the sword of the sword saw.

In conjunction with a sword saw according to patent application DE-P 43 02 653.2 which may used like a sword to make infeed cuts into workpieces, a stop according to the invention is of particular value because it enables an immediate transition from the infeed cut to the separating cut, with it being possible to keep the saw blade length projecting from the separating line constantly short.

Advantageous developments and improvements of the feature indicated in claim 1 or 5 arise from the features described in the sub-claims.

Drawings An embodiment of the invention is explained in greater detail in the following description with reference to the associated drawings.

Figure 1 shows a three-dimensional view of a sword saw of the type described without a stop, Figure 2 a side view of an embodiment of the invention, Figure 3 a front view of a stop according to the invention, Figure 4 an inverted plan view of a stop part according to Figure 3, Figure 5 a side view partially in section of the stop, Figure 6 a rear view of a collet chuck half, Figure 7 a side view of the collet chuck half according to Figure 6, and Figure 8 a plan view of a sword saw with a stop effecting a mitre cut at an angle of 450 relative to the workpiece.

2 Description of the embodiment

The sword saw 1 shown in Figure 1 comprises a machine housing 2, which is composed of a left and a right housing shell 3, 4 made of insulating material. The machine housing 2 is formed out into a solid operating handle 5 with an ONIOFF switch 6 and carries an adjustable, curved additional handle 7 and a sword 8, which is connected to the machine housing 2 and in which are guided two saw blades 9, 10 designed to be reciprocable as a pair, said saw blades passing through a through opening 11 into the machine housing 2.

Disposed at the sword point 12, one on either side of the sword 8 and close to the saw blades 9, 10 are longitudinal slots 13, 14, in which projections 15, 16 of the saw blades 9, 10 fit like slide blocks and are guided in a captive manner. The sword 8 carries marking lines 17 on its back 18 for controlling the cutting depth and for controlling the position of a stop 20 to be described below.

The side view of Figure 2 shows the sword saw 1 in the process of sawing through a workpiece 19 with the help of a stop 20, which is releasably fastened like a rider on the back 18 of the sword 8 between the sword point 12 and the machine housing 2. The stop 20 comprises a stop part 21, a clamping part 22, and a screw wheel 23 similar to a threaded nut which is adjustable about an axis of rotation 24 or about the external thread of a screw (Fig.5). With the aid of the stop 20, the front region of the saw blades 9, 10 is used for sawing and the back region of the saw blades 9, 10 is held remote from the workpiece 19. The part of the sword 8 projecting beyond the workpiece 19 is only short. Any other workpieces lying closely adjacent to the workpiece 19 cannot be damaged.

Figure 3 shows the stop 20 as a detail - corresponding to a fitted position on the sword 6, viewed from the front - with the screw wheel 23 for releasing and clamping the stop 20 on 3 the sword 8, the stop part 21 having the limbs 21 a, 21 b, and the clamping part 22 comprising the supporting body 25 and two collet chucks 26, 27. The supporting body 25 and the collet chucks 26, 27 have a common, aligned slot 28 which is slightly wider than the cross-section of the sword 8. Clamping surfaces 29, by means of which the collet chucks 26, 27 are operated, may be seen on the supporting body 25.

Figure 4 is an inverted plan view which shows the stop part 21 and its limbs 21 a, 21 b according to Figure 3 rotated through 1800 about the axis of rotation 24. The contour of the stop part 21 is an equilateral triangle with rounded corners, in the centre of which a bore 30 may be seen. The axis of rotation 24 extends through the bore 30 and it is penetrated (Fig.5) by the shaft of a hexagon head cap screw 31, which secures the collet chucks 26, 27. Disposed at regular intervals on a common circle around the centre of the bore 30 are detent recesses 32, with which detent projections 33 (Fig.5) on the clamping part 22 are associated. The bottom side 34 of the triangle reveals the contour of the stop faces of the limbs 21 a, 21 b.

From its 900 position, the stop part 21 may be rotated in any direction about the axis of rotation 24 through at least 450 (Fig.8).

Figure 5 shows, partially in section, the side view of the stop 20. The screw wheel 35 is screwed onto the hexagon head cap screw 31 and holds the stop part 21 with detent recesses 32 firmly applied against the supporting body 25 with the detent projections 33. The hexagon head cap screw 31 by means of its head in the supporting body 25 moreover secures the collet chuck halves 26, 27 disposed in the supporting body 25 so that they are axially displaceable in screw direction. The collet chuck halves 26, 27 are coupled to one another by means of a joggle joint produced by pins and bores 35, 36.

4 Figure 6 is a front view of a collet chuck half 26 or 27. Said view reveals the clamping surfaces 37, 38 on either.side of the clamping slot 38, the pins 35 and bores 36 and a location hole 39 for the head of the hexagon head cap screw 31.

Figure 7 shows the collet chuck half 26 or 27 according to Figure 6 from the side adjacent to the limb 21 a, with the interrupted arrangement of the clamping surface 38 and the arrangement of the pins 35 and bores 36 being evident.

Figure 8 is a plan view of the sword saw 1 in the process of effecting a mitre cut in a further workpiece 40 with the aid of the stop 20. The stop part 21 is rotated about the axis 24 in such a way that the limb 21 b touches the sword 8 laterally at the front. The maximum mitre angle is thereby set.

The stop 20 is fitted in the following manner. By turning the screw wheel 23 into the release position, the hexagon head cap screw 31 is moved downwards so that the collet chuck halves 26, 27 are lowered relative to the supporting body 25 and open so that the clamping slot 39 presents its maximum width. The oblique surfaces 29, 37, 38 are supported on one another in the manner of a clamping cone. At the desired position of the sword 8, possibly identified by markings 17. the stop 20 is guided with the clamping slot 39 over the sword 8 until the back 18 of the sword 8 meets the end of the clamping slot 39 in the top region of the collet chucks 26, 27. By tightening the screw wheel 23, clamping of the collet chuck 26, 27 is effected, the clamping slot 39 narrows and the stop 20 is secured non-positively on the sword 8. If a saw cut according to Figure 2 is to be effected. the stop part 21 is set into the 900 position relative to the sword 8, i.e. the two Ushaped limbs 21 a, 21 b lie in a plane extending at an angle of 900 to the flat side of the sword.

If a mitre cut is to be effected, then (Fig.8) the stop part 21 is adjusted relative to the supporting body 25 about the axis of rotation 24 and set by means of the detent device 32, 33 at the desired mitre angle. The adjustable mitre angle is determined by the dimensions of the stop part 21, i.e. by the distance of the limbs 21 a, 21 b from one another and from the sword. The further away the limbs 21 a, 21 b are from the clamping slot 39, the more the stop part 21 may be rotated relative to the supporting body 25 and the greater the possible angle of adjustment.

By displacing the stop 20 and varying the clamping position along the sword back 18, the front half, for example, of the saw blades 9, 10 may be preferentially used, e.g. in the event of a series of equal diameters to be sawn. After removal of the stop 20, the regions of the saw blades 9, 10 close to the housing may be preferentially used. This prevents uncontrolled, extremely high wear of some sections of the saw blades 9, 10, while other sections of the saw blades 9, 10 retain their original sharpness.

For a mitre cut, the inclination of the saw blades 9, 10 relative to a warkpiece is adjustable between 900 and 450 in increments of 150 with the aid of the stop 20.

When the sword saw 1 is used to effect infeed cuts into workpieces, e.g. when carrying out installation work in plasterboard partition walls, it may be important for the part of the sword 8, which comes out at the opposite side of the wall to the operator, to project only minimally beyond the wall so that the saw blades do not to catch, for example, service installations preassembled on the outer wall, i.e. so as to prevent damage to either the installations or the saw blades.

In an embodiment which is not shown, the contour of the machine housing adjacent to the sword is shaped in such a way 6 that the stop may be seated, flush mounted in the housing, on the sword and so is deposited close to the housing. with.the stop faces not limiting the sword length or the useful length of the saw blades. The stop faces of the stop verge evenly into the housing contour. From said deposit position, the stop may be moved over the length of the sword into any position on the sword back.

In a further embodiment of the invention which is not shown, the sword is provided, at the region close to its back, with detent means which enable an accurately reproducible positioning of the stop over the length of the sword.

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Claims

1. Power operated sword saw (1) having saw blades (7, 8), which are reciprocable parallel to one another, are coupled to a drive and are guided alongside one another in the bottom region of the plate-like sword (8), in particular for infeed cutting into workpieces, characterized in that the sword (8) carries, preferably on its back (18), a firmly clampable, rider-like stop (20) which supports the sword saw (1) relative to a workpiece (19; 40) during sawing.

2. Sword saw according to claim 1, characterized in that the cutting depth and the mitre angle of the sword saw (1) are adjustable by means of the stop (20).

3. Sword saw according to claim 1 or 2. characterized in that the stop (20) comprises a stop part (21) and a clamping part (22), the stop part (21) being adjustable, in particular rotatable about an axis of rotation (24), relative to the clamping part (22).

4. Sword saw according to claim 2 or 3, characterized in that the stop part (21) is adjustable. preferably in increments of 150, relative to the clamping part (22) by means of detent means (32; 33).

5. Sword saw, in particular according to one of claims 1 to 4, characterized in that the sword (8) carries, preferably on its back (18), graduated markings (17) and/or detent devices for positioning the stop (20).

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6. Stop (20) for setting the cutting depth of a small electric tool (1), characterized in that the small electric tool is a sword saw (1), in particular having saw blades (9, 10) capable of infeed cutting, and that the stop (20) is positionable, in particular clampable at a plurality of points, on the sword (8) and is used to support and guide the sword saw (1) on a workpiece (19).

7. Stop according to claim 6, characterized in that it is adjustable relative to the sword (8) in such a way that, when it rests on the workpiece (19), it determines the mitre angle of the sword saw (1).

8. Stop according to claim 6 or 7, characterized in that the stop (20) comprises a stop part (21) supported on a clamping part (22), which may be fastened on the sword (8), rotatably relative to said clamping part so that at least one stop face (21 a, 21 b) of the stop part (21) may be positioned at right angles or swivelled through 450 relative to the flat side of the sword (8).

9. Stop according to claim 8, characterized in that detent means (32; 33) are disposed between the stop part (21) and the clamping part (22).

10. Stop according to claim 8 or 9, characterized in that the clamping part (22) comprises a supporting body (25) with oblique inner surfaces (29), on which at least one collet chuck (26, 27) is supported by wedgeshaped, in particular external clamping surfaces (37, 38) so that the collet chuck (26, 27) upon axial displacement relative to the supporting body (25) opens and closes.

11. Stop according to claim 10, characterized in that the collet chuck (26, 27), operated by means of a clamping screw (31), in particular by means of a screw wheel (23), 9 may be fastened in the manner of a collet chuck on the sword (8) so as to be firmly clampable and releasable.

12. A power operated sword saw substantially as herein described with reference to the accompanying drawings.

13. A stop substantially as herein described with reference to the accompanying drawings.

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