GB2299539A

GB2299539A - Jig saw

Info

Publication number: GB2299539A
Application number: GB9605401A
Authority: GB
Inventors: Alfred Odendahl; Nicolantonio Aldo Di; Urs Ruepp
Original assignee: Scintilla AG
Current assignee: Scintilla AG
Priority date: 1995-04-07
Filing date: 1996-03-14
Publication date: 1996-10-09
Anticipated expiration: 2016-03-14
Also published as: CN1070398C; GB2299539B; FR2732629A1; CN1139603A; DE19513077B4; DE19513077A1; CH691763A5; FR2732629B1; GB9605401D0; JPH09141604A

Description

iiq saw

Background art

2299539 The invention proceeds from a jig saw according to the preamble of claim 1.

Such a jig saw is known from DE-OS 41 04 296. It carries under its base plate a sword described as a tongue, which is aligned with the saw blade and disposed in a housing-fixed manner. Said sword is used to receive a second base plate, which is displaceable along the sword and aligned parallel to the first base plate. The base plate may be clamped firmly on the sword. Said sword serves primarily as a carrier for the second base plate and together with the second base plate adds a relatively high amount of weight to the jig saw. Furthermore, for jobs where the sword and the second base plate are not required, the effort involved in the removal of said parts is high.

Furthermore, the large parallel distance of the sword from the jig saw blade is disadvantageous when the saw is used to cut curved contours with a small radius of curvature because the sword may become jammed in the curved cutting channel.

Advantages of the invention In contrast, the jig saw according to the invention having the characterizing features of claim 1 has the advantage of being lightweight, more convenient to handle and easier to dismantle. Moreover, the jig saw according to the invention is particularly good at cutting curves with a small radius of curvature. Here, there is the special advantage 2 that, without further aids, relatively precise circular contours may be sawed with a high reproducible accuracy.

Further advantageous refinements of the invention are indicated in the dependent claims.

Drawings There follows a detailed description of embodiments of the invention with reference to the accompanying drawings.

of said drawings, Figure 1 is the side view of a jig saw according to the invention, Figure 2 an enlarged view of the saw blade region according to Figure 1, Figure 3 a sectional view of the saw blade and the sword from Figure 2, Figure 4 the view according to Figure 3 in the setting for small radii of curvature, Figure 5 a cutout of an embodiment of the sword with fixing device and Figure 6-a three-dimensional view of the arrangement according to Figure 5.

Description of the embodiments

The jig saw 10 shown in Figure 1 comprises a motor housing 12 serving as a handle, which carries an on-off switch 14 and is flange-mounted on a gearbox 16, which carries an upwarddirected additional handle 18. A diagrammatically illustrated joint 22 is disposed between the gearbox 16 and a base plate 20. The jig saw 10 is supported by its base plate 20 on a workpiece 24. Extending vertically downwards through a through-opening 26 in the base plate 20 is a saw blade 28, which is supported by its back 30 against a guide roller 32. Disposed parallel to, in alignment with and behind the saw blade 28 is a sword 34 acting as a splitting wedge, which prevents jamming and tilting of the saw blade 28 during sawing.

In Figure 2, an enlarged cutout from Figure 1 shows the 3 gearbox 16 with a lifting rod 36 which carries the saw blade 28. Also visible are the guide roller 32 with its roller axis 33 and the serrated side 27 with the teeth 29 of the saw blade 28.

It is also evident from Figure 2 that the sword 34 may be swivelled like the blade of a pocket knife about a folding axis 38 along the direction arrow 39 aligned in the plane of the saw blade 28 and in its outermost swivel position, having been folded back - in viewing direction - to the right parallel to the axis of the motor housing 12, may remain in a retaining slot 40 (not described in detail) of the gearbox 16 above the base plate 20 if its use is not required.

The sword 34 is moreover disposed so as to be capable of swivelling relative to the saw blade 28 about a paraxial swivelling axis 42 in a similar manner to the vertical rudder of an aircraft rudder unit.

Figure 3 shows a joint cross section of the saw blade 28 and the sword 34, in which the vertical rudder-like construction of the sword 34 relative to the saw blade 28 and the swivelling axis 42 parallel to the saw blade axis are visible. The cross section of the sword 34 diminishes in the direction of its sword back 35.

Figure 4 shows the arrangement according to Figure 3 in the setting for cutting a curve. Here, the sword 34 is adjusted about the swivelling axis 42 by the swivelling angle a relative to the saw blade 28 so that it may follow the saw blade 34 in the curved cutting channel and determines the radius of curvature of the cutting channel.

During sawing with the jig saw 10, the following occurs. When, after operation of the manual switch 14, the motor (not shown) and hence the lifting rod 36 with the saw blade 28 have been set in reciprocating motion, the jig saw 10 is placed 4 with the base plate 20 onto the workpiece 24 in such a way that the saw blade 28, as a result of the cutting action of its teeth 29, laterally penetrates the workpiece 24. By displacing the jig saw 10 parallel to the workpiece in the direction of the saw teeth 29, a cutting channel is sawn in the workpiece 24. The saw blade 28 and the sword 34 project down through said cutting channel.

In the case of straight cuts, the sword 34 in the position according to Figure 3 prevents extensive swivelling of the jig saw 10 about the longitudinal axis of the saw blade. By virtue of the arrangement of the sword 34, cutting along a line substantially as straight as if drawn by a ruler is possible and deviations from the straight line are virtually ruled out.

After the sword 34 has been swivelled about its swivelling axis 42 and subsequently arrested, the saw blade 28 and the sword 34 are so positioned relative to one another that, without compasses or similar aids, the cutting channel contour produced corresponds substantially to an arc of a circle. Depending on the angular position, the radius of curvature of the cut circle is greater or smaller, i.e. when the swivelling angle a is large, the radius of curvature is small, when the swivelling angle a is small, the radius of curvature is greater.

Figure 5 shows the bottom region of a jig saw in a cutout manner with a Ushaped fixing bracket 75 for a sword 74 without a saw blade. A base plate 60 has a common throughopening 66 for a saw blade (not shown), the sword 74 and the fixing bracket 75, which has two vertical limbs 76, 77 connected, e.g. welded or screwed, to a gearbox (not shown) of the jig saw.

A transverse piece 78 connecting the two limbs 76, 77, extending parallel to the base plate 60 and having a drilled hole 81 carries the sword 74. A threaded stub 83 of the sword 74 penetrates the drilled hole 81 and is secured by means of a snap ring 84 (Fig.6). A swivelling axis 82, about which the sword 74 is capable of swivelling, is shown by a dash-dot line.

The through-opening 66 of the base plate 60 is wide enough for the fixing bracket 75 to pass through and rest, with the underside of its region 78 flush with the underside of the base plate 60, on the workpiece. The upward extension of the swivelling axis 82 is simultaneously the axis of symmetry or transverse axis of a guide roller 72, which is supported so as to be rotatable about an axis 73 parallel to the base plate 60. The guide roller 72 is provided with a circumferential Vshaped annular groove, in which a saw blade (not shown) is supported by its back.

The jig saw (not shown) carrying the base plate 60 is in principle identical to that according to Figure 1.

Figure 6 shows an enlarged, three-dimensional view of a fixing device of a sword 74. A U-shaped fixing bracket 75 is fastened to the gearbox (not shown) of a jig saw in such a way that the limbs 76, 77 of the U extend parallel to the sword 74, the transverse surface which connects the limbs 76, 77 of the U extending parallel to the base plate 60. In alignment with the swivelling axis 82, an axle stub 83 as an extension of the sword 74 passes through a drilled hole 81 in the transverse piece 78 of the fixing bracket 75. The axle stub and hence the sword 74 are prevented from falling out of the drilled hole 81 by means of a snap ring 84.

In parallel next to the axle stub 83, the sword 74 carries an axial second stub, which serves as link finger 85 and which as an axial extension of the sword 74 passes through a semicircular link slot 86 in the transverse piece 78 of the fixing bracket 75. The link finger 85 is screwed by means of a 6 hexagon nut 80 to the transverse piece 78, a predetermined friction being adjusted which is high enough to prevent the sword 34 during sawing from being already rotated about the swivelling axis 82 by slight contact with the workpiece. The friction is low enough to allow the sword 74 to be manually moved about the swivelling axis 82 into the desired angular position. A scale 87, which is disposed on the transverse piece 78 of the fixing bracket 75, allows reproducibly precise adjustment of the swivelling angle of the sword 74 and facilitates its control.

Figures 5 and 6 do not show the means illustrated in Figure 2 for folding back the sword 74.

In an embodiment of the invention which is not shown, a fixing bracket is disposed so as to be foldable about an axis parallel to the roller axis. As a result, the sword may, if necessary, be swivelled back parallel to the base plate and sawing may be effected without the sword. Alternatively, however, the sword may be folded far enough towards the saw blade to enable the tip of the saw blade back to be supported against the bottom end of the sword, like in a guide.

7

Claims

Claims

1. Jig saw (10), having a saw blade (28) driven in a reciprocating manner and having a sword (34, 74) disposed behind and in alignment with the saw blade (28), characterized in that the sword (34, 74) is disposed so as to be capable of swivelling about a swivelling axis (42, 82) extending parallel to the saw blade.

2. Jig saw according to claim 1, characterized in that the sword (34) is disposed so as to be foldable, in particular about a folding axis (38), away from its position parallel to the saw blade (28).

Jig saw according to claim 1 and 2, characterized in that the sword (34) is disposed so as to be arrestable in its folded-away position, in particular in a retaining slot (40) of the housing (12) of the jig saw (10), like the blade of a pocket knife.

Jig saw according to one of the preceding claims, characterized in that the sword (74) is capable of swivelling about its swivelling axis (42, 82) guided by link guide means (85, 86).

Jig saw according to claim 4, characterized in that the link guide means comprise a link finger (85), which is disposed on the sword (34, 73) and is guided so as to be capable of swivelling in a housing-fixed link slot (86) extending in the shape of an arc around the swivelling axis (82).

8 Jig saw according to claim 5, characterized in that disposed along the link slot (86) is at least one scal (87) serving as a position control for positioning the link finger (85).

7. Jig saw according to one of the preceding claims, characterized in that the sword (34), when moved about its swivelling axis (42, 82), is arrestable and serves as a guide means for curved cuts and, when set in alignment with the saw blade, serves as a guide means for straight cuts.

8. A jig saw substantially as herein described with reference to the accompanying drawings.