GB2324499A

GB2324499A - Portable planing machine.

Info

Publication number: GB2324499A
Application number: GB9807993A
Authority: GB
Inventors: Adolf Zaiser
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-04-26
Filing date: 1998-04-15
Publication date: 1998-10-28
Anticipated expiration: 2018-04-15
Also published as: GB2324499B; DE19717701B4; IT1299093B1; DE19717701A1; ITMI980800A1; GB9807993D0

Abstract

A portable planing machine (10) having a plane housing (12), which receives in a rotatable manner a plane shaft (20) provided with at least one longitudinal groove (34), into which at least one plane knife (21) with a standard cutting edge (22) is releasably clampable, the plane shaft (20) carrying at least one radial stop for positioning the standard cutting edge (22) of the plane knife (21) on an intended circular path (24), is improved in terms of its quantitative and qualitative performance in that the plane knife (21) is flexible and twistable and is made of metal and at the opposite side to the cutting edge (22) carries at least one limb (50) bent at an angle for locking it radially in position relative to the plane shaft (20) and that the longitudinal groove (34) takes the form of a helical groove, which in the radially inner region of the plane shaft (20) is bent into an L-shape for engagement of the limbs (50).

Description

1 Portable planing machine

Background art-

2324499 The invention proceeds from a portable planing machine according to the preamble of claim I and from a plane knife according to the preamble of claim 7.

From DE-OS 9152 65 a portable planing machine is known, which has a plane shaft carrying at least one oblong plane knife, which extends over the width of the plane shaft. and is clamped by means of centrifugal wedges. The plane shaft and the centrifugal wedges disposed therein are of a relatively complicated design and suitable only for clamping straight plane knives. Plane knives disposed in a straight manner do not offer the advantage of a drawing cut or of the drawing drive-in sector of the knife into the workpiece. Thus, with straight plane knives it is not nearly as possible to work with such freedom from vibration and with such large depths of cut or with a higher specific cutting force as with obliquely or helically disposed plane knives, because the cutting edge of the knife drives in along its full length simultaneously.

From EP 0 117 991 a planing machine is known having a plane shaft 2 0 composed of shaped discs, in which a straight plane knife is clamped by means of a centrihgal wedge. A helical knife is not clampable on said plane shaft.

Advantages of the invention In contrast, the planing machine according to the invention and the plane knife having the characterizing features of claim 1 and 7 respectively have the advantage that thinner and lighter helical knives than before are very easily clampable on the plane shaft of a portable planing machine. Thus, besides the advantages of the drawing cut or of the drawing drive-in of the knife, exchange of the plane knife is simplified. As a result with less vibration greater depths of cut with a lower specific cutting force are achievable so that a second knife is possibly superfluous. The knife, which is only, say, 0.5 min thick and 5.5 nun high and has a length corresponding to the width of the_ plane shaft, is particularly easy and inexpensive to manufacture.

By virtue of the fact that the plane knife is flexible and twistable and is made of metal and at the opposite side to the cutting edge carries at least two spaced-apart limbs bent at an angle for locking it radially M position relative to the plane shaft, the longitudinal slot taking the form of a helical groove which in the radially inner region of the plane shaft is bent into an L-shape for engagement of the limbs, the plane knife may be manufactured using a minimum of material III a similar manner to a razor. blade.

Because of the low mass, any unbalances are smaller then before.

By virtue of the hook-shaped refinement of the plane knife, it may with little effort be clamped particularly securely on the plane shaft.

By virtue of the fact that the plane knife has a lateral limb for axial is support against the end face of the plane shaft, the plane knife is axially locked in position particularly well.

By virtue of the fact that the cutting edge of the plane knife is curved outwards in a convex manner, in particular with a radius of curvature of around 2800 mm, the helical groove may extend at an angle of 5', i.e. helically, resulting in a drive-in sector of around 15'. In said case, the plane knife upon clamping on the plane shaft is shapable in such a way that the cutting edge extends parallel to the contour of the plane shaft.

By virtue of the fact that the plane shaft is composed of shaped discs using a punching/stacking technique, the curvature and the angular course of the 2 5 helical groove may be determined through mutual rotation of said shaped discs.

By virtue of the fact that the plane knife only through insertion into the helical groove becomes the helical knife with a drawing cut, the plane knife as a result of the bracing action is secured against loss on the plane shaft.

3 The plane shaft composed of shaped discs may in a particularly simple manner through'mutual displacement of the individual discs receive the plane knife in a helical groove or longitudinal slot of vanable shape.

By virtue of the helical arrangement of the plane knife, said plane knife is bent and twisted m the helical groove and in said manner is held locked against axial displacement on the plane shaft.

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

Drawings There now follows a detailed description of an embodiment of the invention with reference to the accompanying drawings.

Figure 1 shows a side view of the portable planing machine according to the invention, Figure 2 a three-dimensional view of the plane shaft according to the invention, Figure 3 a side view of the plane shaft according to Figure 2, Figure 4 a view of the flat side of the plane knife, Figure 5 a view of the narrow side of the plane knife according to Figure 4 and Figure 6 a side view of the plane knife according to Figure 4.

2 0 Descnption of the embodiment The portable planing machine 10 shown in side view in Figure I comprises a machine housing 12 with a motor housing 14 and a handle 16. The handle 16 canies an electric switch 18.

In the machine housing 12, a plane shaft 20 is supported on an axle 19 2 5 so as to be rotatable in the direction of the direction-of-rotation arrow 11. Said plane shaft carries two oblong, helically disposed plane knives 21, which each have a cutting edge 22 and in front of which clamping grooves 25 are formed in the external contour 23 of the plane shaft 20.

When the plane shaft 20 rotates, the knives 21 with their cutting edges 3 0 22 define a circular path 24, which is indicated by dash-dot lines and projects beyond - 4 the sole 26 of the portable planing machine 10 so that the cutting edges 22 may engage in a cutting manner into a workpiece 27 extending level with the sole 26.

An opening 28 disposed in the sole 26 for downward passage of the cutting edges 22 is closable by means of an articulated protective hood 30. The latter S automatically closes the opening 28 as soon as the portable planing machine 10 is lifted off the workpiece 27. The risk of the operator being injured by the rotating cutting edges 22 is thereby reduced.

The machine housing 14 has, on either side of the plane shaft 20 in the region of the sole 26, lateral recesses 32 through which the plane knives 21 are laterally removable from the plane shaft 20 or insertable into the plane shaft and clampable. By means of centrifugal wedges, which are described below with reference to Figure 3, the plane knives 21 are automatically clamped when the portable planing machine 10 is set in operation.

The plane shaft 20 shown as a detail In Figure 2 comprises an axle 19 carrying the body of the plane shaft 20, which body is composed of the individual shaped discs 201 which are shown merely in a suggested manner on the left in viewing direction. The circular external contour 23 of the plane shaft 20 as well as the clamping grooves 25 are clearly visible. Extending longitudinally over the external contour 23 or the lateral surface of the plane shaft 20 is a continuous helical groove 34, which verges in a radially inward direction into a centrifugal wedge recess 35 and is ised to receive the plane knife 21. The helical groove 34 in its radial course or in cross section is moreover bent, in viewing direction to the right, into an L-shape and verges there into a limb 37 (Fig. 3). At the - in viewing direction - left side, the helical groove 34 verges into a catch groove 44 and from there into the centrifugal wedge recess 35. The oblong plane knife 21 is seated in the radially straight region of the helical groove 34 and the bottom hook limbs 50, 52 of the plane knife 21 are seated in the limb 37 of the spiral groove 34 bent at an angle to said radially straight region. By means of said bottom hook limbs the plane knife 21 is locked radially in the helical groove 34.

The plane knife 21 is supported by means of a hook limb 48 disposed along its end against the end face of the plane shaft 20 so that the axial end position of the plane knife is secured thereby.

With the supporting surface 29 lying opposite the cutting edge 22 (Fig.

5) the plane knife 21 is supported against a transverse step 36 of the plane shaft 20, with the result that the cutting edge 22 is precisely and securely positioned even in the event of high radial cutting forces.

A centrifugal wedge 42 spring-guided by means of a leaf spring-like part 40 of the plane shaft 20 is supported in a prestressed manner against the flat side, referred to as the knife breast 39 and pointing in the direction of rotation, of the plane knife 21 and holds the latter, with increasing speed, more tightly clamped in its clamped position on the plane shaft 20. The cavities 38 penetrating the plane shaft on radially opposing sides serve to reduce the weight of the plane shaft 20 and hence of the portable planing machine 10.

The centrifugal wedge 42 is movable by radial Inward pressure into its release position so that the helical plane knife 21 may then easily be removed laterally from the plane shaft 20.

Figure 4 shows the detail of a helically clampable plane knife 21 with a cutting edge 22 and two lateral, so-called folding cutting edges 46. On the right in 2 0 viewing direction, the folding cutting edge 46 is separated by a punched-out portion 47 from a lateral hook II'LMb 48. The latter projects, in viewing direction, out of the drawing plane, as do the bottom hook limbs 50, 52 of the plane knife 2 1.

As an alternative or in addition to the hook limb 48, the plane knife 21 has a rectangular recess 49 shown by a dash-dot line, into which a resilient cam (not shown) of one of the groove flanks of the helical groove 34 may latch as soon as the plane knife 21 has reached its intended position there. By said means, the axial position of the plane knife 21 is lockable just as reliably as by means of a hook limb 50.

The cutting edge 22 of the plane knife 21 is curved into the shape of an arc, the radius of curvature characterized by the arrow 54, given a length of the plane knife corresponding to the plane shaft width of between 35 and 56 mm, being approximately 2800 mm.

The new type of centrifugal wedge clamping with a very narrow helical groove allows the helical plane knife 21 to be only around 0.5 min thick, similar to a razor blade. The latter has to be supported directly behind the cutting edge, as it were at the knife back, so that during planing it does not bend significantly and thereby lose its cutting ability.

By virtue of the minimal size of the plane knife 2 1, expensive material is spared and the weight of the planing machine reduced. Furthermore, by virtue of the low mass of the plane knife, the vibration response of the plane shaft at the high planing speeds of around 20,000 rpm may be positively influenced.

- 7

Claims

1. Portable planing machine (10) having a plane housing (12), which receives in a rotatable manner a plane shaft (20) provided with at least one longitudinal groove (34), into which at least one oblong plane knife (21) with a cutting edge (22) is releasably clampable, the plane shaft (20) carrying at least one radial stop (3 6) for supporting the plane knife (2 1) in order to position the cutting edge (22) on an intended circular path (24), characterized in that the plane knife (2 1) at the opposite side to the cutting edge (22) carries at least one limb bent at an angle, preferably two spaced-apart limbs (50, 52) for the hook-like engagement of the plane knife (21) into the helically curved longitudinal groove (34), which in a radially inward direction has a region (37) bent into an L-shape for receiving the limb (50, 52).

2. Portable planing machine according to claim 1, characterized in that the plane shaft (20) comprises axially abutting shaped discs (33) positionable through mutual rotation by a specific amount, which positioning may be used to determine and adjust the helically curved course of the longitudinal groove (34).

3. Portable planing machine according to claim 1, characterized in that the plane knife (2 1) has at one end a limb (48) bent longitudinally at an angle for axial support against the end face (60) of the plane shaft (20).

4. Portable planing machine according to claim 1, characterized in that the helical groove (34) extends at an angle of 5 0 relative to the longitudinal axis of the plane shaft (20) on the lateral surface of the plane shaft (20).

5. Portable planing machine according to claim 1, characterized in that the plane knife (21) through insertion into the helical groove (34) is clampable and shapable into a helical knife.

6. Plane knife for a portable planing machine according to the preamble of claim 1, characterized in that the plane knife (21) is flexible and twistableol preferably made of metal and at the opposite side to the cutting edge (22) carries a limb bent at an angle, preferably two spaced-apart limbs (50, 52) for the hook-like engagement of the plane knife (2 1) into the helically curved longitudinal groove (3 4), which in a radially inward direction has a region (37) bent into an L-shape for receiving the limb (50, 52).

7. Plane knife claim 6, characterized in that the plane knife (2 1) at one end carries a limb. (48) for axial support against the end face (60) of the plane shaft (21).

8. Plane knife claim 6 or 7, characterized in that the cutting edge (22) of the plane knife (21) is curved outwards m a convex manner, m particular with a radius of curvature (54) of approximately 2800 mm for a helical angle of 5'.

9. Plane knife claim 6, 7 or 8, characterized in that the plane knife (2 1) through insertion into the helical groove (34) is clampable and shapable into the helical knife with a drawing cut, the plane knife being locked in a frictionally engaged manner against displacement in the helical groove (34) and against loss.

10. A portable planing machine substantially as herein described with reference to the accompanying drawings.

11. A plane knife for a portable planing machine substantially as herein described with reference to the accompanying drawings.