GB2340440A

GB2340440A - Planing head

Info

Publication number: GB2340440A
Application number: GB9917615A
Authority: GB
Inventors: Adolf Zaiser
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-08-07
Filing date: 1999-07-27
Publication date: 2000-02-23
Anticipated expiration: 2019-07-27
Also published as: GB9917615D0; DE19835724A1; DE19835724B4; FR2782028A1; FR2782028B1; JP2000052311A; JP4418557B2; GB2340440B

Abstract

In a planning head for a hand-held planing machine, the said planing head having a cylindrical base body (11) which receives a planing knife (14) in at least one longitudinal groove (13), and having at least one pre-tensionable clamping or centrifugal wedge (16) which is held on the base body in a movable manner and which is received inside a base body clearance (151) and clamps the planing knife (14) fast on the base body (11) by centrifugal force, the position of the centrifugal wedge (16) can be set, for the purpose of facilitated knife-changing and improvement of the sensitivity to tolerances in the knife-clamping range, by means of at least one positioning screw (29) which can be screwed radially into the base body (11) (figure 2).

Description

2340440 Planing head

Prior art

The starting point of the invention is a planing head for a hand-held planing machine in accordance with the pre-characterising clause of claim 1.

In a known planing head of this kind (DE 195 36 559 Al), which is also called a "knife-carrier" or "planing shaft" and is rotatably mounted in the housing of the hand-held planing machine and driven by an electric motor, the integrated centrifugal wedge is secured elastically to the planing head, inside a clearance in the base body of the latter, in a captive manner solely via a spring, that is to say so that it cannot be demounted in a non-destructive manner, and, when the planing head is at a standstill, exerts on the planing knife enclosed in the longitudinal groove a pre-tensioning force which prevents the said planing knife from slipping out. When the planing head is rotating, the centrifugal wedge is forced outwards, as a result of which its contact pressure on the planing knife increases. At the same time, a catching groove, which is constructed in the centrifugal wedge and interacts with a projection on the base body, limits the radial stroke of the said centrifugal wedge towards the inside and towards the outside. The base body is formed by a continuous pack of essentially identical profiled discs or profiled lamellae which are seated on a planing head shaft in a torsion-proof manner and are axially braced against one another by clamping bodies supported on the shaft. A centrifugal wedge profile and a leaf spring profile are constructed in each profiled disc, so that, as a result of the packeting, the centrifugal wedge is also produced with a leaf spring which elastically secures the said wedge to the base body.

Advantages of the invention 2 The planing head according to the invention having the features in claim 1 has the advantage that the possibility of altering the pre-tensioning force both facilitates knife-changing and also improves the sensitivity to tolerances in the knifeclamping region, since the centrifugal or clamping wedge can be positioned by means of a positioning screw, of which there is at least one. A smaller channel depth than before is needed for knife-changing purposes. The planing knife is supported by the positioning screw, of which there is at least one, against the effects of impingement (by a knot or nail). The risk of deflection of the wood is reduced by the screw pre-tensioning.

Advantageous further developments of, and improvements to the planing head indicated in claim 1 are possible through the measures set out in the other claims.

Drawings The invention is described in greater detail below with the aid of an exemplified embodiment represented in the drawings, in which:

figure 1 shows a perspective view of a planing head for a hand-held planing machine, figure 2 shows a cross-section along the line II-II in figure 1, figure 3 shows a side view of a positioning screw for screwing into the planing head according to figure 1, represented in enlarged form, figure 4 shows a longitudinal section along the line W-W in figure 2, 3 figures 5 to 9 show plan views, in each case, of various profiled lamellae in the planing head according to figure 1.

Description of the exemplified embodiment

The planing head represented in perspective in figure 1 has a cylindrical base body 11 with an essentially circular outer contour in which there are incorporated a depression called a clamping groove 12 and also a longitudinal groove 13 for receiving a planing knife 14. The planing knife 14, which projects radially above the outer contour of the base body 11 to some extent, is pre-tensioned in the longitudinal groove 13 by means of a centrifugal wedge 16 (figure 2) enclosed in a base body clearance 15, for which purpose the said centrifugal wedge 16 is connected to the base body 11 in one piece via a spring 17. The base body 11 is seated in a torsion-proof manner on a shaft 10 which is received, by its two ends which protrude at the end faces of the said base body 11, in pivot bearings in the housing of the hand-held planing machine. One end of the shaft 10 is coupled to an electric motor via a gear unit. When the planing head is rotating, the centrifugal wedge 16 is forced outwards, as a result of which its contact pressure on the planing knife 14 increases.

As is partially indicated in figure 1 and can be seen in figure 4, the base body is formed from a continuous pack having a plurality of profiled lamellae 18, which are mutually adjacent axially, in a total of five different forms of embodiment which are represented individually in figures 5 to 9. The profiled lamellae 18 are stamped, anti-corrosively galvanised or gas-nitrided and packeted after being provided with knobs, so that they are secured to one another in a non-rotatable manner. The entire pack of lamellae forming the base body 11 is received on the shaft 10 in a torsion-proof manner. With the exception of the two outer lamellae 4 18 in the pack of lamellae, which outer lamellae are represented in figure 9 and will hereinafter be called covering lamellae 18 1, all the profiled lamellae 18 have two opposed cavities 20, 21 for weightreduction purposes and pressed-out knobs 19 for mutual positioning against one another, and also a clearance 151. The totality of the mutually aligned clearances 151 in the profiled lamellae 18 forms the base body clearance 15, which has already been mentioned, in the base body 11. The centrifugal wedge 16 enclosed in the base body clearance 15 is formed by the totality of the mutually aligned centrifugal wedge profiles 161 in the totality of the profiled lamellae 18 (figures 5 to 7) which, together with a spring profile 171, are stamped clear in the profiled lamellae 18 in such a way that they are enclosed in the clearances 151. All the centrifugal wedge profiles 161 are connected rigidly together via knobs 23 impressed in the said profiles 161. Together with the totality of a longitudinal edge constructed on them, the centrifugal wedge profiles 161 form the left-hand groove flank 131 of the longitudinal groove 13, while the right-hand groove flank 132 is formed by the plurality of longitudinal edges stamped out, in each case, in each profiled lamella 18. The profiled lamellae 18 according to figures 7, 6 and 5 are all constructed as described above and are, in addition, further modified among themselves. Thus the profiled lamella according to figure 5, hereinafter called the lever lamella 185, and the profiled lamella according to figure 7, hereinafter called the wedge lamella 183, each have a blind clearance 24 which is a continuation of the clearance 15 1. In the case of the lever lamella 185, a lever arm 25, which projects into the blind clearance 24, is constructed on the centrifugal wedge profile 161 in one piece. In the case of the wedge lamella 183 according to figure 7, there is no such lever arm on the centrifugal wedge profile 161. Instead of the blind clearance, the profiled lamella according to Figure 6, hereinafter called the spacer lamella 184, possesses a perforation 26 which is closed on all sides and is disposed in such a way that it is congruent, when the profiled lamellae 18 are packeted, with the blind clearance 24 in the lever lamellae 185 and wedge lamellae 183. The two covering lamellae 181 according to figure 9 also have an identical perforation 26. The profiled lamella 18 delineated in figure 8, hereinafter called the latching lamella 182, likewise has a blind clearance 24 adjoining the clearance 151, but is modified, compared with the wedge lamella 183 according to figure 7, insofar as the spring profile 171 does not have a centrifugal wedge profile at its free end, but a latching profile 27. This latching profile 27 engages, with a catching groove 271, round a projection 38 constructed in the profiled lamella 182 and likewise forms, with a straight side leading radially outwards, the left-hand groove flank 131 of the longitudinal groove 13 which is adjoined, radially outwards, by the clamping groove 12. The right-hand groove flank 132 of the longitudinal groove 13 is, once again, formed by a straight side, which leads radially outwards, of the latching lamella 182. That straight side of the latching profile 27 which forms the left-hand groove flank 131 is constructed in such a way that the longitudinal groove 13 is narrower than in the case of the other profiled lamellae 18, so that the planing knife 14 is clamped in a pincer-like manner and its axial location cannot change in an unintended manner or be lost when the planing head is at a standstill. For the purpose of releasing this pre- tensioning, an auxiliary tool can be introduced into the blind clearance 24 and pushed under the latching profile 27, and the latter can thereby be pivoted into its releasing position. The latching lamella 182 is disposed on one end face of the pack of lamellae, directly next to a covering lamella 181 according to figure 9, so that the auxiliary tool can be slipped through the perforation 26 in the adjacent covering lamella in order to be introduced into the blind clearance 24.

The packeting of the profiled lamellae 18 is represented in figures 1 and 4. A plurality of wedge lamellae 183 is disposed between the two externally located covering lamellae 181 and the latching lamella 182 adjoining a covering lamella 6 181. At a distance a from the two end faces of the pack of lamellae, a group consisting of lever lamellae 185 and spacer lamellae 184 is disposed between two wedge lamellae 183 in each case. The two groups have the same kind of construction, each group consisting of two externally located lever lamellae 185 and two spacer lamellae 184 located between the said lever lamellae 185. After packeting, there is now cut into each group of lever lamellae 185 and spacer lamellae 184 a radial threaded hole 28 which opens into the perforations 26 in the spacer lamellae 184 and the blind clearances 24 in the two lever lamellae 185, as can be seen in the sectional representation in figure 2. A positioning screw 29, as represented in figure 3, is now screwed into each threaded hole 28.

The positioning screw 29 has a threaded section 291 with an external thread for screwing into the internal thread in the threaded hole 28, and also a positioning section 292 which is located in front of the threaded section 29 1, referred to the direction of screwing-in, and the smallest clear width or thread core diameter of which is smaller than the outer diameter of the threaded section 291. The positioning section 292 is provided with an undercut 293 which extends from the threaded section 291 as far as the vicinity of the free end of the positioning section 292 and the depth of undercutting of which approximately corresponds to the axial thickness of a lever arm 25 on the centrifugal wedge profiles 161 of the lever lamellae 185, that is to say to the thickness of the stamped profiled lamellae 18. The axial length of the undercut 293, and that dimension h of the lever arm 25 (figure 5) which points in the same direction, are coordinated with one another in such a way that the lever arm 25 lies in the undercut 293 with axial play. The free front end of the positioning section 292 is of truncated cone-shaped construction. A radial shoulder 293a and 293b is constructed, in each case, at the transition from the positioning section 292 to the undercut 293 and from the undercut 293 to the threaded section 29 1. The outer diameter of the positioning section 292 on the 7 radial shoulder 293a is of somewhat larger dimensions than the clear axial distance between the lever arms 25 of the two lever lamellae 185, while the outer diameter of the undercut 293 approximately corresponds to the clear axial distance between the lever arms 25. A socket 294 for applying an auxiliary tool is incorporated in the end face of the threaded section 291 for the purpose of screwing the positioning screw 29.

If the positioning screw 29 is now screwed into the threaded hole 28, the positioning section 292 penetrates between the lever arms 25 of the two lever lamellae 195 with its frontal truncated cone-shaped head and presses the said lever anus apart from one another. If the truncated cone- shaped head is pushed past the lever arms 25, the said two lever arms 25 snap into the undercut 293, so that they are now enclosed in the undercut 293 at diametrical points between the front radial shoulder 293a and the rear radial shoulder 293b of the said undercut in a captive manner. The two lever arms 25 are now entrained by the radial shoulder 293b or by the radial shoulder 293a, depending upon the direction of rotation of the positioning screw 29, as a result of which the lever arms 25 are pressed radially inwards or radially outwards. Since all the centrifugal wedge profiles 161 in the profiled lamellae 18 are rigidly connected to one another via the knobs 23, the pretensioning force of the centrifugal wedge 16 on the planing knife 14 is reduced and releases the latter, for example for changing purposes, in the first case, that is to say when there is a movement of the lever arms 25 which is directed radially inwards, while in the second case, that is to say when there is a movement of the lever arms 25 which is directed radially outwards, the pre-tensioning force of the centrifugal wedge 16 on the planing knife 14 is augmented. By this means it is possible both to release the planing knife 14 and also to pre-tension it in a defined manner. Because of the axial play of the lever arms 25 which exists in the undercut 293, the increase in the clamping of the knife as a result of centrifugal 8 force is not hindered. Since the centrifugal wedge 16 can be positioned very accurately by the two positioning screws 29, the knife-clamping region is substantially less sensitive to tolerances when the centrifugal wedge profiles 161 are stamped in 1 e profile lamellae 18.

9

Claims

Claims

Planing head for a hand-held planing machine, the said planing head having a cylindrical base body (11) which receives a planing knife (14), which protrudes radially above the base body contour, in at least one longitudinal groove (13) in each case, and having at least one pretensionable clamping or centrifugal wedge (16) which is held on the base body (11) in a movable manner and which is received inside a base body clearance (15) and clamps the planing knife (14) fast on the base body (11) by centrifugal force, characterised in that the position of the centrifugal wedge (16) can be set, for the purpose of altering the pretensioning of the centrifugal wedge (16) or of releasing the planing knife (14), by means of at least one positioning screw (29) which can be screwed radially into the base body (11).
2. Planing head according to claim 1, characterised in that the centrifugal wedge (16) is connected to the base body (11) in a captive manner via a spring (17), that the said base body (11), with the base body clearance (15), the centrifugal wedge (16) and the spring (17), is composed of a plurality of profiled lamellae (18) which are mutually adjacent axially and in which there are stamped clear, in each case, a centrifugal wedge profile and spring profile (161, 17 1) and also a clearance (15 1), and that the centrifugal wedge profiles (16 1) of at least two profiled lamellae (18) located in the region of the positioning screw (29), of which there is at least one, have a lever arm (25), in each case, which protrudes from the centrifugal wedge profile (161) and is in engagement with the said positioning screw (29) and which projects into a blind clearance (24) in the profiled lamella (18), which blind clearance is a continuation of the clearance (15 1).
3. Planing head according to claim 2, characterised in that there are disposed, between profiled lamellae (lever lamellae 185) having two lever arms (25), at least one, and preferably more, profiled lamellae (18) which have, in each case, a perforation (26) which is congruent with the blind clearance (24) in the lever lamellae (185) and is closed on all sides, and that a threaded hole (28) for the positioning screw (29) is cut radially in such a way into the group of mutually adjacent lever lamellae (185) and profiled lamellae (18) (spacer lamellae 184), which profiled lamellae (18) (spacer lamellae 184) have a perforation (26) in each case, that the said threaded hole (28) opens into theblind clarances (24) in the lever lamellae (185) and into the perforations (26) in the spacer lamellae (184).
4. Planing head according to claim 3, characterised in that the mutually adjacent profiled lamellae (18) are packeted and welded to one another after being provided with knobs, and that the threaded hole (28), of which there is at least one, is cut into the finished pack of profiled lamellae.
5. Planing head according to one of claims 2 to 4, characterised in that the positioning screw (29) has a positioning section (292) which is located in front of the threaded section (29 1), referred to the direction of screwing-in, and the outer diameter of which is 11 smaller than the core diameter of the threaded section (29 1), and that there is incorporated in the positioning section (292) an undercut (293) of which the outer diameter, which is reduced in relation to the said positioning section (292), corresponds to the clear axial distance between the lever arms (25) of the two lever lamellae (185).
6. Planing head according to claim 5, characterised in that the depth of undercutting of the undercut (293) is of approximately the same dimensions as the lamella breadth of the lever lamellae (185).
7. Planing head according to claim 5 or 6, characterised in that the axial length of the undercut (293) in the positioning section (292) and that dimension (h) of the lever arm (25) which points in the same direction, are coordinated with one another in such a way that the lever arm (25) lies in the undercut (293) with axial play.
8. Planing head according to one of claims 5 to 7, characterised in that the free front end of the positioning section (292) is bevelled in a truncated cone-shaped manner.
9. Planing head according to one of claims 1 to 8, characterised in that the positioning screw (29), of which there is at least one, is screwed completely into the base body (11) and has a socket (294) for applying an auxiliary tool.

12 A planing head for a hand-held planing machine substantially as herein described with reference to the accompanying drawings.