DE10350851A1 - Router bit in particular for woodworking, comprising individually adjustable blades - Google Patents

Abstract

The router head (1) is provided with several recesses (3) around its outer surface suitable for the insertion of cutting blades (2) exceeding the outer contours of the tool (1) with their pointed cutting edges (4). Each of the blades (2) can be radial or tangential adjusted, depending on their specific purpose. The blades (2) can be secured with a screw, a wedge, acting on the blade (2) by the centrifugal forces, or with a rotary locking element. The adjustment can be performed hydraulically or with other suitable methods.

Description

The The invention relates to a milling tool with a plurality of axially or radially outwardly open Receiving recordings carrying body, wherein in each recording one with its cutting edge on the support body protruding Knife is clamped, in which the knife against a formed in the receptacle stop surface is pressed.

One such milling tool is known for example from WO 96/36452 A1. In this milling tool It is a profile cutter head, where each knife with a knife carrier is connected by means of screws against a stop surface of the him receiving receiving the support body is stretched. The knife carrier has a in cross-section T-shaped Walk up, in a corresponding, over the axial length of the supporting body trained T-shaped Groove is inserted. If the knife is reground, its Dikke reduced. The formation of the T-slot and the knife carrier allowed it, that the circle diameter of the knife edge also after the Regrinding unchanged is maintained, since the knife holder parallel to the free surface of the Mes serprofils is displaced until the breast surface of the Knife back at the stop surface in the supporting body is applied.

by virtue of production-related tolerances have multi-bladed milling tools a round or axial runout on the cutting on, depending on Tooling range is in the range of 0.02 to 0.07 mm. tools, where the cutting edges are ground in the tool when installed will reach a value in the lower range. For tools with interchangeable cutting edges, the value is in the upper range.

conditioned This error causes the cutting edges of a tool to produce a different chip thickness or a different material removal. In extreme cases, individual cutting edges are not involved in the cutting process at all.

• a. Die Spanbildung an jeder Schneide ist unterschiedlich. Während dünnere Späne biegsam sind und sich eher wie ein Fließspan verhalten, sind dickere Späne biegesteifer und neigen zur Vorspaltung in Faserrichtung, was zur Verschlechterung der bearbeiteten Oberfläche in Form von Ausrissen und Absplitterungen führt. Der dickste Span bestimmt die Vorschubgeschwindigkeit. Deshalb muss ein Werkzeug mit Rundlauffehler (radialwirkende Schneiden) oder Planlauffehler (axialwirkende Schneiden) bei kleineren Vorschubgeschwindigkeiten betrieben werden, als dasselbe Werkzeug, bei dem alle Schneiden gleichmäßig am Zerspanungsprozeß ohne Rundlauf- oder Planlauffehler – beteiligt sind. Bei gegebener Vorschubgeschwindigkeit ließen sich also mit einem idealen Werkzeug ohne Rundlauf- oder Planlauffehler die Schneidenanzahl und damit insbesondere die laufenden Kosten für Nachschärfen und Ersatzschneiden verringern.
• b. Neben dem Einfluss auf den Spanbildungsprozeß wirkt sich der Rundlauf- oder Planlauffehler eines Werkzeuges auch auf die sogenannte kinematische Rauheit der bearbeiteten Oberfläche aus. Unter kinematischer Rauheit wird die Abbildung der Bearbeitungsspuren der einzelnen Schneideneingriffe auf der Oberfläche verstanden, die durch die Relativbewegung zwischen Werkzeug und Werkstück entstehen. Nur bei einem idealen Werkzeug ohne Rundlauf- oder Planlauffehler bilden sich alle Schneideneingriffe gleichmäßig auf der Oberfläche ab. Je größer der Rundlauf- oder Planlauffehler wird, desto weniger Schneideneingriffe sind auf der Oberfläche sichtbar. In der Regel ist nur eine einzige Schneide, nämlich die mit dem größten Wirkdurchmesser oberflächenbestimmend. Wenn es auf ein gleichmäßiges Bild der sichtbaren Schneideneingriffe auf der Oberfläche, die sogenannten Messerschläge, als Qualitätskriterium ankommt, kann ein mehrschneidiges Werkzeug nur mit der Vorschubgeschwindigkeit eines einschneidigen Werkzeuges betrieben werden. Bei einer Drehzahl von 6000 min^–1 liegt die Grenze für die Vorschubgeschwindigkeit eines konventionellen Werkzeuges etwa bei 20 m/min. Bei sehr hohen Ansprüchen an die Oberflächengüte liegt die Grenze für die Vorschubgeschwindigkeit etwa bei 10 m/min.

When machining wood and wood-based materials, this results in the following machining disadvantages:

• a. The chip formation at each cutting edge is different. While thinner chips are more flexible and behave more like a smooth chip, thicker chips are more rigid and prone to fission in the fiber direction, resulting in deterioration of the machined surface in the form of tears and chipping. The thickest chip determines the feed rate. For this reason, a tool with concentricity error (radially acting cutting edges) or axial misalignment (axially acting cutting edges) must be operated at lower feed rates than the same tool, in which all cutting edges are involved evenly in the machining process without concentricity or axial runout. For a given feed speed, it would thus be possible to reduce the number of cutting edges and thus in particular the running costs for re-sharpening and replacement cutting edges with an ideal tool without concentricity or axial runout.
• b. In addition to the influence on the chip formation process, the concentricity or runout error of a tool also has an effect on the so-called kinematic roughness of the machined surface. Under kinematic roughness is the mapping of the machining marks of the individual cutting interventions on the surface understood, resulting from the relative movement between the tool and the workpiece. Only with an ideal tool without concentricity or run-out errors, all cutting operations are evenly formed on the surface. The greater the concentricity or runout error, the less cutting operations are visible on the surface. As a rule, only a single cutting edge, namely the surface with the largest effective diameter. When it comes to a uniform image of the visible cutting operations on the surface, the so-called knife strokes, as a quality criterion, a multi-bladed tool can only be operated with the feed rate of a single-edged tool. At a speed of 6000 min ^-1, the limit of the feed speed of a conventional tool is about 20 m / min. For very high demands on the surface quality, the limit for the feed rate is about 10 m / min.

The US 2,652,749 discloses a milling tool in which the blades are hydraulically clamped. For this purpose, the hydraulic pressure acts on an elastic hose which cooperates with a pressure piece acting on the knife back and a wedge-shaped clamping jaws arranged in the recess. The hydraulic medium is passed through a central, arranged in the support body axial bore and leading from this radially to the flexible hoses pressure lines for clamping the jaws. In each radial line, a valve is used, via which the clamping systems can be decoupled from each other. Thus, the pressure for each clamping system can be increased or reduced. The circle diameter of the cutters can be set individually by reducing the respective pressure and guiding the cutter head past a set-up tool. The knife will fall radially into the recess as it passes through the setup tool postponed. Then the pressure on the clamping jaws is increased again and the knife firmly clamped. In this way, each individual knife is adjusted to the circle of flight.

There the concentricity or axial runout error of a tool at operating speed not only depends on the accuracy generated in the static state, but by balancing quality and vibrations are impaired provides a highly accurate, hydro-tensioned tool, its cutting on the machine at operating speed be dressed (joints) according to the state of the art the Ideal condition as regards the uniformity the cutting interventions on the machined surface and so that the achievable feed rates. This Technique is on the one hand very expensive, especially if profile tools have to be trained because this special technical requirements necessary and on the other hand, by dressing the clearance angle becomes immediate at the cutting edge in an area less tenths of a millimeter to 0 °, causing the friction increases becomes.

From Based on this problem, the above-described Tool be improved so that its concentricity or Planlauferigenschaften with those at operating speed averaged (Joined) tools is comparable.

to Troubleshooting is a generic milling tool characterized in that the axial or radial position of the cutting edge every single, tight knife is finely adjustable.

By the fine adjustment can be set the circle diameter of each cutting edge individually, so that after the clamping of the knives the production-related Concentricity inaccuracies can be eliminated. It is advantageous here it, if the fine adjustment is independent of the fixed tension of the blades.

For this the fine adjustment is preferably possible only in the micrometer range. On In any case, however, the accuracy of the fine adjustment in the micrometer range.

The Fine adjustment can be done mechanically by means of at least one each knife associated screw or by means of an eccentric or a wedge respectively.

Especially it is advantageous if the fine adjustment takes place hydraulically, because here are good power gains possible are. The hydraulics is also a sensitive, low-friction Setting possible without stick-slip effect.

A Radial fine adjustment of the circle diameter of the knife can done by a radial or tangential displacement of the knife.

Preferably each knife is fixed to a knife carrier, which in the Recording by means of at least one clamping screw is clamped and a cross-sectionally T-shaped Foot has, whose pointing in tangential direction transverse part with two arms in opposite, engages provided in the receptacle axial grooves. Such training is of the generic milling tool known.

For the hydraulic Adjustment is preferably at least one bore opening into the base of the receptacle provided in which a displaceable by means of the hydraulic medium Piston is arranged.

Especially It is advantageous if the mechanical forces for fine adjustment, ie the wedge, the eccentric or the at least one screw or the Hydraulic piston on the radially inward surface of the foot attack.

If the fine adjustment by means of screw force or hydraulics (open System with grease gun or closed system with screw and Piston), in particular preferably a plurality in axial direction of spaced screws or hydraulic piston intended. This is about the axial length a uniform, in the Micron range lying displacement of the knife, and thus one adjustment accuracy possible in the micrometer range. Around To compensate for production-related tolerances, is the adjustment range preferably at a few hundredths of a millimeter.

With Help a drawing to embodiments of the invention below explained become. It shows:

1 A schematic representation of the fine adjustment,

2 A further basic representation of the fine adjustment,

3 The axial view of a tool according to a first embodiment,

4 - The section along the line IV-IV after 3 .

5 - the axial view of a tool according to a second embodiment,

6 The axial view of a tool according to a third embodiment,

7 - The section along the line VII-VII according to 6 .

8th The axial view of a tool according to a fourth embodiment,

9 The axial view of a tool according to a fifth embodiment,

10 The axial view of a tool according to a sixth embodiment,

11 - The section along the line XI-XI after 9 .

12 - The section along the line XII-XII after 10 ,

1 and 2 show the principal possibility, the circle diameter of the cutting edge 4 of the knife 2 set by the knife according to the arrow P ₁ in the radial direction or according to the arrow P ₂ in the tangential direction in the recording 3 is moved. The dashed lines of the arrangement (in the drawing above) indicate the smallest adjustable circle diameter F _min , the solid lines the maximum circle diameter F _max . As if from a comparison of 1 and 2 can be seen, the tangential adjustment has the advantage that the adjustment effect to a much lesser extent on the change in diameter. The disadvantage here, however, that the pitch of the blades to each other and chip and clearance angle of the blades are changed, which means a profile distortion in profile cutting. This disadvantage does not affect the radial adjustment. For this, it must be done very sensitively, since a positioning movement is not understated, but expressed directly in a change in diameter.

At the in 3 The embodiment shown, the knives 2 about one in the recording 3 arranged wedge 5 tensioned by centrifugal force by the force acting on the back of the knife wedge 5 is moved radially outward by the rotational movement of the tool, causing the knife 2 with his breast surface 2 ' against in the recording 3 trained stop surface 3 ' is pressed. Below the wedge 5 is radially further inside an axial bore 6 , from the parallel spaced radial bores 7 into the ground 8th the recording 3 to lead. In the radial bores 7 are on the bottom of the wedge 5 acting pistons 9 used. Is about the the axial bore 6 closing nipple 10 a medium, for example fat pressed, become the pistons 9 pressed radially outwards and act on the underside of the wedge 5 a, whereby this further pressed radially outward, so that the recording 3 expands and the knife 2 performs a lying in the micrometer range pivoting movement in the direction of arrow P ₃ , whereby the circle diameter changes.

The adjustment of the cutting edge 4 of the knife 2 is done by stationary a measuring device (for example, a probe or a measuring optics) is installed, against which each knife 2 with the cutting edge 4 created and measured the diameter or then fine tuned.

In the particularly preferred embodiment according to 5 a hydrostatic system is provided. The knife 2 is with a knife carrier 11 cohesively connected, for example, soldered. The knife carrier 11 has a cross-sectionally T-shaped foot 12 on, whose both arms 12 ' . 12 '' in opposite axial grooves 13 in the supporting body 1 are guided. The knife 2 gets over the knife carrier 11 in the recording 3 tightened by the screw 18 is screwed in, over a wedge 19 on the back of the knife carrier 11 acts, which is thereby shifted in the tangential direction P ₅ . Below the foot 12 is at least one or more axially spaced pistons 14 (see 4 ), which from radially inward to radially outward on the knife 2 Act. For this purpose, non-designated radial bores are provided, in which the piston 14 are used. On the peripheral side in the supporting body 1 introduced holes 15 cut those into the ground 8th the recordings 3 reaching holes 26 , The holes 15 . 26 are filled with a hydraulic medium, preferably fat. By turning the screws 16 will the pressure in the holes 15 increased, causing the piston 14 on the bottom of the foot 12 of the knife carrier 11 act, so that this slightly pivoted in the direction of arrow P ₄ .

At the in 6 illustrated embodiment acts on the underside of the foot 12 of the knife carrier 11 a wedge 20 (see 7 ). The wedge 20 can over the screw 21 be moved in the axial direction, so that the knife carrier 11 a corresponding lying in the micrometer range pivoting movement takes place. The same pivot movement of the knife carrier 11 can through the in 8th shown eccentric 22 be initiated.

In the in the 9 and 11 embodiment shown are the hydrostatic systems for the individual cutting blades 2 via a ring-shaped connecting channel 25 With connected to each other. The connection channel 25 can via valves 23 optionally open or closed. When open, it can be used to preload all pistons 14 the same pressure is applied. If all valves then 23 closed, every knife can 2 , or each knife carrier 11 to be fine tuned by individual pressure.

In the in the 10 and 12 illustrated embodiment, the axial runout error of the knife 2 by a in the support body 1 used in the axial direction screw 24 set.

In the embodiments described above, the movement that the knife carrier finds 11 and with it the knife 2 accomplishes, by elastic deformation of knife foot 12 and tool carrier 1 instead of. After pressure release, the deformation is reversible. As a result, the production tolerance-related concentricity error of a tool in the range of 100ths of a millimeter can be eliminated or reduced to a range of less than 5 μm.

If on the knife carrier 11 or the knife foot 12 two axially spaced and engaging in the outer region piston 14 It is also possible to adjust the angular position of the knife with an adjustment accuracy in the micrometer range 2 to influence.

1

supporting body

2

knife

2 '

chest area

3

admission

3 '

stop surface

4

cutting edge

5

wedge

6

axial bore

7

radial bore

8th

reason

9

piston

10

grease nipple

11

blade carrier

12

foot

12 '

poor

12 ''

poor

13

groove

14

piston

15

drilling

16

screw

17

piston

18

screw

19

wedge

20

wedge

21

screw

22

eccentric

23

valves

24

screw

25

connecting channel

26

drilling

Claims (16)

Milling tool with a plurality of axially or radially outwardly open receptacles ( 3 ) having supporting body ( 1 ), whereby in each photograph ( 3 ) with its cutting edge ( 4 ) over the support body ( 1 ) protruding knife ( 2 ) is tightened by the knife ( 2 ) against one in the recording ( 3 ) formed stop surface ( 3 ' Is pressed), characterized net gekennzeich that the axial or radial position of the cutting edge ( 4 ) of each single clamped knife ( 2 ) is finely adjustable. milling tool according to claim 1, characterized in that the fine adjustment possible in the micrometer range is. Milling tool according to claim 1 or 2, characterized in that the fine adjustment by means of at least one each knife ( 2 ) associated screw ( 24 ) he follows. Milling tool according to claim 1 or 2, characterized in that the fine adjustment by means of an eccentric ( 22 ) or a wedge ( 20 ) he follows. milling tool according to claim 1 or 2, characterized in that the fine adjustment hydraulically. Milling tool according to one or more of the preceding claims, characterized in that the radial fine adjustment by a radial or tangential displacement of the blade ( 2 ) he follows. Milling tool according to one or more of the preceding claims, characterized in that each knife ( 2 ) on a knife carrier ( 11 ), which is in the receptacle ( 3 ) by means of at least one clamping screw ( 18 ) and a cross-sectionally T-shaped foot ( 12 ), whose tangentially pointing transversal bar with both arms ( 12 ' . 12 '' ) in the opposite one in the receptacle ( 3 ) provided axial grooves ( 13 ) intervenes. Milling tool according to claims 4 and 7, characterized in that the wedge ( 20 ) or the eccentric ( 22 ) on the radially inward surface of the foot ( 12 ) acts. Milling tool according to claims 3 and 7, as characterized in that the at least one screw ( 24 ) on the radially inwardly directed surface of the foot ( 12 ) attacks. Milling tool according to claim 9, characterized in that a plurality of axially spaced apart screws ( 24 ) are provided. Milling tool according to claim 5 or 7, characterized by at least one in the reason ( 8th ) of the recording ( 3 ) opening bore ( 7 . 26 ), in which a displaceable by means of a hydraulic medium piston ( 9 . 14 ) is arranged. Milling tool according to claim 11, characterized by a plurality of axially spaced-apart, in the receptacle ( 3 ) drilling ( 7 . 26 ) with an axial bore ( 6 ) communicate. Milling tool according to claim 11 or 12, characterized in that the piston or pistons ( 9 . 14 ) on the radially inward surface of the foot ( 1 ) acts. Milling tool according to one or more of the preceding claims, characterized in that each knife ( 2 ) is associated with a hydrostatic system, wherein the hydrostatic systems via at least one connecting channel ( 25 ) and in the at least one connecting channel ( 25 ) a valve ( 23 ) is provided. Milling tool according to claim 1, characterized in that the device for the fine adjustment of the device for the fixed tension of the knife ( 2 ) is executed independently. Milling tool according to one or more of the preceding claims, characterized in that the fine adjustment via elastic deformation in the supporting body ( 1 ) and / or the knife carrier ( 11 ) he follows.