DE3405979A1 - MILLING MACHINE WITH A WORK HEAD DESIGNED ON THE SHAFTSHIPED INSERT BRACKET - Google Patents

Description

PATENT LAWYERS RW. HEMMEHICH · GEHD-Müller · "D. -GROSSE; F. f-OLLMEIER

in. us.

INGERSOLL Maschinen und Werkzeuge GmbH, 5 909 Burbach

End mill with a shank-shaped insert carrier spherical working head

The invention relates to an end mill with an am
Shank-shaped cutting insert carrier spherically designed working head which has at least one pocket-shaped recess in which at least one after a chip space
Cutting plate is arranged interchangeably.

End mills of this type are used to create fillets. They are used, for example, in the production of
Press dies or when machining aircraft parts, in order to prevent undesired and harmful stress concentrations by means of fillets.

In known end mills of this type, a slot-shaped radial recess is incorporated in the head of the cutting insert carrier, in which a cutting insert is arranged, which with
their main plane both radially with respect to the shaft axis
also runs in the axial direction of the shaft. A cutting edge, which extends over a quarter-circle arc, is formed on the cutting plate. When the end mill rotates around its axis, the cutting edge creates a hemispherical cut.

PATENT LAWYERS ..F.W. HEMMERICH · GtE ^ D'MULLbR -D. GROSSE F.-POLLMEIE

34053.79

The slot-shaped recess and the cutting plate can also extend over the entire head diameter. In In this case, the cutting insert has a second cutting edge sweeping a quarter-circle arc, that of the first Cutting edge is diametrically opposite and describes the same envelope curve as this.

These known end mills have proven to be disadvantageous insofar as the main cutting force acts against the flat cutting insert cross section is directed. The resilience of the cutting inserts is therefore low. In addition, the service life of the cutting edges relatively short. After the cutting edge has become blunt, the plate must be replaced with a new one.

The invention is based on the object of the service life to extend the known end mill of the type mentioned, to increase their resilience and to reuse the To enable cutting inserts when a cutting edge is consumed

To solve this problem, it is proposed according to the invention that that the cutting tip has a convex surface and a base opposite this, both through im Compared to the surface and the base area smaller side surfaces are limited that at least one of the side surfaces is designed as a rake face which intersects the surface and forms with this an arcuate cutting edge and which The rake face also cuts at least one of the adjacent side faces at an acute angle and that the cutting insert with their base on the dome bottom of the pocket-shaped recess rests and so with its larger cross-section in Direction of the cutting force component extends, the arcuate Cutting edge describes a cutting path, which in the projection onto a radial plane running through the shaft axis

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PATENTANWÄLTE F.W''hEMMERICH · G E S D. MÜLL E R -ID. SIZE .-. "F-OLLMEIER

, Kfeisbogen-shaped continuously from the shaft axis to the largest Radius of the cutting path runs. '

Further useful refinements and developments of the invention can be found in claims 29 to 9. i

With the end mill according to the invention, grooving work, i.e. a drilling operation to initiate a milling operation, the greater cutting load of the two Cutting inserts together by the overlapping of their cutting paths is received and wherein at least one of the two cutting plates is designed and arranged so that under By using a negative radial and a positive axial rake angle, maximum bevel cutting performance is achieved.

The end mill according to the invention is characterized by: vibration-free Working out. By dividing the cutting paths on the cutting edges of two opposing cutting inserts a smooth cutting behavior is guaranteed. Finally, it proves to be advantageous that after a cutting edge becomes blunt a cutting insert the other cutting edge can be brought into effect.

An exemplary embodiment of the invention is explained in more detail with the aid of the drawing. Show it

Figure 1 is a plan view of the end mill with a spherical working head,

Figure 2 is a side view of the end mill with the two Inserts with hemispherical contact arc and with a third insert for milling one essentially cylindrical and provided with curved cutting edges for a hemispherical section of the two Tangential cutting inserts,

PATENT LAWYERS F.W. HEMMERICH · GE ^ D- iviP LLh R-D. GROSSE-fVPOLLMEIER

Figure 3 is a profile diagram of the cutting path, which is placed in the radial plane to the shaft axis and which the. Assignment of each cutting insert to the combined total cutting path can be recognized and

FIG. 4 is an enlarged end view (FIG. 4a), rear view (FIG. 4b), top view (FIG. 4c) and front view (Fig. 4d) of the adjustable and curved cutting edges having cutting plate.

The details of the actual milling tool are explained below "with the aid of the various views shown with FIGS. 4a to 4d described. The edgewise cutting insert 10 is a block made of a suitable material is made. It is essentially a flat and even block with six sides that has two major faces, namely a flat and planar base surface 12 and a surface 14 opposite this surface 12 which is convex. A bore 16 which passes through the surfaces 12 and 14 and which has a countersink on the convex surface 14 takes a fastening element, not shown, with which the cutting tip 10 is in a pocket-shaped recess of the insert carrier 18 (Fig. 1 and 2) is attached.

The convex surface 14 of the insert is shown in FIG Embodiment made cylindrical. It is limited by four smaller side surfaces. With the preferred one In the exemplary embodiment, two of these smaller side surfaces are the rake faces 20, which have arisen as a result that they are intersected by converging planes in such a way that to a bisecting plane perpendicular to the axis of the cylindrical Surface 14 of the cutting plate (FIG. 4a) creates angles of the same size. The convex surface 10 becomes pointed in one

PATENTANWÄLTE FW HEMMERICH · GE'XD.IVTCLLER · 1ϋ. G ^- ROSSE Γ .'- POLLMEIER -

Cut an angle / which then creates the curved cutting edge 28. The other smaller side surfaces 24 act they are parallel secondary surfaces to the base surface of the cutting insert, but at an angle to the parallel edges 26 of the planar ones Base surface 12, which are formed by the converging rake faces 20. For this reason, the cutting insert has essentially a rhomboid shape (Fig. 4a). The diagonally opposite corners in the transition from the rake faces 20 to the secondary surfaces 24 adjacent to them each acute and obtuse angled.

The surface 14 and the imaginary and intended cutting path of the end mill have the same radius. Because now in the plane of this surface, the two identical rake faces 20 of the insert are in fact elliptical have, the profile of the cutting path generated with such cutting inserts depends on the orientation of the cutting edge and especially from the protrusion of the convex surface along a rotational path in a plane through the axis of rotation of the Milling tool. Figures 1 and 2 show this geometry.

In the case of the end mill according to the invention, the hemispherical Cutting path generated by the two cutting tips 10 and 10 ', which are designed according to Figure 4 and which are at the tip of the shaft-shaped cutting insert carrier 18 are arranged such that they generate a contact arc and thereby each other Let overlapping cutting paths arise, namely projected onto a radial plane through the shaft axis 30 of the cutting insert carrier 18 as a circular quadrant 32 to the axis of rotation of the point according to FIG. 3 on the largest radius of this axis.

As can be seen in FIGS. 1 and 2, the cutting insert 10 is arranged in such a way that the rake faces 20 are essentially are aligned radially to the insert carrier 18, wherein the

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PATENT LAWYERS F.W. HEMMERICH · GEHDMCLLEf! -; D..6ROS5E ■. Γ: POLLMEIER

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outermost end of the cutting edge '28 lies at the corner with the acute angle of the cutting plate on the axis of rotation. Figure 1 clearly shows what "the purpose of the acute-angled corner." Has; namely, it forms a centering point that enables the workpiece to be pierced and at the same time a free space behind the cutting tip. For the same reason, the contact surface of the pocket-shaped recess, which has to accommodate the cutting insert IO, designed such that the opposite and trailing edge of it Cutting insert, i.e. the reserve cutting edge, behind that generated by the working cutting edge during the rotary movement hemispherical outline is held.

The need for a rear clearance angle to prevent the insert from entering the freshly milled surface of the Workpiece "cuts in" and the desire that. Direction of the cutting forces acting on the insert carrier as follows Keeping it tangential as far as possible limits the dimensions of the insert in the axial direction of its cylindrical surface. In the case of end mills with a very small diameter, the limited space even makes it necessary that you have to forego the adjustability in favor of a solid attachment of a narrow single-edged cutting plate.

The second cutting insert 10 '- this corresponds in its Vorm of the cutting tip 10 and can be exchanged for this is arranged and aligned in such a way that the hemispherical Cutting path of larger radius on the axis of rotation of the milling cutter along the circular quadrant shown with FIG. 3 32 runs downwards, but ends just before the tip. Here, too, FIG. 1 shows that the cutting edge 10 'with its cutting edge 28 'of the cutting edge 28 which is arranged almost opposite the cutting tip 10, but with a substantially different orientation. The contact surface for the cutting insert

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PATENTANWÄLTE .PW "hEMMERICH · GE '.'', D. MULLCR --Ü. SftÖSoE Γ. Ί-OLLMEIER *

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10 '■' certain pocket-shaped recess is designed so that the cutting tip 10 'is held by it in such a way that it has a negative radial rake angle and a positive axial rake angle and thus experiences the optimal alignment for the bevel cutting, from which the greater part of the cutting load the cutting tip 10 'results. The advantages of such a bevel cut arrangement are already known (US Pat. No. 2,186,417).

A third cutting tip 36, which has a straight cutting edge / is used to make the cutting path -cylindrical tangential to extend the circular quadrant projection 32 of the overlapping cutting paths of the two cutting inserts 10 and 10 '. "The cutting tip 10" preferably also has a rhomboid shape Shape that ensures good resistance of the cutting edge, albeit arranged with a positive axial rake angle. The third cutting tip 36 is arranged similarly to ensure that its trailing reserve cutting edge does not protrude into the cut. All three cutting inserts are still arranged and aligned in such a way that their effective cutting edges opposite and irregularly shaped chip spaces 38, 40 and 42 at an angle to the axis of rotation are incorporated into the body of the insert carrier 18 that the chips when drilling even when a feed takes place transversely to the cutter axis, can flow upwards.

It can now be seen from the description given so far that the individual cutting inserts 10 and 10 'and their alignment on the cutting insert carrier 18 are the cause that the cutting edges 28 and 28 'are not an exact create a circular cutting path in the radial plane, but rather one that is somewhat elliptical with a somewhat narrower one Radius of curvature deviates from the circular path. However, this deviation is very small and has no significant influence on the processing of contours, for example during production

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PATENTANWÄLTE FW HEMMERiCH ■ GEfIDzMeLLER -: D _v oROS5E; r ".TOLLMEIER

of dies or in the production of grooves on workpieces. It is also clear that the cutting edge of the "cylindrical" cutting plate 36, which has an axial and straight rake angle, sweeps over a cutting path that is not exactly cylindrical, but rather hyperbolic. Here, too, the deviation from an exactly straight surface tangent to the fillet ^s to be generated has no effect in most cases and can be achieved with a slightly convex or helical cutting edge on the third insert for those cases in which an almost flat surface is required on the workpiece. be resolved.

FIG. 3 shows a sketch of the projection of the aforementioned various cutting paths on a radial plane that extends extends through the center line of the axis of rotation, i.e. through the shaft axis 30 of the insert carrier 18. FIG 3 is just a sketch and not an exact ortographic projection. The cutting inserts 10, 10 'and 36 are only outlined shown on a radial plane of its cutting insert carrier 18. It is important to what extent the respective cutting inserts 10 and 10 ″ the circular quadrants 32 of their combined cutting paths claim for yourself. The superimposing or overlapping of these cutting paths, which it enables the two cutting inserts to absorb the greater cutting force or cutting load. To make things easier the part that is only milled by the cutting insert 10 is marked with "A", the overlapping part with "B" and the Part that is only milled by the cutting insert 10 ', with "C".

The cutting load in zone "A" during ordinary transverse milling is different from plunge milling, i.e. for Drilling, very little during the chip thinning effect due to the bevel of the cutting edge. In contrast, in zone "C" which is only assigned to the cutting tip 10 ', the peripheral chip thinning due to the cross feed is very drastic, while

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PATENT LAWYERS F.W. HEMMERICH ■ GERD MULLEG ■ C. GPOSSE · »- ·. PQLllMEIER

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chip thinning due to the bevel is negligible is small. The largest amount of material removal occurs in the overlap zone "B", with the one almost diametrically opposite one another Arrangement of the cutting tip 10 and the cutting tip 10 '. These cutting inserts share in the receptacle of the heavy ones Load. Each picks up a new chip that is only half as thick / as is the case with a single milling cutter, the machined the same sector at the same feed rate.

The end mill according to the invention with a spherical working head is a high-performance tool that can also handle large cutting loads can withstand because its inserts work on edge, i.e. because they essentially reduce the cutting load Record and transfer over the larger dimension.

In addition, they are designed in such a way that they cut their paths with a strong overlap and thus enable a longer tool life.

The new cutting inserts can be used interchangeably in any working position, i.e. as a tip cutting insert 10 or as a cutting insert 10 '. Both cutting inserts can be rotated and thus used twice.

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Claims (9)

PATENT LAWYERS F.W. HEMMERICH · GERi; MÖLLER 'CX .GROSSE "· F / .POLLMEIER * \ 1..JfVw. ϋυ ·! ^v INGERSOLL Maschinen und Werkzeuge GmbH, 5909 Burbach Claims 1. ; End mill with an on the sheep-tförinigen insert carrier spherical working head, which has at least one pocket-shaped recess, in the connection at least one cutting insert is arranged on a chip space in an exchangeable • manner, '.' ■ '•'J'd, se d u., R ch characterized in that the Schneldpaltte (10, 10 ') has a convex surface (14) and a base area (12) opposite this, both by in comparison smaller side surfaces (20, 24) are limited to the surface and to the base, that at least one of the side faces as a rake face (20) is formed which intersects the convex surface (14) and forms with this an arcuate cutting edge and the rake face (20) further intersects at least one of the adjacent side faces (24) at an acute angle and that the cutting plate (10, 10 ') rests with its base (12) on the bottom of the pocket-shaped recess and thus extends with its largest cross-section in the direction of the cutting edge component, the arcuate The cutting edge (28, 28 ') describes a cutting path which, in the projection onto a through the shaft axis (30) Radial plane in the shape of a circular arc continuously from the shaft axis (30) to the largest radius of the cutting path runs (Fig. 3). PATENT LAWYERS. F.W. HEMMERICH · GE - ^. Cr "MuLLbR · Π.! 2.ROSSE" F.TOLLMEIER 2. End mill according to claim 1, characterized in z-e i-chnet, that two of the side surfaces of a cutting insert (10, 10 ') are designed as rake faces (20). 3. End mill according to claim 1 or 2, characterized in that at least two secondary surfaces (24) on the cutting plate forming adjacent side surfaces are provided and the cutting tip (10, 10 ") is essentially rhomboid Owns shape. 4. End mill according to one of claims 1 to 3, characterized in that that the convex surface (14) of the cutting tip (10, 10 ') is cylindrical. 5. End mill according to at least one of claims 1 to 4, characterized in that that the two rake faces (20) running at an acute angle to the surface (14) and in one to the axis of the cylindrical Surface (14) vertical plane in one line and at the same angle (cO intersect with the vertical plane. 6. End mill according to at least one of claims 1 to 5, characterized in that that the base (12) is flat and aligned parallel to the axis of the cylindrical surface (14) and the secondary surfaces (24) run parallel to one another and perpendicular to the base surface (12). 7. End mill according to at least one of claims 1 to 6, characterized in that that two cutting plates (10, 10 ') are provided, the effective cutting edges (28, 28') of which in relation to the shaft axis PATENTANWÄLTE FW HEMMERICH · GElU) "&AüLLtP-'P.-GfiOSS £ · * F. ¹ POLLMEIER - ^ 3 ~ - , 3- (30) are opposite one another, the effective cutting edge (28) of one cutting insert (10) "extending from the end of the cutting insert carrier (18) on the working head side over more than half of the cutting path, while the effective cutting edge (28 ') of the second cutting insert ( 10 ¹ ) from the largest radius of the cutting path also extends over more than half of the cutting path. 8. End mill according to at least one of ^ claims 1 to 7, characterized in that the second cutting insert (1O ¹ ) is arranged with a negative radial rake angle and a positive axial rake angle in the pocket-shaped recess. 9. End mill according to at least one of claims 1 to 8, characterized in that that another cutting plate (36) in a further recess in the shaft of the cutting plate carrier (18) in such a way is arranged that it describes a cutting path which is cylindrical to the shaft axis (30) and to the cutting path of the two cutting plates (10, 10 ') with circular arc-shaped cutting edges (28, 28') runs tangentially.