Reamer comprising a cutting plate

The invention relates to a reamer consisting of a shank with a clamping element on one side thereof and a working area located on its opposite side in the axial direction, with at least one replaceable tool element and at least one clamping body therefor tool element being a cutting insert made of a hard metal alloy up to 25 mm long, up to 8 mm wide and high or about 4 mm thick, it is mainly made as an indexable indexable insert, which cutting insert forms along the cross section a profile with an even contact surface, showing each time at least one main cutting edge and one auxiliary cutting edge that form the face of the blade, one rake surface and one concave pressure surface in general for each fastener, and in the top view, the auxiliary cutting edge used for cutting, generally outlined parallel to the shank axis, which has in the feed direction of the reamer at its end side an angled cutting part with at least one main cutting edge.

[0002] A number of indexable indexable inserts for turning, peeling, planing, milling, drilling and the like are known in the machining technique, which in the tool are to exhibit the highest possible cutting efficiency with favorable chip production and removal from the cutting area. In the first place, as previously mentioned, the cutting efficiency is set as the target quantity, the substantially coarse chips obtained being reformed by means of the possibility of rolling and breaking by cutting inserts, possibly being broken and / or prepared for rapid deliberate removal.

[0003] During accurate boring, the holes provided with the machining allowance are enlarged to highly precise small sizes to achieve or secure the exact dimension of the structural elements to be fitted.

[0004] Reamers are tools for smooth surface machining of holes, wherein the holes can be made in the form of blind holes or in the form of a through hole, and are usually made of a clamping element and a tool part with at least one cutting plate. Cutting inserts have at least one major cutting edge, which may consist of several parts, and at least one auxiliary cutting edge.

[0005] During smooth machining of the surface, especially during fine boring, there are naturally significantly different conditions compared to the performance-oriented chip collection from machined parts in terms of the preferably applied insert form as well as chip production, but the type, as well as the form and flow of fine chips, also when boring an exact hole, has a significant impact on the quality of the surface of the machined hole and the tool life.

[0006] Reamers according to the state of the art are equipped with variously arranged main and auxiliary cutting edges.

[0007] From EP 1 160 042 for example, according to the preamble of claim 1 or 2, a rake surface is known which, opposite to the cutting, in the area of ​​the main cutting edge and the secondary cutting edge is constantly limited by means of a coiler and chip breaker, wherein the coiler and chip breaker in the area of ​​the main cutting edge increases or exhibits a decreasing distance from the main cutting edge. The view is expressed that the main cutting edge is for pre-treatment, while the secondary cutting edge is for smoothing, and the chips collected from the cutting edges mainly touch the straight retractor and chip breaker and are broken, as well as receive an impulse to move in one direction, which is given by the slope of the retractor and chip breaker.

[0008] The cutting reamer for the smooth machining of metal workpieces with the help of the main and auxiliary cutting edges, as well as the leading surface reaching these cutting edges as well as the bounding reel and chip breaker are disclosed in EP 0 631 834 B1. To obtain short chips during smooth machining, it has been provided that the retractor and chip breaker at the cutting edge tip point have a height point from which the retractor and chip breaker fall each time in the area of ​​the main cutting edge, and in the area of ​​the auxiliary cutting edge is made parallel to her or also falls.

[0009] All cutting inserts for the reamer according to the prior art, however, have the common disadvantage that the even rake surfaces of the main and auxiliary cutting edges, opposite the cutting edges, contain retractors and chip breakers that can collect chips especially in the area of ​​the auxiliary cutting edge, so that during increased chip reception due to chip accumulation, higher coefficients of friction with heating and lower surface quality during smooth machining of the workpiece can occur.

[0010] The present invention overcomes the disadvantages and aims to create a reamer, which was named at the beginning, in which a hard metal cutting insert in the area of ​​the main cutting edge ensures the formation of short chips, and in the area of ​​the secondary cutting edge, in which mainly surface smoothing the machined hole runs with extremely small collection of fine chips, prevents chip accumulation.

[0011] This object is achieved according to claim 1 due to the fact that the rake surface of the cutting insert at a distance of at least 0.02 mm from the cutting edge on the end side in the area of ​​the cutting part has at least partially at least 0.01 mm increased roughness depth .

[0012] The advantages achieved thanks to the invention are seen in the main outline in that only in the cutting part at a distance from the cutting edge the rake surface has an increased roughness depth, whereby the chips that fall off due to the increased exact friction of the hole are compacted and therefore contribute to start chip breaking. Broken chips can easily leave the machined hole because there is no increased surface roughness in the area of ​​the secondary cutting edge.

[0013] The above-mentioned object is achieved according to the invention according to claim 2 also due to the fact that the cutting insert in its rake surface at a distance of at least 0.02 mm from the main cutting edge on the end side in the area of ​​the cutting part has at least one depression on shavings.

[0014] Surprisingly, chips can be obtained during smooth machining with the help of a cutting plate broken into small pieces, which can be removed without hindrance, if, according to the invention, only in the cutting part, i.e. in the area of ​​the main cutting edge, in which, when drilling the exact hole, or fine machining of the hole, most chips are formed, which are moved to the rake surface of the chip cavity at a distance to the cutting edge. On the one hand, the area of ​​the rake surface before the chip recess acts through the enlarged blade angle, extending the tool life of the cutting edge tool, on the other hand, the visibly produced chips when picked up by the workpiece are kneaded and immediately after this inlet into the chip recess they are pulled out to the surface away from the tool and are broken into short pieces. In the area of ​​the uneven rake surface of the secondary cutting edge, the smallest chips with broken coarser chips that form at the main cutting edge can be picked up by the workpiece and erected there without hindrance. In this way, the reamer according to the invention can also counteract chip accumulation in the area of ​​the secondary cutting edge with an increased amount of chips, which leads to an improvement in the surface of the machined hole and to an increase in the tool life.

[0015] According to a preferred embodiment of the invention, thanks to which a particularly shaped and uniform surface smoothness of the machined hole can be achieved during smooth machining by means of accurate reaming of the hole, the cutting insert has a cutting part with at least one cutting edge with an angle of 10 ° to 80 ° to the longitudinal axis of the shank with a length of at most 4 mm, wherein the transition of the main cutting edge to the axially parallel area of ​​the auxiliary cutting edge is made gradually, relatively polygonously or rounded.

[0016] In a further embodiment of the invention it may be particularly advantageous for long chipping materials when the cutting part of the cutting insert has at least two main cutting edges with different angles relative to the shank axis and that the chip cavity on the rake face of the cutting insert perpendicular to the main cutting edges each time has a different width, in particular in the area where the cutting edges pass in the cutting part, the width of the chip recess narrows in some places, especially to less than 0.15 mm.

[0017] Implementation of a cutting insert with a major cutting edge in two parts with different angles relative to the shank axis induces an overlapping tension in the axis direction in the chips falling off and contributes to the formation of smaller chips. The benefits of chip breaking supported by the action of the varying width of the chip pit have not yet been scientifically explained, however it could depend on the induction of further tension in the chips taken from the main cutting edge.

[0018] As provided in accordance with the invention, if the cutting insert has a chip recess that is at a distance of at least 0.02 mm from the main cutting edge, it is made perpendicular to it and is recessed in the form of a wedge in the rake surface, and the recess surface, which also has an increased roughness depth, is rounded on the other hand, most preferably it is rounded with a radius of about 0.05 mm, is retracted to the rake surface, in this way only extremely short chip lengths with high safety in the area of ​​the cutting part are achieved. The shavings get from the workpiece to the rake surface of the cutting insert and are kneaded in the outer area. During the transition to the chip cavity, in particular because of their wedge-shaped form, the chips are bent in the opposite direction to the cavity, and the tensile stresses that occur during this can contribute to chip breaking. Certainly, the increased depth of the surface of the chip cavity or rounding when retracting to the rake surface ultimately breaks the chips into small parts.

[0019] Regarding the chip breaking function and avoiding breakage of the insert, as well as the prolonged use of the reamer, it has proved beneficial if the chip cavity (cavities) exhibits (show) the greatest depth greater than 0.03 mm, however less than 0.16 mm , wherein the surface (s) of the chip cavity have (or have) a structure.

[0020] In the following, the invention is further elucidated by means of drawings based solely on the method of implementation.

[0021] Shown

Fig. 1 a top view of the indexable insert;

Fig. 2 an indexable indexable cutting plate according to Fig. 1;

Fig. 3 an enlarged view of the region of the indexable insert of Fig. 1;

Fig. 4 a sectional view in the area of ​​CC Fig. 3 of the indexable insert according to Fig. 3;

Fig. 5 a cross-sectional view in the BB area of ​​the indexable insert according to Fig. 3.

[0022] In Figs. 1 and 2, an indexable indexable insert is shown for use in a reamer in a horizontal and transverse view. The indexable insert 1 has, for example, a length L with a dimension of 16.5 mm, a width B with a dimension of 3.6 mm and a thickness H with a dimension of 2 mm and has cutting parts 6, 6 'on opposite vertices. In the cutting part 6, a main cutting edge can be formed of two cutting edge parts 5, 5 'which include a passage 51. In the opposite direction to the shown feed direction V of the reamer, or in the extension of the main cutting edge (major cutting edges) 5, 5 ', an auxiliary cutting edge 7 was formed.

[0023] Fig. 2 shows the indexable indexable plate 1 in a lateral view with a contact surface 2 for seating the reamer within the working range. The flank faces 3, 3 'and the clamping surface 4 each form the main cutting edges 5, 5' and the auxiliary cutting edge 7.

[0024] The cutting part 6 of the insert 1 is shown in Fig. 3. This cutting part 6 has a major cutting edge 5 with a larger angle and a main cutting edge 5 'with a sharper angle relative to the longitudinal axis of the shank, an auxiliary cutting edge attached thereto 7 in its main outlines runs parallel to the axis. According to the invention, on or in the rake face 4 forming the cutting edges 5, 5 ', 7 only in the area of ​​the cutting part 6, i.e. only in the area of ​​one or more of the major cutting edges 5, 5', a surface with an increased depth of roughness is provided (not shown) or chip cavity.

The increased surface roughness or chip recess 8 of the rake surface or in the rake surface 4 has its origin at a distance S from the main cutting edge 5,

5 ', which has a positive effect on increasing its durability and creating short chips.

The transition 51 from the front main cutting edge 5 to the next main cutting edge 5 'as well as to the adjacent auxiliary cutting edge 7 can be made in an angular, polygonal or rounded form.

[0025] In a preferred embodiment, the chip recess 5, 5 ', offset from the cutting edge 5, wedging at an angle P, is recessed in the rake surface 4 and has different widths 9, 9', 9 ", 9" 'in each case. As also shown in Fig. 4 for the cross section CC of the cutting part area 6, the surface of the chip recess 8 with a normal spacing of 9, 9 ', 9 "is in each case retracted from the main cutting edge 5, 5' to the rake surface 4.

[0026] In the transition area 51 of the main cutting edges 5, 5 ', the narrow width 9 "' of the chip recess 8 is formed in the narrow embodiment, whereby, as previously shown, breaking of the received chips in the area of ​​the cutting part 6 is greatly facilitated.

MAPAL Fabrik Wr Prazisionswerkzeuge, Dr. Kress KG, Germany

Proxy:

EP 1 896 211 B1

Z-11079