Tool for reaming very precise bores, especially in grey cast iron and ductile iron.

Abstract

Reaming tool for reaming very precise bores, especially in gray and ductile iron, comprising a clamping element adapted for clamping in the clamping devices of machine tools, and a cutting element according to the invention, on the circumferential part of which at least two cylindrical longitudinal support surfaces with an angular distance of 60° to 160° are formed, and on the remaining circumference of the cutting element at least three cutting teeth with longitudinal cutting edges and face cutting edges are formed, wherein a cylindrical longitudinal support surface is formed behind the first cutting tooth in the working direction of rotation and the other cylindrical longitudinal support surface is formed in front of the last cutting tooth in the working direction of rotation, characterized in that at the first cutting tooth (4) the distance (L1) of the intersection point (P1), i.e. the longitudinal cutting edge (9) and the inclined cutting edge (10), from the face plane (π) is smallest and at the last cutting tooth (4'') the distance (L1'') of the intersection point (P1'')that is, the longitudinal cutting edge (9'') and the inclined cutting edge (10'') are greatest from the face plane (π), and at least one cutting tooth (4') is formed between the cutting teeth (4) and (4'') with a distance (L1') of the intersection point (P1'), i.e., the longitudinal cutting edge (9') and the inclined cutting edge (10'), from the face plane (π), wherein, for individual cutting teeth (4') and (4), the distances (L1') and (L1) of the intersection points (P1') and (P1) from the face plane (π) decrease from the distance (L1'') in the working direction of rotation, and the distances (L2) and (L2') between the face plane (π) and the intersection points (P2) and (P2'), i.e., the cylindrical longitudinal support surfaces (6) and (6') and the lead-in surfaces (5) and (5'), decrease by at least 0.2 mm as the distance (L1'') between the frontal plane (π) and the intersection point (P1'') are larger.

Description

field of technology

[0001] The invention relates to a reaming tool for reaming very precise bores from accuracy level IT5 upwards, with high demands on dimensional accuracy and surface quality, particularly in the production of components made of gray or ductile iron. The reaming tools are primarily intended for high-volume production on modern, fully automated machining centers with internal cooling and lubrication systems operating at a minimum pressure of 40 bar. State of the art

[0002] Reaming bores is primarily the final production step. Therefore, it is crucial that the reaming process achieves high reproducibility of the geometric and dimensional accuracy of the reamed bores, as well as high reproducibility of the tool life of the reamers. These requirements are particularly important in fully automated production, where production machines operate without human oversight. Failure to meet these requirements results in significant downtime for expensive production equipment, substantially increasing production costs.

[0003] Currently, there are many known designs of reaming tools. They differ in the geometry of the cutting edges, the materials used for the cutting edges, and their construction. Many factors influence their technical and economic performance.

[0004] A reaming tool known from the latest state of the art is described in document EP1657014B1, the cutting part of which consists of a compact carbide disc with a cylindrical clamping shank.

[0005] The cutting teeth with longitudinal and transverse cutting edges are located on one half of the circumference of the forming disc, while cylindrical longitudinal support surfaces are formed on the opposite half. The cylindrical clamping shank is supported in the bore of a tool holder with an overlap, thus enabling the thermal clamping and release of the cutting part of the reaming tool.

[0006] The main disadvantage of this solution is that the design of the reaming tools is only conceived with cutting edges made of carbide or cermet, which means that these tools are only suitable for reaming bores in steels with a strength of up to 1200 MPa and at a maximum cutting speed of 160 m / min.

[0007] According to document EP1657014B1, these tools experience vibrations at higher cutting speeds, which are required, for example, when machining grey and ductile iron, leading to a deterioration in the quality of the machined surfaces and a deterioration in the form accuracy of the reamed bores.

[0008] Another disadvantage of this technical solution is that the reaming tools are designed so that the cutting element is permanently connected to the cylindrical carbide clamping shank and is mounted with an overlap in the bore of the tool holder. Such tools can be manufactured economically up to a maximum cutting element diameter of 32 mm; for larger diameters, manufacturing reaming tools is very complex and not practically feasible for economic reasons.

[0009] The object of the invention is to present the design of reaming tools with advantageous economic manufacturability up to a cutting part diameter of 100 mm, which do not exhibit the aforementioned disadvantages and whose main application lies in the reaming of very precise bores from accuracy level IT5 up to a cutting speed of up to 500 m / min. on fully automated CNC machines, in particular in the production of components made of spheroidal graphite cast iron and gray cast iron.

[0010] The aforementioned disadvantages are eliminated by the friction tool with a cutting element according to the invention, the essence of which is contained in the patent claims, see page 10. Explanation of the drawings

[0011] Each invention is explained in more detail with reference to the drawings, which show: • Fig. 1 a front view of a cutting part according to the invention from the exemplary reaming tool according to Fig. 4, • Fig. 2 a detail of the incisor, • Fig. 3 a cutting part of the tool according to the cutting line A - A Fig. 1, • Fig. 4 An exemplary reaming tool with a cutting part according to the invention, shown in partial longitudinal section, • Fig. 5 an assembly of a pre-assembled friction tool with a replaceable cutting ring with a cutting element according to the invention, wherein this tool enables the replacement of only the cutting ring and the holder remains in place, • Fig. 6 a front view of the friction tool made of Fig. 5, • Fig. 7 a front view of an interchangeable cutting ring with a cutting element according to the invention, made from a carbide or cermet monoblock, • Fig. Figure 8 schematically shows the uncoiled circumference of the cutting part of the tool in the working direction of rotation with three cutting teeth with a non-linear reduction of the distance of the intersection points of the longitudinal and face cutting edges from the face plane π, • Fig. Figure 9 schematically shows the uncoiled circumference of the cutting part of the tool in the working direction of rotation with five cutting teeth with a non-linear reduction of the distance of the intersection points of the longitudinal and face cutting edges from the face plane π, • Fig. Figure 10 schematically shows the uncoiled circumference of the cutting part of the tool in the working direction of rotation with three cutting teeth with a linear reduction of the distance of the intersection points of the longitudinal and face cutting edges from the face plane π, • Fig. Figure 11 schematically shows the uncoiled circumference of the cutting part of the tool in the working direction of rotation with five cutting teeth with a linear reduction of the distance of the intersection points of the longitudinal and face cutting edges from the face plane π. Exemplary embodiments of the invention

[0012] The Fig. Figure 1 shows the cutting part of a reaming tool 1 made of Fig. 4, which in this basic version is manufactured from a solid carbide monoblock. At one end is a clamping element 2, which is adapted for clamping in the clamping devices of machine tools, and at the other end is a cutting element 3.

[0013] In this Fig. In the front view of the friction tool 1, it is best seen that on the circumferential part 7 of the cutting part 3 two cylindrical longitudinal support surfaces 6 and 6' are formed, between which there is an angular distance of 100° and on the remaining circumference of the cutting part 3 three cutting teeth 4, 4' and 4" with longitudinal cutting edges 9, 9' and 9" and inclined cutting edges 10, 10' and 10" are formed.

[0014] In detail, in Fig. 2 clearly shows that the longitudinal cutting edges 9, 9' and 9" are formed by surface 12 of the chip drainage area for the metal chips and outer cylindrical clearance surfaces 13. The width of the outer cylindrical clearance surfaces 13 is 0.1 mm.

[0015] As in Fig. As can be seen in Figure 1, the first cutting tooth 4 is formed in the working direction in front of the cylindrical longitudinal support surface 6 and has the smallest distance L1 of the intersection point P1 (of the longitudinal cutting edge 9 and the inclined cutting edge 10) from the face plane π, and the last cutting tooth 4'' is formed in the working direction behind the cylindrical longitudinal support surface 6' and has the largest distance L1'' of the intersection point P1'' (of the longitudinal cutting edge 9'' and the inclined cutting edge 10'') from the face plane π.Between the cutting teeth 4 and 4'', a cutting tooth 4' is formed with a distance L1' of the intersection point P1' (of the longitudinal cutting edge 9' and the inclined cutting edge 10') from the face plane π, wherein, in the working direction of rotation, the distances of the intersection points P1' and P1 of the longitudinal cutting edges 9' and 9 and the inclined cutting edges 10' and 10 from the face plane π preferably decrease by 0.05 to 0.2 mm from the distance L1'', and the distances L2 and L2' between the face plane π and the intersection points P2 and P2', i.e., the cylindrical longitudinal support surfaces 6 and 6' and the lead-in surfaces 5 and 5', are 0.5 mm greater than the distance L1'' between the face plane π and the intersection point P1''.

[0016] Both cylindrical longitudinal support surfaces 6 and 6' have the same perpendicular distance R2 from the longitudinal axis Q1 of the reaming tool 1, and both cylindrical longitudinal support surfaces 6 and 6' have an abrasion-resistant coating. The perpendicular distance R1 of the cutting edges 9, 9' and 9'' is greater than the perpendicular distance R2 of the cylindrical longitudinal support surfaces 6 and 6' by 0.007 mm, and the length of the longitudinal cutting edges 9, 9' and 9'' is 6 mm. All cutting teeth 4, 4' and 4'' have an abrasion-resistant coating.

[0017] As in Fig. 3 and Fig. As shown in Figure 4, a blind central channel 11 is formed in the longitudinal axis Q1 of the friction tool 1 for guiding a coolant and lubricant, which enters the side channels 15 and opens into the tooth gaps 14 and into the longitudinal grooves 21, thereby supplying the cylindrical longitudinal support surfaces 6 and 6' with this coolant and lubricant.

[0018] The Fig. Figure 5 shows the arrangement of the friction tool 1 in a longitudinal section, where the holder 16 can be seen, which allows the replacement of only the cutting ring 19, and the holder 16 remains in place.

[0019] On the Fig. 6 is a front view of Fig. 5 shown.

[0020] The friction tool 1 from Fig. 5 and Fig. Assembly 6 consists of a cylindrical holder 16, which has a clamping element 2 at one end for connection to the respective part of the clamping device, and a connection interface 17 for the detachable fastening of the interchangeable cutting ring 19 is formed at the opposite end of the cylindrical holder 16. The technical solution of the connection system of the cutting ring 19 with the holder 16 is not the subject of this invention and is therefore not described in detail here.

[0021] The Fig. 5, Fig. 6 and Fig. Figure 7 shows two variants of cutting rings 19, on whose surface five cutting teeth 4, 4', 4', 4' and 4'' with longitudinal and end cutting edges as well as with two cylindrical longitudinal support surfaces 6 and 6' are formed, the arrangement of which in Fig. 9 is shown schematically.

[0022] The friction ring 19 in Fig. 5 and Fig. 6 consists of a hard metal body 22, on the surface of which five tooth projections 18 and two longitudinal grooves 21 are formed, in which guide strips 23 made of polycrystalline diamond are brazed, on which cylindrical longitudinal support surfaces 6 and 6' are formed. Cutting inserts 20 made of cubic boron nitride are brazed to the tooth projections 18, on which longitudinal cutting edges and end cutting edges are formed.

[0023] The Fig. Figure 7 shows the own interchangeable cutting ring 19, which is made from a hard metal monoblock with a cutting part 3, on the circumferential part 7 two cylindrical longitudinal support surfaces 6 and 6' and five cutting teeth 4, 4', 4', 4' and 4'' with longitudinal cutting edges and face cutting edges are formed.

[0024] Both variants of the interchangeable cutting rings 19 made of Fig. 5, Fig. 6 and Fig. 7 have a drive groove 8 formed in the angular space between the cylindrical longitudinal support surfaces 6 and 6', which interacts with a drive projection 24 formed on the face of the holder 16 of the friction tool 1.

[0025] The essential technical advantage of the new design, in particular the monolithic cutting rings 19 of the friction tool 1, lies in the economically very advantageous manufacturability of the cutting ring 19, which can be produced from a semi-finished product made of powdered metals and a binder metal by pressing in compression molding machines and further finished by grinding on CNC machines.

[0026] Another significant technological advantage is that the shape and dimensions of the cutting rings 19, according to the new technical solution, make it possible to apply abrasion-resistant coatings in vacuum chambers very advantageously compared to currently known designs of friction tools, thereby reducing the production costs for the coating by at least 50%.

[0027] Technical solutions according to the examples given were tested during large-scale production on modern, fully automated machining centers, demonstrating that the technical and economic results of the respective reaming process, such as dimensional accuracy, form accuracy, surface quality of the machined surface, cutting edge service life, feed rate and cutting speed, the distance between the individual intersection points of the longitudinal and end cutting edges, and at the same time the distance between the intersection points of the cylindrical longitudinal support surfaces and running surfaces from the face plane of the cutting part of the reaming tool, have a significant influence.During the long-term development of the technical solution for the cutting part of the reaming tool, numerous combinations of distances between the intersection points of longitudinal cutting edges and intersection points of cylindrical longitudinal support surfaces and circumferential arrangements of cutting edges were tested, where the technical solution according to the invention proved to be the most advantageous, achieving very significant technical and economic results compared to currently known technical solutions for reaming tools. Industrial applicability

[0028] The new reaming tools according to the invention are advantageously usable for the final machining of very precise bores at high cutting speeds on all CNC machining centers with internal pressure cooling, in particular on fully automated machines, which are used, for example, in the manufacture of components for cars, aircraft, medical devices, household appliances, machine tools, agricultural machinery and in many other machine-building productions, especially in the production of components made of spheroidal graphite and gray cast iron, the machining productivity can in many cases be increased many times over with the reamers according to the invention. List of reference symbols 1 friction tool 2 clamping part 3 Cutting part 4 First incisor 4' incisor 4'' Last incisor 5 approach area 5' approach area 6 Cylindrical longitudinal support surface 6' Cylindrical longitudinal support surface 7. Scope section 8 drive groove 9 longitudinal cutting edge 9' longitudinal cutting edge 9'' longitudinal cutting edge 10 slanted cutting edge 10' slanted sheath edge 10'' angled cutting edge 11 Middle channel 12 Flat front surface 13 Outer cylindrical free surface 14 gaps in teeth 15 side channels 16 holders 17 Connection interface 18 tooth projections 19 cutting ring 20 cutting plates 21 longitudinal grooves 22 bodies 23 guide rails 24 Driver advantage π Front plane P1, P1', P1'' Intersection P2, P2' Intersection L1, L1', L1'' Length L2, L2', length R1 Perpendicular distance from the longitudinal axis Q1 R2 Perpendicular distance from the longitudinal axis Q1 Q1 Longitudinal axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1657014B1 [0004, 0007]

Claims

[1] Reaming tool for reaming very precise bores, in particular in gray and ductile iron, comprising a clamping part adapted for clamping in the clamping devices of machine tools, and a cutting part according to the invention, on the circumferential part of which at least two cylindrical longitudinal support surfaces with an angular distance of 60° to 160° are formed, and on the remaining circumference of the cutting part at least three cutting teeth with longitudinal cutting edges and end cutting edges are formed, wherein a cylindrical longitudinal support surface is formed behind the first cutting tooth in the working direction of rotation and the other cylindrical longitudinal support surface is formed in front of the last cutting tooth in the working direction of rotation, characterized by, that at the first cutting tooth (4) the distance (L1) of the intersection point (P1), i.e., the longitudinal cutting edge (9) and the inclined cutting edge (10), from the face plane (π) is smallest, and at the last cutting tooth (4'') the distance (L1'') of the intersection point (P1''), i.e., the longitudinal cutting edge (9'') and the inclined cutting edge (10''), from the face plane (π) is largest, and that between the cutting teeth (4) and (4'') at least one cutting tooth (4') is formed with the distance (L1') of the intersection point (P1'), i.e., the longitudinal cutting edge (9') and the inclined cutting edge (10'), from the face plane (π) is formed, wherein, for individual cutting teeth (4') and (4), the distances (L1') and (L1) of the intersection points (P1') and (P1) from the face plane (π) in the working direction of rotation are of the distance (L1'') decrease and reduce the distances (L2) and (L2') between the end plane (π) and the points of intersection (P2) and (P2'), i.e., the cylindrical longitudinal support surfaces (6) and (6') and the run-up surfaces (5) and (5'), by at least 0,2 mm greater than the distance (L1'') between the front plane (π) and the intersection point (P1''). [2] Tool according to claim 1, characterized by , that for individual cutting teeth (4') and (4) the distances (L1') and (L1) of the intersection points (P1') and (P1) from the face plane (π) in the working direction decrease non-linearly from the distance (L1''). [3] Tool according to claim 1, characterized by , that for individual incisors (4') and (4) the distances (L1') and (L1) of the points of intersection (P1') and (P1) from the face plane (π) in the working direction decrease linearly from the distance (L1''). [4] Tool according to claim 1, characterized by , that the longitudinal cutting edges (9,9' and 9'') are formed by a surface (12) of the chip drainage of the metal chips and outer cylindrical clearance surface (13) which is advantageously 0.05-0.2mm wide. [5] Tool according to claim 1, characterized by, that both cylindrical longitudinal support surfaces (6) and (6') have the same perpendicular distance (R2) from the longitudinal axis (Q1), wherein the perpendicular distance (R1) of the longitudinal cutting edges (9, 9' and 9'') is advantageously greater than the perpendicular distance (R2) by 0.005-0.010 mm. [6] Tool according to claim 1, characterized by , that the cylindrical longitudinal support surfaces (6, 6') are made of such a material whose coefficient of friction is optimally 0.05 -0.2 in combination with the material to be machined. [7] Tool according to claim 6, characterized by , that the cylindrical longitudinal support surfaces (6,6') are made of a material group such as polycrystalline diamond, cermet, ceramic and the cutting teeth (4,4' and 4'') with longitudinal cutting edges (9,9' and 9'') and inclined cutting edges (10,10' and 10'') are made of a material group such as cubic boron nitride, polycrystalline diamond, cermet. [8] Tool according to claim 6, characterized by, that the cutting part (3) of the reaming tool (1) is entirely made from a carbide monolith, wherein the cylindrical longitudinal support surfaces (6,6') have an abrasion-resistant coating and the cutting teeth (4,4' and 4'') with longitudinal cutting edges (9,9' and 9'') and inclined cutting edges (10,10' and 10'') have a different type of coating. [9] Tool according to claim 7, characterized by , that the cutting plates (20) with longitudinal cutting edges (9, 9' and 9'') and inclined cutting edges (10, 10' and 10'') are attached to the tooth projections (18) of the cutting part (3) with an adhesive. [10] Tool according to claims 1 to 8, characterized by, that in the clamping part (2) of the friction tool (1) a central channel (11) is formed for guiding a cooling lubricant, which enters the side channels (15) which open into the tooth gaps (14) and the longitudinal grooves (21) which are formed in front of the cylindrical longitudinal support surfaces (6,6') in the working direction of rotation. [11] Tool according to claims 1 to 9, characterized by , that the cutting part (3) of the reaming tool (1) is detachably connected to the holder (16) of the clamping part (2), which is adapted for clamping into the clamping devices of the machine tools.

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