DEEP HOLE DRILLING

Description

[0001] The invention relates to a deep hole drilling method for producing a pipe.

[0002] Deep drilling or deep hole drilling is a machining process for producing and machining holes with diameters between d = 0.2 and 2000 mm and a hole depth that is usually greater than three times the diameter.

[0003] From WO 2012 / 154866 A1 a deep hole drilling method for producing a pipe with an inner profile which has at least one recess extending helically along the inside of the pipe, namely n recesses extending helically along the inside of the pipe, is known, in which a tool having a base body extending along a longitudinal axis and a cutting edge arranged on the outer circumference of the base body (2) is pulled through the interior of the pipe using a deep hole drilling machine and is rotated about its longitudinal axis so that the cutting edge makes a cut along a helical cutting line on the inside of the pipe.

[0004] From US 2003 / 0019533A1 a deep hole drilling method is known for producing a pipe with an inner profile which has at least one recess extending helically along the inside of the pipe, wherein the pipe is a centrifugally cast pipe (5) and the inner profile has a plurality of recesses, namely n recesses extending helically along the inside of the pipe, in which a tool having a base body extending along a longitudinal axis and n cutting edges arranged on the outer circumference of the base body is pushed through the interior of the pipe using a deep hole drilling machine and is rotated about its longitudinal axis so that the cutting edges make a cut along a helical cutting line on the inside of the pipe.

[0005] From EP 1 525 289 B9 a finned tube for the thermal cracking of hydrocarbons is known, which has inclined, helically extending inner fins relative to the tube axis.

[0006] From WO 2010 / 043375 A1 a nickel-chromium alloy with high oxidation and carburization resistance, creep rupture strength and creep resistance is known, consisting of 0.4 to 0.6% carbon, 28 to 33% chromium, 15 to 25% iron, 2 to 6% aluminum, up to 2% silicon, up to 2% manganese, up to 1.5% niobium, up to 1.5% tantalum, up to 1.0% tungsten, up to 1.0% titanium, up to 1.0% zirconium, up to 0.5% yttrium, up to 0.5% cerium, up to 0.5% molybdenum, up to 0.1% nitrogen, the remainder being nickel, including impurities resulting from the melting process.

[0007] Against this background, the object of the invention was to propose a manufacturing method for producing a pipe with an inner profile having a recess extending helically along the inside of the pipe, which can be carried out more efficiently than the methods known from the prior art.

[0008] This object is achieved by the deep hole drilling method according to claim 1. Advantageous embodiments are set out in the subclaims and the description below.

[0009] The deep-hole drilling method according to the invention achieves advantages when the cutting edges of the tool are not moved solely in the circumferential direction at a specific location within the pipe, but rather the section of the inner profile located at that location is created by radially advancing the cutting edges. The cutting direction of the cutting edge in the deep-hole drilling method should no longer be solely in the circumferential direction. Rather, the invention proposes guiding the cutting edges of the tool helically along the inside of the pipe, thus creating the recesses extending helically along the inside of the pipe.For this purpose, the invention proposes, within the scope of the deep hole drilling method according to the invention, to pull a tool, which has a base body extending along a longitudinal axis and n cutting edges arranged on the outer circumference of the base body, through the interior of the pipe using a deep hole drilling machine and to rotate the tool about its longitudinal axis and / or to rotate the pipe about its longitudinal axis so that the cutting edges make a cut along a helical cutting line on the inside of the pipe.Alternatively, the invention provides for pushing or pulling the pipe with a device along its longitudinal axis via a tool which has a base body extending along a longitudinal axis and n cutting edges arranged on the outer circumference of the base body, and in doing so rotating the pipe about its longitudinal axis and / or rotating the tool about its longitudinal axis so that the cutting edges make a cut along a helical cutting line on the inside of the pipe.

[0010] The deep-hole drilling method according to the invention offers the advantage that the cutting edges leave the tool more frequently, thus making it possible to replace the indexable inserts, which are particularly preferably used and on which the cutting edges are made, when the cutting edges are worn. Cutting only in the circumferential direction and gradually moving the tool in the axial direction once the circumferential cutting has been completed at a particular location leads to long engagement times of the cutting edges in the pipe and poses the problem that, if the cutting edges need to be replaced, the tool must be precisely retracted to the point where the cutting process ended before the cutting edges were replaced.

[0011] The method according to the invention thus provides for a superimposed rotational movement and axial movement of the tool relative to the pipe during cutting. The rotational movement and the axial movement can be coordinated in such a way that a helical cutting line of the cutting edges is created on the inside of the pipe, which has the same pitch as the recesses to be produced on the inside of the pipe, extending helically along the inside of the pipe.

[0012] The invention is described using the terms deep hole drilling method and deep hole drilling. It is assumed that these terms are typically used to describe a machining process used to produce and machine bores whose diameters are between d = 0.2 and 2000 mm and whose bore depth is usually greater than three times the diameter. In the context of the description of the invention, however, the terms deep hole drilling method and deep hole drilling should be understood to generally describe a machining process with which the intended superimposed rotational movement and axial movement of the tool relative to the pipe can be carried out during cutting. For example, it is conceivable that the method according to the invention is carried out using a lathe or a CNC machine.Both a lathe and a CNC machine offer the possibility of implementing the rotational movement and axial movement of the tool relative to the pipe during cutting, as superimposed by the invention. Only in a particularly preferred embodiment, the terms "deep-hole drilling method" and "deep-hole drilling" are understood to describe a machining process used for the production and machining of holes with diameters between d = 0.2 and 2000 mm and a hole depth typically greater than three times the diameter.

[0013] The intended superimposed rotational movement and axial movement of the tool relative to the pipe during cutting can be achieved in various ways.

[0014] In the deep-hole drilling method according to the invention, the tool is pulled through the interior of the pipe using a deep-hole drilling machine and rotated about its longitudinal axis, so that the cutting edges make a cut along a helical cutting line on the inside of the pipe. Particularly preferably, the pipe is not rotated about its longitudinal axis. According to the invention, the tool is pulled through the interior of the pipe using a deep-hole drilling machine and rotated about its longitudinal axis, so that the cutting edges make a cut along a helical cutting line on the inside of the pipe. Particularly preferably, the tool is not rotated about its longitudinal axis.According to the invention, the tool is pulled through the interior of the pipe using a deep hole drilling machine, and in the process the pipe is rotated about its longitudinal axis and the tool about its longitudinal axis, such that the cutting edges make a cut along a helical cutting line on the inside of the pipe. According to the invention, the pipe is pulled over the tool using a device, and in the process the tool is rotated about its longitudinal axis, such that the cutting edges make a cut along a helical cutting line on the inside of the pipe. Particularly preferably, the pipe is not rotated about its longitudinal axis. According to the invention, the pipe is pushed over the tool using a device, and in the process the tool is rotated about its longitudinal axis, such that the cutting edges make a cut along a helical cutting line on the inside of the pipe. Particularly preferably, the pipe is not rotated about its longitudinal axis.According to the invention, the pipe is pulled over the tool using a device and the pipe is rotated about its longitudinal axis so that the cutting edges make a cut along a helical cutting line on the inside of the pipe. Particularly preferably, the tool is not rotated about its longitudinal axis. According to the invention, the pipe is pushed over the tool using a device and the pipe is rotated about its longitudinal axis so that the cutting edges make a cut along a helical cutting line on the inside of the pipe. Particularly preferably, the tool is not rotated about its longitudinal axis. According to the invention, the pipe is pulled over the tool using a device and the pipe is rotated about its longitudinal axis and the tool is rotated about its longitudinal axis so that the cutting edges make a cut along a helical cutting line on the inside of the pipe.According to the invention, the pipe is pushed over the tool using a device, and the pipe is rotated about its longitudinal axis and the tool about its longitudinal axis, so that the cutting edges make a cut along a helical cutting line on the inside of the pipe.

[0015] In a preferred embodiment, the method according to the invention provides that the recesses extending helically along the inside of the pipe are created by a plurality of cuts, wherein the tool is pulled through the interior of the pipe with each cut and is rotated about its longitudinal axis and / or the pipe is rotated about its longitudinal axis so that the cutting edges make the respective cut along a helical cutting line on the inside of the pipe. In an alternative, likewise preferred embodiment, the pipe is pulled or pushed over the tool with each cut and the pipe is rotated about its longitudinal axis and / or the tool is rotated about its longitudinal axis so that the cutting edges make the respective cut along a helical cutting line on the inside of the pipe.This approach also makes it possible to minimize the stress on the cutting edges by keeping the material removal per cut small and creating the recesses in multiple cuts. In a preferred embodiment, the recess is created with at least three, particularly preferably with at least four, particularly preferably with at least five, and most preferably with at least six cuts.

[0016] In a preferred embodiment of the above-described embodiment, in which the recesses are created with multiple cuts, the radial distance of the cutting edge relative to the longitudinal axis of the base body is changed between a first cut and a second cut. This allows the cutting edges to be adapted to the increasing depth of the recesses.

[0017] Additionally or alternatively, a preferred embodiment may provide the cutting edges of the tool with indexable inserts and change the indexable inserts between a first cut and a second cut. The term "cutting edge" in the present description of the invention is therefore not limited to a specific cutting edge on a tool, but is used generally to describe the cutting edge currently located on the tool in the respective process step.

[0018] In a preferred embodiment, a first cut is performed with a first cutting edge geometry and a second cut with a second cutting edge geometry. Particularly preferred are indexable inserts from the group with the type designations RNMG 160500, RPMT 160500, RCMT 160500, or RDMT 160500.

[0019] In a preferred embodiment, the cut to be made leads from one end of the tube to the other end of the tube. Embodiments are conceivable in which a tube is to be produced with a helical recess on the inside of the tube that extends only over part of the longitudinal extent of the tube, for example end zones without a recess are provided at the respective ends of the tube. However, it is particularly preferred to produce tubes with a helical recess on the inside of the tube that extends over the entire tube. This also has the advantage at the beginning of each cut when the cutting edge comes into engagement with the material of the tube at the beginning of a cut.

[0020] In each process step, several recesses are created in the pipe. The pipe has n recesses extending helically along the inside of the pipe. The method according to the invention provides for this purpose: using the deep-hole drilling machine, the tool, which has a base body extending along a longitudinal axis and n cutting edges arranged on the outer circumference of the base body, is pulled through the interior of the pipe, rotating it about its longitudinal axis and / or rotating the pipe about its longitudinal axis, so that the cutting edges each make a cut along a helical cutting line on the inside of the pipe.In an alternative embodiment, the pipe is pushed or pulled along its longitudinal axis using a device via a tool having a base body extending along a longitudinal axis and n cutting edges arranged on the outer circumference of the base body, and in the process the pipe is rotated about its longitudinal axis and / or the tool is rotated about its longitudinal axis so that the cutting edges each make a cut along a helical cutting line on the inside of the pipe. The respective recesses of the n recesses are also created by multiple cuts, with the tool being pulled through the interior of the pipe for each cut and being rotated about its longitudinal axis so that the cutting edge makes the respective cut along a helical cutting line on the inside of the pipe.Although it is conceivable, in a variant not forming part of the invention, to produce a tube with n recesses extending helically along the inside of the tube sequentially (possibly by performing multiple cuts per recess), machining times are reduced if multiple cuts are performed simultaneously per work step. In a preferred embodiment, the number n of recesses in the tube is >3. It is not mandatory that the recesses to be produced in the tube be worked on simultaneously per work step.For example, it is conceivable to machine a pipe with six recesses extending helically along the inside of the pipe in such a way that, using a tool which has a base body extending along a longitudinal axis and three cutting edges arranged on the outer circumference of the base body, only three of the six recesses are produced in a first sequence of work steps and then the remaining three of the six recesses are produced in a second sequence of work steps. It is also conceivable to first make the first cuts for the first three recesses during the first pass through the pipe, to make the first cuts for the second three recesses during the second pass through the pipe and then, during a third pass - if necessary,after changing an indexable insert with a cutting edge - to carry out the second cut for the first three recesses in order to carry out the second cuts for the second three recesses during a fourth pass through the pipe.

[0021] In a preferred embodiment, a drilling oil or cooling lubricant is introduced into the interior of the tube, which flows through the tube counter to the pulling or pushing direction of the tool. The drilling oil or cooling lubricant serves, in particular, to remove chips from the interior of the tube and / or to cool and / or lubricate the tool and / or the workpiece.

[0022] In a preferred embodiment, the radial distance of the cutting edge relative to the longitudinal axis of the body is reduced after completing a first cut (the cutting edge is displaced inward toward the longitudinal axis of the base body), the base body is reinserted into the pipe until it is in the starting position from which the next cut is to be made, whereupon the radial distance of the cutting edge relative to the longitudinal axis of the base body is increased again and—in a preferred embodiment—is selected to be even greater relative to the previous step. By "retracting" the cutting edge while the base body is moved back to the starting point for the next cut, the risk of the cutting edge colliding with a protruding section on the inside of the pipe or with a chip that may still be present in the pipe is reduced.Furthermore, this eliminates the need to simultaneously rotate the base body when returning it to its starting position during the longitudinal movement, thus essentially retracing the helical shape of the recesses. In a preferred embodiment, the base body is moved solely in the longitudinal direction with the cutting edges retracted. Only upon reaching its axial starting position for the next cut is it rotated into a position where the cutting edge assumes the correct starting position for the next cut.

[0023] In a preferred embodiment, the radial section of the cutting edge relative to the longitudinal axis of the base body remains unchanged during a cut. This significantly simplifies the design of the tool, as mechanisms that require the cutting edge to advance during a cut can be omitted.

[0024] In a preferred embodiment, the tool is pulled through the interior of the pipe at a speed of more than 6 m / min, particularly preferably more than 9 m / min, or the pipe is pushed or pulled over the tool at a speed of more than 6 m / min, particularly preferably more than 9 m / min. It has been shown that at higher speeds a smoother cutting process can be achieved, in particular lower vibrations of the tool, the pipe and / or the cutting edges. This applies particularly to workpieces (pipes) made of tough materials. The speed specification refers in particular to the linear component of the movement, i.e. the speed of the movement in the direction of the longitudinal axis of the pipe or the tool.

[0025] The tool for a deep-hole drilling machine that can be used in the method according to the invention comprises a base body extending along a longitudinal axis and at least one cutting edge arranged on the outer circumference of the base body. The base body is particularly preferably tubular.

[0026] The tool has several, in particular more than three, cutting edges arranged on the outer circumference of the base body.

[0027] In a preferred embodiment, at least two cutting edges are arranged at the same height along the longitudinal extension of the base body, but at different positions along the circumference of the base body. Particularly preferably, cutting edges arranged at the same height along the longitudinal extension of the base body, but at different positions along the circumference of the base body, are distributed symmetrically over the circumference of the base body. In a preferred embodiment, the cutting edge geometry of the cutting edges arranged at the same height along the longitudinal extension of the base body, but at different positions along the circumference of the base body, is identical.

[0028] In a preferred embodiment, at least two cutting edges are arranged at different heights along the longitudinal extension of the base body and at different positions along the circumference of the base body. Particularly preferably, two cutting edges are arranged at different heights along the longitudinal extension of the base body and at different positions along the circumference of the base body such that they lie on a helical line. Particularly preferably, the position of the second cutting edge is rotated by less than 90° about the longitudinal axis relative to the position of the first cutting edge, particularly preferably by less than 45°. In a preferred embodiment, the cutting edge geometry of the cutting edges, which are arranged at different heights along the longitudinal extension of the base body but at different positions along the circumference of the base body, is the same.In an alternative embodiment, the cutting edge geometry of the cutting edges, which are arranged at different heights along the longitudinal extension of the base body but at different positions along the circumference of the base body, is different. Different cutting edge geometries are also conceivable, for example, one cutting edge, for example the front cutting edge, with an interrupted geometry and another cutting edge, for example the following cutting edge, with a full, closed geometry.

[0029] The cutting edge is formed on an indexable insert, wherein the indexable insert is detachably provided as part of a cartridge. Particularly preferably, an indexable insert is screwed to a part of the cartridge.

[0030] The cassette is designed to be movable relative to the base body. In a preferred embodiment, the cassette is precisely ground around its circumference and is guided in a pocket machined into the base body of the tool. In a preferred embodiment, the cassettes can slide within the pockets in an adjustment direction.

[0031] In a preferred embodiment, the cassette can be moved along an inclined plane that is at an angle to the longitudinal axis of the base body. This allows an adjustment movement of the cutting edge and the radial distance of the cutting edge relative to the longitudinal axis of the base body to be changed. In a preferred embodiment, this can be achieved in that the bottom of a pocket in the base body of the tool in which the cassette is arranged runs at an angle to the longitudinal axis of the base body. In an alternative embodiment, this can be achieved in that the pockets in the base body of the tool have no bottom (are open at the bottom) and the cassette arranged in the pocket is supported by a push rod arranged inside the base body, wherein the push rod has surface sections on its outer circumference that run at an angle to the longitudinal axis of the base body and on which surface sections the cassette is supported.If the push rod is moved relative to the pockets, the cassette moves along the surface section running at an angle to the longitudinal axis of the base body and thus changes its distance from the longitudinal axis of the base body.

[0032] In a preferred embodiment, a bar spring is provided that pushes the cassette in the direction of the longitudinal axis of the base body. Alternatively or additionally, the cassette can be positively guided via a T-slot located in an inclined plane of the push rod.

[0033] In a preferred embodiment, an adjustment mechanism is provided for adjusting the position of a cassette, which is movable relative to the base body, relative to the base body. The adjustment mechanism particularly preferably comprises an adjustment rod, for example a push rod, on the outer surface of which a cassette located in a pocket is supported. A separate drive can be provided with which the position of the adjustment rod relative to the remaining part of the base body can be changed. This enables automatic adjustment of the position of the adjustment rod relative to the base body. Alternatively, a manually operated adjustment option can be provided.

[0034] In a preferred embodiment, a support plate is provided on the outer circumference of the base body. This can be used to determine the position of the base body within the pipe during the cutting movement. In a preferred embodiment, several support plates are provided distributed around the circumference. In a preferred embodiment, a first group of support plates distributed around the circumference is provided at one end of the tool, and a second group of support plates distributed around the circumference is provided at the opposite end of the tool.

[0035] In a preferred embodiment, the support plates are resiliently mounted in the radial direction to the base body. The resilient mounting can be achieved by springs, for example leaf springs or spiral springs, which can be arranged below the support plate. It is also conceivable to achieve the resilient mounting by fluid cushions, for example gas or hydraulic cushions, which are arranged below the support plate. The resilient mounting of the support plates offers the advantage that the support plates can change their position depending on the radial forces acting on them. This allows the support plates to deflect when chips are present. However, with several support plates distributed around the circumference, it also enables a centering function. This allows the tool to center itself in the tube.The tool's position makes it more tolerant of dimensional deviations in the pipe, particularly with regard to deflection or deviations from the circular cross-section. The tool is held in place in the pipe by the support plates.

[0036] In a particularly preferred embodiment, the tool has a collet unit, particularly preferably a first collet unit at one end of the tool and a second collet unit at the second end of the tool. The collet unit has at least three, particularly preferably more than three collets, each of which assumes the function of a support plate. The respective collet is movably attached to the outer circumference of the base body, in particular pivotably mounted about a pivot axis running in the circumferential direction of the base body. Furthermore, the collet unit has a counterpart for each collet, which is also connected to the outer circumference of the base body and can be moved axially along the outer circumference. The counterpart is spring-loaded, so that an axial movement of the counterpart along the outer circumference of the base body from a first position to a second position tensions the spring.The collet can be pivoted with its free end into contact with the counterpart. It is particularly preferred if the counterpart and / or the free end of the pivoting collet have inclined contact surfaces. The use of inclined contact surfaces can ensure that when the collet is pivoted towards the outer circumference of the base body, an initial contact is made between the free end of the collet and the counterpart. When the collet is pivoted further towards the outer circumference of the base body, the free end of the collet slides along the counterpart, causing an axial movement of the counterpart, which preloads the spring (the counterpart is pushed back against the spring). In this way, in a collet unit, the collet can take on the function of a support plate that is spring-mounted in the radial direction.The spring exerts a restoring force on the counterpart, which is translated into a radially acting restoring force on the collet by the inclined contact surface.

[0037] In a preferred embodiment of the collet unit, all of the collet counterparts are combined on one element, preferably on a ring that can be moved axially on the outer circumference of the base body. This ring is preferably designed with a conical surface that can provide the inclined contact surfaces of the counterparts. In particular, the ring is preferably mounted with play on the outer circumference of the base body so that it can tilt about an axis perpendicular to the longitudinal axis of the tool. By tilting the ring, a spring assembly located behind the ring can be compressed to varying degrees, whereby axially acting restoring forces of varying magnitudes can be generated around the circumference of the ring. These restoring forces can be translated into radially acting restoring forces of varying strengths on the collets by the inclined conical surface of the ring.

[0038] In a preferred embodiment of the collet unit, the counterpart is preloaded into a preferred position. In a preferred embodiment, the preload can be varied.

[0039] In a preferred embodiment of the collet unit, the spring of the counterpart has a counterbearing. In a preferred embodiment, the position of the counterbearing on the base body is axially adjustable. The preload can be adjusted by axially displacing the counterbearing on the base body.

[0040] In a preferred embodiment of the collet unit, the springs of the counterparts are provided by a single sleeve-shaped spring assembly. Providing a sleeve-shaped spring assembly offers advantages, particularly in conjunction with a ring that represents the summary of all counterparts.

[0041] The use of a collet unit with pivoting collets as support plates offers the advantage that an inclined surface, namely the radially outward-facing surface of the inclined collet, comes into contact with the inner surface of the pipe. This is particularly advantageous for tough materials that tend to smear. With tough materials, there is a risk that an edge of the fixed bar will dig into the tough material or that material will build up in front of this edge, which can lead to the bar tearing off.

[0042] In a preferred embodiment, a nozzle for a drilling oil or cooling lubricant is provided on the outer circumference of the base body. Particularly preferably, a channel is provided within the base body, which leads from a drilling oil or cooling lubricant inlet of the base body to the nozzle. Particularly preferably, several nozzles for a drilling oil or cooling lubricant are provided on the outer circumference of the base body. Additionally or alternatively, in the context of the method according to the invention, it can be provided to flush the space between the outer circumference of the tool and the inside of the tube with drilling oil or cooling lubricant. This can be done in particular by introducing the drilling oil or cooling lubricant into this space at one end of the tube and exiting this space at the other end of the tube.In a preferred embodiment, the flow direction of the drilling oil or cooling lubricant is opposite to the movement of the cutting edge during the cut. Accordingly, if the cutting edge is moved from one end of the pipe to the other end of the pipe, in this preferred embodiment the drilling oil or cooling lubricant flows from the other end of the pipe to one end of the pipe. Alternatively, the flow direction of the drilling oil or cooling lubricant can be selected to be parallel to the movement of the cutting edge during the cut.

[0043] The deep hole drilling machine which can be used with the method according to the invention has a tool and a linear drive for the tool with a rotary drive for the tool.

[0044] In a preferred embodiment, the rotary drive can advance the cutting edge to at least two different starting points for a cut, with the starting points differing in their rotational position around the longitudinal axis. An embodiment was described above in which the base body, with the cutting edges retracted, moves solely in the longitudinal direction and only upon reaching its axial starting position for the next cut is it guided by rotation into a position in which the cutting edge assumes the correct starting position for the next cut. How far the base body must be rotated after reaching the axial starting position depends on the shape of the helix to be produced, namely the rotational position in which the cutting edge left the workpiece at the end of the cut relative to the starting point of the helix.In order for the deep-hole drilling machine to be used to produce a variety of different helical recesses, it must be capable of positioning the cutting edge to at least two different starting points for a cut, wherein the starting points differ in their rotational position around the longitudinal axis. Particularly preferably, the deep-hole drilling machine can position the cutting edge to any point of a 360° pitch, i.e., to a total of 360, 3600, 36,000, or 360,000 different starting points. Particularly preferably, the deep-hole drilling machine can position the cutting edge to more than 360 different starting points for a cut, wherein the starting points differ in their rotational position around the longitudinal axis.

[0045] A system usable for the method according to the invention comprises a deep-hole drilling machine with a tool, wherein several different cassettes are provided for the tool, to which an indexable insert having the cutting edge can be detachably attached. By varying the shape of the cassette, in particular by varying the distance between the connection point of the indexable insert and the cassette (usually the thread into which a screw holding the indexable insert to the cassette is screwed) and the surface with which the cassette is supported on the base body, the distance between the connection point of the indexable insert and the longitudinal axis of the base body and thus the distance of the cutting edge from the longitudinal axis of the base body can be influenced. With such a system, it is possible to machine pipes with different inner diameters while maintaining a single base body by selecting the appropriate cassette.

[0046] In a preferred embodiment, the method according to the invention is carried out with the deep hole drilling machine.

[0047] In a preferred embodiment, the centrifugally cast tube is made of an alloy with 0.4 to 0.6% carbon, 28 to 33% chromium, 15 to 25% iron, 2 to 6% aluminum, up to 2% silicon, up to 2% manganese, up to 1.5% niobium, up to 1.5% tantalum, up to 1.0% tungsten, up to 1.0% titanium, up to 1.0% zirconium, up to 0.5% yttrium, up to 0.5% cerium, up to 0.5% molybdenum, up to 0.1% nitrogen, the remainder being nickel including impurities resulting from the melting process. Particularly preferably from an alloy which individually and side by side contains 0.4 to 0.6% carbon, 28 to 33% chromium, 17 to 22% iron, 3 to 4.5% aluminum, 0.01 to 1% silicon, 0.01 to 0.5% manganese, 0.01 to 1.0% niobium, 0.01 to 0.5% tantalum, 0.01 to 0.6% tungsten, 0.001 to 0.5% titanium, 0.001 to 0.3% zirconium, 0.001 to 0.3% yttrium, 0.001 to 0.3% cerium, 0.01 to 0.5% molybdenum, 0.001 to 0.1% nitrogen.

[0048] A centrifugally cast pipe produced using the method according to the invention has an inner profile that has at least one recess extending helically along the inside of the pipe, wherein the centrifugally cast pipe was produced using a method according to the invention. The centrifugally cast pipe is characterized in particular by helically extending inner ribs inclined at an angle of 20° to 40° with respect to the pipe axis, and by rib valleys and rib crests that border one another in a mirror image in the form of a wavy line, each with the same radius of curvature, wherein the flank angle (β) of the respective tangent at the point of contact of the two radii of curvature (R) with respect to the perpendicular to the radius (Ri) of the circle touching the rib crests at the apex of each rib valley or rib crest is 16° to 25°.The centrifugally cast pipe particularly preferably has one of the geometries of the inner ribs and rib valleys and rib crests described in EP 1 525 289 A1.

[0049] The invention is explained in more detail below with reference to drawings illustrating exemplary embodiments of the invention. In these drawings: Fig. 1 a schematic, perspective view of a tool in a pipe showing the cutting line to be made by the cutting edge of the tool; Fig. 2 a perspective view of a tool; Fig. 3 a perspective view of a base body of a tool with a section of a removed push rod; Fig. 4 a subassembly of the base body according to Fig. 3 with an inserted push rod subassembly; Fig. 5 a schematic side view of a deep hole drilling machine and Fig. 6 a schematic side view of a collet unit.

[0050] The Fig. 1 shows a tool 1 with a base body 2 extending along a longitudinal axis A and a cutting edge 3 arranged on the outer circumference of the base body 2. In the base body 2, a push rod 4 is provided, which can be moved relative to the base body 2. The base body 2 of the tool 1 is connected to a Fig. 1 not shown thread with a (in Fig. 1 not shown) drill pipe 101 of the deep hole drilling machine 100. The deep hole drilling machine 100 can drill the base body 2 via the drill pipe 101 both through the Fig. 1 The centrifugally cast pipe 5 shown in the drawing can be pulled and rotated during the pulling movement. The dotted line 6 shows Fig. 1 the cutting line is shown along which the cutting edge 3 cuts the material of the centrifugally cast pipe 5, while the base body 2 is pulled and rotated through the centrifugally cast pipe 5.

[0051] It is from the Fig. 1 It can be seen that in an embodiment in which the base body 2 has a further cutting edge on its outer circumference, which is arranged at the same height as the cutting edge 3 shown, but at a different position in the circumferential direction, for example opposite the cutting edge 3 shown, a second helical cut is made in the centrifugally cast tube 5 at the same time.

[0052] At the Fig. 2 In the embodiment shown, the tool 1 has a base body 2, on whose outer circumference cutting edges 3 are formed. The cutting edges 3 are formed on indexable inserts 10. The indexable inserts 10 are each detachably connected to a part of a cartridge 11, namely, screwed thereto. The cartridge 11 is slidably arranged in a recess (pocket) on the base body 2. They are held in the recesses (pockets) by bar springs 14.

[0053] The sectioned area of ​​the Fig. 2 It can be seen that the push rod 4 has a surface section 20 in the area of ​​the pockets and the cassettes 11 arranged in the pockets, which extends at an angle to the longitudinal axis A of the base body 2. In the Fig. 2 illustrated embodiment, the push rod 4 has two opposite surface sections 20, each of which extends at an angle to the longitudinal axis A of the base body 2, since in the embodiment shown in Fig. 2 illustrated embodiment, two opposing cutting edges 3 are provided on opposing indexable inserts 10, each at the same height along the longitudinal axis A of the base body 2, which are each screwed to a part of a cassette 11 assigned to them, wherein the respective cassette 11 is located in a pocket assigned to it in the base body 2 and is supported on the surface section 20 of the push rod 4 assigned to it.

[0054] The sectioned area of ​​the Fig. 2 it can be seen that - when the push rod 4 is moved relative to the base body 2 - the respective cassette 11 slides along the obliquely running, associated surface section 20 of the push rod 4 and thus the position of the cutting edge 3 relative to the longitudinal axis A can be changed.

[0055] Five cutting edges 3 are arranged at different heights along the longitudinal extension of the base body 2 and at different positions along the circumference of the base body 2, so that they lie on a helical line. Two cutting edges are arranged at the same height along the longitudinal extension of the base body 2, but at different positions along the circumference of the base body 2.

[0056] The Fig. 2 also shows that the base body 2 of the tool 1 is held between two collet units 21 which are spring-loaded.

[0057] The Fig. 3 shows a perspective view of a base body 2 of a tool 1 with a section of a removed push rod 4. It can be seen that the base body 2 can be assembled from subassemblies 22. This makes it possible to adapt the length of the base body 2 and / or the number of cutting edges of the base body 2 to the desired machining operation.

[0058] The Fig. 3 The section of the removed push rod 4 shown in the drawing shows that the push rod 4 can also be assembled from subassemblies 23, so that the adjustment of the base body 2 can also be achieved by adjusting the push rod 4. In addition, the Fig. 3 It is easy to see how the surface sections 20 running at an angle to the longitudinal axis A can be designed.

[0059] Fig. 3 further shows that a base body 2 can be designed with five recesses (pockets) at the same height along the longitudinal extension of the base body 1, in each of which cassettes 11 with indexable inserts 10 can be arranged. Thus, with such a base body 2, five recesses extending helically along the inside of the tube can be created with a single cut. For better illustration, the cassettes 11 and indexable inserts 10 are shown resting on the surface sections 20 of the leftmost subassembly 23 of the push rod 4.

[0060] The Fig. 4 shows a subassembly 22 of the base body 2 according to Fig. 3 with inserted subassembly 23 of the push rod 4. The Fig. 4 illustrates that the subassembly 22 of the base body 2 has through holes 24 through which fitting screws are passed, with which the individual subassemblies 22 of the base body 2 can be connected to one another

[0061] Furthermore, the Fig. 4 that the subassembly 23 of the push rod 4 has, as part of the angular surface section 20, a likewise angular T-shaped groove 25. The cassette 11 has a (in Fig. 4 not shown) which engages in the T-shaped groove 25 and is slidably guided therein. A spring can be provided between the T-shaped foot and the remaining parts of the cassette 11, which spring acts on the remaining parts of the cassette 11 relative to the foot in the direction of a preferred position. When the push rod 4 moves in the longitudinal direction A, the foot moves within the T-shaped groove 25 and migrates outwards along this groove, so that the position of the cassette 11 relative to the longitudinal axis A can be adjusted.

[0062] Fig. 5 shows a schematic side view of a deep-hole drilling machine 100. The tool 1 is visible, which is connected to a drill pipe 101 via a thread. A first drive unit 102 can rotate the drill pipe 101 (and thus the tool 1 connected to the drill pipe 101) and axially push (pull) or pull it. The drive unit 102 has an angle indexing mechanism so that the workpiece 1 can be precisely inserted into the pipe 104 to be machined at a desired angular position.

[0063] The push rod 4 runs in the drill pipe 101. A further drive unit 103 is provided on the drive unit 102, with which the axial position of the push rod 4 relative to the base body 2 of the tool 1 can be adjusted.

[0064] In Fig. 1 the tool is shown in a position between the left end of the pipe 104 to be machined and the right end of the pipe being machined. To create the recess running helically along the inside of the pipe 104, the tool 1 is moved with retracted cutting edges 3 to the left end of the pipe 104 and there brought into a desired angular position in the circumferential direction of the inside of the pipe 104. The cutting edges 3 are then extended by axial movement of the push rod 4 relative to the base body 2 and then pulled through the interior of the pipe 104 with the deep hole drilling machine 100, rotating it about its longitudinal axis so that the cutting edges 3 make a cut along a helical cutting line on the inside of the pipe 104.

[0065] The deep-hole drilling machine 100 has a further drive unit 105, with which the pipe to be machined can be moved and rotated axially. The superimposed rotational movement and axial movement of the tool relative to the pipe during cutting, as provided by the invention, can thus be achieved via the drive unit 102 alone, the drive unit 105 alone, or by a combination of the drive units 102 and 105.

[0066] The Fig. 6 The collet unit 21 shown has three collets 40, each of which assumes the function of a support plate. The respective collet 40 is pivotally mounted about a pivot axis 41 running in the circumferential direction of the base body 2 (see pivot arrow B). Furthermore, the collet unit 21 has a conical ring 42, which is displaceably mounted in the axial direction on the outer circumference of the base body 2. The ring 42 combines the counterparts provided for each collet 40 in one element. The ring 42 is spring-loaded by a sleeve-shaped spring assembly 43, so that an axial movement of the ring 42 along the outer circumference of the base body 2 from a first position (cf. Fig. 6 ) into a second position (further to the right of the one in Fig. 6 shown position) tensions the spring assembly 43. The ring 42 is mounted with play on the outer circumference and can thus tilt about an axis perpendicular to the longitudinal axis A, for example starting from the position shown in Fig. 6 In the position shown above, the springs move more to the right than the springs at the bottom. This generates restoring forces of varying strengths around the circumference of the ring 42.

[0067] The ring 42, which combines the counterparts into one element, has a conical contact surface 44. The free ends of the collets 40 have an inclined contact surface 45. The use of inclined contact surfaces ensures that, upon movement of the collet 40 toward the ring 42, an initial contact is made between the free end of the collet 40 and the ring 42. Upon further pivoting of the collet 40 toward the outer circumference of the base body 2, the free end of the collet 40 slides along the contact surface 44 of the ring 42, causing an axial movement of the counterpart, which preloads the spring assembly 43. Fig. 6 An arrangement is shown in which the collets 40 are not preloaded; they rest on the outer circumference of the base body 2. The ring 42 and the abutment of the spring assembly 43 are positioned so far to the right in the Fig. 6 moved so that the spring pack 43 is extended and does not press the ring 42 against the free end of the collets 40. This setting represents the minimum diameter of the collet unit 21. The Fig. 2 and 3 For example, the figures show embodiments in which the collets 40 rest against the ring 42. It can be seen that the collets 40 project radially beyond the remaining parts of the base body 2.

[0068] The pivoting of the collets 40 towards the outer circumference of the base body 2 is carried out by the Fig. 6 Contact (not shown) of the radially outward-facing surfaces 46 of the collets 40 with the inner circumference of the pipe. A smaller inner circumference of the pipe forces the collets 40 further inward than a wider inner circumference of the pipe. It is clear that by providing multiple collets 40, deviations of the inner circumference of the pipe from a circle can also be accommodated.

[0069] At the end of the spring assembly 43, a counterbearing is provided in the form of a threaded ring 47. The threaded ring 47 has an internal thread and can be moved axially by rotation along an external thread 48 provided on the outer circumference of the base body 2. The preload of the spring assembly 43 can be adjusted by axially displacing the threaded ring 47.

[0070] In the Fig. 6 The base body 2 continues to the right with the part of the base body 2 that has the pockets and cassettes 11. To the left in Fig. 6an external thread 49 is provided with which the base body 2 can be connected to the drill pipe 101.

Claims

1. Deep-hole drilling method for producing a pipe having an inner profile which has at least one recess extending helically along the inside of the pipe, wherein the pipe is a centrifugal casting pipe (5) and the inner profile has a plurality of recesses, namely n extending helically along the inside of the pipe, characterized in that • with a deep-hole drilling machine, a tool (1), which has a base body (2) extending along a longitudinal axis and n cutting edges (3) arranged on the outer circumference of the base body (2), is pulled through the interior of the pipe and thereby rotated about its longitudinal axis (A) and / or the pipe is rotated about its longitudinal axis (A), such that the cutting edges (3) make a cut along a helical cutting line on the inside of the pipe or • the pipe is pushed or pulled with a device along its longitudinal axis (A) via a tool (1), which has a base body (2) extending along a longitudinal axis and n cutting edges (3) arranged on the outer circumference of the base body (2), and, thereby, the pipe is rotated and / or the tool (1) is rotated about its longitudinal axis (A), such that the cutting edges (3) make a cut along a helical cutting line on the inside of the pipe.

2. Deep-hole drilling method according to claim 1, characterized in that the recesses extending helically along the inside of the pipe are produced by a plurality of cuts, wherein • the tool (1) is pulled through the interior of the pipe during each cut and the tool is thereby rotated about its longitudinal axis (A) and / or the pipe is rotated about its longitudinal axis, such that the cutting edges (3) make the respective cut along a helical cutting line on the inside of the pipe or • the pipe is pulled or pushed over the tool (1) during each cut and, thereby, the pipe is rotated about its longitudinal axis and / or the tool (1) is rotated about its longitudinal axis (A), such that the cutting edges (3) make the respective cut along a helical cutting line on the inside of the pipe.

3. Deep-hole drilling method according to Claim 1 or 2, characterized in that the radial distance of the cutting edges (3) relative to the longitudinal axis (A) of the base body (2) is changed between a first cut and a second cut.

4. Deep-hole drilling method according to one of Claims 1 to 3, characterized in that a drilling oil or cooling lubricant is introduced into the interior of the pipe and flows through the pipe counter to the pulling or pushing direction of the tool (1).

5. Deep-hole drilling method according to one of Claims 1 to 4, characterized in that it is performed with the deep-hole drilling machine, wherein the deep-hole drilling machine has a linear drive for the tool and a rotary drive for the tool, wherein the tool has a tubular base body (2) and the respective cutting edge (3) is formed on an indexable insert (10), wherein the respective indexable insert (10) is releasably connected to a part of a cassette (11), wherein the cassette (11) is movable relative to the base body (2).

6. Deep-hole drilling method according to Claim 5, characterized in that the cassette (11) can be displaced along an inclined plane which is at an angle to the longitudinal axis (A) of the base body (2).

7. Deep-hole drilling method according to one of Claims 5 or 6, characterized in that a support plate (16) is provided on the outer circumference of the base body (2).

8. Deep-hole drilling method according to one of Claims 5 to 7, characterized in that the rotary drive can feed the cutting edge (3) into at least two different starting points for a cut, wherein the starting points differ in their rotational positions about the longitudinal axis (A).