Patent Application
20190105717
The invention relates to a chip-removing tool, in particular rotationally driven, chip-removing tool, for deburring bores, which laterally open into a cylindrical recess for example.
The deburring of bores, which laterally open into a cylindrical recess for example, represents a large problem. Such bores are unavoidable for example in the field of motor vehicle technology—in the case of radial bores, which open into a central axial bore of the camshaft or of the crankshaft—and of mobile hydraulics, when the idea is to control a valve piston accommodated in a central bore via control connections in the form of radial channels. Due to the fact that these radial channels need to on principle be produced in a drilling process, it cannot be ruled out reliably even in the case of a special design of the drilling tool that a burr or residual chips remain in a region, in which the radial channel opens into the central bore recess.
Apart from the fact that this chip influences the flow ratios and thus adversely affect the adjustment and function of the corresponding hydraulic control, there is the particular problem that such a chip, if it is not removed prior to starting up, is torn off after a certain time and causes damages with serious consequences in the system.
Attempts have thus always been made and in the course of the increasingly sensitive control technology with increasing effort to remove these residual chips from the radial channel opening as completely as possible. Specifically designed tools have been used thereby, by means of which it was possible to guide the cutting head located on the shaft could be guided towards the chip to be removed as positionally accurately as possible. The required high precision, however, has the result that it made the production process significantly more expensive.
A chip-removing tool for deburring such bores, which solves this object with relatively small effort, is known for example from DE 103 21 670 A1. This publication shows and describes a rotationally driven tool for deburring apertures, e.g. bores. The tool has a cutting head located on a shaft, comprising at least one cutting edge, which extends in the axial direction at least in some sections. A radial force generating unit, by means of which the cutting head can be deflected radially so as to be controlled in response to its rotational movement, is integrated into the tool. The radial force generating unit has an internal fluid channel, from which at least one puncture channel starts, which opens into an outer circumferential surface of the tool in the region of the cutting head. The fluid, which escapes from the opening of the at least one puncture channel, accumulates on the opposite inner wall of the recess, whereby a dynamic pressure is formed between the tool and the inner wall of the recess, which deflects the cutting head radially elastically.
The tool specified in the above-mentioned publication can carry out the deburring process in the case of bores, which open laterally into a cylindrical recess for example, in a reliable and error-free manner. The formation of the at least one puncture channel in the region of the cutting head, however, requires a precise and thus relative comprehensive processing, so as not to damage the cutting edges of the cutting head. In the case of this tool, a relatively high supply pressure of the fluid is also necessary, so as to create a sufficiently large dynamic pressure and thus a sufficiently high radial force, which effects a radial deflection of the cutting head.
A further chip-removing tool for deburring the above-described bores is known from DE 10 2008 056 782 A1. In contrast to DE 103 21 670 A1, the cutting head of the tool from DE 10 2008 056 782 A1 consists of a cutter partial region and a no-cutter partial region, which has a cross section in the form of a segment of a circle, into the outer circumferential surface of which at least two puncture channels, which start radially from a central fluid channel, open. As in the case of the tool from DE 103 21 670 A1, a relatively high supply pressure of the fluid is also necessary in the case of the tool of DE 10 2008 056 782 A1, in order to create a sufficiently large dynamic pressure and thus a sufficiently large radial force, which effects a radial deflection of the cutting head.
Based on the tool, which is known from DE 10 2008 056 782 A1, the invention is thus based on the object of providing a tool, with which it is possible to create a higher radial force on the cutting head without large effort and to thus be able to carry out the deburring process highly effectively, but still precisely, economically, reliably and without error.
This object is solved by means of a chip-removing tool comprising the features of independent claim 1. Advantageous further developments are the subject matter of dependent claims.
A chip-removing tool according to the invention, in particular a rotationally driven, chip-removing tool, e.g. a reamer, for deburring bores, which laterally open into a cylindrical recess for example, has a shaft; a cutting head with at least one cutting wedge on the circumference, said cutting wedge being paired with a flute and having a cutter, which extends in an axial direction at least in some sections, carries out a cutting process on the basis of a relative movement between tool and workpiece, and lies on a virtual cylindrical rotational surface with a diameter that corresponds to the nominal diameter of the chip-removing tool, and at least one cutting wedge- and flute-free surface region on the rotational surface side; at least one fluid channel, which is closed on the cutting head side; and at least one puncture channel, which starts from the fluid channel and comprises an opening that lies in the cutting wedge- and flute-free surface region. In contrast to the above-discussed prior art, the opening located in the cutting wedge- and flute-free surface region in the case of the chip-removing tool according to the invention, lies in a dynamic pressure active surface, which is radially recessed relative to the virtual cylindrical rotational surface of the cutting head, and which is larger than a flow cross sectional surface of the at least one puncture channel at the opening.
In the circumferential direction, the cutting head can thus be divided into a cutting wedge partial region and a cutting wedge- and flute-free surface region. The cutting wedge partial region has the at least one cutting wedge, which defines a cutter and a cutting and free surface in the usual way, and which is paired with a flute. The cutting wedge- and flute-free surface region, in contrast, neither has cutting wedge nor a flute.
The cutting wedge- and flute-free surface region, which has the dynamic pressure active surface, provides for a distribution of the fluid, which escapes at the opening of the at least one puncture channel, in the region or volume between the tool and the inner wall of the recess to be processed. The dynamic pressure building in this region or volume by means of the fluid, which leaves the opening of the at least one puncture channel, acts on the dynamic pressure active surface, whereby a radial force is created, which effects a deflection of the cutting head in the direction of the at least one cutting wedge.
The dynamic pressure active surface is any even or uneven, e.g. convex or concave surface, which lies in the cutting wedge- and flute-free surface region of the cutting head and which is radially recessed relative to the virtual rotational surface of the cutting head, i.e. which lies radially inside the virtual rotational surface, which defines the nominal diameter of the tool. The dynamic pressure active surface is thus a surface, on which the dynamic pressure, which forms between the cutting head and the opposite inner wall of the recess acts in response to a deburring of a bore and a fluid supply of the tool. The dynamic pressure active surface lies opposite, advantageously at least essentially diametrically opposite, the at least one cutting wedge. In the case of a number of cutting wedges, the dynamic pressure active surface lies opposite, advantageously at least essentially diametrically opposite, the center of the cutting wedge region, which has a segment-shaped cross section and in which the number of cutting wedges lie.
Due to the fact that the dynamic pressure active surface is recessed relative to the virtual rotational surface of the cutting head, the surface content of the dynamic pressure active surface, which is responsible for creating a radial force on the tool, is larger than the flow cross sectional surface at the opening of the at least one puncture channel. Under the condition of a sufficiently large fluid supply into the tool, which can readily be realized from a machine tool technology-related aspect, the dynamic fluid pressure forming between the cutting head of the tool and the opposite inner wall of the recess creates a radial force as a function of the size of the dynamic pressure active surface, which radial force deflects the cutting head radially in the direction of the at least one cutting wedge.
As a result of the radial deflection, the at least one cutter of the cutting wedge of the tool, which performs a tumbling motion, moves essentially on a circular path around the longitudinal central or rotational axis of the tool. It has been shown that it is possible in this way to remove the burr or the residual chips, which may be present, respectively, in a gentle and nonetheless reproducible and reliable manner, without running the risk that further residual chip formation occurs at a different location. It goes without saying that a number of cutting wedges can be attached to the cutting head, so that the required processing time of the workpiece can be reduced.
The chip-removing tool according to the invention is thus characterized in that the dynamic pressure active surface is provided in such a way that the sum of the dynamic pressure forces created in the region of the dynamic pressure active surface between the cutting head and the inner wall of the recess, can deflect the shaft radially in the direction of the at least one cutting wedge. As already mentioned, condition for this is that the amount of supplied fluid is sufficiently large and that a stationary flow state can set in the region or volume between the cutting head, in particular the dynamic pressure active surface of the cutting wedge- and flute-free surface region and the opposite inner wall of the recess. This condition can readily be fulfilled by means of a corresponding control of a fluid supply unit provided on the machine tool side.
Compared to the prior art, a larger radial force is created with the same fluid pressure and the deburring process can be carried out highly effectively and efficiently by means of the design of the chip-removing tool comprising a dynamic pressure active surface. A further advantage is attained with the chip-removing tool according to the invention in that a large radial force can be created with little effort and that one and the same chip-removing tool can thus be used to deburr bore diameters of different sizes.
It is thereby irrelevant, how the dynamic pressure active surface was created on the cutting head. For example in the case of the tool specified in DE 103 21 670 A1, a cutting wedge- and flute-free surface region or a dynamic pressure active surface, respectively, can be created easily in that a surface region, in which a part, which is limited in the axial direction and/or in the circumferential direction, of one or a number of cutting wedges are removed, is created on the cutting head in a region, in which an opening of at least one puncture channel lies, by means of an at least partial grinding for example or the like of one or a number of cutting wedges. The cutting wedge- and flute-free surface region obtained in this manner then has a dynamic pressure active surface, in which the opening of the at least one puncture channel lies and the surface area of which is larger than the flow cross sectional surface of the at least one puncture channel.
In the case of the tool specified in DE 10 2008 056 782 A1, a cutting wedge- and flute-free surface region or a dynamic pressure active surface, respectively, can likewise simply be created in that a (cutting wedge- and flute-free) surface region is created in the cutter-free partial region of the cutting head by means of a grinding or the like, which surface region is radially recessed relative to the virtual rotational surface of the cutting head, in which the cutting edges of the cutting head are located and in which the opening of at least one puncture channel lies. The (cutting wedge- and flute-free) surface region obtained in this manner then forms a dynamic pressure active surface according to the invention
The at least one fluid channel preferably runs along the longitudinal central or rotational axis of the chip-removing tool and thereby extends from a clamping section of the shaft into the cutting head. In this case, the fluid channel can in particular easily be formed as a centrical bore, e.g. blind hole, into the tool. On its end located in the tool feed direction, the cutting head is closed, so that fluid cannot escape there from the fluid channel. The fluid does instead escape from the chip-removing tool via the at least one puncture channel, the opening of which is located in the cutting wedge- and flute-free surface region. However, the chip-removing tool according to the invention can also have a number of fluid channels, which run in the shaft, e.g. parallel.
The at least one puncture channel runs essentially in the radial direction, preferably at right angles to the fluid channel. In this case, the at least one puncture channel can be formed particularly easily as a radial bore. In the cutting wedge- and flute-free surface region, however, the chip-removing tool can also have a number of puncture channels, the openings of which lie in the cutting wedge- and flute-free surface region. By means of a number of puncture channels, the fluid supplied into the tool can be distributed more quickly across the dynamic pressure active surface, whereby a more effective and quicker processing is possible. The course of the puncture channels from the fluid channel to the openings lying in the cutting wedge- and flute-free surface region, can on principle be designed arbitrarily.
It has been shown that the fluid itself can be a gaseous medium, e.g. air or an aerosol, but a liquid coolant, which is common for processing, is preferably used.
Tests have shown that the radial force created by the dynamic pressure is larger, the larger the dynamic pressure active surface is as compared to the flow cross sectional surface of the at least one puncture channel at the opening. The dynamic pressure active surface can thereby be arranged axially parallel or at an angle to the longitudinal central axis of the chip-removing tool. The dynamic pressure active surface can thereby have the shape of a concave, convex or even surface, but also the shape of a trough-shaped depression, e.g. of an axial groove. The even surface can be formed to be surface-ground or face-milled. It is also possible that a number of differently oriented dynamic pressure active surfaces are arranged inside the cutting wedge- and flute-free surface region.
The dynamic pressure active surface can have the same axial length as the cutting head, can thus extend across the entire length of the cutting head in the axial direction. The dynamic pressure active surface of the chip-removing tool, however, can also have a smaller axial length than the cutting head. In this case, the dynamic pressure active surface can end at an axial distance upstream of the front and/or shaft-side end of the cutting head. In particular, the dynamic pressure active surface can end at a defined distance upstream of the front and rear end of the cutting head. This results in a type of pocket-like space between the cutting head and the inner wall of the recess to be processed. The axial discharge of the fluid along the cutting wedge- and flute-free surface region or the dynamic pressure active surface, respectively, of the chip-removing tool is impeded thereby and the dynamic pressure is increased.
In contrast to the cutting head, the part of the shaft of the chip-removing tool, which does not serve to clamp the tool, can be tapered in its diameter. This ensures a higher elasticity of the chip-removing tool and facilitates the radial deflection of the cutting head.
The cutting head of the chip-removing tool can have a gate, which is known per se, at least one its side, which faces away from the shaft. The insertion of the chip-removing tool is simplified further thereby. If a gate is formed on both sides of the cutting head, the chip-removing tool can also be used to deburr the interior outlet of a bore, into which the chip-removing tool is inserted.
As in DE 10 2008 056 782 A1, the cutting head can be divided in the circumferential direction into a cutting wedge region and a cutting wedge- and flute-free surface partial region, which forms the cutting wedge- and flute-free surface region. In this case, the cutting wedge- and flute-free surface region according to the invention lie inside the cutting wedge- and flute-free surface partial region.
The chip-removing tool can be realized as a stationary cutting tool, e.g. as turning tool, or as a cutting tool, which rotates around a longitudinal central axis as rotational axis, e.g. as a milling, drilling, in particular deep hole drilling, straight-fluted drilling or spiral drilling tool, or as reamer.
There are virtually no limitations for the material selection of the chip-removing tool. The chip-removing tool can either be made of a high-strength material, such as, e.g. wear-resistant steel, high-speed steel (HSS, HSSE, HSSEBM), hard metal, ceramic or cermet, either as a whole, but at least in the region of the cutting head, wherein suitable coatings can also be used.
In a preferred embodiment, the chip-removing tool is a reamer and the dynamic pressure active surface has the shape of an even surface. The tool further has a fluid channel running along the longitudinal central axis of the chip-removing tool, a cutting head, the diameter of which is larger than the diameter of the shaft, as well as a cutting wedge partial region comprising three cutting wedges with straight grooves based on the model of DE 10 2008 056 782 A1. With regard to the complexity in terms of production and the possible radial force, which can be created, this embodiment turns out to be highly advantageous.
Different embodiments of a chip-removing tool according to the invention will be described below by means of the enclosed drawings.
The tool 10 has a shaft 20, a cutting head 30, a fluid channel 21 and two puncture channels 50.
The shaft 20 serves the purpose of clamping the tool in a clamping chuck or the like.
The cutting head 30 sits axially on the tapered longitudinal section 22 of the shaft 20. The cutting head 30, which is straight-fluted in the shown embodiment, has three cutting wedges comprising three cutters 31, which extend in a straight line in the axial direction and which carry out a cutting process on the basis of a relative movement between the tool 10 and a workpiece to be processed, and which lie on a virtual cylindrical rotational surface 40 (see
The tool 10 furthermore has an interior fluid channel 21, which is closed on the cutting head side and which extends through the shaft 20 along the longitudinal central axis 11 into the cutting head 30, and from which two radial puncture channels 50 originate in the region of the cutting head 30. The puncture channels 50 are arranged in such a way that they open with an opening 51 into a dynamic pressure active surface 60, which lies inside the cutting wedge- and flute-free surface region 32, as it is shown in
In the shown embodiment according to
The cutting wedge- and flute-free surface region 32 provides for a distribution of the fluid, which escapes at the openings of the puncture channels 50, in the region or volume between the tool 10 and the opposite inner wall of the recess 2 of a workpiece to be processed, via the dynamic pressure active surface 60. Assuming a sufficient fluid supply into the fluid channel 21, the dynamic pressure, which builds up in this region or volume, of the fluid, which leaves the openings 51 of the puncture channels 50, acts on the dynamic pressure active surface 60, whereby a radial force is created, which effects a deflection of the cutting head 30 in the direction of the cutting wedges with cutters 31.
As a result of the radial deflection, the cutters 31 of the cutting wedges move essentially on a circular path around the longitudinal central axis 11. It has been shown that it is possible in this way to remove a burr or residual chips, which may be present, respectively, in a bore 1, which opens laterally into a cylindrical recess 2 for example, in a gentle and nonetheless reproducible and reliable manner, without running the risk that further residual chip formation occurs at a different location.
On its side facing away from the shaft 20, the cutting head 30 of the tool 10 furthermore has a gate 34, which is known per se.
The chip-removing tool 10 according to the invention is thus characterized in that the dynamic pressure active surface 60 is provided in such a way that the sum of the dynamic pressure forces created in the region of the dynamic pressure active surface 60 between the cutting head 30 and the inner wall of the recess 2 can radially deflect the shaft 20 in the direction of the cutting wedges with cutters 31. As already mentioned, condition for this is that the amount of fluid supplied into the fluid channel 21 is sufficiently large, so that a stationary flow state can set in the region or volume between the cutting head 30, in particular the dynamic pressure active surface 60 of the cutting wedge- and flute-free surface region 32, and the opposite inner wall of the recess 2. A sufficiently large fluid supply can readily be realized from a machine tool-related aspect.
In the embodiments shown in
In contrast to the shown embodiments, the dynamic pressure active surface can have the shape of a concave or convex surface.
It is also possible that a number of differently oriented dynamic pressure active surfaces are arranged inside the cutting wedge- and flute-free surface regions.
In contrast to the design of the cutting wedge- and flute-free surface region shown in
More or fewer than three cutting wedges can furthermore be arranged in the cutting wedge partial region.
The chip-removing tool can likewise have more or fewer than two puncture channels. The course of the puncture channels from the central fluid channel to the openings lying in the cutting wedge- and flute-free surface region can on principle be designed arbitrarily.
The chip-removing tool can furthermore also have a number of fluid channels, which run in the shaft, e.g. parallel, and which each lead to a paired puncture channel.
In addition to its side, which faces away from the shaft, the chip-removing tool can on principle also have a section on its side of the cutting head, which faces the shaft, so that the chip-removing tool can also be used to deburr the interior outlet of a recess, into which the chip-removing tool is inserted.
It is also irrelevant, how the dynamic pressure active surface was created on the cutting head. For example in the case of the tool specified in DE 103 21 670 A1, a cutting wedge-free and flute-free surface region or a dynamic pressure active surface, respectively, can be created easily in that a surface region, in which a part, which is limited in the axial direction and/or in the circumferential direction, of one or a number of cutting wedges are removed, is created on the cutting head in a region, in which an opening of at least one puncture channel lies, by means of a grinding or another machining.
The cutting wedge- and flute-free surface region obtained in this manner then has a dynamic pressure active surface, in which the opening of the at least one puncture channel lies and the surface content of which is larger than the flow cross sectional surface of the at least one puncture channel. In contrast to the design shown in
In the shown embodiments, the chip-removing tool is realized for example as a reamer. It can, however, also be realized as a stationary cutting tool, e.g. as turning tool, or as a cutting tool, which rotates around a longitudinal central axis as rotational axis, e.g. as a milling, drilling, in particular deep hole drilling, straight-fluted drilling or spiral drilling tool.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 205 657.3 | Apr 2016 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2017/057921 | Apr 2017 | US |
| Child | 16153031 | US |
