WO2018215179A1

WO2018215179A1 - Method for finish-machining a channel in a workpiece

Info

Publication number: WO2018215179A1
Application number: PCT/EP2018/061244
Authority: WO
Inventors: Daniel Frey; Franz Sebastian KRUEGER
Original assignee: Robert Bosch Gmbh
Priority date: 2017-05-24
Filing date: 2018-05-03
Publication date: 2018-11-29
Also published as: DE102017208783A1

Abstract

The invention relates to a method for finish-machining a channel (20) in a workpiece (10), wherein the channel (20) has a curved channel central axis (22) and is formed by at least two workpiece parts (12, 14) of the workpiece (10), having the steps of: - arranging the at least two workpiece parts (12, 14) with respect to one another so as to form the channel (20) with the curved channel central axis (22), and - finish-machining the channel (20) by means of a subtractive method.

Description

Description title

Method for reworking a channel in a workpiece Prior art

The invention relates to a method for reworking a channel in a workpiece and a flow component with a curved channel according to the preamble of the independent claims. The subject matter of the present invention is also a computer program and a storage medium.

The production of flow or channel geometries in spiral housings is done today by means of sand casting, precision casting and milling, the flow geometry is then mechanically reworked, for example. By methods such as blasting, flow grinding, polishing, etc., to improve the surface quality. The entire manufacturing process for

Realization of a flow geometry with a sufficiently high

Surface quality is very expensive.

In the case of multipart spiral housings, the individual housing parts must be individually reworked due to the complex flow or channel geometry, so that after the assembly of the housing parts, the channel to the

Transitions or separation points edges or paragraphs, which lead to unfavorable flow conditions, in particular to a reduction of the efficiency.

Furthermore, the machining is very time-consuming, because the geometry is not typical of milling and therefore must be traversed in many lanes. EP 2 095 894 A1 discloses a process for producing a

Turbine wheel blade with straight outlet channels for a cooling medium, wherein the introduction of the exhaust ducts eroding methods such. As the electrochemical erosion (ECM) or the spark erosion (EDM) are proposed.

In DE 44 28 207 AI a method for generating curved

Cooling air ducts in an air-cooled turbine blades bearing

Impeller disc revealed. These cooling air ducts are produced by

Electro-erosion or electrochemical machining, with a

circular arc-shaped tool is used, which is pivoted about the center of the arcuate curved cooling air duct.

DE 10 2010 032 701 Al discloses a process for producing a

Metal component having a generated by a material-removing and / or a material-forming machining generated three-dimensional shape. Here, a processing of one or more excellent component sections by electrochemical machining by means of a nozzle-like cathode via which an electrolyte is discharged into the work area, wherein the cathode or the metal component is moved by means of a manipulator element freely in space.

Disclosure of the invention

The present invention is a method for reworking a channel in a workpiece, wherein the channel is a curved

Has channel central axis and of at least two workpiece parts of the

Workpiece is formed, with the steps:

Arranging the at least two workpiece parts relative to each other so that the channel is formed with the curved channel central axis, and

- Post-processing of the channel by means of a removing process.

The subject matter of the present invention is furthermore a flow component, in particular a spiral casing, with a channel for guiding a fluid flow, wherein the channel is formed by at least one first housing part of the flow component and a second housing part of the flow component and a curved one Channel centerline, wherein the channel further at least one

Transition region is continuously formed from the first housing part to the second housing part due to a post-processing of the channel by means of an erosive method.

The subject of the present invention is also a computer program which is adapted to the o.g. Execute method, and a machine-readable storage medium on which the computer program is stored.

The workpiece may be formed as a flow component, in particular as a spiral housing, for guiding a fluid flow. The spiral housing can for

Leakage of a fluid flow from an impeller to be formed

kinetic (moving) energy of fluid flow in static pressure

convert. The volute may be part of a turbo compressor stage.

The at least two workpiece parts or the two housing parts can

have metallic areas. The at least two workpiece parts or the two housing parts may also be formed metallic or from a

Metal exist. The metal may be selected from the group consisting of: iron, aluminum, copper and alloys thereof.

The at least two workpiece parts are arranged to one another or

composed so that the channel is formed with the curved channel center axis. That is, in other words, the at least two

Workpiece parts before the step of arranging already one each

Channel section, wherein the channel is then completely formed in the step of arranging the at least two workpiece parts. Consequently, the

Channel with the curved channel center axis in the step of arranging the

at least two workpiece parts and not only subsequently formed.

Accordingly, the at least two workpiece parts can already by a

suitable molding process known to those skilled in the art

be prepared or preprocessed, that they each have a channel section

exhibit. The at least two workpiece parts can, for example, be arranged or assembled adjacent to each other in the step of arranging, in order to form the channel with the curved channel center axis. In the context of this invention, the central axis of the channel can essentially be understood as the connecting line of the center points of the channel cross sections of the channel. The central channel axis is curved. In other words, that the channel central axis of the channel or the connecting line of the centers of the channel cross-sections has at least one portion which has a curvature. Preferably, a major part of the central channel axis or the entire central channel axis is curved. The channel central axis of the channel may be arcuate, helical or spiral. The channel central axis preferably runs along a flow direction of a fluid stream flowing during operation or use.

The channel can be elongated. That is, in other words, that the channel may have a greater extent along the channel center axis than transverse to the channel center axis. The channel may have varying channel cross sections in the direction of the channel center axis. The surface of the channel cross-sections of the channel can steadily increase in the direction of the central axis of the channel or steadily reduce. The channel cross sections may in this case be substantially rounded, circular or oval. The channel is preferably formed closed in the circumferential direction. The channel can be used to guide a

Fluid flow may be formed.

Subsequent editing is to be understood as subsequent editing of an already existing channel. Postprocessing can be a

Include or be fine machining. The reworking can take place, in particular, on at least one transition region from the first workpiece to the second workpiece. The reworking preferably takes place in the channel at all transitional areas from the first workpiece to the second workpiece. A transition region can be understood as meaning the region of a separation point between the assembled workpiece parts or housing parts. In other words, a transition region can be understood as meaning the region of a channel inner surface which has a transition from the first workpiece to the second workpiece or from the first housing part to the second housing part. The transition regions may have multiple, non-contiguous subsections. The transition areas may include paragraphs, steps, and / or edges prior to the post-processing step.

In the context of this invention, the term "continuous" can be understood as meaningless, stepless, edgeless and / or continuous.

In the context of this invention, a removal process can be understood as meaning a process in which at least one chemical and / or thermal removal takes place. In other words, in the ablation process, layers of material in the channel are chemically and / or thermally removed in the channel.

By the method according to the invention, it is now possible edges and paragraphs, which arise in a channel at the separation points or transition areas between the assembled workpiece parts or housing parts and have a negative effect on the flow or the efficiency in operation, subsequently remove and Thus, to ensure a continuous course of the channel inner surface, in particular at the transition areas of the. In contrast to the prior art, in which to minimize the edges or paragraphs the workpiece parts are each individually reworked by expensive methods to obtain a high surface quality, and then assembled (without performing a post-processing in the assembled state), takes place according to the invention common post-processing of the workpiece parts or the channel inner surface by means of an erosive method. Accordingly, the workpiece parts can first be produced or preprocessed individually by a favorable method, without having to pay attention to a high surface quality, since post-processing of the channel or the channel inner surface takes place after assembly. As a result, among other things, the edged or uneven

Transition regions on the channel inner surface "smoothed", so that a high surface quality and shape accuracy of the channel can be provided at low cost and low cost Accordingly, in a cost effective manner, a flow component with a

flow-optimized channel are provided. The reworking step can be repeated several times using the same ablation method. However, the reworking step can also be repeated several times using different removal methods. As a result of this measure, the dimensional accuracy and surface quality can be configured or adapted as required and correspondingly further increased.

It is advantageous if, in the step of reworking or in the

abtragenden process of the channel is flowed through by an active medium. In this case, it is particularly advantageous if the channel is completely separated from the active medium, i. flows through the entire channel cross-section. The active medium may be selected from the group consisting of: electrolyte, etching medium, dielectric. In the context of this invention, an active medium can be understood as meaning a medium, in particular a liquid or solution, which is an ablation or the step of ablation alone or in the

Interaction with other elements causes. By this measure, the removal in the channel or on the channel inner surface can be carried out inexpensively and thus a high surface quality can be achieved. It is also advantageous if the channel is flowed through by the active medium in the direction of the central axis of the channel, in particular from a channel inlet to a channel outlet which is different from the channel inlet. That is to say, in other words, that the passage is flowed through by the active medium, as in operation of the flowing fluid flow. Accordingly, the equivalent

Flow direction of the active medium of the flow direction of a flowing during operation fluid flow. By this measure, a flow-optimal geometry or surface can be generated in the channel.

Furthermore, it is advantageous if the erosive method is selected from the group consisting of: electrochemical method, in particular electrochemical erosion or metal etching, chemical method, in particular etching, thermal method, in particular spark erosion, or combinations thereof. In this case, in a step of reworking, a plurality of identical or also different ablation methods can be executed. However, it is also conceivable that between the ablating procedures The two parts of the workpiece are disassembled and reassembled to change, for example, a tool electrode. As a result, the removal in the channel or on the channel inner surface can be carried out inexpensively and the surface quality can be further increased.

It is also advantageous if the erosion method is an ECM method, wherein prior to the step of arranging the at least two workpiece parts, a step of inserting a curved tool electrode into one

Channel section of one of the workpiece parts and after the step of

Post-processing the channel a step of removing the curved ones

Tool electrode is performed from the channel section. The curved tool electrode in this case has a shape corresponding to the curved channel section or to the curved channel. Alternatively, it is advantageous if the erosion method is an ECM method, wherein after the step of arranging the at least two workpiece parts, a step of inserting a curved variable geometry tool electrode into the channel and after the step of reworking the channel a removal step the curved variable geometry tool electrode is carried out of the channel. The curved variable geometry tool electrode is configured to vary or change its geometry, for example, by fanning. In this case, it is particularly advantageous if the steps of inserting the curved tool electrode, arranging the at least two workpiece parts, reworking the channel and removing the curved tool electrode are repeated at least once, wherein in the step of insertion different curved

Tool electrodes, in particular curved tool electrodes are used with different geometry or different cross-section or the geometry of the curved tool electrode is varied with variable geometry. The ECM process is an electrochemical removal with external voltage source and stands for electrochemical machining. By means of ECM machining can be a very good surface finish and

Form accuracy can be realized at low cost. Here, due to the multi-part of the workpiece or the spiral housing, the curved tool electrode for the ECM method - before the channel through the

Arranging the two workpiece parts is formed - in a channel section used a workpiece part and after processing again

be removed, so that the accessibility (without undercut) for the insertion and removal of the curved tool electrode

is guaranteed. Alternatively, inaccessible undercuts in the channel can be machined by means of a variable geometry tool electrode so that the electrode, after assembly of the two

Workpiece parts used and after the processing of the channel again

can be removed without the workpiece parts must be disassembled again. Consequently, by targeted design of the electrode geometry, the geometry of the channel can be influenced.

For example, planar surfaces can be formed curved from the pre-machining in order to produce a streamlined geometry. The target geometry can be optimized in advance by iterations of ECM removal simulations and flow simulations.

The at least two workpiece parts or housing parts can be releasably connected to each other. The detachably connecting step may be performed after the step of arranging the at least two workpiece parts and before the step of post-processing the channel. However, the releasably connecting step may also be done after the post-processing step of the channel.

A releasable connection can be understood as meaning a connection which can be released without destroying the at least two workpiece parts or housing parts.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially when the program product or program is executed on a computer or a device.

The inventive method can, for example, in software or hardware or in a hybrid of software and hardware, for example in a

Be implemented control unit. drawings

The invention will now be described by way of example with reference to the accompanying drawings. Show it:

Fig. 1 a designed as a spiral housing according to the invention

Flow component according to an embodiment;

Fig. 2a-c is a sequential representation of the sequence of several steps of the post-processing of the channel of the flow member of Fig. 1; and

3 is a flowchart of a method according to a

Embodiment.

In Fig. 1, a flow component according to the invention is provided in its entirety by the reference numeral 10.

The flow component 10 is formed as a spiral housing 10. The

Flow member 10 and the spiral housing 10 has a first housing part 12 and second housing part 14. The first housing part 12 has a first channel section 16. The second housing part 14 has a second

Channel section 18. The two housing parts 12, 14 and the two

Channel cuts 16, 18 together form a channel 20. The two

Housing parts 12, 14 are formed metallic.

The channel 20 is designed to guide a fluid flow, in particular during operation or use of the flow component 10. The channel 20 has a curved channel central axis 22. The channel 20 or the channel central axis 22 extends from a channel inlet 24 to a channel outlet 26. The channel 20 has rounded channel cross sections. The channel 20 further includes along the channel centerline 22 - from the channel inlet 24 to the

Kanalauslass 26 toward - a steadily increasing cross-sectional area. Furthermore, the channel 20 has at a channel inner surface 28 transition regions 30 from the first housing part 12 to the second

Housing part 14 and from the first channel section 16 to the second

Channel section 18. Since the channel 20 and the channel inner surface 28 has been reworked by means of an erosive method, the

Transition regions 30 formed continuously. In other words, the transition region 30 is formed free of steps, steps and / or edges and thus without any chamfer or edges.

In Fig. 2a-c, the sequence of several steps of the post-processing of the channel 20 of the flow member 10 of Fig. 1 is shown in sequence. In the exemplary embodiment shown, an ECM method is selected as the ablative method, wherein any electrochemical, chemical and thermal methods and combinations thereof are conceivable within the scope of the invention.

FIGS. 2 a - c show a section of the flow component 10 or spiral casing 10 from FIG. 1. The spiral casing 10 is not yet completely finished and thus formed as a workpiece 10. Accordingly, the first housing part 12 as the first workpiece part 12 and the second housing part 14 as the second workpiece part 14 are formed. As a result, the first workpiece part 12 has the first channel section 16 and the second workpiece part 14 has the second channel section 18. For the ECM process both housing parts 12, 14 must be metallic.

Fig. 2a shows a state before the first post-processing. Accordingly, prior to the first post-processing, a curved tool electrode 32 has been inserted into the first channel section 16 of the first workpiece part 12.

Subsequently, the two workpiece parts 12, 14 were arranged or assembled to each other, so that the channel 20 with the curved

Channel center axis 22 has been formed, wherein the curved

Tool electrode 32 is disposed in the channel 20. Here, the channel inner surface 28 at the transition regions 30 of the first

Workpiece part 12 to the second workpiece part 14 edges or steps. Thereafter, the first post-processing of the channel 20 and the

Channel interior surface 28 by means of the ECM method. Here, an external voltage source is applied to the two workpiece parts 12, 14 as the anode (+) and the tool electrode 32 as the cathode (-). Following this, an active medium, which is an electrolyte (for example, aqueous sodium nitrate or

Sodium chloride electrolyte solution) is delivered to the channel 20. The

The active medium or the electrolyte then flows through the channel 20 between the channel inner surface 28 and the tool electrode 32 along the

Channel centerline 22 from the channel inlet 24 to the channel outlet 26 and transports the resulting Abtragprodukte out of the channel 20 out. Here, anodic metal dissolution occurs at the channel inner surface 28, the anode, i. the two workpiece parts 12, 14 emit electrons, thereby forming metal ions, which pass into the electrolyte or the electrolyte solution. Certain metals, such as iron coincide with

Hydroxide ions that form at the cathode (-) arise as a solid and can be mechanically separated from the electrolyte. Other metals such as copper remain in solution and initially remain in solution.

Due to this reworking of the channel 20 by means of an erosive method, namely the ECM method in which both the channel 20 forming workpiece parts 12, 14 are simultaneously reworked, a simultaneous ablation takes place on the channel inner surface 28, whereby the edges and steps at the transition areas 30th be removed. This "smoothing" of the channel inner surface 28 creates a continuous course on the

Transition regions 30 with a high surface quality and dimensional accuracy, so that the channel 20 has a flow-optimized design.

Subsequently, the two workpiece parts 12, 14 are disassembled so that the curved tool electrode 32 can be removed from the first channel portion 16. Provided that achieved by the post

Surface quality of the channel inner surface 28 is sufficient, the two workpiece parts 12, 14 can be reassembled to the finished

Form flow component 10. In the embodiment shown, however, another two reworks follow analogously to the post-processing explained above. In detail, the above-mentioned steps from FIG. 2a are respectively shown in FIGS. 2b and 2c

repeatedly, i. the steps of inserting the curved tool electrode 32, arranging the at least two workpiece parts 12, 14, of the

Post-processing of the channel 20 by means of the ECM method and the removal of the curved tool electrode 32. Here, however, in each of the three post-processing shown in FIG. 2a-c is a curved

Tool electrode 32, 32 ', 32 "with different geometry, namely

used or used different cross section. The cross section takes in the embodiment shown by the first post-processing of FIG.

2a to the third post-processing of FIG. 2c. This allows the

Shape accuracy and surface quality of the channel 20 and the channel inner surface 28 further configured or adapted depending on the requirements and increased accordingly.

3 shows a flow chart of an embodiment of a method 100 according to the invention for reworking a channel 20 in a workpiece 10, wherein the channel 20 has a curved channel central axis 22 and is formed by at least two workpiece parts 12, 14 of the workpiece 10. The method 100 comprises a step 102 of arranging the at least two workpiece parts 12, 14 relative to one another so that the channel 20 is formed with the curved channel central axis 22. The method 100 further includes a step 104 of

Post-processing of the channel 20 by means of a removing process.

If the ablating process is an ECM process, as shown in FIGS. 2a-c, prior to step 102 of arranging the at least two workpiece parts 12, 14, the method 100 includes a step 106 of inserting a curved one

Tool electrode 32, 32 ', 32 "in a channel section 16, 18 of the one

Workpiece parts 12, 14 and after the step 104 of reworking the channel 20, a step 108 of removing the curved tool electrode 32, 32 ', 32 "from the channel section 16, 18th

The method 100 may also optionally include a step 110 of the releasable

Connecting the at least two workpiece parts 12, 14 include. If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims

claims

A method of reworking a channel (20) in a workpiece (10), wherein the channel (20) has a curved channel central axis (22) and is formed by at least two workpiece parts (12, 14) of the workpiece (10) steps:

Arranging (102) the at least two workpiece parts (12, 14) relative to each other so that the channel (20) is formed with the curved channel central axis (22), and

- Post-processing (104) of the channel (20) by means of a removing process.

2. The method (100) according to claim 1, characterized in that in step (104) of the reworking of the channel (20) is flowed through by an active medium.

3. Method (100) according to claim 2, characterized in that the

Active medium is selected from the group consisting of: electrolyte,

Etching medium, dielectric.

4. The method according to claim 2 or 3, characterized in that the channel (20) of the active medium in the direction of the central channel axis (22), in particular from a channel inlet (24) to one of the channel inlet (24).

different channel outlet (26) is flowed through.

5. The method (100) according to any one of the preceding claims, characterized

in that the erosive method is selected from the group consisting of: electrochemical method, in particular electrochemical removal or metal etching, chemical method, in particular etching, thermal method, in particular radio erosion, or combinations thereof.

6. The method (100) according to claim 5, characterized in that the

erosive method is an ECM method, wherein before the step (102) of arranging the at least two workpiece parts (12, 14) a step (106) of inserting a curved tool electrode (32, 32 ', 32 ") into a channel section (16, 18) of one of the workpiece parts (12, 14) and

after step (104) of reworking the channel (20), a step (108) of removing the curved tool electrode (32, 32 ', 32 ") from the channel section (16, 18) is performed.

Method (100) according to claim 5, characterized in that the erosive method is an ECM method, wherein

after the step (102) of arranging the at least two workpiece parts (12, 14), a step (106) of inserting a curved variable geometry tool electrode (32, 32 ', 32 ") into the channel (20) and

after step (104) of reworking the channel (20), performing a step (108) of removing the variable geometry curved tool electrode (32, 32 ', 32 ") from the channel (20).

Method (100) according to claim 6 or 7, characterized in that the

Steps (102, 104, 106, 108) of inserting the curved tool electrode (32, 32 ', 32 "), arranging the at least two workpiece parts (12, 14), reworking the channel (20) and removing the curved ones

Tool electrode (32, 32 ', 32 ") are repeated at least once, wherein in step (106) of insertion different tool electrodes (32, 32', 32"), in particular curved tool electrodes (32, 32 ', 32 ") with different geometry be used or the geometry of the curved

Tool electrode (32, 32 ', 32 ") is varied with variable geometry.

Method according to one of the preceding claims, characterized

characterized in that in the step (102) of arranging the at least two workpiece parts (12, 14) are arranged adjacent to one another to form the channel (20) with the curved channel center axis (22).

10. The method according to any one of the preceding claims, characterized

characterized in that the channel (20) is elongated.

11. The method according to any one of the preceding claims, characterized in that the channel (20) in the direction of the channel central axis (22) has varying cross sections.

12. The method according to any one of the preceding claims, characterized

in that the channel central axis (22) of the channel (20) is arc-shaped, helical or spiral-shaped.

13. The method according to any one of the preceding claims, characterized by the additional step:

Releasably connecting (110) the at least two workpiece parts (12, 14).

14. The method according to any one of the preceding claims, characterized

in that the at least two workpiece parts (12, 14) of the

Workpiece (10) are formed metallic.

15. The method according to any one of the preceding claims, characterized

in that the workpiece (10) is designed as a flow component (10),

in particular as a spiral housing (10), designed to guide a fluid flow.

16. Flow component (10), in particular spiral housing (10), with a channel (20) for guiding a fluid flow, wherein the channel (20) of at least a first housing part (12) of the flow component (10) and a second housing part (14) the channel (20) is further formed on at least one transition region (30) from the first housing part (12) to the second housing part (14) due to post-processing of the channel (30). 20) is formed continuously by means of an erosive method.

A computer program adapted to perform the method (100) of any one of claims 1 to 14.

18. Machine-readable storage medium on which the computer program is based

Claim 16 is stored.