DE102011120399B4 - Method for producing at least one through-hole in a workpiece - Google Patents

Abstract

Method for producing at least one through-hole (3, 33, 34) in a workpiece (1, 31), in which a pilot hole is first produced by means of a first tool and subsequently reworked with a second tool (5), wherein at least one tool (5) has at least one cooling bore (19), which can be supplied with a coolant, and wherein a region of the workpiece (1, 31) in which the at least one through-bore (3, 33, 34) is provided or positioned on one of the tool insertion side facing away from the workpiece (1, 31) with a covering device (9, 35, 39) is coupled, which in the region of at least one through hole (3, 33, 34) to the workpiece (1, 31) adjacent recess (11) in which at least one tool (5) is immersed during the respective machining operation, characterized in that a plurality of through-holes (33, 34) in the workpiece (31) are produced, wherein the Abdeckeinr Means (35, 39) has a plurality of recesses (11) which cooperate in coupled to the workpiece (31) position each with a portion of the workpiece (31) in which a through hole (33, 34) is provided or arranged.

Description

The invention relates to a method for producing at least one through hole in a workpiece according to the closer defined in the preamble of claim 1. Art.

From practice, methods are known with which very close tolerances having blind holes can be made. First of all, a pilot hole is produced with a pre-driller. Subsequently, the pilot hole is drilled with a finishing tool to the desired diameter with the desired surface finish. In order to meet the high tolerance requirements, a cooling device is provided, by means of which during the preparation of the pilot hole and the post-processing of the pilot hole in the region of a cutting edge of the pilot drill and the finishing tool is cooled. For this purpose, both the pre-drill and the post-processing tool on central cooling holes, through which a coolant flow exiting in the region of a tool tip, flows back through flutes of the tool and thereby supports a removal of chips generated during the machining process. The working cutting area of the respective tool is continuously cooled by the flow of coolant and overheating of the workpiece and the cutting edge by which the workpiece or tool cutting edge can be damaged is prevented.

In the manufacture of through-holes by this method, overheating of cutting edges may occur during pre-drilling when the pilot drill exits the workpiece, the coolant from the cooling hole through the hole outlet splashes forward and the cutting edges still engaged no longer or no longer be sufficiently lapped by the coolant. By no longer present at this moment coolant flow, the workpiece and / or the cutting tool can be damaged and also a jam of chips occur.

A subsequent to the preparation of the pilot hole finishing the pre-drilled through hole is not possible with a fine machining tool used in the manufacture of blind holes with a central cooling bore, since the coolant flow would escape through the through hole to the front. In order nevertheless to ensure cooling during the fine machining, it is known to use external cooling of the tool. However, this is not as effective as an internal cooling via the post-processing tool and can also counteract a chip removal of a positively twisted tool.

In order to improve cooling in the production of through-bores, tools are used which have an inner coolant bore with a coolant outlet in a region facing the cutting edges. However, a coolant throughput with such cooling is very low, whereby the risk of overheating of the tool and a concomitant damage to the surface of the through hole is large and also a chip removal is partially not sufficiently supported. Furthermore, the production of such tools in particular by the complicated production of the cooling holes is expensive.

From the DE 22 55 354 C3 a device is known which is provided for cleaning bores. After making a hole through a deep hole tool, the hole is cleaned by shutting off a coolant supply and introducing compressed air through the coolant channel. If it is a through hole, it is proposed to provide the free end of the through hole with a cover to at least throttle the compressed air at the pressure flow of the bore.

A machine tool for introducing holes in a workpiece is in the DE 102 08 572 A1 described. In this case, a contact device can be provided which can be applied to the workpiece in the region of a bore breakthrough in order to block an outflow of coolant. An abutment surface of the abutment device is positioned over the abutment device in that region in which the bore breakthrough occurs when a drilling tool has completely penetrated the workpiece.

The DE 199 38 856 A1 discloses a deep drilling device, by means of which in particular in crankshafts holes at different positions and in different orientation can be introduced. A covering device is described which is formed with three sealing shells and by means of which a workpiece section can be sealed. For this purpose, the shells are placed by the formation of an almost complete sealing ring around the workpiece to be sealed, so that only on one side of the shell a gap for the implementation of the drilling tool remains. This prevents leakage of pressurized drilling fluid upon breakthrough of the drilling tool.

The present invention has for its object to provide a quick and inexpensive feasible method for producing a plurality of through holes available, in which a continuous flushing and cooling of the each tool can be ensured with sufficient coolant in all stages of processing in a simple and cost-effective manner.

According to the invention this object is achieved by a method having the features of claim 1.

It is proposed a method for producing at least one through hole in a workpiece, in which first by means of a first tool, a pilot hole is made and then reworked with a second tool, wherein at least one tool has at least one can be supplied with a coolant cooling hole, and wherein a region of the workpiece, in which the at least one through hole is provided or arranged, is coupled on a side of the workpiece facing away from the tool insertion with a covering device, which has a recess adjoining the workpiece in the region of the at least one through hole into which at least one Dips tool during the respective machining process. According to the invention, it is provided that a plurality of through bores are produced in the workpiece, wherein the covering device has a plurality of cavities which cooperate in a position coupled to the workpiece with a region of the workpiece in which a through bore is provided or arranged.

The production of several through holes is possible in the method according to the invention with a single cover, whereby the method is fast and inexpensive to carry out.

By arranged on a side facing away from a tool entrance recess, in which the respective tool can dive in particular contactless, it is ensured that the respective tool is lapped in all processing phases of coolant. This results from the fact that the production of the through-hole is configured by the covering device similar to the production of a blind hole and the coolant is conveyed to the outside only via flutes or the like of the respective tool. As a result, a defined coolant pressure is adjustable. Thus, sufficient coolant is always present in the region of a shearing zone of the respective tool and reliably prevents, for example, a brief overheating of cutting edges still in engagement when the first tool penetrates through a surface of the workpiece.

In addition, chip removal is consistently supported by the constant flow of coolant, so that a jam of chips is also reliably prevented. A lifetime of the first and / or second tool is thereby increased with the method according to the invention compared to tools in known methods.

The advantage of the method according to the invention over known methods is the greater the deeper the at least one through hole to be produced.

The post-processing tool is designed in particular for fine machining of the predrilled through-hole, wherein the post-processing tool can be designed as a reamer, a drill or the like. It can also be provided several finishing steps for fine machining of the pre-drilled through hole.

In an advantageous method according to the invention, the cover device is coupled to the workpiece before the production of the pilot hole by the first tool. In this way, even in the production of the pilot hole ensures that the coolant flow at any time, especially at an outlet of the first tool from the workpiece, breaks and thus effectively counteracts a brief overheating of the tool with an optionally resulting damage to the through hole.

Alternatively, it can also be provided that the cover is coupled to the workpiece after the preparation of the pilot hole through the first tool and before the post-processing by the second tool.

In an advantageous embodiment of the method according to the invention, the recess of the cover at least approximately in the form of a blind hole, the center axis is arranged in arranged on the workpiece position of the covering in particular at least approximately congruent to a central axis of the through hole. Such a covering device is easy and inexpensive to manufacture. The blind bore of the covering device has in particular only a slightly larger cross section than the through hole.

In order to prevent leakage of the coolant, in particular between the cover and the workpiece and associated losses, the cover is advantageously arranged sealingly on the workpiece.

For sealing the covering device relative to the workpiece, at least one sealing ring or a sealing washer can be used become. As an alternative or in addition thereto, adjacent surfaces of the workpiece and of the covering device may be elastically coated at least in regions. Furthermore, provision may be made for the covering device to be arranged precisely fitting the workpiece, at least in the region of the at least one through-bore, in order to prevent the coolant from escaping from the recess.

The covering device can in particular be screwed or braced in a simple manner for connection to the workpiece or can be inserted in a form-fitting manner into the workpiece.

In order to be able to easily arrange the covering device even on complex workpieces, such as rotationally symmetrical components, on the workpiece, the covering device can be designed in several parts and the individual parts can be arranged, in particular successively on the workpiece.

The method according to the invention advantageously makes it possible for the cooling bore of the first and / or second tool to be arranged in the region of a central axis of the first and / or second tool. This has in particular over the known design with lateral outlet openings for the coolant, in which a part of the coolant from the outlet for cooling of cutting edges is conveyed forward, but another part is also moved directly to the rear and thus ineffective for cooling, the Advantage that the entire coolant is conveyed in the backflow at the cutting edges of the tool and thereby a very good cooling effect is achieved. Furthermore, such a cooling hole is easy to manufacture and has only a very small effect on the stability of the tool, as acting on the tool torsional forces in the region of a central axis of the tool are the lowest.

The coolant hole can thus be chosen substantially larger than the lateral outlet openings in known tools with the same stability, so that very large coolant flow can be adjusted. In the design of the tool geometry with regard to helix angle, flute depth and the like must therefore not be taken into account the swirl of lateral cooling holes. In addition, a regrinding of the tool is not limited by lateral outlet openings.

In order to be able to monitor the coolant flow at any time in a simple manner, a flow rate measuring device can be provided, by means of which a coolant flow in the region of the first and / or second tool is measured. In this way it can be determined whether a tool cutting edge of the respective tool is sufficiently supplied with coolant at any time.

The method is suitable for the production of through holes in all types of workpieces. However, it is particularly advantageous in the manufacture of through holes in workpieces with high tolerance requirements, such as components from the aerospace sector, can be used. The method can be used in particular for the production of through holes in very complex formed, for example rotationally symmetrical components, such as turbine blade or the like components of engines.

Both the features specified in the claims and the features specified in the subsequent embodiments of the method according to the invention are each suitable for use alone or in any combination with each other to develop the subject invention. The respective feature combinations represent no limitation with respect to the development of the subject matter according to the invention, but essentially have only an exemplary character.

Further advantages and advantageous embodiments of the method according to the invention will become apparent from the claims and the embodiments described in principle below with reference to the drawings.

It shows:

1 a simplified sectional view of a Aufbohrwerkzeugs for boring a pilot hole in a workpiece, wherein on a side facing away from an insertion of the Aufbohrwerkzeugs end of the workpiece, a cover is arranged with a recess;

2 a simplified partial cutaway view of a turbine disk of an engine with a boring tool, wherein a covering device with a recess covering the through hole on a side facing away from the insertion of the Aufbohrwerkzeugs page;

3 one of the 2 corresponding sectional view through the through hole of the turbine disk with the cover;

4 a simplified partial view of the cut turbine disk of 3 with the cover device shown in three dimensions;

5 a simplified three-dimensional representation of a section of the covering in isolation; and

6 one of the 3 corresponding sectional view through the through hole of the turbine disk, wherein two cover means are provided for different through holes of the turbine disk.

1 shows a workpiece 1 with a pre-drilled through hole 3 , wherein the through hole 3 with a boring tool 5 is reworked.

On one of an insertion side of the boring tool 5 along the arrow 21 opposite side 7 of the workpiece 1 is a covering device 9 arranged, which is a recess 11 having. The recess 11 forms together with the workpiece 1 before introducing the through hole 3 a cavity.

The recess 11 is presently designed as a blind hole whose central axis 13 here congruent to a central axis 15 the through hole 3 is arranged. A depth of the blind hole 11 is chosen such that both a pre-drilling tool and the boring tool 5 contactless in the blind hole 11 can dive. For this purpose, the blind hole 11 a diameter which is as close as possible to a diameter of the through hole 3 is trained.

The boring tool 5 has an integrated coolant device 17 on, with coolant - for example, water or oil - via a dashed central coolant hole 19 in the boring tool 5 towards a top 21 of the boring tool 5 and at its end in the insertion direction P1 of the boring tool 5 from the boring tool 5 in the direction of the blind hole 11 is encouraged.

Starting from the blind hole 11 For example, the coolant can only have flutes arranged with a helix angle 23 of the boring tool 5 against the insertion direction P1 of the boring tool 5 in the direction of the arrows 22 . 23 be promoted back. Due to the described coolant flow is a chip removal of cutting edges of the boring tool 5 supported.

To a leakage of coolant between the cover 9 and the workpiece 1 To prevent or minimize as possible, is a the workpiece 1 facing surface 25 at least in the area of the through hole 3 fit exactly to one of the cover 9 facing surface 27 of the workpiece 1 customized.

This causes a bore exit of the coolant hole 19 on a front side of the boring tool 5 can, a bearing surface of the boring tool 5 be provided with frankings.

The cover 9 was here before introducing the pilot hole, in particular via a screw connection not apparent to the workpiece 1 coupled, so that a sufficient pressure force for sealing arrangement on the workpiece 1 is present. This can be reliably prevented that the coolant flow at a passage of the pre-drilling tool from the workpiece 1 tears off, resulting in heat spikes and the material of the workpiece 1 is damaged.

In the 2 to 6 is one each as a turbine disk 31 shown trained workpiece, in which a plurality of distributed over the circumference cooling holes forming through holes 33 . 34 be arranged for a blade root of a blade. This area of the turbine disk 31 is mechanically highly loaded during operation and thermal damage to the material in this area can be the starting point for the formation of cracks in the material. With the inventive method for producing the through holes 33 . 34 Ensures that a coolant supply in the production of through-holes 33 . 34 is ensured at all times and thus the emergence of material damage in the area of the through holes 33 . 34 safely prevented.

The respective through holes 33 . 34 be analogous to the through hole 3 in the workpiece 1 brought in. To cover the example in the 3 radially outwardly inwardly upwardly directed through holes 33 is one as a sealing ring 35 trained cover provided. The sealing ring 35 points to this, as in the 5 it can be seen, several blind holes 36 on, being in on the turbine disk 31 arranged position of the sealing ring 35 every central axis 38 the blind holes 36 at least approximately congruent to the respective central axis 40 the corresponding through hole 33 is arranged.

The sealing ring 35 is present segmented formed with several parts, part of which 37 in the 5 is apparent. The division of the sealing ring 35 is chosen such that the sealing ring 35 in a simple way to the area of the through holes 33 introduced and with the turbine disk 31 can be coupled. One of the turbine disk 31 facing and fixed in condition with the turbine disk 31 cooperating outer contour of the sealing ring 35 corresponds in a contact area essentially one of the sealing ring 35 facing contour of the turbine disk 31 ,

The through holes 34 which, for example, in the 3 are directed from radially outside to inside bottom, are another, as a sealing ring 39 trained and in the 6 apparent covering device covered and sealed. The order of making the through holes 33 . 34 can be chosen arbitrarily. It may also be provided that initially all through holes 33 . 34 pre-drilled and subsequently reworked. Alternatively, each individual through hole 33 . 34 be made completely before the next through-hole is made.

The respective sealing rings 35 . 39 are present approximately rotationally symmetrical and in the area of the through holes 33 . 34 each sealed to the turbine disk 31 tethered.

LIST OF REFERENCE NUMBERS

1

workpiece

3

Through Hole

5

Boring Tool

7

Side of the workpiece

9

cover

11

recess

13

Center axis of the recess

15

Center axis of the through hole

17

Coolant system

19

Coolant bore

21

Tip of the boring tool

23

flutes

25

Surface of the covering device

27

Surface of the workpiece

31

turbine disk

33, 34

Through holes

35

seal

36

blind hole

37

first part of the sealing ring

38

Center axis of the blind hole

39

seal

40

Center axis of the through hole

P1 to P3

arrows

Claims (12)

Method for producing at least one through-hole ( 3 . 33 . 34 ) in a workpiece ( 1 . 31 ), in which first a pilot hole is produced by means of a first tool and then with a second tool ( 5 ), wherein at least one tool ( 5 ) at least one can be supplied with a coolant cooling bore ( 19 ), and wherein a portion of the workpiece ( 1 . 31 ), in which the at least one through-bore ( 3 . 33 . 34 ) is provided or arranged, on a side facing away from the tool insertion side of the workpiece ( 1 . 31 ) with a covering device ( 9 . 35 . 39 ), which one in the region of the at least one through-hole ( 3 . 33 . 34 ) to the workpiece ( 1 . 31 ) bordering recess ( 11 ) into which at least one tool ( 5 ) immersed during the respective machining process, characterized in that a plurality of through holes ( 33 . 34 ) in the workpiece ( 31 ), the covering device ( 35 . 39 ) several recesses ( 11 ), which in with the workpiece ( 31 ) coupled position each with an area of the workpiece ( 31 ), in which a through-bore ( 33 . 34 ) is provided or arranged. Method according to claim 1, characterized in that the covering device ( 9 . 35 . 39 ) before the production of the pilot hole by the first tool with the workpiece ( 1 . 31 ) is coupled. Method according to claim 1, characterized in that the covering device ( 9 . 35 . 39 ) after the production of the pilot hole by the first tool and before the post-processing by the second tool ( 5 ) with the workpiece ( 1 . 31 ) is coupled. Method according to one of claims 1 to 3, characterized in that the recess ( 11 ) of the covering device ( 9 . 35 . 39 ) has at least approximately the shape of a blind hole whose central axis ( 13 ) in on the workpiece ( 1 . 31 ) arranged position of the covering device ( 9 . 35 . 39 ) at least approximately congruent to a central axis ( 15 ) of the through hole ( 3 . 33 . 34 ) is trained. Method according to one of claims 1 to 4, characterized in that the covering device ( 9 . 35 . 39 ) sealingly on the workpiece ( 1 . 31 ) is arranged. A method according to claim 5, characterized in that for sealing the covering device ( 9 . 35 . 39 ) opposite the workpiece ( 1 . 31 ) At least one sealing ring or a sealing washer is used. Method according to one of claims 5 or 6, characterized in that for sealing the covering device ( 9 . 35 . 39 ) opposite the workpiece ( 1 . 31 ) adjoining surfaces ( 25 . 27 ) of the workpiece ( 1 . 31 ) and the covering device ( 9 . 35 . 39 ) are at least partially elastically coated. Method according to one of claims 5 to 7, characterized in that for sealing the covering device ( 9 . 35 . 39 ) opposite the workpiece ( 1 . 31 ) the cover device ( 9 . 35 . 39 ) at least in the region of the at least one through-hole ( 3 . 33 . 34 ) precisely fitting the workpiece ( 1 . 31 ) is arranged. Method according to one of claims 1 to 8, characterized in that the covering device ( 9 . 35 . 39 ) for connection to the workpiece ( 1 . 31 ) in particular screwed or braced or positively in the workpiece ( 1 . 31 ) is inserted. Method according to one of claims 1 to 9, characterized in that the covering device ( 35 . 39 ) is formed in several parts and the individual parts ( 37 ) in particular successively on the workpiece ( 31 ) to be ordered. Method according to one of claims 1 to 10, characterized in that the cooling bore ( 19 ) of the first and / or second tool ( 5 ) in the region of a central axis of the first and / or second tool ( 5 ) is arranged. Method according to one of claims 1 to 11, characterized in that a flow rate measuring device is provided, by means of which a coolant flow in the region of the first and / or second tool ( 5 ) is measured.

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