DE202020102652U1 - Combination tool for fine machining bores - Google Patents

Abstract

Tool (10) for fine machining bores (8) in a workpiece (6), with a tool body (11) which comprises a friction section (20) and a honing section (25), characterized in that the honing section (26) is designed in this way is that an axial guidance of the tool (10) can be achieved during operation.

Description

The invention relates to a tool for fine machining bores.

Bores of high dimensional accuracy and surface quality are usually produced in a multi-stage process. First, a rough machining of the workpiece is carried out using drilling, milling or fine spindles; this is followed by finishing the bore, for example by means of a reaming process, and a final fine machining, in particular by means of honing.

WO 84/03461 describes a drilling tool with a tool body, which comprises a drilling section, a friction section and a honing section. This combination of several differently designed sections in a single drilling tool is intended to enable processing of a wide range of different materials. Here, the friction section serves in particular to facilitate the removal of tough chips when drilling into soft materials, while the honing section is then intended to smooth the inner wall of the hole. With the tool described in the cited document, it can easily happen that the sharp cutting edges of the friction sections or the drill engage in the bore wall and injure it, in particular if the tool does not run perfectly, which is almost always the case.

This is also suitable WO 84/03461 known combination tool not for the production of large diameter bores, for example connecting rod eyes or cylinder bores. When machining such bores, the raw shape of the workpiece is typically first subjected to roughing, for example by means of fine spindles, before fine machining of the bore can be carried out by honing. In this case, a combination of a drilling section with a honing section on a single tool body is not useful.

The object of the present invention is to propose a tool for machining bores, the use of which avoids the problems mentioned above.

This object is achieved by a tool with the features of independent claim 1. The subclaims relate to advantageous developments and variants of the invention.

A tool according to the invention for fine machining bores comprises a tool body on which a friction section and a honing section are arranged, the honing section being designed such that axial guidance of the tool can be achieved during operation. In this context, axial guidance means that the axes of rotation of both the honing section and the friction section are aligned in the feed direction during operation. This enables improved, reproducible, dimensionally stable combined machining, in particular of long, thin and also interrupted bores. The honing section therefore fulfills a double function according to the invention, namely on the one hand the internal machining of bores and on the other hand the guidance of the upstream friction section, so that a good straightness of the bore can be achieved.

This advantageous property of the tool can be achieved in particular in that the ratio of the axial extension of the honing section to the axial extension of the friction section is at least 2. Additionally or alternatively, it can be advantageous if the honing section is spaced from the friction section in the axial direction by less than the outer diameter of the tool between the sections. In other words, in this case the honing section and the friction section follow one another briefly in the axial direction, that is to say in the direction of advance of the tool.

In an advantageous variant of the invention, the tool body is provided with honing stones in the honing section. This design of the tool has the advantage that an outer diameter of the honing section can be selected independently of the outer diameter of the friction section. During the machining of the bore, the honing stones act as guide strips for the friction section and ensure that the friction section is guided in alignment in the bore to be machined during the machining of the bore.

It is advantageous to choose the outside diameter of the honing section to be somewhat larger than the outside diameter of the friction section, so that the honing stones protrude radially beyond the friction section. The honing stones of the honing section then cause the tool to be clamped in the bore to be machined. With such a design of the tool, retraction grooves of the reaming blades can be effectively avoided when the tool is withdrawn from the bore. In practice, it has proven expedient to choose the outer diameter of the honing section to be approximately 20 μm larger than the outer diameter of the friction section.

In a first embodiment of the invention, the honing stones are firmly connected to the tool body, in particular fastened to the tool body by means of a soldered or adhesive connection; also a screw connection is conceivable. Alternatively, the honing stones can be positioned on the tool body and can be adjusted radially in advance and / or during the process using a suitable adjustment mechanism. In this way, a better centering of the tool and thus an improved guidance can also be achieved over longer machining or service lives compared to fixed honing stones.

The friction section is advantageously designed with multiple cutting edges; it can in particular also be designed as a friction ring. Furthermore, the friction section can comprise one or more indexable inserts.

The combination of a reaming section and a honing section on a single tool body enables a reduction of the cycle time, because - in contrast to the otherwise usual way of working with separate tools - the two machining operations of reaming and honing can be carried out in a single process step without changing tools. The inventive design of the honing section with honing stones, which advantageously protrude radially beyond the friction section, ensures the production of high-quality bores, the honing stones functioning as guide strips for the friction section. In comparison to conventional single-edged reamers with guide strips, the design according to the invention further enables higher feed rates.

• 1 eine perspektivische Ansicht eines erfindungsgemäßen Werkzeugs;
• 2 eine Schnittansicht des Werkzeugs der 1;
• 3 eine Detailansicht des Werkzeugs gemäß dem Ausschnitt III in 2.

Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawing. Show it

• 1 a perspective view of a tool according to the invention;
• 2nd a sectional view of the tool of the 1 ;
• 3rd a detailed view of the tool according to section III in 2nd .

1 and 2nd show a perspective view and a sectional view of a tool according to the invention 10 for fine machining of bores 8th in workpieces 6 . The tool 10 includes a tool body 11 , the end with a receiving section 12th is provided for receiving in a machine tool (not shown in the figures). At one of the receiving sections 12th opposite end 13 of the tool body 11 there is a friction section 20 and a honing section 25th for machining the bores 8th . In the embodiment of the 1 and 2nd points the tool 10 between the receiving section 12th and the friction section 20 a long shaft 15 on the processing of difficult to access component areas in the workpiece 6 to facilitate or enable.

3rd shows a detailed view of a section of the area 13 of the tool body 11 with the friction section 20 and part of the honing section 25th . The friction section 20 includes a friction ring 22 with multiple reamers 23 . In the honing section 25th there are several honing stones 27 by adhesive connections to the tool body 11 are connected. The honing stones 27 protrude from the tool body in such a manner in the example shown 11 out that the outside diameter 26 of the honing section 25th is about 10 - 30 µm larger than the outside diameter 21st of the friction section 20 .

When machining the workpiece 6 (Directional arrow 30th in 1 ) the friction section penetrates first 20 in the hole 8th a. The tool 10 facing inner surface 9 the hole 8th is through the friction section 20 machined, reducing the diameter of the hole 8th on the outside diameter 21st of the friction section 20 is enlarged. When the tool is advanced 10 (Directional arrow 30th ) comes the honing section 25th in engagement with the bore 8th . Now the honing section is working 25th the inner surface 9 the hole 8th and provides them with a desired honing pattern, especially a cross cut. Because the outside diameter 26 of the honing section 25th is slightly larger than the outside diameter 21st of the friction section 20 the honing section is seated sufficiently well 25th in the bore and thus reliable guidance of the tool 10 reached.

When the tool is advanced again 10 into the workpiece 6 serve the honing stones 27 as guide rails for the tool 10 in the workpiece and ensure a highly precise aligned alignment of the tool 10 towards the holes 8th . When the tool is withdrawn 10 from the workpiece 6 (Directional arrow 31 in 1 ) after completion of processing, the honing stones prevent 27 due to the larger outside diameter 26 that the friction cutting of the friction ring 22 Retraction grooves in the bore wall 9 leave. This allows high quality drilling 8th with flawless inner surfaces.

Alternatively to that in the 1 to 3rd shown embodiment, in which the honing stones 27 by soldering or gluing to the tool body 11 are attached, the honing stones can also be guided in the tool body and can be adjusted to the desired outside diameter by a feed mechanism.

Reference list

6

workpiece

8th

drilling

9

Inner surface of the hole

10th

Tool

11

Tool body

12th

Receiving section

13

opposite end of the tool body

15

shaft

20

Friction section

21

Outside diameter friction section

22

multi-edged friction ring

23

Reaming

25th

Honing section

26

Outer diameter honing section

27

Honing stones

30th

Direction arrow feed

31

Withdrawal directional arrow

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 8403461 [0003,0004]

Claims (11)

Tool (10) for fine machining bores (8) in a workpiece (6), with a tool body (11) which comprises a friction section (20) and a honing section (25), characterized in that the honing section (26) is designed in this way is that an axial guidance of the tool (10) can be achieved during operation. Tool (10) after Claim 1 , characterized in that the ratio of the axial extension of the honing section (25) to the axial extension of the friction section (20) is at least 2. Tool (10) according to one of the Claims 1 or 2nd , characterized in that the honing section (25) is spaced from the friction section (20) in the axial direction by less than the outer diameter of the tool between the sections (20, 25). Tool (10) according to one of the preceding claims, characterized in that the tool (10) in the honing section (25) has honing stones (27). Tool (10) after Claim 4 , characterized in that the honing stones (27) protrude radially beyond an outer diameter (21) of the friction section (20). Tool (10) after Claim 4 or 5 , characterized in that the honing stones (27) are firmly connected to the tool body (11). Tool (10) after Claim 6 , characterized in that the honing stones (27) are soldered to the tool body (11). Tool (10) after Claim 4 or 5 , characterized in that the honing stones (27) are arranged radially adjustable on the tool body (11). Tool (10) according to one of the preceding claims, characterized in that the friction section (20) is designed with multiple cutting edges Tool (10) according to one of the preceding claims, characterized in that the friction section (20) comprises a friction ring (22). Tool (10) according to one of the preceding claims, characterized in that the friction section (20) comprises at least one indexable insert.

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