EP1236539A2 - Honing method - Google Patents

Abstract

To machine the surface of a drilling (3) tool to give hone tracks (5), it is worked by a spindle honing tool, with at least one forward stroke and one reverse stroke. The ratio of the stroke movement speed to the rotary speed of the tool (3) is increased over the normal spindle honing ratios. The ratio of the stroke speed to the rotary speed of the tool is increased when the tool movement is reversed.

Description

It is known to drill holes with the highest form accuracy To process thorn honors. Application examples are the smallest machining Bores for injection systems for cars, the machining of bores in hydraulic components as well as machining the large and small eyes in connecting rods.

With mandrel honing, the honing tool is set to the final diameter at high speed but at least low lifting speed once, at most three times through the hole. As a result of the high peripheral speed in relation to the lifting speed of the honing tool is the honing angle during mandrel honing tiny.

The invention is based on the object of maintaining a honing process the advantages achieved by thorn honing with regard to to develop a tribologically favorable surface topography.

To achieve this object, the invention proposes a method with the features mentioned in claim 1. Developments of the invention are the subject of subclaims.

While in normal mandrel honing with a mandrel honing tool Drilling with a high number of revolutions is slow proposes the invention, the mandrel honing tool at least partially in to use a way that is not common in thorn honing. With little The hole to be machined can already be measured, for example the first stroke with the mandrel honing tool with an enlarged ratio passed through from lifting speed to speed, differently expressed very quickly.

If the oversize is not that small, the first stroke, d. H. driving through the hole for the first time at the usual speed done, and then the tool can be quickly withdrawn. This may also result in a Cross structure are generated.

In a further development, however, it can also be provided that the bore processed in the usual way first with a stroke and a return stroke and that only afterwards the mandrel honing tool in the is used in an unusual way.

The hole to be machined is the same as before processed as usual. A mandrel honing tool is used, which with high Rotational speed but low lifting speed in at least a stroke and a return stroke is moved through the bore. Then either the peripheral speed is changed or the lifting speed increases. Then with the same Tool reworked the hole, which is now due to the higher the lifting speed in relation to the speed, the larger The angle of the honing marks results. When pulling back can be taken care of that there is a crossing structure, which then leads to the desired one leads to improved tribological properties.

During the return stroke, due to the properties of a mandrel honing tool that relaxes, the possibility may arise that the removal becomes deeper than the honing marks of the
Forward stroke. This can lead to the risk that a cross structure does not arise. In order to rule out this danger under all circumstances, it can be provided in a further development according to the invention that the tool is reset before the return stroke of the post-processing and thus relaxed. This resetting or relaxation can take place to such an extent that the honing marks created during the return stroke have the same depth as those created during the forward stroke.

However, it is also possible and is proposed by the invention post-processing with several particularly fast strokes to carry out, so that due to the multiple strokes also cross structures of the same depth.

It can be provided to advance the tool to the to surely cover previously created traces.

It is also possible to reduce the removal as little as possible during the downward stroke to design that with a fixed tool in the upstroke not all traces of the downward stroke are removed.

In a further development of the invention it can be provided that after the post-processing, a second post-processing takes place in which the tips of the surface structure are smoothed. This forms a kind of plateau machining around a certain support structure to be able to manufacture.

For this smoothing, the same tool as for the previous post-processing can be used.

However, it is also possible and is proposed by the invention that using another tool to smooth the tips Thorn honing or normal honing can be done.

Fig. 1

schematisch den Querschnitt durch eine Bohrung vor Beginn der von der Erfindung vorgeschlagenen Honbearbeitung;

Fig. 2

den Zustand der Bohrung nach dem ersten Hub;

Fig. 3

den Zustand der Bohrung nach dem ersten Rückhub;

Fig. 4

den Zustand der Bohrung nach dem ersten Hub der Nachbearbeitung;

Fig. 5

den Zustand der Bohrung nach Beendigung der Nachbearbeitung.

Further features, details and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention, the patent claims, the wording of which is incorporated in the description by reference, and with reference to the drawing. Here show:

Fig. 1

schematically the cross section through a bore before the start of the honing proposed by the invention;

Fig. 2

the state of the hole after the first stroke;

Fig. 3

the state of the hole after the first return stroke;

Fig. 4

the condition of the hole after the first stroke of post-processing;

Fig. 5

the state of the hole after finishing the post-processing.

Figure 1 shows schematically the cross section through a workpiece 1 with a bore 2 contained therein. The bore 2 is through a previous one Processing step originated and by grinding, turning or some other machining process to a certain extent has been brought. The bore 2 should now be smoothed in its structure and brought to the final finished dimension. This is indicated Honing tool 3 used, which is a mandrel honing tool is. This tool 3 contains a front slightly conical Cutting zone 4, which is greatly exaggerated in the schematic representation is shown. The tool 3 is at high speed and low stroke speed moved through the bore 2. This removes the wall of the bore 2, that is to say the surface. The bore increases in diameter and proves the passage of the tool 3 a surface structure with traces of honing 5 on. The state after the first pass of the tool 3 through the bore 2 is shown in Figure 2. The honing marks 5 run almost parallel to the surface 6 of the workpiece 1 or in other words almost perpendicular to the axis of rotation of the honing tool 3. This only angles deviating slightly from zero result from the high Tool speed in relation to the lifting speed.

After the first passage through the bore 2, the tool 3 is then withdrawn again so that it is the position shown in Figure 3 occupies. When pulling back, new honing marks 5 are generated are again very flat due to the kinematics described. she now have a different orientation, however, since the one when retracting resulting honing traces in the example shown are deeper than they previously generated honing marks. This leaves only those on the return stroke traces of honing are visible. Up to this point this corresponds A conventional mandrel honing process.

Now in a subsequent postprocessing process the speed of the honing tool 3 is reduced and / or its lifting speed increased. After the first stroke of this post-processing 4 shows the image of the honing marks 5, which are now under run at a much larger angle. This angle corresponds to that Angle in a conventional normal honing process with many Strokes works. To create this existing structure of the However, a single stroke is sufficient as the material is removed in the previous step with the help of mandrel honing took place.

Tool 3 must now be pulled back through hole 2 become. Due to a small difference in diameter between tools and workpiece there is a small penetration depth of the cutting grains. The traces of the previous downstroke remain. The slight difference in diameter can be achieved under certain circumstances that the tool is relaxed a little so that its outer diameter slightly reduced. This makes it possible for the honing marks created when pulling back have the same depth like the honing marks that were created during the forward stroke, which are shown in Figure 4. So there is a structure of Honing traces, as shown in Figure 5 after the honing tool has been withdrawn are shown.

The invention combines the advantages of mandrel honing with the advantages of normal honors. The advantages of the Dorhhones such as high cylinder shape accuracy, low tool costs, low machine costs and low processing and idle times can be achieved with a tribological suitable surface properties, as with the help of normal Honens can be achieved.

Claims (11)

Method for machining the surface of a bore (2), with the following method steps: 1.1 the bore (2) is machined with a mandrel honing tool with at least one stroke and one return stroke, 1.2 With at least one stroke or return stroke, the ratio of the lifting speed to the speed of the tool (3) is increased compared to the ratio that is usual for mandrel honing. The method of claim 1, in which the first stroke Ratio of lifting speed to tool speed (3) enlarged compared to the ratio used in thorn honing becomes. The method of claim 1, wherein the first stroke with a the usual ratio of lifting speed to when honing Speed of the tool (3) is carried out while the first Return stroke the ratio is increased. The method of claim 1, wherein after withdrawing the Tool (3) from the bore (2) the ratio of lifting speed to the speed of the tool (3) and the Bore (2) with at least one stroke and one return stroke is reworked. Method according to the preceding claims, in which the Tool (3) before returning the post-processing to a smaller one Dimension is postponed. Method according to one of the preceding claims, in which in several strokes are carried out after finishing. A method according to claim 6, in which before or during post-processing a delivery of the Honing tool takes place. Method according to one of the preceding claims, in which after finishing the tips of the surface structure to be smoothed. The method of claim 8, wherein the smoothing of the tips of the Surface structure using the same tool (3) as that previous processing is done. The method of claim 8, wherein the smoothing of the tips of the Surface structure is done with the help of another tool. Method according to one of the preceding claims, in which Dorn honing comprises a maximum of three strokes and three back strokes.

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