CN110871409A

CN110871409A - Straightening method for correcting unbalance of camshaft

Info

Publication number: CN110871409A
Application number: CN201811017248.3A
Authority: CN
Inventors: 马克·米勒
Original assignee: ThyssenKrupp Engine System Dalian Co Ltd
Current assignee: ThyssenKrupp Engine System Dalian Co Ltd
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2020-03-10

Abstract

The invention relates to a straightening method for correcting an imbalance of a camshaft. The straightening method comprises a) measuring the camshaft (10) with a measuring device (50) for determining the unbalance, and b) applying an at least locally formed plastic surface deformation (30) to the surface of the camshaft (10) by means of a deformation device (20), thereby correcting the unbalance of the camshaft (10).

Description

Straightening method for correcting unbalance of camshaft

Technical Field

The invention relates to a straightening method for correcting an unbalance of a camshaft, in which the camshaft is measured with a measuring device to determine the unbalance and then the camshaft is machined with a deformation device, so that the unbalance of the camshaft is corrected. Furthermore, the invention relates to the use of the needle device for correcting an unbalance of a camshaft and a camshaft machined with the needle device.

Background

Camshafts are subjected to application-specific loads during various manufacturing and machining steps. Such machining steps may include machining, gear shaping, drilling, grinding or at least partially hardening. Through the individual machining steps, the camshaft sometimes experiences considerable shape deviations and must then be readjusted in order to reduce the shape deviations to tolerable levels.

The prior art is so-called bend straightening, whereby the material is loaded beyond the yield point and plastically deformed by a radial feed force offset from the abutment. The force is always chosen to be high enough that the material is in the permanent plasticity range.

A method for surface hardening of components, in particular engine and transmission components in motor vehicles, is known from the handbook DE 102006048712 a 1. These parts are treated by ultrasonic peening. During this process, the pellets are ultrasonically excited and directed to a processing region of the surface of the part.

Publication DE 3005847 a1 discloses a method for straightening a thin-walled ring or annular shell with a non-circular curvature, in which part locations with too little curvature (i.e. with too large a radius of curvature) are partially peened from the outside, part locations with too large a curvature (i.e. with too small a radius of curvature) are covered, or part locations with too large a curvature are peened from the inside, and locations with too small a curvature are covered.

Patent AT 361273B discloses a method for straightening preferably elongated workpieces of metal, such as iron, tool steel or the like, such as strips, plates, shafts or rods, by impact machining of the workpiece, whereby a firing pin with a curved tip and a series of targeted blows with a high frequency are distributed inside the curved portion.

A disadvantage of the prior art is that the known method for straightening a camshaft can be very time-consuming and costly. Bend straightening reaches an additional limit due to the higher and higher requirements on the straightening quality of the camshaft. The different process steps for the specific application ensure that the exact transition from the plastic to elastic range does not have the same value at each straightening point. This results in an iterative search process to determine the exact value of each fiducial point. This means that the time required to straighten the camshaft exceeds any acceptable level.

Disclosure of Invention

The task of the invention is to provide an efficient straightening method which is neither cost-intensive nor time-consuming and which in addition meets the high requirements of straightening quality.

This object is solved according to the invention by a straightening method according to claim 1, by a needle device using the object of claim 10 and by a camshaft according to the object of claim 11.

Advantageous and appropriate designs of the smart straightening method are indicated in the dependent claims.

The invention is based on the idea of first measuring the camshaft with a measuring device to determine its unbalance. In a subsequent step, an at least locally formed plastic surface deformation is applied to the surface of the camshaft by means of a deformation device, so that an imbalance of the camshaft is corrected.

The advantage of the clever straightening method is that the exact unbalance of the camshaft can be determined by measurement. Due to the locally formed plastic surface deformation, a certain stress is applied to the circumference of the shaft. The voltage corrects the unbalance previously measured, thereby compensating for shape deviations of the camshaft with high alignment quality.

The camshaft is a machine component in the form of a lever to which at least one circular projection (cam) is attached. The shaft rotates on its own axis, which rotational motion is repeatedly converted into short longitudinal motion by the cam(s) mounted thereon. The camshaft is usually cast in one piece of cast iron or forged from steel. In certain applications, the camshaft is also referred to as a sliding camshaft or a gear shaft.

The measuring device is a measuring system adapted to perform a complete measurement of the camshaft. This requires, for example, geometric measurements, weight measurements and determination of the rotational properties. In addition, the measurement device may determine the location and level of stress to be applied to the surface of the shaft from the detected imbalance of the shaft, which may result in a correction of the detected imbalance. For example, the measuring device may comprise a laser scanner.

The deforming means is a means adapted to plastically deform the surface of the shaft. Thus, any object having a hardness higher than the hardness of the surface to be deformed is suitable for plastically influencing the microstructure on the surface. Due to the fact that the stresses to be applied in individual cases are limited to precisely defined locations on the surface of the shaft, the deformation device must be suitable for achieving plastic deformation with local limitations in the range of a few millimeters.

According to a preferred design, the plastic surface is deformed by the fact that the needle device is deformed. The needle device offers the possibility of plastic deformation at a precisely defined point. The resulting stresses correct the imbalance measured previously, so that deviations in the shape of the camshaft can be compensated for with a high alignment quality. Thus, accurate positioning can be achieved with relatively little effort and readily available technical means.

According to a further embodiment, after the local plastic surface deformation has been applied to the camshaft, the camshaft is measured again with the measuring device to determine the permanent imbalance. By means of a further measurement it can be checked whether the applied plastic deformation has in fact sufficiently corrected the imbalance.

After another design form, other localized plastic surface deformations are applied to the camshaft to correct for continued imbalance of the camshaft. This ensures that the required straightening quality is achieved by a new process with the forming apparatus.

In order to determine the specific shape deviations of the camshaft precisely, the actual axis of rotation of the camshaft is determined when the camshaft is measured with the measuring device. Thus, the actual axis of rotation is used to align with the actual desired axis of rotation.

According to a further preferred embodiment, when measuring the camshaft with the measuring device, a suitable position on the camshaft for local surface deformations and the necessary stresses for correcting an unbalance of the camshaft are determined. This has the technical advantage that the plastic surface deformation is only applied to the extent absolutely necessary to achieve straightening quality. In this way, the desired straightening quality is achieved very efficiently and reliably.

In order to be able to measure efficiently and to achieve as high a precision as possible, the camshaft is measured with a laser scanner.

According to a further embodiment, the camshaft is designed as a toothed camshaft, whereby local plastic surface deformations are applied in the tooth root of the camshaft. This has the technical advantage that, for example, even if the toothed camshaft is reground, the applied stresses can be prevented. Since the plastic deformation is arranged in the tooth root, the shape correction by grinding is still contained in the toothed camshaft.

According to a variant, the local surface deformation is carried out by shot peening. This enables plastic deformation to be imparted to the camshaft by the shot peening process. A prerequisite for this is that the particles used, which are sprayed onto the surface, have a sufficient hardness to cause the required plastic deformation.

With regard to the method of use of the needle device, this object is achieved by the features of claim 10.

The smart use of such a needle device makes it possible to correct the unbalance of the camshaft. With similar advantages to those already explained in connection with the clever straightening method for correcting the unbalance of the camshaft.

With regard to the camshaft, this object is achieved by the subject matter of claim 11.

Such smart camshafts include localized plastic surface deformation caused by the needle device. Has similar advantages to those already associated with the smart straightening method for correcting the unbalance of the camshaft and when using the needle device for correcting the unbalance of the camshaft.

Drawings

The invention is explained in more detail below using design examples with reference to the accompanying schematic drawings. Shown in the drawings are:

FIG. 1 is a schematic illustration of a camshaft having an imbalance;

FIG. 2 is a schematic view of a camshaft having an imbalance, in which plastic surface deformation is partially applied;

FIG. 3 shows a schematic view of a toothed camshaft with plastic surface deformation partially applied;

FIG. 4 is a schematic view of a toothed camshaft with sliding cams; and

fig. 5 shows a perspective view of a toothed camshaft with sliding cams.

Detailed Description

Fig. 1 shows a schematic view of a camshaft 10 with an imbalance. The imbalance is caused by previous processing steps. The shaft lacks a certain straightening quality due to unbalance or shape deviations. Therefore, a straightening axis is required to correct the shape deviation to a tolerable level.

Fig. 2 shows a schematic view of a camshaft 10 with an imbalance, wherein a plastic surface deformation 30 is partially applied. By applying the locally formed plastic surface deformation 30, the imbalance of the camshaft 10 is corrected. The alignment process for correcting the imbalance of the camshaft 10 requires that the camshaft 10 be first measured with a measuring device 50 (not shown). For example, the geometric axis of rotation is compared to the actual axis of rotation of the camshaft 10. This enables the position and level of stress on the surface of the camshaft 10 to be accurately calculated, which is necessary to correct the determined imbalance. In a subsequent step, a plastic surface deformation 30 is applied at least locally to the surface of the camshaft 10 using the deformation device 20. The surface deformations 30 may be point-like or over a larger portion or a larger area. The specific location of the plastic surface deformation 30 depends on the degree of imbalance and stress calculations based on the measured camshaft 10. Due to local plastic surface deformations specific stresses are generated which compensate the previously measured unbalance with a high straightening quality.

FIG. 3 shows a schematic view of a camshaft 12 with a partially applied plastic surface deformation 30. Correction of the imbalance by applying localized plastic surface deformations 30 is applied to camshaft 12 in the same manner, wherein the imbalance of camshaft 12 is measured using measuring device 50 (not shown). Based on the measurements, the precise location and level of stress on the surface of the camshaft 12 required to correct the determined imbalance may be calculated. An at least partial plastic surface deformation 30 is then applied to the surface of the toothed camshaft 12 using the deforming device 20.

The surface deformation 30 can also take place here selectively or over a larger part. The only difference is that the surface deformation 30 is applied directly to the root of the camshaft 12. This can ensure, for example, that the applied stresses are not relieved in further processing steps, such as over-grinding. In other words, grinding on the camshaft 12 does not affect the shape correction.

Fig. 4 shows a schematic view of a camshaft 12 with a sliding cam 40, the camshaft 12 having been measured and a local plastic surface deformation 30 applied to the surface of the camshaft 12 with a deformation device 20. Therefore, the camshaft 12 is in a state in which the imbalance previously determined has been corrected.

Fig. 5 shows a perspective view of the camshaft 12 with the sliding cam 40, wherein the same features of the preceding figures are not repeated.

List of reference numerals

10 camshaft

12 cam shaft with teeth

20 deforming device

22-needle device

30 surface deformation

40 sliding cam

50 measuring the device.

Claims

1. A straightening method for correcting an imbalance of a camshaft (10), the method comprising the steps of:

a) measuring the camshaft (10) with a measuring device (50) for determining the unbalance, and

b) at least partially formed plastic surface deformations (30) are applied to the surface of the camshaft (10) by means of a deformation device (20), whereby an imbalance of the camshaft (10) is corrected.

2. Straightening method according to claim 1, characterized in that the plastic surface deformation (30) is carried out with a needle device (22).

3. Straightening method according to claim 1 or 2, characterized in that the camshaft (10) is measured again with the measuring device (50) for determining a continuous unbalance after the local plastic surface deformation (30) has been applied to the camshaft (10).

4. Straightening method according to any one of the preceding claims, characterized in that further local plastic surface deformations (50) are applied to the camshaft (10) in order to correct a continuous imbalance of the camshaft (10).

5. Straightening method according to any one of the preceding claims, characterized in that the actual axis of rotation of the camshaft (10) is determined by the measuring device (50) when measuring the camshaft (10).

6. Straightening method according to any one of the preceding claims, characterized in that, when measuring the camshaft (10), the measuring device (50) determines the suitable position on the camshaft (10) for the local surface deformation (30) and the stress required for correcting the unbalance of the camshaft (10).

7. Straightening method according to any one of the preceding claims, characterized in that the camshaft (10) is measured with a laser scanner.

8. Straightening method according to any one of the preceding claims, characterized in that the camshaft (10) is formed as a toothed camshaft (12), the local plastic surface deformation (30) being applied in the dedendum of the toothed camshaft (12).

9. Straightening method according to any one of the preceding claims, characterized in that the local surface deformation (30) is carried out by means of a shot peening process.

10. A method of using a needle device (22) for correcting imbalance of a camshaft (10).

11. A camshaft (10), the camshaft (10) comprising a local plastic surface deformation (30) caused by a needle device (22).

12. A camshaft (10) as claimed in claim 11, characterized in that the camshaft (10) comprises a toothed camshaft (12).