Method for producing cam for camshaft

Abstract

The invention relates to a method for producing a cam (1) for a camshaft, in which method the cam (1) is finish-forged together with a chamfer (4); the chamfer (4) is not subjected to supplementary processing. In this way, the cam (1) can be produced in a significantly faster and more cost-effective manner, as a troublesome supplementary machining of the chamfer (4) can be omitted.

Description

Field of the Invention

[0001] The present invention relates to a method for manufacturing a cam for a camshaft. Furthermore, the present invention relates to a cam manufactured according to this method. Background Art

[0002] A method for manufacturing a cam for a camshaft is known from EP 1 707 763 A1, in which a cam blank with a pre-forged cam chamfer is produced in a cold forging method in a plurality of single process steps. The cam chamfer and the working surface are both additionally machined by subsequent turning processes and / or milling processes. Generally, in the case of a forged cam chamfer, it is not possible to prevent: due to the inclined facets usually generated between 30° and 60°, burrs are formed in the area of the side / working surface adjacent to the cam chamfer, and the burrs generated here lead to an increased risk of injury and thus need to be additionally machined.

[0003] Here, the additional machining of the cam chamfer constitutes a significant additional cost, which significantly increases the piece cost for such cams. Summary of the Invention

[0004] Therefore, the present invention addresses the following problem: to provide a method by which cams with chamfers can be manufactured significantly more cost-effectively but still precisely.

[0005] According to the present invention, this problem is solved by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0006] The present invention is based on the following general concept: instead of only pre-forging a cam with a chamfer located between the working surface and the side surface and then additionally machining it by a laborious and costly milling operation or turning operation as hitherto, the forging is already completed initially and the chamfer is not additionally machined. Therefore, the cam chamfer is initially forged and finally forged (fertiggeschmiedet) in terms of its angle and width implementation within the scope of the forging process. Here, all dimensions (such as component width, chamfer width, chamfer depth, chamfer angle or radius) are designed according to technically reasonable and achievable forging tolerances. By finally forging the cam together with the chamfer and by omitting the additional machining of the chamfer, the cam itself can be manufactured significantly more quickly and cost-effectively.

[0007] In an advantageous refinement of the method according to the invention, the cam together with the chamfer is finish-forged, the chamfer having an angle α of between 5° and 40° relative to the cam working surface. Herein, generally speaking, a chamfer angle α of between 10 and 80°, preferably between 8 and 37°, relative to the cam working surface can be finish-forged. In a particularly preferred embodiment of the method according to the invention, the cam together with the chamfer is finish-forged, the chamfer having an angle α with 10° ≤ α ≤ 30° relative to the cam working surface. Herein, the angle ranges mentioned cover all the angles that usually occur between the chamfer and the cam working surface, such that preferably all cams can be manufactured by means of the method according to the invention.

[0008] In a particularly preferred embodiment of the method according to the invention, the chamfer is finish-forged to have a region with a radius R ≤ 2.0 mm. Thus, the chamfer itself does not necessarily have to have a straight surface in cross-section, but can also form an arc, where, purely theoretically, even a chamfer can be considered: the chamfer having not only a straight region but also an arcuate region in cross-section. Thus, by means of the method according to the invention (in which the chamfer is finish-forged regardless of its shape and not post-processed), depending on the forging tool used, almost any chamfer can be manufactured.

[0009] In a particularly preferred embodiment of the method according to the invention, the side surfaces of the cam are ground. By grinding the side surfaces (which can alternatively also be done by turning), a flat side surface can be achieved and at the same time possible unevenness caused by forging can be compensated. It can be considered herein to machine the two side surfaces in parallel, i.e., simultaneously, where the side surface machining offers the great advantage that pre-machining of drilling the cam can be omitted. By omitting the pre-machining of drilling the cam, the cam can be manufactured more cost-effectively.

[0010] In an advantageous refinement of the method according to the invention, the cam is cold-forged. This offers the great advantage that compared to hot forging, the forging of the cam can be achieved significantly more energy-efficiently and thus significantly more cost-effectively.

[0011] In a particularly preferred refinement of the method according to the invention, the cam together with the chamfer is finish-forged in a single forging step. Thereby, the forging process can be significantly compacted and thus the cycle can be shortened.

[0012] In addition, the present invention is based on the following general concept: manufacturing a cam corresponding to the method described in the above paragraph. Thus, the advantages described in terms of the method can be transferred to the cam according to the present invention. Specifically, these advantages lie particularly in that the finish-forged cam with chamfers can preferably be used without further supplementary machining of the chamfers. In particular, turning or milling of the chamfers is not required either, whereby the cam according to the present invention can be manufactured more easily and thus significantly more cost-effectively.

[0013] Other important features and advantages of the present invention are obtained from the dependent claims, the drawings, and the associated drawing descriptions according to the drawings.

[0014] It should be understood that the features mentioned above and those to be described below can be used not only in the correspondingly given combinations, but also in other combinations or individually, without departing from the framework of the present invention. The individually named components mentioned above and still to be mentioned below of the superior unit (such as a device, equipment, or component) can form separate members or parts of the unit or can be integrated regions or sections of the unit, even if this is not shown as such in the drawings.

[0015] Preferred embodiments of the present invention are shown in the drawings and are described in more detail below, where the same reference numerals refer to the same, similar, or functionally identical components. Brief Description of the Drawings

[0016] Here, the drawings schematically show respectively:

[0017] Figure 1 A view showing a cam manufactured according to a method of the present invention and having finish-forged chamfers

[0018] Figure 2 Showing Figure 1 Detailed schematic view A of the chamfer surface having a straight line in the cross-section in

[0019] Figure 3 Showing the same as Figure 2 but a schematic view having a chamfer surface that is arcuate in the cross-section. Detailed Description of the Preferred Embodiments

[0020] According to Figures 1 to 3 , the cam 1 according to the present invention has a cam working surface 2, two side surfaces 3, and two chamfers 4. The cam 1 according to the present invention is used, for example, on the camshaft of an internal combustion engine, especially an internal combustion engine in a motor vehicle.

[0021] Here, according to the present invention, the cam 1 is finish-forged together with at least one chamfer 4, preferably together with two chamfers 4, preferably in a single step, such that compared with the cams known from the prior art heretofore, additional machining of the chamfer 4 is no longer required. Purely theoretically, it is also conceivable that the cam 1 is finish-forged together with only one chamfer 4, preferably in a single step, such that compared with the cams known from the prior art heretofore, additional machining of this chamfer 4 is no longer required.

[0022] This enables the cam 1 to be manufactured not only faster and more easily, but also significantly more cost-effectively.

[0023] Here, if one observes Figure 2 , the cam 1 can be finish-forged to have a chamfer 4, where the chamfer 4 has an angle α of 5° ≤ α ≤ 40° relative to the cam working surface 2, preferably an angle α of 8° ≤ α ≤ 37°, and most preferably an angle α of 10° ≤ α ≤ 30°. The smaller the angle α, the smaller the tendency to form burrs during grinding of the working surface (the chamfer remains unprocessed). In the case of α = 10° to 30°, subsequent deburring can be omitted.

[0024] The chamfer 4 can also have a region with a radius R ≤ 2 mm and can be finish-forged to have such a radius R (see Figure 3 ). It is also conceivable to finish-forge a chamfer 4 below, which has a region with a chamfer surface that is straight in cross-section (see Figure 2 ) and a chamfer surface that is curved in cross-section (see Figure 3 ). Thereby, a mixed form of the chamfer 4 in Figure 2 and 3 is produced.

[0025] Here, the side surface 3 can also be additionally machined, in particular turned, milled or ground, and the overall width of the cam 1 can also be adjusted thereby. Grinding of the side surface 3 can be achieved, for example, by disk grinding, in which case the side surfaces 3 of the (plural) cams 1 that are parallel to each other are ground with a grinding tool. The key in this process is the combination of the forged chamfer and disk grinding. Cost reduction is achieved by grinding at least two cams simultaneously. This could not be achieved previously by milling or turning.

[0026] Generally, the cam 1 is cold-forged by means of the method according to the present invention, whereby a higher tool life can be achieved with respect to the forging tool.

[0027] By means of the method according to the invention and a cam 1 manufactured corresponding to the method according to the invention, i.e., end-forged to have at least one chamfer 4 of the end-forging, the manufacture of a cam 1 of this type can be achieved significantly more easily and thus significantly more cost-effectively.

Claims

1. A method for producing a cam (1) for a camshaft, in which method, - Final forging the cam (1) to have a chamfer (4), The chamfer (4) is not subjected to additional machining.

2. The method according to claim 1, It is characterized in that The cam (1) is final forged to have the following chamfer (4), wherein the chamfer has an angle α of 5°≤α≤40° relative to the cam working surface (2).

3. The method according to claim 1 or 2, It is characterized in that The cam (1) is final forged to have the following chamfer (4), wherein the chamfer has an angle α of 8°≤α≤37° relative to the cam working surface (2).

4. The method according to any one of the preceding claims, It is characterized in that The cam (1) is final forged to have the following chamfer (4), wherein the chamfer has an angle α of 10°≤α≤30° relative to the cam working surface (2).

5. The method according to any one of the preceding claims, It is characterized in that The chamfer (4) is finish forged to have a radius R of R≤2.0 mm at least in one region.

6. The method according to any one of the preceding claims, It is characterized in that The side surface (3) of the cam (1) is ground.

7. The method according to any one of the preceding claims, It is characterized in that The cam (1) is cold forged.

8. The method according to any one of the preceding claims, It is characterized in that In a single forging step, the cam (1) is final forged to have a chamfer (4).

9. A cam (1) manufactured according to a method according to any one of the preceding claims.

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