DE19606397A1 - Multiple cam module - Google Patents

Abstract

The invention concerns a multiple cam (5, 6) which can be used in a modular manner as a structural component for joining assembled camshafts. The multiple cam is produced in a plurality of stages from a sheet metal blank (1) by profiling, shaping and welding. The invention further concerns processes for producing multiple cams according to the invention.

Description

The invention relates to multiple cam modules as components for Joining assembled camshafts and a method for their production.

In the field of camshafts, the advance of Multi-valve technology is increasingly the question of shafts with many, very narrow adjacent cams and other functional parts such as To build plain bearings and axial stops. This prepares with conventional technology increasingly difficult. Especially at Solid shafts with larger diameters come with the problem of weight increasing by the square of the diameter.

There are particularly interesting approaches to solving this problem the area of constructed hollow camshafts. Here, the Solve cam clearance problems with decreasing weight, however problems with decreasing torsional rigidity arise at the same time. Relative improvements can be made by using Achieve tube profiles with multiple cams produced by twisting. Here but you are on the same cam profiles and relatively low Limited angular misalignment of the cam tips. They also offer individual hollow cams without side flanks no high rigidity against the Tappet pressure loads.

The invention is based on the technical problem of multiple cams Propose components for joining assembled hollow shafts, which too for larger diameters maximum precision and torsional rigidity have, simple, light and little effort in construction and Manufacturing and advantages in mechanical processing of the Offer functional parts, as well as a method for producing such Multiple cams.

According to the invention, this problem is solved by a multiple cam Module that is at least partially the functional elements for a cylinder or includes adjacent cylinders and as a component for joining built-up camshafts can be used, in which the product  Wall thickness and circumference of the module elements at every point in the is essentially the same radially over the inner shaft base circle protruding parts of the functional elements are hollow, the Multiple cams made of ductile material as well as a Process in which in each section the contours of those lying in it Functional elements that correspond in a lower die and in a Press stamps are formed, pressed and the finished profiled Pitch circle sections in further deformation steps, in particular over an inner mandrel bent in a ring and the colliding Side edges of the sheet metal blank are welded.

A sheet is used to produce a multiple cam according to the invention cut to the dimensions from which the desired cam package can be manufactured. This sheet metal blank is made with the cam flanks and tips, the bearing surfaces and other functional parts profiled corresponding web-shaped features. The profiled Sheet metal is deformed in several stages. In the first stage of deformation, the Sheet metal cut in a lower die deformed by a stamp in which the contours of the cam and functional elements are worked out, and which are bent in sections according to the wave base circle. In At least one further deformation stage is the part-circular Sections over an internal mandrel bent into a ring, the Butt side edges.

Are the axially running outer edges of the different Functional elements of the multiple cam module maximally parallel to each other, the deformation can also take place in two stages. The Sheet cutting in the first deformation stage in a U-shaped Lower die deformed so that a U-shaped structure is approximately parallel running legs results. In the second stage of deformation it will now U-shaped intermediate product that remains in the lower die with an O- shaped upper die so deformed that the U-legs into one closed profile are formed. The second is advantageous Deformation step worked with an internal mandrel.

Alternatively, the sheet metal blank, which has not been pre-profiled, can be multi-stage by means of presses, so that at the same time the pressing The functional elements are profiled.  

The now practically round intermediate product is at the joint welded, for example by resistance, laser, plasma or Electron beam welding. The joints in front of the Welding added to ensure a parallel edge course. After welding, the mechanical processing of the Welding point, for example grinding, and one as required Heat treatment, carburizing or surface hardening. If the Treads of different functional parts in different materials are necessary or advantageous, these can be by plating or through appropriate sandwich construction of the sheet metal cut in easier Create way. The profiling is particularly advantageous and in particular the press forming was carried out cold.

While normally the one overgrown by the silhouette of the Shaft base circle of radially protruding parts of the functional elements sideways closing flanks can be in a special Embodiment the material on the side of these functional elements, particularly at the tips of the cams.

The use of a conventional one is particularly advantageous Case hardening steel with 0.1 to 0.15% C, for example, which is easily deformable and is weldable. Such a material can be carburized of the welded multiple cam package and by hardening to the required for the requirements for cams and functional elements Material properties are brought. That's why it's very important because materials that meet the required operating and Have inherent wear properties, very difficult are weldable and often more difficult to deform.

The weld path does not have to be straight, but it should be advantageous always lie in the cam base circle.

The multiple cams according to the invention offer great advantages when joining assembled camshafts. Especially in the joining process, in which various functional elements and in the present case the Multiple cams are pushed onto a shaft tube, the shaft tube hydraulically expanded in sections in the area of the joint and is plastically deformed so that the outside on the shaft tube Functional elements located at the joints only elastic  can be expanded, the multiple cam elements Optimize joints overall. Especially with waves with larger ones Diameters are advantageous in that the weight only increases linearly with the pipe diameter, while the Torsional rigidity increased fourfold with the diameter. This allows even with relatively small wall thicknesses for the shaft tube and the functional elements are very light and extremely torsionally stiff shafts getting produced.

These and other advantages are described in the description of the Embodiments of a multiple cam package according to the invention clarifies, which are shown in the drawing. Show in the drawing

Figure 1 is a lower die and a press ram with inserted sheet metal blank before forming.

FIG. 2 device according to FIG. 1, but after the first forming step;

Fig. 3 device according to Fig 1, but with upper die and after the second shaping step.

Fig. 4 shows a multiple cam according to the invention in a sectional view and

Fig. 5 lower die with three part-circular deformation sections.

Fig. 1 shows schematically a section of a deforming means for the production of multiple cam, consisting of a bottom die 2, a pressing plunger 3 and an inserted sheet metal section 1. In the lower die, the contours 5 'and 6 ' for two cams 5 and 6 are indicated in this example. If the ram 3 lowers further in the direction of the arrow, it presses the sheet metal blank 1 into the form 4 in the lower die 2 .

The same situation is shown in FIG. 2, however after the first forming step has ended. The ram 3 is again in a backward movement upwards and the sheet metal blank 1 forms a U-shaped intermediate product, in the middle of which two cams 5 and 6 are formed. It can be clearly seen that the corresponding cam contours are formed in the press ram 3 in such a way that in the downwardly lowered position of the press ram 3 between the latter and the lower die 2 exactly the free space remains, which is filled by the sheet metal blank 1 formed into a u-shaped intermediate product becomes.

Fig. 3 shows the next shaping step. Instead of the press ram 3 , the upper die 10 is pressed down here, the shape of which grips the U-shaped legs of the intermediate product and bends in part-circle fashion as it is lowered further. The side edges of the sheet metal blank 1 abut against each other at the joint 7 , so that after this second deformation step the basic shape of the multiple cam is finished, but still gaps apart at the joint. In a further processing step, the abutting edges are worked in such a way that they run parallel to one another. In the following document, the joint is welded so that a multiple cam 1 with cams 5 and 6 and a weld 8 is formed from sheet metal blank 1 .

While the deformation stages in FIGS. 1 to 3 correspond to a two-stage forming process for the production of the multiple cam according to FIG. 4, the method according to the invention can also work in multiple stages, for example three stages. This is always necessary if the free ends of the axially extending outer edges of the various functional elements do not run parallel to one another, but are at an angle to one another, that is to say the flanks diverge downwards over the parallel course.

In Fig. 5 it is shown schematically what the lower die looks like for the production of a multiple cam, the six cams of which, for example, are arranged in such a way that three cam tips are offset by 120 °, two adjacent cams being offset by approximately 15 °, similar to the multiple cam as shown in FIG. 4. the sheet-metal blank 1 would be divided in this case into three part-circular sections and deformed, said two cam tips are arranged in each part-circle portion. In further deformation steps, the two outer sections are bent over an inner mandrel so that their side edges face each other at the joint. The welding then takes place in a similar form to that described in the two-stage deformation embodiment.

Claims (5)

1. Multiple cam module, which at least partially the functional elements for a cylinder or two adjacent cylinders and as Component for joining assembled camshafts can be used, in which the product of the wall thickness and the circumference of the module elements on each Place is substantially the same radially over the inner Projecting parts of the functional elements are hollow and the multiple cams are made of ductile material. 2. Multiple cams according to claim 1, characterized in that the Functional elements projecting axially beyond the outer shaft base circle have closing side flanks. 3. Multiple cams according to claim 1 or 2, characterized in that the weld seam is in the cam base circle. 4. Process for the production of multiple cams, in the multi-stage first a sheet metal blank in several part-circular sections is deformed so that in each section the contours of it lying functional elements, correspondingly in a lower die and are formed in a press ram, are pressed in and finished profiled pitch circle sections in further deformation steps via a Inner mandrel bent in a ring and the colliding Side edges of the sheet metal blank are welded. 5. The method according to claim 4, in which for the production of Multiple cams, the axially extending outer edges of the different Functional elements are at an angle of less than 0 ° to each other, the sheet in a first forming step in a lower die a ram, both in the lower die and on the Press stamp the contours of the functional elements formed accordingly are formed into a U-shaped intermediate and in one second forming step the U-shaped legs of the intermediate through an O-shaped upper die to an annular multiple cam  are formed using the side edges of the sheet metal blank collide.