WO1996027076A1

WO1996027076A1 - Multiple cam module

Info

Publication number: WO1996027076A1
Application number: PCT/DE1996/000355
Authority: WO
Inventors: Helmut Swars
Original assignee: Emitec Gesellschaft Für Emissionstechnologie Mbh
Priority date: 1995-02-25
Filing date: 1996-02-26
Publication date: 1996-09-06

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

Multiple cam module

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 mechanical valve technology increasingly raises the question of shafts with many, very closely spaced cams and other functional parts such as

To build plain bearings and axial stops. This is becoming increasingly difficult with conventional technology. Especially at

Massive shafts with larger diameters are accompanied by the problem of the weight increasing with the square of the diameter.

There are interesting approaches to solving this problem, particularly in the field of hollow camshafts. The problems of the cam distance can be solved with decreasing weight, but problems with decreasing torsional rigidity arise at the same time. Relative improvements can be achieved by using multiple cams made from tube profiles by twisting. Here, however, one is limited to the same cam profiles and relatively small angular misalignment of the cam tips. In addition, the individual hollow cams without side flanks do not offer a high degree of rigidity against the loads of the ram pressure.

The invention is based on the technical problem of proposing multiple cams as components for joining assembled hollow shafts which, even with larger diameters, have the highest precision and torsional rigidity, are simple, light and inexpensive to construct and manufacture and offer advantages in the mechanical processing of the functional parts, and a method for producing such multiple cams.

This problem is solved according to the invention by a multiple cam module which at least partially comprises the functional elements for a cylinder or adjacent cylinders and can be used as a component for joining assembled camshafts, in which the product consists of The wall thickness and circumference of the module elements is essentially the same at every point, the parts of the functional elements which project radially beyond the inner shaft base circle are hollow, the multiple cams being made of ductile material and by means of a process in which the contours of the functional elements in each section are in each section , which are formed according to a lower die and a pressing die, are pressed, and the finished profiled part circle sections are bent in a further shape, in particular by means of an internal mandrel, and the colliding side edges of the sheet metal blank are welded.

To produce a multiple cam according to the invention, a sheet is cut to the dimensions from which the desired cam package can be produced. This sheet metal blank is profiled with the cam flanks and tips, the bearing surfaces and other functional parts corresponding to the shape of the web. The profiled sheet metal is deformed in several stages. In the first deformation stage, the sheet metal slug is deformed in a lower die by a stamp, in which the contours of the cam and functional elements are worked out, and the sections are bent in accordance with the shaft base circle. In at least another deformation stage, the part-circle-shaped sections are emem over an internal mandrel Ring bent, the side edges of which abut each other.

If the axially extending outer edges of the various functional elements of the multiple cam module are parallel to each other at the most, the deformation can also take place in two stages.The sheet metal blank is deformed in the first deformation stage with a U-shaped lower die, so that a U-shaped structure with approximately parallel legs results In the second deformation stage, the now U-shaped intermediate product, which remains in the lower die, is deformed with a 0-shaped upper die so that the U-legs are formed into a closed profile. In the second deformation step, an internal mandrel is advantageously used

Alternatively, the might pre-profiled sheet metal blank can be formed in several stages by means of presses, so that the functional elements are profiled at the same time as the presses The now practically round intermediate product is welded at the joint, for example by resistance, laser, plasma or electron beam welding. The butt joints are advantageously worked on before welding to ensure a parallel edge course. After welding, the welding point is mechanically processed, for example grinding, and, depending on requirements, heat treatment, carburizing or surface hardening. If the treads of different functional parts in different chen materials are necessary or advantageous, these can be produced in a simple manner by plating or by sandwiching the sheet metal blank accordingly. In a particularly advantageous manner, the profiling and in particular the press forming are carried out cold.

While normally the parts of the functional elements protruding radially beyond the silhouette of the completed wave base circle have flanks which close off on the sides, in a special embodiment the material can be sheared off to the side of these functional elements, in particular at the cam tips.

It is particularly advantageous to use a conventional case hardening steel with, for example, 0.1 to 0.15% C, which is easily deformable and weldable. Such a material can be brought to the material properties required for the requirements of cams and functional elements by carburizing the finished welded multiple cam package and by hardening. This is very important because materials that have the required operational and wear properties are very difficult to weld and are often more difficult to shape.

The welding path does not have to run straight, but it should advantageously 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 is hydraulically expanded in sections in the area of the joint and is plastically deformed in such a way that the functional elements located on the outside of the shaft tube are only elastic at the joints With the multiple cam elements, the joints can be optimized overall. Particularly in the case of shafts with larger diameters, it is advantageous that the weight only increases linearly with the tube diameter, while the torsional stiffness increases by a factor of four with the diameter.This means that even with relatively small wall thicknesses for the shaft tube and the functional elements, it can be very light and extreme torsionally stiff shafts are produced.

These and other advantages are illustrated in the description of the exemplary embodiments of a multiple cam package according to the invention, which are shown in the drawing. Show in the drawing

1 shows a lower die and a press die with inserted sheet metal before forming;

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

3 design according to FIG. 1, but with an upper die and after a second shaping step,

Fig 4 emen multiple cams according to the invention m sectional view and

Fig. 5 lower die with three partial circular deformation sections

Fig. 1 shows a schematic section of a deformation device for the production of multiple cams, consisting of a lower die 2, an embossing die 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 on this example the press ram continues 3 m in the direction of the arrow, it presses the sheet metal 1 m the finished shape 4 in the lower die 2

The same situation is shown in FIG. 2, but after termination

^'of the first Umformschπttes. The ram 3 is in again

Backward movement upwards and the sheet metal blank 1 forms an U-shaped intermediate product, in the middle of which two cams 5 and 6 are formed. It can be clearly seen that the press ram 3 has the - 5 -

Corresponding cam contours are formed so that the downward position of the press ram 3 between the latter and the lower die 2 remains exactly the free space which is filled by the sheet metal layer 1 which is formed into a u-shaped intermediate product

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

While the deformation stages m correspond to FIGS. 1 to 3 in a two-stage forming process for producing 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 falling ends of the axially extending outer edges of the various functional elements do not run parallel to one another, but rather stand at an angle to one another, i.e. 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 ° in each case, two adjacent cams in each case offset by approximately 15 °. Similar to the multiple cam according to FIG. 4, the sheet metal filler 1 was divided and deformed in this way in three part-circular sections, two cam tips being arranged in each partial ice section. In further deformation sections, the two outer sections were bent over an internal mandrel so that their side edges bent face at the joint. This is followed by welding in a similar form to that described in the two-step deformation example

Claims

1 multiple cam module, which at least partially includes the functional elements for a cylinder or two adjacent cylinders and can be used as a component for joining assembled camshafts, in which the product of the wall thickness and circumference of the module elements is essentially the same at every point, which is radial over the inner shaft base circle protruding parts of the hollow smd functional elements and the multiple cams are made of ductile material.

2 multiple cams according to claim 1, characterized in that the functional elements projecting beyond the outer shaft base circle have axially 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 which a sheet metal blank is first deformed in several stages in a multi-stage manner in such a way that in each section the contours of the functional elements lying on it, which are formed according to my lower die and in a press ram, are pressed and finished profiled part circle sections m further deformation sections bent over an inner mandrel 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 various functional elements with an angle of less than 0 ° to each other, the sheet in a first forming step with a lower die by means of a press die, both in the lower die and on the contours of the functional elements are formed in accordance with the press ram, are formed into a U-shaped intermediate product, and the U-shaped legs of the intermediate product are formed into an annular multiple cam by an O-shaped upper die with a second shaping step are reshaped, in which the side edges of the blecli cut meet.