Patent Application
20080184756
The present invention relates to a deep rolling roller head with two housings for the deep rolling of the outer radii or indentations of split-pin crankshaft lobes by means of two deep rolling rollers each of which is pressed into one of the two radii or indentations by the rolling force while the crankshaft rotates around its axis of rotation, whereby the housings follow the different lifting movements of the lobes and bear upon each other on a supporting element with their insides facing each other, whereby each deep rolling roller bears upon a guide roller that is mounted inside its respective housing so as to be capable of axial and radial rotation.
The English language term “split-pin” is also known to the German person schooled in the art. This is understood to be a crankshaft for a multi-cylinder combustion engine whose cylinders may be arranged e.g. in V formation, so that the crankshaft is provided with lobes offset at an angle and adjoining each other.
Deep rolling tools for the deep rolling of the outer radii or indentations of crankshafts of the above-mentioned type are known e.g. from U.S. Pat. No. 5,575,167 or from EP Patent 0 661 137 B1.
The known deep rolling tools have two housings independent of each other in which deep rolling rollers are rotatably mounted and are pressed by the rolling force respectively into one of the two outer radii or indentations of a split-pin lobe. At the same time the crankshaft rotates around its rotational axis and the housings follow the different lifting movements of the split-pin lobes independently of each other. At the same time the housings bear with their flat inner walls upon each other with a supporting element installed between the flat inner walls of the housings. The support is necessary because the reaction forces transmitted by the rolling force from the deep rolling rollers to the housings of the deep rolling roller head must be absorbed. In the case of the first-named US patent the supporting element consists of a pair of ring-shaped flat bearing plates made of teflon, nylon or some other suitable plastic material with good sliding characteristics and low tendency to wear. In the case of the EP patent the supporting element consists of a ring-shaped thrust-bearing unit with cage, installed between the tool housings. The ring-shaped thrust-bearing unit maintains the alignment of the tool housings in parallel vertical planes while the latter are rotated relative to each other around the axis of a motor crankshaft or while the motor crankshaft rotates under the tool housings. It is therefore very important for the thrust-bearing unit to absorb and eliminate the resulting lateral pressure forces produced during the rolling process by the deep rolling rollers opposite of each other and inclined to the outside.
Since the deep rolling rollers are however “shackled” in the axial direction of the crankshaft by the crank arms delimiting the radii or indentations, reactions occur in the upper area of the housing of the deep rolling roller heads, i.e. the area away from the crankshaft. This area has the tendency to gape apart under the deep rolling force. The gaping apart renders the deep rollers uncontrollable and leads to unsatisfactory results.
For this reason measures have already been taken to provide clamping arrangements on the deep rolling devices of which the deep rolling roller heads are a part, their purpose being to suppress the gaping apart of the housings of the deep rolling roller heads. The EP patent describes such a solution (see EP 0 661 137, p. 1, col. 2, lines 4-15, col. 8, lines 18-21 and FIG. 4C).
The means known so far for the suppression of the gaping apart phenomenon are however too far away from the location of that occurrence because of to design constraints, so that they cannot be an effective remedy. Due to the natural elasticity of the deep rolling devices in the axial direction of the crankshaft, narrow limitations are imposed on reinforcement by means of clamps.
This leads to the problem to be solved by the present invention, i.e. to provide a simple, secure and economical support for the housings of the deep rolling roller heads.
This problem is solved in that each of the insides of the housings is provided with an extended segment on either side of the rotational axis of the crankshaft and at a radial distance from it, extending in the direction of the rolling force until below the contact point between the deep rolling rollers and the radii or indentations to be deep rolled, and in that the supporting element is made in form of a sliding surface that is permanently connected to the inside and the extensions of one of the two housings.
In this manner the housings of the deep rolling roller heads receive additional support in an area located below the contact point between the deep rolling roller and the crankshaft, as seen in direction of the rolling force. Hereby the gaping of the upper regions of the housing of the deep rolling roller head can be effectively prevented under the effect of the deep rolling force. It is advantageous if the supporting areas are extended in the direction of the rolling force up to the level of the rotational axis of the crankshaft and, insofar as the design conditions permit, even beyond this.
By extending the supporting forces under the action of the deep rolling rollers on the crankshaft it is even possible to leave the bearing surface around this area open to a great extent. A circular opening, concentric with the main rotational axis of the crankshaft has proven itself here.
The supporting surface according to the invention is made of a material with good sliding characteristics. Materials of this type are for instance those that contain nylon, Teflon or carbon, in particular of the kind containing graphite. Material with portions of the above-mentioned materials is also suitable.
In addition to the insides of the housing of the deep rolling roller heads made of steel, brass has been found to be especially well suited as a material for the bearing surface. Brass is known to have better sliding characteristics than steel. Screw connections are provided for attachment to the inside of one of the two housings of the deep rolling tool, but pins can be used just as well or the bearing surface can be bonded to the inside of one of the two housings.
Furthermore, openings in the form of lubrication channels are provided on the surface of the brass bearing surface towards the inside of the opposite housing of the deep rolling tool. An outlet through which additional lubricants such as grease, oil or graphite can be supplied to the openings on the outside of the bearing surface is installed on a lateral face of the housing concerned.
To improve the support of the guide rollers on which the deep rolling rollers bear within the housing, an axial bearing in form of a radial needle bearing in addition to those provided in the state of the art.
The invention is described in greater detail below through an example of an embodiment. At a reduced scale,
The deep rolling roller head 1 for the deep rolling of indentations 2 and 3 on the split-pin lobe 4 of a crankshaft 5 is provided with two housings 6 and 7 the insides 8 and 9 of which are turned towards each other. The deep rolling of the indentations 2 and 3 is achieved by means of deep rolling rollers 10 and 11 acting under the deep rolling force 12 exerted by the deep rolling machine 13 on the housings 6 and 7 of the deep rolling roller head 1. During deep rolling the crankshaft 5 rotates in the direction of arrow 14 around its main axis of rotation 15 that extends at a perpendicular to the plane of the drawings in
The deep rolling rollers 10 and 111 in turn bear on guide rollers 16 and 17 that are respectively mounted rotatably in one of the housings 6 or 7 on radial bearings 18 and 19 and axial bearings 20 to 23.
A bearing plate 24 is provided between the insides 8 and 9 of the housings 6 and 7. In
The bearing plate 24 is attached on the inside 8 of the housing 6 by suitable means such as e.g. screws 29 or pins. On its upper side, facing the inside 9 of the housing 7 across from it, the bearing plate 24 is provided with recesses 30 in the form of channels. The recesses 30 let out in a zone 31 on one of the faces 32 of the housing 7. A lubricant can be supplied from outside the deep rolling machine 13 through the outlet 31 to the channel-shaped recesses 30. For the sake of completeness, the supporting roller head 33 serving to support the crankshaft 5 during deep rolling is shown below the deep rolling roller head 1.
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 103.57.441.7 | Dec 2003 | DE | national |
