Deep rolling roller head for split-pin crankshafts

A deep rolling roller head includes two housings for the deep rolling of the outer radii or fillets of split-pin crankshaft journals by means of two deep rolling rollers which are pressed into one of the two fillets under a rolling force while the crankshaft rotates around its axis of rotation. The two housings follow at the same time the different movements of the journals and support each other with their insides across from each other on a bearing plate. The insides of the housings bear on either side of the axis of rotation of the crankshaft and at a distance from it on an extension segment extending in the direction of the rolling force to below a contact point between the deep rolling rollers and the fillets to be deep-rolled. The bearing plate connected permanently to the inside and the extensions of one of the two housings.

RELATED APPLICATIONS

This application claims the benefit of and priority to German Patent Application No. DE 103.57.441.7, filed on Dec. 9, 2003, the disclosure of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a deep rolling roller head with two housings for the deep rolling of the outer radii or fillets of split-pin crankshaft journals by means of two deep rolling rollers each of which is pressed into one of the two radii or fillets by a rolling force while the crankshaft rotates around an axis of rotation, whereby the housings follow the different movements of the journals 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.

BACKGROUND OF THE INVENTION

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 journals offset at an angle and adjoining each other.

Deep rolling tools for the deep rolling of the outer radii or fillets 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 fillets of a split-pin journal. At the same time the crankshaft rotates around its axis of rotation and the housings follow the different movements of the split-pin journals 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 fillets, 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 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.

SUMMARY OF THE INVENTION

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 fillets 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 axis of rotation 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 is provided in addition to those provided in the state of the art.

DETAILED DESCRIPTION OF THE INVENTION

The deep rolling roller head1for the deep rolling of fillets2and3on the split-pin journal4of a crankshaft5is provided with two housings6and7the insides8and9of which are turned towards each other. The deep rolling of the fillets2and3is achieved by means of deep rolling rollers10and11acting under a deep rolling force12exerted by the deep rolling machine13on the housings6and7of the deep rolling roller head1. During deep rolling the crankshaft5rotates in the direction of arrow14around its main axis of rotation15that extends at a perpendicular to the plane of the drawings inFIGS. 1 and 3.FIGS. 1 to 3show this process in a simplified mostly schematized manner.

The deep rolling rollers10and11in turn bear on guide rollers16and17that are respectively mounted rotatably in one of the housings6or7on radial bearings18and19and axial bearings20to23.

A bearing plate24is provided between the insides8and9of the housings6and7. InFIG. 1the bearing plate24is indicated by broken lines. On either side of the axis of rotation15and at a radial distance25from it, the two insides8and9are extended by segments26and27which extend respectively vertically as far as below the axis of rotation15, vertically as seen in the direction of the rolling force12. The bearing plate24follows the contours of the two extended segments26and27but is cut out above the deep rolling rollers10or11in an arc of circle28whose central point in turn constitutes the axis of rotation15in this case. It should be noted that either of the two insides8and9and the bearing plate24have the configuration shown inFIGS. 1 and 3, i.e. each with an extension segment26or27.

The bearing plate24is attached on the inside8of the housing6by suitable means such as e.g. screws29or pins. On its upper side, facing the inside9of the housing7across from it, the bearing plate24is provided with recesses30in the form of channels. The recesses30let out in a zone31on one of the faces32of the housing7. A lubricant can be supplied from outside the deep rolling machine13through the outlet31to the channel-shaped recesses30. For the sake of completeness, the supporting roller head33serving to support the crankshaft5during deep rolling is shown below the deep rolling roller head1.

InFIG. 2the crankshaft5with its two adjoining split-pin journals4is shown and is delimited in the direction of the main axis of rotation15by the crank arms34and35. The fillets2and3that are deep-rolled by means of the deep rolling roller head1are located between the splint-pin journals4and the crank arms34and35. For this purpose the deep rolling rollers10and11enter the fillets2or3and roll them respectively at a point of contact (i.e., contact point36).

LIST OF REFERENCE NUMBERS