EP1265722A1

EP1265722A1 - Method and device for fracture-splitting a machine component with bearing eye

Info

Publication number: EP1265722A1
Application number: EP01921303A
Authority: EP
Inventors: Günter Knoll; Andreas Kalman
Original assignee: Motorenfabrik Hatz GmbH and Co KG
Current assignee: Motorenfabrik Hatz GmbH and Co KG
Priority date: 2000-03-21
Filing date: 2001-03-02
Publication date: 2002-12-18
Also published as: US20020104864A1; WO2001070440A1; US20050116004A1; DE10013980A1

Abstract

The invention relates to a method for fracture-splitting a connecting rod (1) of a piston engine into two bearing shells representing one half each of the bearing eye (2). The inventive method comprises the following steps: putting the machine component, before splitting, with its bearing eye onto a mandrel (10) divided into two equal parts; pretensioning the bearing eye in the splitting direction, by expanding the two mandrel halves (11, 12); fixing the position of the bearing eye (2) on the one side of the predetermined parting plane (4) by means of adjustable stops (29) with respect to the allocated mandrel half (11); driving in a wedge (16) between the two mandrel halves (11, 12), thereby splitting the bearing half whose position has been fixed and the associated mandrel half (11) from the bearing half fixed on the other mandrel half (12) by substantially fracturing simultaneously both sides.

Description

Method and device for breaking a machine component with a bearing eye

The invention relates to a method for breaking a machine component with a bearing eye, in particular a connecting rod of a reciprocating piston engine, m two bearing shells each forming one half of the bearing eye, and a device therefor.

In US Pat. No. 1,630,759 for the break separation of hollow-cylindrical workpieces such as bearing shells and bushings it is described that when the separation process is initiated by means of a wedge, the two sides of the workpiece break one after the other and that the side which is broken last is twisted. is coming. Such twisting generally leads to permanent deformation, with the result that the two fractions no longer fit exactly together. This disadvantage is particularly serious if the workpiece has already been machined before breaking.

To break the hollow cylindrical workpiece, a device is used which comprises a two-part mandrel which fills the interior of the workpiece and a wedge is driven in between the mandrel parts. Two spring elements on the outside of the workpiece are clamped together using compression screws against compression springs.

The arrangement of spring elements on the outer circumference of the workpiece should result in a uniform distribution of the breaking forces when the workpiece is blasted in two fractions, so that their deformation remains even if the two sides break one after the other.

According to EP-Bl 0167320, too, it is assumed that in the case of a machine component with a bearing eye, when breaking by means of a wedge, the two bearing sides break in succession, which can lead to undesirable deformations. Such deformations are to be reduced by a two-stage separation process in which the bearing legs of the first broken side are clamped together again, after which the other side is broken. To reduce the breaking forces and to achieve fracture surfaces that are as flat as possible, it may be expedient to manufacture the workpiece from a brittle material or to remove the workpiece e.g. B. temporarily by a strong cooling m a state with low breaking strength. In this sense it can also be expedient to have the workpiece on the inside of the bearing eye with grooves, notches, rows of holes or the like running along the later fracture plane. to weaken the fracture cross-section or to facilitate fracture conduction.

A comparable method for breaking connecting rods for reciprocating piston engines is described in EP-Bl 0304162. The bearing eye is clamped transversely to the fracture plane by means of clamping jaws against a split mandrel provided in the interior of the bearing eye. This clamping of the two halves of the bearing eye is maintained even after fracture separation by means of a wedge, the two sides of the bearing breaking shortly after one another. By maintaining this clamping of the bearing halves between the assigned mandrel half and the corresponding clamping baking should be achieved as linearly as possible moving away the fractions after separation, so that an adverse deformation of the two bearing halves is avoided in the region of the lateral bearing legs adjacent to the fracture surface. Immediately after the break separation, the two mandrel halves move together with the attached parts of the connecting rod, namely on the one hand the connecting rod cover and on the other hand the connecting rod on slide guides, after which the clamping is released and the broken parts of the connecting rod can be removed.

According to another method known from DE-C2 4037429 for breaking a connecting rod, the two bearing halves are pulled apart transversely to the later parting plane by means of a press, with each bearing half being tension-free against the assigned half of an inner mandrel by stops lying in the separating direction and transversely thereto, and this Piston pin eye of the connecting rod is only supported laterally. In this case, the bearing half connected to the connecting rod and movable on a slide is blasted off the other bearing half arranged fixed to the frame. The two bearing shells remain essentially aligned with one another during fracture separation, so that constraints in the area of the bearing eye, which can lead to undesirable deformations, occur significantly less.

Finally, EP-A2 0507519 describes a method for producing connecting rods, according to which the two halves of the bearing eye are separated from one another by using controlled breaking forces. For this purpose, the inside of the bearing eye the existing mandrel halves are moved apart by moving the mandrel half assigned to the connecting rod cover away from the other mandrel half while building up tensile stress in the bearing eye until it breaks. During the cracking process, the connecting rod is only spring-loaded transversely to the separating direction between stops; in addition, the connecting rod cover is resiliently supported against the separating direction; finally, the piston pin eye m is received in a stop block with lateral play so that it can carry out lateral compensating movements during cracking. Here, twists of the two fractions during the cracking in the macro range are consciously taken into account. The above-described limited lateral compensation movement of the piston pin eye is intended to avoid permanent deformation of the two bearing shell halves.

In contrast, the object of the present invention is to avoid undesired deformations of the two bearing shell halves in the area of the fracture surfaces even under the action of high fracture forces when fracture separation is used by means of a fracture wedge; the method of fracture separation should thus also be applicable for the production of connecting rods from materials with a relatively high fracture rigidity.

To achieve this object, the method according to the invention consists of the method steps according to claim 1.

According to EP-Bl 0304162, a half-split mandrel is used, on which the bearing eye is attached. In a departure from the known solution, the bearing eye is prestressed in the separating direction in that the two mandrel halves are clamped apart, similar to the solution described in EP-A2 0507519, which relates to a method in which the two mandrel halves are slow, not by a wedge stroke but by hydraulic forces and gradually move apart. However, there is a risk that the fracture surfaces obtained will run obliquely.

Characterized in that in the present invention, the bearing eye is fixed in position on only one side of the intended parting plane by means of adjustable stops, the other side can easily follow small twists during breaking, so that permanent deformations are avoided. It is essential that the position is not merely elastic, but in the sense of a play-free fixing of the corresponding side of the bearing eye. In this respect, the present invention differs from EP-A2 0507519, where the bearing half connected to the rod of the connecting rod is also supported with play in the area of the piston pin eye, but where the connecting rod cover is supported only by flexible holding forces. As a result, it is not possible in the known method to achieve the essentially simultaneous breaking of both sides of the bearing eye. However, the latter is an important prerequisite for the breaking forces m occurring on both sides of the bearing eye to be approximately the same size, so that permanent deformations due to stresses beyond the elastic limit of the connecting rod material are reliably avoided. The degree of deformation is therefore largely independent of the size of the breaking forces that occur. In the context of the method according to the invention, the mandrel half assigned to the positionally fixed bearing shell is expediently moved away from the other mandrel half fixed to the frame during breaking. Thus, while the bearing shell, which is fixed without play, is movably supported, for example on a slide, the bearing shell arranged fixed to the frame enables the support with limited play desired to compensate for macro twists.

If the breaking forces are to be kept low, it can be useful to run grooves or the like on the inside of the bearing eye along the parting plane. Provide measures to reduce breaking strength. Instead of grooves, a number of holes along a line, z. B. fine laser holes can be provided, which also have the advantage that they cause local embrittlement of the material and also take the effect of typical notches in the shape of a conical hole.

A suitable device for carrying out the method according to the invention is designed according to claim 4. A half split mandrel is provided, the circumference of which corresponds approximately to the bore of the bearing eye. The two mandrel halves adjoin one another with flat surfaces, which together form a recess for the insertion of a wedge tool, the recess m of the movable mandrel half preferably being designed as a bevel which is adapted to the wedge tool, while the recess m is fixed to the frame Half of the mandrel with a constant cross-section is continuously formed.

The mandrel halves are blown apart by the wedge stroke, the mandrel half assigned to the rod of the connecting rod being arranged fixed to the frame, while the other is fastened on a slide arrangement, so that it performs a stroke movement of 8 to 10 mm after breaking with the slide.

Compared to the mandrel half arranged on the slide arrangement, the connecting rod cover is fixed in position by means of two stops, the stops against the shoulders of the connecting rod on both sides, i.e. H. Fit over the mouths of the connecting rod screw holes without play. To protect the screw holes, but also for the purpose of better pressure distribution in the area of the abutment surfaces, according to one embodiment of the invention it is provided that the abutments are mounted on spherical caps so that their flat abutment surfaces can be adapted to the respective angle of rotation of the connecting rod-side mating surfaces.

The play-free fixing of the position of the cover is achieved in that the stops can be adjusted hydraulically, but are locked against evasion in the separating direction after being turned on by a mechanical adjusting device. This mechanical adjusting device is preferably implemented as a wedge deflection which can be actuated by means of a hydraulic support in the sense of a hydraulically actuatable piston-cylinder arrangement. The position of the connecting rod cover remains unchanged throughout the breaking process; it will only be released if the connecting rod cover is removed after the sledge stroke is full. For this purpose, the hydraulic support of the mechanical adjusting device is depressurized or retracted, after which the actuating piston controlled by the wedge deflection for the stop is moved according to the separating direction.

The two stops are expediently brought back into the fixed position after the bearing eye is again under tension for the next connecting rod to be machined, by the carriage arrangement ensuring that the bearing eye is subjected to a tensile bias supported by the two mandrel halves before breaking. The carriage arrangement is biased by a hydraulic piston-cylinder arrangement against the frame of the device in the separating direction. The half of the bearing eye connected to the rod of the connecting rod is fixed with play between the mandrel half fixed to the frame on the one hand and a pin holder which, on the other hand, engages the inside of the piston pin eye. This pin holder is advantageously a so-called sword pin, which engages the piston pin eye with play m, so that it cannot deflect laterally to the longitudinal direction of the rod, but is mounted with play in the longitudinal direction of the rod.

In order to intercept the sled arrangement thrown off after breaking at the end of the stroke of its evasive movement, according to a further embodiment Carriage arrangement movable against a compression spring arranged between this and the frame.

It is advantageous to assign the mandrel half fixed to the frame to the connecting rod bearing with the connecting rod. This simplifies the sled construction; in addition, the leverage in the support of the piston pin enables precise adjustment of the permissible movement play. If these advantages are dispensed with, it is also possible to arrange the connecting rod the other way round with respect to the two mandrel halves, the connecting rod cover being assigned to the fixed mandrel half.

An exemplary embodiment of the invention is explained below with reference to the drawing. It shows

Fig. 1 is a partially sectioned side view of the

Separating device and Fig. 2 is a plan view of the device according to

Fig. 1.

1 and 2, a connecting rod 1 of a reciprocating piston machine is inserted as the workpiece in the device for breaking separation of a machine component with a bearing eye. The connecting rod 1 has a bearing eye 2 within a bearing shell 3, which can be separated into two halves in the parting plane 4 by a controlled break. One half is formed by the connecting rod cover 5, the other half by the connecting rod bearing 6, with which the actual rod 7 is connected in one piece, at the end of which the piston pin eye 8 is formed within the piston pin bearing 9. Inside the bearing eye 2 there is a split mandrel 10 with a movably mounted mandrel half 11 and a mandrel half 12 fixed to the frame. A recess 13 adjoins the parting plane 4 between the two mandrel halves 11, 12 for the impact of a wedge tool 14. Within the movable mandrel half 11, the recess 13 is delimited by a bevel 15 which is adapted to the wedge angle of the wedge tool 14; In the area of the most extended mandrel half 12, the recess 13 is formed throughout with a constant right corner cross section.

The wedge tool 14 is arranged centrally above the mandrel 10 in such a way that a separating wedge 16 at the lower end of the wedge tool 14, which is guided in a guide block 17, is driven into the recess 13 in the direction of the arrow P1 when a striking cap 18 at the top End of the wedge tool 14, a blow is applied by a press, not shown. Between the striking cap 18 and the guide block 17, a compression spring 20 is arranged on a guide rod 21 on both sides of a plunger 19 of the wedge tool 14. The compression springs 20 ensure that after the wedge impact and release of the wedge tool by the press, the plunger 19 returns to its upper starting position, as shown in FIG. 1.

The movable mandrel half 11 is fastened on a carriage 22, which in turn is mounted on a frame 23 such that it can be moved horizontally. Between the carriage 22 and a head part 24 of the frame 23, a compression spring 25 is supported, which dampens the carriage before it reaches its left end position. In this end position, the carriage 22 is due to the wedge impact which causes the connecting rod 1 to break. The stroke of the slide is only 8 to 10 mm. The carriage 22 thrown in the separation direction according to arrow P2 is connected via a hydraulic piston 26 to a hydraulic cylinder 27 which is fastened on the outside of the head part 24 of the frame 23. The hydraulic cylinder arrangement 26, 27 serves to pretension the carriage 22 m in the separation direction according to arrow P2, the mandrel half 11 attached to the carriage transmitting a breaking force corresponding to this preload to the connecting rod eye 2, which is fixed by the mandrel half 12 fixed to the frame. The base 50 of the fixed mandrel half 12 is fixedly connected to a mounting plate 51, which in turn is fastened on the frame 23 of the device. In this way, a corresponding tensile preload in the separating direction is generated in the bearing shell 3 of the connecting rod 1 before the wedge-wrench which causes the break occurs. The carriage 22 is then reset after the wedge stroke by the compression spring 25.

After the bearing eye 2 of the connecting rod 1 has been preloaded, the bearing shell 3 is fixed in position in the area of the connecting rod cover 5 which is later produced, namely after fracture separation, by means of two stops 29 resting on opposite shoulders 28 of the connecting rod 1. The stops 29 have flat stop surfaces 30, which are mounted with limited movement by means of spherical caps 31 m corresponding stop housings 32. The stop housing 32 are screwed into a piston element 33 which is received in a cylindrical bore in a cylinder housing 34. Piston element 33 and cylindrical bore 34 have a Stage 35, which is connected to a compressed air supply 36. The latter serves to return the stop 29 from its stop position in order to release the connecting rod cover 5 for removal. The return of the stop 29 is only possible after the lifting of a mechanical lock by a mechanical adjusting device 37, which is designed as a wedge deflection, which can be actuated by a hydraulic support 38 m in the form of a hydraulic piston-cylinder arrangement. The wedge deflection consists of a vertical piston 39 which adjoins a horizontal piston 41 via a common wedge surface 40. The horizontal piston 41 ends outside the housing 42 of the adjusting device 37 that receives it with a piston end 43 which is turned to a smaller diameter. Inside the housing 42, the horizontal piston 41 is provided with a spiral spring 44, which lifts the horizontal piston 41 from the piston element 33 connected to the stop 29 and pushes the horizontal piston back. The spiral spring 44 thus acts like a compression spring, which has the tendency to retract the piston end 43 m into the interior of the housing 42. At the upper end, the adjusting device 37 has a connection housing 45 with a hydraulic connection 46 for actuating the vertical piston 39 downwards and a hydraulic connection 47 for actuating it upwards.

To tighten the stop 29, the vertical piston 39 is moved downward and accordingly moves the horizontal piston 41 to the right via the wedge surface 40, that is to say counter to the separating direction according to P2. Accordingly, the piston end 43 extends from the housing 42, strikes the piston element 33 of the Stop 29 and moves the latter against the corresponding stop surface on the shoulder 28 of the connecting rod cover 5. In this way, the stop 29 is fixed in position exactly, ie without play, so that it is not under tension. The stops 29 provided on both sides of the bearing shell 3 hold the associated half of the bearing shell 3 of the connecting rod 1 against the mandrel half 11 m corresponding to the stop position connected to the slide 22 in the stop position thereof. In principle, nothing changes at this stop position as a result of the fracture separation as a result of the wedge impact, ie it remains unchanged 22 m separation direction according to arrow 2 after the fracture separation has taken place during the movement of the slide. Only when the connecting rod cover 5 is removed is the hydraulic support 38 switched so that it moves upward and clears the way for the horizontal return of the horizontal piston 41 of the adjusting device 7 to the left. This retraction of the horizontal piston 41 is supported by the compression spring 44 located on its end. The piston end 43 of the horizontal piston 41 thus releases the piston element 33 of the stop 29; Thereafter, the stop 29 can be raised by means of compressed air via the compressed air supply 36 from the counter surface on the shoulder 28 of the connecting rod 1, after which the connecting rod cover 5 can be removed.

On the other hand, the connecting rod bearing 6 sits loosely on the mandrel half 12 fixed to the frame, so that it can be lifted off at any time. There is no obstruction by a sword pin 48, over which the piston pin eye 8 is placed, since the piston pin eye 8 of the piston pin bearing 9 contains the sword pin 48 takes up with little play, such that it is essentially fixed in a direction transverse to the axis 49 of the connecting rod 7, but in the longitudinal direction thereof is taken up with play. In this way, the connecting rod bearing 6 is secured against twisting during fracture separation, but can deviate to a limited extent in the direction of the connecting rod 7 under the fracture forces that occur, so that constraints and thus peaks in the fracture forces during the fracture separation are largely avoided.

Characterized in that the bearing eye 2 is displaced in the direction of separation P2 according to arrow P2 prior to fracture separation under prestress, there is only a very short-term effect on the bearing shell 3 by the wedge impact, so that both sides of the bearing shell 3 break practically simultaneously. This breaking of the two sides of the bearing takes place at such a short time interval that the human ear can only detect a coherent separation noise.

Another essential prerequisite for the simultaneous separation of the two bearing sides is that only one half of the bearing, in this case the connecting rod cover 5, is fixed in position, while the other half, in the present case the connecting rod bearing 6, is held with little play. The two sides of the bearing are broken with essentially equal refractive powers. Because the movable mandrel half 11 is fixed without play, there are no unfavorable twists during the cracking process and thus undesirable permanent deformations of the two bearing shell halves relative to one another.

Claims

Expectations

1. Method for fracture-separating a machine component with a bearing eye (2), in particular a connecting rod (1) of a reciprocating piston mechanism, m two bearing shells each forming one half of the bearing eye (2), with the following method steps:

1.1 the machine component is placed with its bearing eye (2) on a half-split mandrel (10) before breaking;

1.2 the bearing eye is biased in the separation direction by the two dome halves (11, 12) being stretched apart;

1.3 the bearing eye (2) is fixed in position on one side of the intended parting plane (4) by means of adjustable stops (29) with respect to the assigned mandrel half (11);

1.4 by driving a wedge (16) between the two mandrel halves (11, 12) the positionally fixed bearing shell with the associated mandrel half (11) is separated from the bearing shell fixed on the other mandrel half (12) by essentially simultaneously breaking both sides.

2. The method according to claim 1, characterized in that the mandrel half (11) assigned to the fixed bearing shell is moved away from the other mandrel half (12) fixed to the frame during breaking.

3. The method according to claim 1, characterized in that the breaking strength of the bearing eye (2) is weakened on the inside thereof along the intended parting plane (4) during the manufacture of the machine component.

4. Device for fracture-separating a machine component with a bearing eye (2), in particular a connecting rod (1) of a reciprocating piston mechanism, m two bearing shells each forming one half of the bearing eye (2), with the following features:

4.1 it comprises a half-split mandrel (10), the mandrel halves (11, 12) of which form a common recess (13) for driving in a wedge tool (16);

4.2 the circumference of the mandrel corresponds approximately to the bore of the bearing eye (2), the mandrel half (11) assigned to the connecting rod cover (5) being movable on a slide arrangement (22) in a separating direction, the other mandrel half (12) being arranged fixed to the frame;

4.3 the slide arrangement (22) carries two stops (29) for fixing the connecting rod cover (5) on both sides without play with respect to the associated mandrel half (11);

4.4 the connecting rod (6, 7) between the fixed mandrel half (12) and a pin holder in the interior of the piston pin eye (8) is limited movable;

4.5 the carriage arrangement (22) is biased in the separation direction (P2), so that the bearing eye (2) is subjected to a tensile stress supported by the two mandrel halves (11, 12) before breaking.

5. The device according to claim 4, that the stops (29) can be actuated hydraulically and are additionally blocked by a mechanical adjusting device (37) against evasion in the separating direction (P2).

6. The device according to claim 5, characterized in that the mechanical adjusting device (37) is designed as a wedge deflection which can be actuated by means of a hydraulic support (38).

7. The device according to claim 4, characterized in that the movable mandrel half (11) is rigidly connected to the slide assembly (22) and that the latter by means of a hydraulic cylinder arrangement (26, 27) against a base frame (23) of the device separating direction (P2) can be preloaded.

8. The device according to claim 7, characterized in that the carriage arrangement (22) against a between the carriage arrangement (22) and frame (23) arranged compression spring (25) can be biased, so that the carriage (22) after breaking the connecting rod (1 ) is cushioned.

9. The device according to claim 4, characterized in that the stops (29) are mounted on spherical caps (31), so that flat stop surfaces (30) to the respective angle of rotation of the connecting rod side counter surfaces are adaptable in a surface-oriented manner.

10. The device according to claim 4, characterized in that the recess (13) in the movable mandrel half (11) is designed as a slope (15) which is adapted to the wedge tool (16), and that the recess (13) in the most posed Half of the mandrel (12) with a constant cross-section is continuous.

11. The device according to claim 14, characterized in that the piston pin eye (8) is fixed by a sword pin (48) engaging therein with play in the longitudinal direction of the connecting rod (1).