WO2013121328A1

WO2013121328A1 - Reshaped bush-like part and method and device for the production thereof

Info

Publication number: WO2013121328A1
Application number: PCT/IB2013/051015
Authority: WO
Inventors: Thomas Körner; Peter Kolbe; Ernst-Peter Schmitz
Original assignee: Gesenkschmiede Schneider Gmbh
Priority date: 2012-02-16
Filing date: 2013-02-07
Publication date: 2013-08-22
Also published as: DE102012101246A1

Abstract

The invention relates to a reshaped bush-like part, which has a base (10), a wall (30), which adjoins the base, is integral therewith and comprises a wall portion of reduced outside diameter (32) and an opening portion (20), wherein the wall (30) is cold-hardened and has a grain flow substantially parallel to the outer contour, and relates to a method for the production thereof and to a device for the production of a bush.

Description

Reshaped female part and method and apparatus for his

manufacturing

The invention relates to a reshaped sleeve-like part, an apparatus and a method for its production.

Bushing-like forming parts, such as bearing bushes, pump punches, hydraulic pistons, piston skirting of pistons for internal combustion engines, are often produced as forgings from forgeable non-ferrous metals, such as bronzes, brass, light metal alloys, but also a variety of iron alloys. Blanks are at least partially - usually warm - transformed to solidify the forged areas - for example, forged. Such bushings are used for a variety of applications, so that the invention is by no means limited to the production of forged steel bushings, although it will be explained in more detail below with reference to bushings, which are particularly suitable for pistons for internal combustion engines.

In this context, a sleeve is understood as meaning a hollow component which is essentially annular in cross-section and has a closed, circular end.

So far, metal bushings are generally drilled with uniform wall thickness of solid material or reshaped - for example, forged. Many forged or obtained by hydroforming or rotary swaging bushings have the advantage of work hardening of the material.

Usually, a solid blank is in one or more engravings of forms - eg. Schmiedegesenken - introduced (eg. Vorgravur and finished engraving) to high degrees of deformation of greater than 6 and more depending on the material. to be able to realize. When swaging is over a spike kneaded, which keeps the inner shape stable. However, after swaging, a forming step, such as a calibration step in a forging mold, must take place to maintain shape fidelity.

Since, for example, piston for hydraulic pumps or internal combustion engines require a high degree of deformation, is often used to fill the engraved parts with burr pad. As a result, the long flow paths of the material to be forged are evenly distributed to the forming stages.

In view of the generally ever increasing demands on lightweight components and / or those with low material consumption, it is an object of the invention, bushes for the o.g. To create applications that are lighter and use less material.

The object is achieved by a jack having the features of claim 1. Furthermore, the invention also relates to a process for their preparation and an apparatus therefor.

The fact that the wall thickness is reduced by a forming process, such as forging, between socket bottom and socket opening with unchanged internal width, a significant material savings can be achieved.

These parts have, if they run as a piston in engines, nor to a reduced friction against the bushing or the cylinder bore, as a smaller contact outer wall surface - for example, on a cylinder bore - is applied. Thus, a reduction in consumption can be achieved. Since they have a lower heat capacity than known parts, less heat is absorbed, which must be dissipated. This is particularly advantageous in plain bearing bushings.

The weight saving achieved by this embodiment is particularly in the use of the jacks in mobile applications (large engines, Vehicles, vehicles of all kinds) are important and for reasons of ambition desirable. But it also allows a better acceleration of the piston itself, if they are parts of engine pistons. By forging in the reduced wall area can still be achieved a good and sufficient mechanical strength of the socket walls for most applications.

However, the mold according to the invention can also be achieved by other forming processes, which ensure solidification in the wall region of the bushing, as by hydroforming or rotary swaging over a mandrel.

According to the invention, therefore, a reshaped sleeve-like part, which: a bottom (10); a wall (30) which adjoins the bottom and thus has a wall section of reduced outside diameter (30) and an opening section (20), wherein the wall (30) is work-hardened and has a fiber path which is substantially parallel to the outside contour. Due to the strain hardening, it is possible to realize low wall thicknesses despite satisfactory mechanical and thermal load capacity of the walls. In particular, this also consumption savings achieved in running pistons in engines of any kind, since there is a greatly reduced friction surface against the bushing wall and less friction energy is overcome.

Advantageously, the socket-like part comprises a wrought alloy-but it can also consist of several layers-for example, the interior of the part may be made of a different material (for example a plain bearing metal) than the exterior of the bush-like part, with both layers then being deformed together become.

In a preferred embodiment, the at least one wrought alloy is selected from titanium, aluminum, magnesium, iron, bronze, brass alloys. In the case of engine pistons, for example, a material has been selected from the group consisting of 42CrMo4, precipitation-hardening steels, proven high chromium steels, but also aluminum alloys etc. are used

A common use of sleeve-like parts according to the invention is as a piston lower part of an internal combustion engine or bearing bush. In bushings comes to fruition that this takes most of the load a bushing in the bottom area of the socket and in the opening area - the intermediate wall is less loaded and therefore usually does not have the same mechanical strength.

It is also possible for a multilayer material to be co-formed to join the layers of material. Typically, such a harder outer socket can be made with a bearing metal inner wall. In this case, for example, two sleeve-like blanks can be arranged one inside the other and then forged together to form the final shape. The two materials can already be joined together by soldering, welding or mechanically, so that the soldered composite is then converted to the final shape. In this way, an inner layer can be formed with better storage properties, whereby the complex glaze of bearing metal or spray coating can be avoided.

In an application of the invention as engine pistons for internal combustion engines of any kind, a shirt length between 40 mm and 200 mm; preferably 60-85 mm and a wall thickness between 3 mm and 12 mm, wherein in the region of reduced thickness, a wall thickness between 3 - 5 mm is set, be achieved with steel as a forging material.

A method according to the invention for producing a bushing reduces the thickness of the bushing walls at least partially by a transversely acting forming tool in a predetermined range while the inner diameter is kept constant by a support. The socket is forged in a forging tool in the usual way, which has transversely to the main forging actuable tools.

An embodiment of a plant for producing a bush-like component according to the invention has a piston-die forged with a split piston-bottom engraving, which has cross-calibration tools which can be actuated transversely to the main axis of the die.

For example. For example, an apparatus for single-stage forging female engine piston bottoms may be a form for forging a preform into a finished female forged part in a single forging step.

an upper forming mandrel C,

- An outer ring A with a transverse to the mandrels transverse tools D;

a lower forming mandrel B

- an ejection device with:

a lower ejector H for ejection through the lower mandrel B

an upper ejector G for ejection through the upper mandrel C; and

a clamping foot E for supporting the lower forming mandrel B, by means of which the lower ejector H can be actuated,

wherein the mandrels C and B and the transverse tool D can enter during forging in the mold ring A with therein Vorpressling and so the same schmiedeumformen and by the actuators C and B actu Baren ejector G, H the forging is subsequently demoldable include.

Today, it is desirable for a variety of reasons, minimum piston wall thicknesses to achieve as long as possible Kolbenhemdlänge. This leads to lower weight, better thermal expansion behavior and long guide in the bush. This desired low wall thickness can be achieved with the largest possible Kolbenhemdlänge only by a very deep engraving and can only be realized on a further Bearbeitungsaufmaß.

Such a procedure is energy-consuming if several - at least two forging stations are provided. Because of the cooling of the forgings between the stations had to take measures to prevent the same, requiring additional handling effort.

By the device according to the invention, it is possible to achieve in a few forming steps, preferably a forging step, sleeve-like parts of small wall thickness and weight, with long bushing wall with good mold filling capacity and a long tool life of starting material.

The temperature control is a major concern when forming warm parts. It is important that the temperature of the hot formed part is removed quickly and as evenly as possible in the mold so that strain hardening of the new shape occurs and distortion of the part is avoided by uncontrolled temperature stresses during cooling outside the mold. For this purpose, it may be provided according to the invention, the inner mandrel B, which due to the fact that it has a lot of material and is arranged in the interior of the tool, thermally to slower cooling than the other tool components tends to cool. For this purpose cooling channels for cooling fluid, such as liquids or gases, can be provided. Depending on the size ratios of the mold used and the heat capacity of the materials such cooling is useful. It is also possible to solve this problem by selecting another material of the forming mandrel having a different thermal conductivity. Another possibility is to form the mandrel, which dissipates heat quickly due to its high thermal conductivity, by cooling the clamping foot E and / or the lower ejector H indirectly via heat to cool down. However, such cooling devices can also be provided in other parts of the mold.

A special feature of the invention lies in the interaction of the lifting and extraction unit. Characterized in that in the engraving of the upper mandrel C a negative extension cone alpha is provided, the forging is lifted safely out of the tool. A sliding back of the forging blank in the blacksmith form prevents the lower ejector H, which is actuated by the clamping foot E. The interaction of the upper and lower ejector can avoid deep ejector marks and distortions due to one-sided force.

It is preferred for better heat management, especially for larger forgings that the lower mandrel and the forging thereon is cooled after forming before opening the same.

By means of the uninterrupted and uniformly fast flow of material made possible according to the invention, a uniform shape, which is filled to the smallest radii, and thus a very dimensionally stable forged part are produced. Forging errors are avoided and many reworks avoided.

Preferably, at least one mold inner wall is coated with lubricant / release agent before inserting the preform, whereby the material flow is promoted and the removal of the forged part is simplified.

A typical sleeve-shaped forged part according to the invention, for example of 42CRMo4, precipitation-hardening steels, high chromium steels, which is particularly suitable as engine pistons for internal combustion engines, has a shirt length between 60 mm and 160 mm and a wall thickness between 3 mm and 12 mm. The above and further aspects of the invention will become apparent to those skilled in the art by reference to the accompanying drawings and the following detailed description of embodiments, to which the invention should by no means be restricted. It shows:

1 is a perspective view of an embodiment according to the invention bush-shaped formed sleeve,

FIG. 2 shows a longitudinal section through the embodiment of FIG. 1 with a reduced wall area; FIG.

2 shows a longitudinal section through a further embodiment of a bush according to the invention;

4 shows schematically the fiber path in the formed bush,

5 shows a forging mold for producing a sleeve-like piston part produced according to the invention

Fig. 6 is an inventively produced piston base with partially reduced Kolbenhemddicke.

In Fig. 1, a sleeve-shaped forging produced according to the invention is shown schematically. Clearly, the bottom 10, the adjoining socket wall 30 with the reduced wall portion 32 and the opening portion 20 can be seen. The fiber course is shown schematically in FIG. 4. Clearly, the uninterrupted fiber flow parallel to the outer walls, which ensures the best mechanical properties and is a prerequisite for the good properties of the novel female-like part, can be seen. In Fig. 2 and 3, longitudinal sections are shown by bush-like forged parts, from which it is apparent that the wall reduction can be done very differently depending on the stability requirements of the wall. In Fig. 3, an embodiment is shown in which in the bottom region of the wall and in its opening portion 20 mechanical stress takes place - such as in bushings - while in Fig. 2, an embodiment is shown in which mainly the opening portion 20 of the socket wall 30 loaded becomes.

A method according to the invention which is suitable for producing such a piston 10 is carried out with a molding tool of FIG. 4. The tool has an upper mandrel C, the special design greatly simplifies the forming of a blank in one step. 4, a cross section through the upper mandrel C is shown. Through the upper mandrel C, an upper ejector G can be extended, which can remove a located in the engraving molding. It may also make sense to use a negative die angle alpha in the engraving of the upper mandrel C for ejection by the ejector G after completion of the stroke, the so-called pull-out angle.

The lower die of the forging die forming the engraving for forging the female part together with the upper die mandrel is formed by the lower die mandrel B and the outer die ring A with cross tool D, between which the female wall is formed in desired length and thickness ,

The lower mandrel B is designed to pass through a lower die

Ausstosser H, which can be round, but also formed by the

Feet E can be actuated, relative to the outer mold ring A is movable and thus facilitates removal of the forging from the lower tool by avoiding sliding back of the blacksmith blank. The combination of upper and lower ejector H, G decreases Ejector marks in the molding as well as forgings by a good force distribution during ejection.

The ring-like mandrel receptacle F supports the circumference of the upper mandrel C and forms with it the upper part of the mold.

The forging tool is completed by the clamping foot E, which supports the lower forming mandrel and allows movement of the lower mandrel B by the ejector H running in it.

An inventive method for forging the sleeve-like forging is as follows: A pre-compressed pre-compact is supplied by a machine heated to forming temperature and placed in the open forging between the retracted upper mandrel C and lower mandrel B in the outer mold ring A. This can be done when both ejectors are withdrawn. Thereafter, the mold is closed in a forging stroke, whereby the two mandrels are moved toward each other, the pre-press pressed against the Formgravurwände and reshaped. In a further stroke, or simultaneously with it, the transverse tools drive on the piston wall and forge these to the desired shape with reduced diameter. Of course, the mold may be conventionally cyclically pre-coated with mold release agents as are well known in the art and known to those skilled in the art. Gas pressures in the mold can be dissipated by conventional venting measures, such as vent holes I, thereby also removing lubricants and their residues. The arrangement of the vent hole is by no means limited to the lower mandrel and may be varied according to the requirements as will be apparent to those skilled in the art.

FIG. 6 shows a piston 1 10 produced according to the invention for internal combustion engines with a partially reduced piston skirt thickness. On For example, such piston for internal combustion engines made of 42CrMo4 steel has the following dimensions: the length of the piston skirt 1 14 is at least about 0.5 times the Kolbenaussendurchmessers, about 135 mm. The thickness of the piston side wall 1 11 is in the range of about 1/6 tel of the Kolbenaussendurchmessers. In a typical 42CrMo4 engine piston for internal combustion engines, the piston skirt length is from 60 to 85 mm, the shell side wall thickness is from 6 to 10 mm, and the piston outside diameter is from 15 to 140 mm. In other embodiments, for example, as piston 1 10 for marine engines or drive motors for energy production plants, depending on the material other dimensions are common, as known to those skilled in the art. The special wall thicknesses depend heavily on the material used and the tasks of the piston.

If mandrel cooling is provided, it must be used prior to ejecting the molded part to obtain the reshaped geometry.

The above description thus merely discloses an exemplary embodiment of the invention. It will be apparent to those skilled in the art from the description and the accompanying drawings and claims that various changes, modifications and variations are possible within the scope of the claims.

LIST OF REFERENCE NUMBERS

10 socket bottom

20 Opening area of the socket wall

30 socket wall

32 thickness reduced area of the socket wall

1 10 piston

1 1 1 piston side wall

1 14 Piston shirt

1 16 reduced thickness range of 1 14

Claims

claims

1. Reshaped female part characterized by:

a floor (10); a wall (30) which adjoins the bottom and thus has a wall section of reduced outside diameter (32) and an opening section (20), wherein the wall (30) is work hardened and has a fiber path substantially parallel to the outside contour.

2. bush-like part according to claim 1, characterized in that it comprises at least one wrought alloy.

3. bush-like part according to claim 2, characterized in that the wrought alloy is selected from aluminum; Magnesium; Iron-; Bronze-; Brass alloys.

4. bush-like part according to one of the preceding claims, characterized in that it is a piston lower part of a

Internal combustion engine, a bearing bush, is.

5. Bush-like forging, especially engine pistons for

Internal combustion engines of any kind, according to one of claims 1 to 3, characterized by: steel as forging material and a shirt length between 40 mm and 200 mm; preferably 60-85 mm and a wall thickness between 3 mm and 12 mm, wherein in the region of reduced thickness 32, a wall thickness between 3 - 5 mm is set.

6. bush-like formed part according to one of the preceding claims, characterized in that a multilayer material is formed into a part together and so the

Material layers are connected.

7. A method for manufacturing a socket according to one of

preceding claims, characterized in that the bushing walls are reduced by a transversely acting forming tool in a predetermined range forming in thickness, while the inner diameter is held constant by a support.

8. The method according to claim 7, characterized in that the bushing is forged in a forging tool in the usual way, which has transversely to the main forging actuable tools.

Device for producing a bushing according to one of the preceding claims, characterized in that it comprises a piston forging die with a split piston lower part engraving, which has transversal calibration tools which can be actuated transversely to the main axis of the die.

10. Device for forging sleeve-like parts after

Claim 9, which comprises:

an upper forming mandrel C,

- An outer mold ring A with transverse to the form dome transverse tools D;

a lower forming mandrel B

- an ejection device with:

a lower ejector H for ejection through the lower mandrel B

an upper ejector G for ejection through the upper mandrel C; and

a clamping foot E for supporting the lower forming mandrel B, by means of which the lower ejector H can be actuated, wherein the mandrels C and B and the transverse tool D can enter during forging in the mold ring A with therein Vorpressling and so the same schmiedeumformen and can be actuated by the actuable by the mandrels C and B ejector G, H the forging.