WO1999046521A1

WO1999046521A1 - Method for making a metal cylinder sleeve

Info

Publication number: WO1999046521A1
Application number: PCT/EP1999/001204
Authority: WO
Inventors: Bernd Stein; Adam Zaboklicki; Wilhelm Zimmermann; Jürgen Zimmermann
Original assignee: Dynamit Nobel Gmbh Explosivstoff- Und Systemtechnik
Priority date: 1998-03-10
Filing date: 1999-02-25
Publication date: 1999-09-16
Also published as: JP2002505959A; DE19810265A1; EP1062441A1

Abstract

The invention concerns a method for making a metal cylinder sleeve (6) to be used in an internal combustion engine cylinder block, said cylinder sleeve (6) internal surface having a surface structure. In order to produce said cylinder sleeve in one single operation, while reducing related production costs, the cylinder sleeve (6) is made with its surface structure in one single operation using the known technique of flow forming.

Description

Method of manufacturing a metallic cylinder liner

The invention relates to a method for producing a metallic cylinder liner for use in the engine block of an internal combustion engine, the inner surface of the cylinder liner having a surface structure.

In engine construction, cylinder liners ("wet" or "dry") are used to line cylinders, which are inserted into the engine blocks, which are usually made of cast materials. The liners are made of wear-resistant materials and have a specially designed topography of the inner surface for better piston guidance and piston lubrication. These inner surfaces are conventionally prepared for use by complex mechanical processing.

The invention is based on the object of specifying a method for producing a metallic cylinder liner for use in the engine block of an internal combustion engine, with which the cylinder liners can be produced in one operation and thus more cost-effectively. In addition, the quality of these cylinder liners should be at least comparable to the quality of the cylinder liners manufactured according to the prior art.

According to the invention, this object is achieved in that the cylinder liner with the surface structure is produced in one operation using the pressure rolling technology known per se.

The pressure rolling technique is described by way of example in DE 24 20 014 A1 or WO 96/200 50. The pressure rolling is also referred to as ironing press in these publications. WO 96/200 50 also describes in detail the counter-flow rolling process and the synchronous flow rolling process.

The pressure rolling technology is briefly described below with reference to FIG. 1. Here, a tubular blank 1 is subjected to a rotating extrusion process. It plastic deformation or a punctiform doughing of the material occurs.

The blank 1 is located on a rotatably driven spinning roll mandrel 2, one or more spinning rollers 3a, 3b, 4a, 4b abutting against the blank 1 during a longitudinal movement. A flow deformation of the metal takes place between the spinning roll mandrel or a forming tool and the spinning rollers 3a, 3b, 4a, 4b, the wall thickness of the blank 1 being reduced and its length being increased.

A pipe (with and without weld seam) is suitable as the raw part. It is also conceivable that a tube as a blank is made from several different materials that are joined together. This also includes preforms that are coated on the inside with a surface protective layer (wear protection, protection against heat influences), e.g. B. are provided with AIO ₃ . These preforms are suitable to support the different loads on the liner. Other preforms are pot-shaped raw parts (e.g. forged or cold-formed parts) or a round blank. In the event that a tube is used as a blank, the counter-flow rolling process or the synchronous flow rolling process is used. The synchronous spinning rolling process is used for the other raw parts.

During the pressure rolling process, the workpiece (tube, cup-shaped part or blank) presses against the tool mandrel under the pressure of the outer forming rollers or pressure rolling rollers in such a way that it takes on the surface quality and its dimensions inside. This means that inner surfaces with a roughness of Ra <0.3 μm and internal tolerances up to an ISO quality of 9-10 can be achieved depending on the dimensions. However, the prerequisite is that the tool mandrel or the spinning roll mandrel has at least the same or better surfaces or tolerances.

Due to the springback of the material after the forming operation has been completed, the workpiece lifts a few micrometers from the spinning roll mandrel (depending on the material and Different dimensions) and can be easily removed from the mandrel.

In the upper part of Fig. 1, the synchronous spinning rolling process is shown. Reference number 3a shows the spinning roller at the beginning of the forming operation, while reference number 3b shows the spinning roller at the end of the forming operation or the pressing operation.

In the lower part of Fig. 1, the counter-flow rolling process is shown. Here too, reference number 4a shows the spinning roller at the beginning and reference number 4b the spinning roller at the end of the spinning-rolling operation. Reference number 5 shows an anti-rotation device for the blank 1. This anti-rotation device 5 consists of a toothing on the end face against which the blank 1 is pressed.

In a first advantageous embodiment, a suitable cut, z. B. a cross section, applied.

Cylinder liners conventionally have not only a ground surface inside, but also e.g. B a "cross-section", which supports the different tribological stresses on the component and reduces wear. According to the invention, this topography is already applied as a negative image on the pressure-rolling mandrel. The surface of this tool dome is of a quality that is at least as high as the required inner surface quality of the workpiece must correspond.

After a press-rolling operation, the workpiece lifts a few micrometers due to the springback of the material, so that the rolled-in surface structure is retained without damage after the workpiece has been stripped from the tool mandrel. The procedure described above describes the production of a conventional cylinder liner. The variant described below using the pressure-rolling technique leads to a new type of inner micro-surface of the cylinder liner via the inner surfaces that are comparable with machining methods or other methods. This has special lubricating properties, as regular elevations and depressions in the μm range are made in the inner surface of the cylinder liner.

The inner surfaces produced in this way have special properties that effectively support and greatly improve the tribological tasks of the cylinder liner. These internal structures are realized by special measures and designs on the pressure rollers as well as special settings of the process parameters during pressure rolling.

To achieve these goals, three pressure rollers x, y, z are advantageously used and the following process parameters are set:

• Circulation speed of the rolls 80 - 150 mm / min.

• Feed of the rolls 50 - 400 mm / min. • Column x, y, z 1/3 sun

• Axis offset Wx, Wy, Wz 1 - 5 mm

These process parameters are advantageously combined with the following parameters for the pressure rollers x, y, z.

• Inlet angle αx = 15 - 40 ° αy = 15 - 30 ° αz = 15 - 30 °

• Outlet angle ß ßx = 3 - 10 ° ßy = 3 - 10 ° ßz = 3 - 10 ° • Roller radius R Rx = 0.5 - 3 mm

Ry = 0.5 - 3 mm Rz = 0.5 - 3 mm

Of course, these parameters are also useful on their own.

4, the individual parameters such as columns x, y, z, axis offset Wx, Wy, Wz, entry angle α, exit angle β and roller radius Rx, Ry, Rz are defined.

The method described above is suitable for producing "lubrication pockets" without requiring special pretreatment of the tool mandrel. However, it is also conceivable for elevations to be applied to the press-rolling mandrel, which present themselves as depressions in the inner surface when the part is press-rolled. These Recesses (or elevations as a negative image on the tool mandrel) can be designed very differently in order to meet the different requirements.As such elevations on the tool mandrel are advantageously only very small (a few μm to a maximum of 0.015 mm high), the workpiece can after the pressure rolling process, because of the springback of the material already described, can be easily stripped off the tool mandrel without destroying the previously introduced internal structure.

For example, these elevations have the shape of a truncated pyramid with a rectangular base. However, all other possible surveys are also useful.

If the elevations described above on the spinning roll mandrel are larger than the possible springback of the workpiece, the workpiece can no longer be stripped from the tool mandrel after the spinning rolling process without damaging or destroying the internal surface structure of the workpiece. In this case, an expanding mandrel (with mechanical, hydraulic, pneumatic or other expanding method) is used according to the invention, which is expanded during the press-rolling operation and is relieved after the forming. This allows Larger differences in diameter are overcome and deeper "lubrication pockets", which go beyond the amount of springback, are produced without the intended internal structure being damaged when the part is stripped off after the shaping operation.

For this purpose, in an exemplary embodiment, the spinning roll mandrel is cup-shaped and has longitudinal slots, so that a locking mandrel that can be pushed into the spinning roll mandrel can spread the spinning roll mandrel.

Further features of the invention are shown in the figures, which are described below. It shows:

1 shows the basic principle of the pressure rolling technology in the co-rotating and counter-rotating pressure rolling method,

2 shows a tool mandrel with indicated cross grinding and a section of a cylinder liner with a cross grinding on the inner surface,

3 shows a basic illustration of a special surface structure of a cylinder liner,

4 an explanation of the individual parameters such as columns, axis offset, entry angle, exit angle and roller radius,

Fig. 5 is a schematic diagram of a mandrel with elevations and the resulting surface structure of the cylinder liner with lubrication pockets and

Fig. 6 shows a special spinning roll mandrel in the unspread and spread state.

1 has already been described in the introduction to the description and shows, by way of example, the synchronous spinning rolling method in the upper part and the counter-rotating in the lower part. Pressure rolling method with a tool dome 2, a blank 1, pressure rollers 3a, 3b, 4a, 4b and an anti-rotation device 5.

2 shows a section of a tool mandrel 2 with indicated cross-cut 7 on its surface. In addition, a section from a cylinder liner 6 produced with the aforementioned tool mandrel 2 is shown. This also shows a cross section 7. The cross section 7 on the tool mandrel 2 is the negative form of the cross section on the surface of the cylinder liner 6.

3 again shows a cylinder liner 6 and an enlarged section of the inner surface. The inner surface shows a special surface structure with drop-shaped elevations 8. This special surface structure has been achieved with a combination of the following features:

Rotation speed of the pressure rollers 80 - 150 mm / min; Feed of the pressure rollers 50 - 400 mm / min; Columns x, y, z 1/3 Sun; Axis offset Wx, Wy, Wz 1 - 5 mm; Entry angle αx = 15 - 40 °, αy = 15 - 30 °, αz = 15 - 30 °; Exit angle ßx = 3 - 10 °, ßy = 3 - 10 °, ßz = 3 - 10 ° and roller radius of the pressure rollers Rx = 0.5 - 3 mm, Ry = 0.5 - 3 mm and Rz = 0.5 - 3 mm.

The height h of these elevations 8 is between 4 and 7 μm.

In Fig. 4, the three spinning rollers x, y, z are shown in the drawing plane for better illustration. In fact, the three spinning rollers x, y, z are circumferentially offset by 120 °. For a better representation, the axis offset Wx, Wy, Wz between the pressure rollers x, y, z is shown larger than it actually is.

The first spinning roller z first comes into contact with the workpiece. With a conical pressing surface 18, it rests on the workpiece. Axial feed reduces the wall thickness of the workpiece by the first pressure roller z, starting from an original wall thickness So, by the thickness z. The first pressure roller z runs on helical tracks over the surface of the workpiece. The feed and 8 the rotational speed at which the pressure roller z turns the workpiece are coordinated so that the pressure roller z covers the entire surface of the workpiece. The entry angle otz is the angle between the pressing surface 18 and the outer surface of the workpiece. The pressing surface 19 of the second pressure roller y has the same geometry. The pressing surface 20 of the third pressure roller x runs at an entry angle αx.

A transition area 21 adjoins the pressing surface 20 and merges into an outlet surface 22 of the pressure roller x. The transition region 21 has a radius Rx. The first and second spinning rollers z, y also each have a transition region with the radii Rz and Ry. The run-out surfaces run at a run-out angle ßx, ßy, ßz with respect to the outer wall of the workpiece.

The pressure rollers x, y, z have a different radial distance from the forming tool or the workpiece. The first spinning roller z has the greatest distance since it processes the workpiece first. At the outlet end of the pressing surface 18 of the first pressure roller z, the original wall thickness So of the workpiece is reduced by the amount z. At this radial distance So-z, the input end of the pressing surface 19 of the second pressure roller y now engages. The wall thickness is reduced by the amount y by the pressing surface 19 of the second pressure roller y. The last press roller x reduces the wall thickness by the amount x until the desired target wall thickness S1 of the workpiece is reached. The wall thickness of the workpiece is thus reduced from the original wall thickness So to the target wall thickness S1. The wall thickness reduction d is composed of the individual reductions x, y, z.

5 is a basic illustration of a spinning roll mandrel 2 with elevations 8 and the surface structure of the cylinder liner 6 with lubrication pockets 11 created thereby. The elevations 8 have the shape of a truncated pyramid with a rectangular base area. It should be emphasized that the shape of the surveys is only exemplary. Many other forms are possible. The elevations 8 expediently have a maximum height of 0.015 mm. This allows the cylinder liner 6 to be easily pushed off the mandrel 2 after machining. Form the lubrication pockets 11 is of course reversed from that of the elevations 8, so that the lubrication pockets 11 have a maximum depth of 0.015 mm.

In Fig. 6 a special spinning roll mandrel 2 is shown, which is expandable. This spinning mandrel 2, also called expanding mandrel, can, for. B. mechanically, hydraulically or pneumatically spread and is spread during the pressure rolling process and relieved after the forming. As a result, the finished cylinder liner can also be pushed by the mandrel 2 if the height of the elevations is greater than z. B. is 0.015 mm.

In the upper part of FIG. 6, the mandrel 2 is shown in the non-spread state. The spinning roll mandrel 2 is cup-shaped and has longitudinal slots 9. The lower part of FIG. 6 shows this mandrel 2 spread. For this purpose, a locking mandrel 10 is inserted, which is slightly thicker than the cup-shaped cavity in the mandrel 2. As a result, the individual parts separated by the longitudinal slots 9 are spread apart. As previously described, the outer surface of this spinning roll mandrel 2 is provided with the surface structure according to the invention.

With the spread angle is designated.

Claims

10 Claims

1. A method for producing a metallic cylinder liner (6) for use in the engine block of an internal combustion engine, wherein the inner surface of the cylinder liner (6) has a surface structure, characterized in that the cylinder liner (6) with the surface structure in one operation with the known pressure rolling technology is produced.

2. The method according to claim 1, characterized in that on the press-rolling mandrel (2) of the press-rolling machine as a negative mold, a suitable cut, z. B. a cross section (7) is applied.

3. The method according to claim 1, characterized in that three pressure rollers (x, y, z) are used and the following process parameters are set during the pressure rolling:

- Circulation speed of the rolls 80 - 150 mm / min.

- Feed of the rolls 50 - 400 mm / min.

- Column x, y, z 1/3 Sun.

- Axial offset Wx, Wy, Wz 1 - 5 mm

4. The method according to claim 3, characterized in that the following parameters of the pressure rollers (x, y, z) are set:

- Inlet angle α ox = 15 - 40 ° αy = 15 - 30 ° αz = 15 - 30 °

- Outlet angle ß ßx = 3 - 10 ° ßy = 3 - 10 ° ßz = 3 - 10 °

- Roller radius R Rx = 0.5 - 3 mm Ry = 0.5 - 3 mm

Rz = 0.5 - 3 mm 11

5. The method according to claim 1, characterized in that elevations (8) are applied to the mandrel (2) of the mandrel.

6. The method according to claim 5, characterized in that the elevations (8) on the mandrel (2) or depressions in the cylinder liner (6) one

Have a maximum height of 0.015 mm.

7. The method according to claim 5 or 6, characterized in that the spinning mandrel (2) is designed as an expanding mandrel, the z. B. is mechanically, hydraulically or pneumatically expandable and spread during the spinning and is relieved after the forming.

8. The method according to claim 7, characterized in that the spinning roll mandrel (2) is cup-shaped and has longitudinal slots (9) so that a locking mandrel (10) which can be pushed into the spinning roll mandrel (2) can spread out the spinning roll mandrel (2).