Method for producing a copper-infiltrated valve seat ring

Abstract

A method for producing a copper-infiltrated valve seat ring and a valve seat ring are disclosed. The method includes introducing a copper powder and a functional material powder mixture into a joint cavity, simultaneously forming the copper powder and the functional material powder mixture into a green body comprising a functional section and a copper section in the joint cavity by the mold element, and sintering the green body formed in step b) to produce the valve seat ring where the copper section liquefies during the sintering and infiltrates pores present in the functional section.

Claims

1. A method for producing a copper-infiltrated valve seat ring, comprising the following steps: a) Introducing a copper-based powder and a functional material powder mixture into a joint cavity provided in a mold element of a molding device, b) Simultaneously forming the copper-based powder introduced in step a) and the functional material powder mixture introduced in step a) into a green body comprising a functional section and a copper section in the joint cavity by the mold element, and c) Sintering the green body formed in step b) to produce the valve seat ring, wherein the copper section liquefies during the sintering and infiltrates pores present in the functional section; wherein while performing step a) the copper-based powder and the functional material powder mixture are essentially not mixed with one another, wherein the functional material powder mixture introduced in step a) includes iron, between 0 and 15% by weight of each of Mo, Si, W, V, C, P, Ni, Cr, Cu, Co, N, and Mn, and production-related impurities, and wherein 90% of the particles of the functional material powder mixture have a maximum diameter of between 25 μm and 344 μm, 20% or less of the particles of the functional material powder mixture have a maximum diameter of less than 40 μm, and 10% or less of the particles of the functional material powder mixture have a maximum diameter of larger than 300 μm.

2. The method according to claim 1, wherein step a) includes introducing the copper-based powder into the joint cavity prior to the functional material powder mixture or vice versa.

3. The method according to claim 1, wherein step a) includes introducing the copper-based powder and the functional material powder mixture simultaneously into the joint cavity.

4. The method according to claim 1, wherein the copper-based powder introduced in step a) is pre-formed by a pre-forming device.

5. The method according to claim 1, wherein at least one of: the copper-based powder introduced in step a) includes production-related impurities and up to 10% by weight of alloying elements, and 5% or less of the particles of the copper powder have a maximum diameter of larger than 177 μm.

6. The method according to claim 1, wherein after performing step b), the copper section has a height of less than 1 mm measured along the axial direction (A).

7. The method according to claim 1, wherein after performing step b), further including arranging the copper section and the functional section next to one another along an axial direction.

8. The method according to claim 1, wherein after performing step b), a surface that completely separates the functional section and the copper section extends in a plane perpendicular to an axial direction.

9. A valve seat ring, comprising: a sintered green body including a copper section and a functional section; wherein the copper section is composed of copper and infiltrates pores present in the functional section; wherein the functional section is composed of a functional material powder mixture including iron, between 0 and 15% by weight of each of Mo, Si, W, V, C, P, Ni, Cr, Cu, Co, N, and Mn, and production-related impurities; and wherein 90% of the particles of the functional material powder mixture have a maximum diameter of between 25 μm and 344 μm, 20% or less of the particles of the functional material powder mixture have a maximum diameter of less than 40 μm, and 10% or less of the particles of the functional material powder mixture have a maximum diameter of larger than 300 μm.

10. The valve seat ring according to claim 9, wherein the valve seat ring has a height of less than 4 mm, measured along an axial direction.

11. A tribological system, comprising: a valve seat ring, the valve seat ring including: a green body including a copper section and a functional section; and wherein the copper section is composed of copper and infiltrates pores present in the functional section; wherein the functional section is composed of a functional material powder mixture including iron, between 0 and 15% by weight of each of Mo, Si, W, V, C, P, Ni, Cr, Cu, Co, N, and Mn, and production-related impurities, and wherein 90% of the particles of the functional material powder mixture have a maximum diameter of between 25 μm and 344 μm, 20% or less of the particles of the functional material powder mixture have a maximum diameter of less than 40 μm, and 10% or less of the particles of the functional material powder mixture have a maximum diameter of larger than 300 μm; and wherein the copper of the copper section is composed of includes production-related impurities and up to 5% by weight of each of Fe, Mn, Sn, Zn, Al and Ni, and wherein 5% or less of the particles of the copper powder have a maximum diameter of larger than 177 μm.

12. An internal combustion engine for a motor vehicle, comprising a valve seat ring as claimed in claim 9.

13. The method according to claim 1, wherein step b) of simultaneously forming the copper-based powder and the functional material powder mixture includes pressing the copper powder and the functional material powder mixture into the green body.

14. The method according to claim 1, wherein the copper-based powder introduced in step a) includes production-related impurities and between 0 and 5% by weight of each of Fe, Mn, Sn, Zn, Al and Ni.

15. The method according to claim 1, further comprising pre-forming the copper-based powder via pressing prior to introducing the copper-based powder and the functional material powder mixture into the joint cavity.

16. The method according to claim 6, wherein the height of the copper section is less than 0.7 mm after performing step b).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings show:

(2) FIG. 1 illustrates a sectional view of a simplified example of a formed green body of a valve seat ring;

(3) FIG. 2 illustrates a sectional view of a simplified example of a valve seat arrangement comprising a valve seat ring; and

(4) FIG. 3 illustrates an example of a molding device configured to carry out a method for producing a valve seat ring according to the disclosure.

DETAILED DESCRIPTION

(5) FIG. 1 illustrates a sectional illustration of a simplified example of a formed green body 1c. The green body 1c comprises a functional section 1a and a copper section 1b. The functional section 1a and the copper section 1b are arranged next to one another along an axial direction A, and are separated by a separation plane T, which is arranged between the functional section 1a and the copper section 1b. In the example of FIG. 1, the separation plane T runs along a radial direction R of the valve seat ring 1, extends in a plane E, which is perpendicular to the axial direction A of the valve seat ring, and completely separates the functional section 1a and the copper section 1b along a cross section of the green body 1c. It is also conceivable that the separation plane T runs along the axial direction A of the valve seat ring 1.

(6) The copper section has a height H.sub.K of less than 1 mm, preferably of less than 0.7 mm, measured along the axial direction A. The copper section 1b can also have between 20% and 30% of the mass of the functional section 1a. The functional section 1 has a height H.sub.R of less than 4 mm, measured along the axial direction A.

(7) FIG. 2 illustrates a sectional illustration of a simplified example of a valve seat arrangement 10 comprising a valve seat ring 1, which is mounted to a cylinder head 2 of an internal combustion engine and which is produced according to the invention, in a cross section along an axial direction A of the valve seat ring 1.

(8) The valve seat ring 1 encases a valve opening of the cylinder head 2, which can be closed by a valve body (not shown in FIG. 2). A section of the valve seat ring 1, which is inclined towards the axial direction A, forms the valve seat 3, on which a valve plate (not shown in FIG. 1) of the valve body abuts in a closing position.

(9) The valve seat ring 1 essentially only still comprises the dimensions of the functional section, which was infiltrated with the liquefied copper section, and has a ring height H.sub.R of less than 4 mm, measured along the axial direction A.

(10) FIG. 3 shows an example of a molding device 100, which is configured for carrying out the method according to the invention. The molding device 100 comprises a multi-part molding element 101, which comprises a molding matrix 102, an upper die 103, lower die 103b, and a core rod 105.

(11) A cavity 104, which is arranged in a ring-shaped manner around an axis in the image plane in the example of FIG. 3 and which can be seen in a cross section along this axis in FIG. 3, is configured between the mold matrix 102 and the core rod 105. A copper powder 100b and a functional material powder mixture 100a are introduced into the cavity 104 in the example of FIG. 1.

(12) The method according to the invention will be described in an exemplary manner below on the basis of FIGS. 1 to 3:

(13) For carrying out the method, the copper powder 100b and the functional material powder mixture 100a are introduced into the same, joint cavity 104. The copper powder 100b can thereby be introduced prior to the functional material powder mixture 100a, or the functional material powder mixture 100a can be introduced prior to the copper powder 100b. The copper powder 100b and the functional material powder mixture 100a can also be introduced simultaneously. The copper powder 100b and the functional material powder mixture 100a can thereby be introduced into the cavity 104 in such a way that the copper powder 100b and the functional material powder mixture 100b are essentially not mixed with one another during the introduction.

(14) The functional material powder mixture can thereby include metal powder on the basis of iron, copper or cobalt, hard phases, carbon, chromium, manganese, nickel, molybdenum, copper, silicon, vanadium, tungsten, cobalt, niobium, copper, sulfur, calcium, tri-iron phosphide, bronze, phosphor, pressing additives, flow improvers, graphite, sulfides, calcium difluoride, organic and inorganic binding agents, waxes, solid lubricants, production-related impurities, and further materials, which are common for the production of wear-resistant valve seat rings. In the example of FIGS. 1 to 3, the introduced functional material powder mixture includes iron and between 0 and 15% by weight of Mo, Si, W, V, C, P, Ni, Cr, Cu, Co, N, and Mn each, as well as production-related impurities. In addition, 90% of the particles of the functional material powder mixture have a maximum diameter of between 25 μm and 344 μm, maximally 20% of the particles of the functional material powder mixture have a maximum diameter of less than 40 μm, and maximally 10% of the particles of the functional material powder mixture have a maximum diameter of larger than 300 μm.

(15) The copper powder can include Fe, Mn, Sn, Zn, Al, Ni, pressing additives, flow improvers, organic and inorganic binding agents, waxes, solid lubricants and production-related impurities. In the example of FIGS. 1 to 3, the introduced copper powder includes production-related impurities as well as maximally 10% of alloying elements, each comprising between 0 and 5% by weight of Fe, Mn, Sn, Zn, Al, and Ni. In addition, maximally 5% of the particles of the copper powder have a maximum diameter of larger than 177 μm.

(16) In the joint cavity 104, the introduced copper powder 100b and the introduced functional material powder mixture 100a are then simultaneously formed in the joint cavity 104 to form a joint green body 1c comprising a functional section 1a and a copper section 1b by the mold element 101, in particular by pressing. In the example of FIG. 3, the introduced copper powder 100b and the introduced functional material powder mixture 100a are thereby formed in a joint pressing process by pressing the upper die 103a against the mold matrix 102 and core rod 105. The lower die 103b is thereby pushed against the pressed-on upper die 103a after the pressure contact thereof with the lower die 103b, in order to further compact the introduced copper powder 100b and the introduced functional material powder mixture 100a. The introduced copper powder 100b can also be pre-formed by means of a pre-forming device (not shown in FIG. 3), which is embodied in particular on the molding device 100, in particular by pressing. The copper green body and the functional green body are integrally formed with one another after the forming.

(17) The formed green body is subsequently sintered to form the valve seat ring in such a way that the copper section liquefies during the sintering and infiltrates pores, which are present in the functional section. The copper section is thereby received completely by the functional section by capillary forces.

(18) The valve seat ring 1 can be machine-finished after the production of the valve seat ring 1 and after the arrangement and the press-in of the valve seat ring 1 on the cylinder head 2.