MXPA06008798A - Sheet material infiltration of powder metal parts - Google Patents
Sheet material infiltration of powder metal partsInfo
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- MXPA06008798A MXPA06008798A MXPA/A/2006/008798A MXPA06008798A MXPA06008798A MX PA06008798 A MXPA06008798 A MX PA06008798A MX PA06008798 A MXPA06008798 A MX PA06008798A MX PA06008798 A MXPA06008798 A MX PA06008798A
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- tablet
- infiltrating
- process according
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Abstract
A powder metal part infiltration process uses a stamped metallic sheet as a source of metal for infiltration to achieve a high strength powder metal part. A powder metal is compacted, and an infiltrant blank is formed from a wrought metal sheet. The infiltrant blank is placed on top of the compact, and the compact is sintered at a temperature sufficient to form a sintered compact with a matrix having pores and to melt the wrought metal such that the melted wrought metal infiltrates the pores of the matrix. The infiltrant blank may be formed with a locating element for engaging a corresponding locating element on the compact to improve positioning of the blank on the compact. Also, the compact may be separately sintered, and the infiltrant blank may then be placed on the sintered compact. The wrought metal is then melted such that the melted wrought metal infiltrates the pores of the matrix.
Description
INFILTRATION OF PLATE MATERIAL IN PULVERIZED METAL PARTS
FIELD OF THE INVENTION The present invention relates to the manufacture of pulverized metal parts, and in particular to the infiltration of pulverized metal parts with a metallic material such as copper. BACKGROUND OF THE INVENTION Powdered metal parts are used to produce many automotive components that have a need for networked components. The pulverized metal components are typically produced by pressing a powdered metal in a die to obtain in a tablet in a desired manner and subsequently sintering the tablet to increase the strength of the piece. It has been reported that conventional powdered metal parts, produced by pressure and sintering, have a lower impact and fatigue resistance due to the presence of pores in the sintered parts.
Consequently, methods have been proposed to eliminate porosity and achieve near total density in the pieces.
One method to obtain approximately the total density "is to infiltrate the powdered metal parts with a metal such as copper. See for example, U.S. Patents Ref .: 174864 Nos. 6,676,894, 6,551,373, 6,500,384, 5,925,836, 5,574,959, 5,031,878, 4,976,778, 4,861,373, 4,836,845, 4,769,071, 4,734,968, 4,731,118, 4,60'6,7 8, 4,485,147, 4,424,953, 4,412,873, 4,168,162, 4, 089551 and 3,829,295. Infiltration is the process of filling the interconnected pores of the pulverized metal tablet with a molten metal or alloy (the "infiltrant") of lower melting point by capillary action, for example copper-infiltrated steel is manufactured by compaction of iron or iron-based powder (with or without graphite powder) in a finished form and infiltrating the pores interconnected with a copper base material during the sintering operation.This may be a one-step or two-step infiltration The result is a unique steel-copper structure for the powder metallurgy process.In comparison with powdered metal parts made of iron or sintered carbon steel, the copper infiltration can improve the tensile strength, fatigue resistance , elongation, hardness, and impact properties In the past, the copper source to infiltrate a piece of powdered metal was a metal copper tablet. Co powder, that is, an elaborate piece of copper powder that is pressed together to maintain its shape. However, the use of a pulverized metal tablet as a source of copper infiltration has its disadvantages. For example, (1) residue may remain after infiltration; (2) erosion of the base metal surface at the infiltrant entry point may occur; (3) the location of the infiltration can be difficult because certain forms can not be practical through the conventional pulverized metal infiltrating tablets; (4) Fracture associated with fragile powdered metal infiltrative tablets may occur; and (5) the placement of copper powder tablets can be difficult. Therefore, there is a need for an improved process for infiltrating porous powdered metal parts with a metallic material such as copper. BRIEF DESCRIPTION OF THE INVENTION The present invention meets the foregoing needs by providing an alternative to the use of a pulverized metal tablet as the source of infiltration. An infiltration process according to the invention uses a stamped metal foil material or metal source for infiltration to reach a high strength powdered metal article. In one form, an infiltration process according to the invention uses a forged copper foil material stamped as a copper source for infiltration to achieve an iron or high-strength powdered metal steel article.
In one aspect, the invention provides a process for the manufacture of a metal piece infiltrated powdered metal. In the process, a pulverized metal is compacted, to form a tablet, and an infiltrating blank is formed from a sheet of forged metal. The infiltrating blank is placed in contact with the tablet, and the tablet is sintered at a temperature sufficient to form a sintered tablet with a matrix having pores and the forged metal is melted in such a way that the molten forged metal infiltrates the pores of the matrix to form a piece of metal infiltrated with metal. The placement of the blank in the upper part of the tablet improves the infiltration of the forged metal. In one embodiment, the pulverized metal is selected from iron and iron alloys, and the forged metal is selected from copper and copper alloys. It may be beneficial for the forged metal sheet to have a thickness less than 1 millimeter. The infiltrating blank can be formed by a method such as stamping; formation of fine preliminary pieces or blasting abrasive water. In another aspect of the invention, the inventive blank can be formed with a positioning element that is suitable for engaging a corresponding positioning element in the tablet, and the infiltrating blank can be placed in contact with the tablet in such a manner that the insertion element of the blank engages the corresponding positioning element on the tablet. For example, the insertion element of the blank may be a section of the piece in. gross that extends outward from a body of the rough piece. As a result, the placement of the blank on the tablet is improved. In yet another aspect of the invention, the tablet is sintered separately at a temperature sufficient to form a sintered tablet with a matrix having pores, and an infiltrating blank is formed from a sheet of forged metal. The infiltrating blank is then placed in contact with the sintered tablet, and the forged metal is melted in such a way that the molten forged metal infiltrates the pores of the matrix to form a metal piece infiltrated by pulverized metal. Some advantages of using a forged metal sheet in place of a powdered metal tablet are: (1) a reduction in the amount of residue after infiltration; (2) a reduction in the amount of erosion of the base metal tablet surface at the infiltrant entry point; (3) location of improved selective infiltration because the sheet stamping process facilitates conformation with non-practical geometry through conventional pulverized metal infiltrating tablet such as in thin frames, and missing areas; (4) Improved quality of the infiltration process due to the elimination of the fracture associated with fragile powdered metal infiltrate tablets; and (5) improved placement of the preliminary pieces of stamped sheet due to the ability of the stamping processes to form placement features to engage or engage with the component to be infiltrated. These and other features, aspects, and advantages of the present invention will be better understood by considering the following detailed description, figures, and appended claims. BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows a top view of an infiltrating crude piece of copper placed on an iron-based tablet before sintering in accordance with a version of the invention. Figure 2 shows the details of the experimental test pieces after sintering and infiltrating. DETAILED DESCRIPTION OF THE INVENTION In an exemplary process for the manufacture of a metal infiltrated pulverized metal in accordance with the present inventionIron or iron alloy powder is introduced into a die having the desired shape of the final piece. The pulverized metal is then compressed in the die until a higher density article commonly known as a "crude tablet" is obtained. Typically, the green compacts based on iron have a density of 6.0 g / cm3 to 7.0 g / cm3 (the theoretical density of iron is 7.88 g / cm3. Then the desired amount of forged copper or copper alloy sheet is formed to the desired shape for the part in infiltrative gross and the blank is placed in contact with the green compact so that copper can infiltrate the pores of the tablet when heated. the tablet and blank copper placed in contact with the tablet are subjected to a conventional sintering process performed at a predetermined temperature above the melting point of the copper (eg 1100 ° C) for a fixed amount of time (eg, 15 minutes) in a suitable atmosphere (eg, a reducing atmosphere containing hydrogen) Typically, the sintering process promotes binding or diffusion between the iron powder or iron alloy particles to create a compressed sintered with a matrix that has pores. During the sintering process, the molten copper flows into the pores in the matrix. The molten copper is absorbed, via surface tension, gravity and capillary action, in the open porosity of the matrix. Therefore, the molten copper fills the pores of the matrix, thereby increasing the density and integrity of the matrix. The amount of copper infiltrated depends on the physical and mechanical properties desired in the matrix. When only partial infiltration into the matrix is desired, the amount of copper is reduced. The porosity measurements of the crude tablet can be used to determine the amount of copper infiltrate required. In an alternative process, the tablet is first subjected to a conventional sintering process only to form a sintered tablet with a matrix. In a second step, the workpiece copper infiltrant blank formed from the forged sheet is placed in contact with the sintered compact and the copper foil and the sintered compact heated to a predetermined temperature. During the second stage, copper melts and <; it flows into the pores in the previously sintered porous matrix. Copper melts and is absorbed, by means of surface tension, gravity and capillary action, within the open porosity of the matrix. Figure 1 shows an example combination of a tablet and an infiltrating blank suitable for use in a process of the invention. A copper infiltrating blank 10 of approximately 0.812-8 mm (0.032 inch) in thickness in the form of a ring is shown placed on top 22 of a tubular iron base tablet 20 prior to sintering. The upper part 22 of the tablet 20 has recessed areas 24a, 24b, 24c and 24d receiving flanges 14a, 14b, 14c and 14d extending outward from the perimeter edge 12 of the body of the blank 10. The flanges 14a, 14b, 14c and 14d provide positioning features for engaging with or engaging the recessed areas 24a, 24b, 24c and 24d in the tablet 20 to be infiltrated with the copper of the blank 10. In the embodiment shown, the. tabs 14a, 14b, 14c and 14d extend outward from the blank 10 and engage the recessed areas 24a, 24b, 24c and 24d in the tablet 20. However, in an alternative configuration, the blank. it can include recesses that engage positioning characteristics that extend outwardly. compressed. The copper infiltrating blank 10 can be formed by stamping, forming fine preliminary pieces or blasting abrasive water from copper foil material or forged copper alloy. By "forged", it is understood that it is a material formed by a mechanical action such as rolling, forging, extrusion or stretching. A forged material typically has a density greater than 99% of the theoretical density. Therefore, pulsed materials are not considered as forged materials because compacted pulverized materials typically have a density of 93% or less of the theoretical density. Forged copper materials, for example, have a thickness of 0.0254 to 6.35 mm (0.001 to 0.25 inches). Forged copper materials that have thicknesses less than 1 mm (0.039 inches) are particularly advantageous. Suitable copper alloys include brass and bronze. EXAMPLES The following examples have been presented for the purpose of further illustrating the invention and are not intended to limit the invention in any way. 1. Experimental Methods Three infiltration techniques were compared against a non-infiltrated control test. Standard test rings measuring nominally 50.8 mm (2.0 inches) in outer diameter x 19.05 mm (0.75 inches) in internal diameter x 28.575 mm (1125 inches) in length, made from a material that meets the Standard 35 FC specification were used. -0208 from the Federation of Metals Industries Pulverizados (MPIF, for its acronym in English) The MP F .Std. FC-0208 is as follows: Elemental iron powder of 93.2-97.9 weight percent; elemental copper powder of 1.5 - 3.9 weight percent; carbon (as graphite powder) of 0.6 - 0.9 weight percent; and other elements 2.0 percent by maximum weight.
The base tablets were pressed to a density of 6.95 g / cm 3. Eighteen test rings were developed for infiltration. The three infiltration techniques explored were: (1) a noninfiltrate (control) based on MPIF Std. 35 FC-0208;
(2) a standard pulverized metal copper infiltration as described in MPIF Std. 35 (FX series), i.e., using a pulverized copper infiltrant material and pressing it in a suitable manner to be placed on top of the metal article of iron or iron base for subsequent copper infiltration during sintering;
(3) a dual feed process where the copper powder was mixed with MPIF Std FC-0208 material, the die was then lowered and a second filler with copper infiltration material was added and compacted; and (4) infiltration using a 0.8128 mm thick (0.032 inch) copper stamping material cut using sheet scissors to produce a shaped copper source. from the same area as the test ring. All the test pieces were sintered in a 61 cm (24 inch) muffle furnace at normal sintering conditions, i.e. at 1121 ° C (2050 ° F) for 15 minutes in a 90% nitrogen atmosphere and 10 minutes in the oven. % hydrogen Figure 2 shows the details of the test pieces after sintering / infiltration. The upper row is of the Dual Feeding process. The second row of the upper part is the standard ring with pressurized pressed copper compact rings placed on top. The second row from the bottom piece is the standard ring with a. prefabricated copper stamp placed on top. The bottom row is the standard ring. Note the amount of solidified film that remains on the two upper rows. The prefabricated pattern leaves no solidified film. 2. Test Results Density measurements were taken and are shown in Table 1. Table 1
Infiltration by copper stamping according to the invention produced the highest density and therefore a suitable replacement for the infiltration of pulverized metal. It may also be possible to use a forged sheet material other than copper as the source of the infiltration material. Erosion readings / degree of cleanliness were taken and are shown in Table 2. Table 2
3. Conclusions The dual feeding of material was not an adequate method for infiltration of pulverized metal articles.
Conventional copper infiltration produces significant residue and erosion. It is difficult to align the infiltrating piece of pressed copper causing an inconsistent infiltration. Due to the fragile unsintered resistance of the infiltrating material pressed, the infiltration process is subject to a high formation of residues when the infiltrating piece is thin due to the fracture caused by the handling. Infiltration by copper stamping is a unique process and has the following advantages: (1) the process is a low erosion infiltration process; - (2) the process is a process of infiltration of low waste content; (3) the process is a process of selective infiltration by the stamping of shapes with non-practical geometry through conventional pulverized metal infiltrating pieces such as thin wefts, and missing areas; (4) the process uses thin gauge copper materials and therefore eliminates the fracture associated with fragile pulverized metal infiltrating pieces, thereby reducing waste formation and improving quality; and (5) the process allows the use of stamping placement features such as "ears", "lips" or "tabs" or other easily stamped orientation features. Therefore, the invention provides an alternative use of a pulverized metal tablet as the source of infiltration. An infiltration process according to the invention uses a stamped metal foil material (e.g., copper) as a source of metal (for example copper) for infiltration to achieve a piece of high-strength powdered metal (for example, iron or steel). Although the present invention has been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other means than those described, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the modalities contained herein. INDUSTRIAL APPLICABILITY The invention relates to a process for producing stronger powdered metal parts, of higher density and improved surface texture. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.
Claims (22)
- CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 5. 1. A process for the manufacture of a piece of pulverized metal infiltrated with metal, characterized in that the process comprises: compacting a pulverized metal to form one tablet; 0 forming an infiltrating blank from a sheet of forged metal; place the infiltrating blank on top of the tablet; and sintering the tablet at a temperature sufficient to form a sintered tablet with a matrix having pores and melting the forged metal such that molten forged metal infiltrates the pores of the matrix.
- 2. The process according to claim 1, characterized in that: the pulverized metal is selected from iron, iron alloys and mixtures thereof; and the forged metal is selected from copper and copper alloys.
- 3. The process according to claim 2, characterized in that: the forged metal sheet has a thickness of less than 1 millimeter.
- 4. The process according to claim 1, characterized in that: the infiltrating blank is formed by means of a selected method of stamping, forming fine preliminary pieces and blasting abrasive water.
- The process according to claim 1, characterized in that it additionally comprises: forming the infiltrating blank with a positioning element that is suitable for engaging a corresponding positioning element in the tablet; and placing the infiltrating blank in contact with the tablet in such a way that the insertion element of the blank engages with the corresponding positioning element in the tablet.
- 6. The process according to claim 5,. characterized in that: the blank part is a section of the blank extending outwardly from a body of the blank.
- 7. A process of manufacturing a piece of pulverized metal infiltrated with metal, characterized in that the process comprises: compacting a pulverized metal to form a tablet; sintering the tablet at a temperature sufficient to form a sintered tablet with a matrix having pores; r forming an infiltrating blank from a sheet of forged metal; placing the infiltrating blank on top of the sintered tablet; and melting the forged metal in such a way that the molten forged metal infiltrates the pores of the matrix.
- The process according to claim 7, characterized in that: the pulverized metal is selected from iron, iron alloys and mixtures thereof; and the forged metal is selected from copper and copper alloys.
- 9. The process according to claim 8, characterized in that: the forged metal sheet has a thickness of less than 1 millimeter.
- 10. The process according to claim 7, characterized in that: the infiltrating blank is formed by means of. a . selected method of stamping, formation of fine preliminary pieces and abrasive water jet cutting.
- 11. The process according to claim 7, characterized in that it additionally comprises: forming the infiltrating blank with a positioning element that is suitable for engaging a corresponding positioning element in the tablet; and placing the infiltrating blank in contact with the tablet in such a way that the insertion element of the blank engages with the corresponding positioning element in the tablet. The process according to claim 7, characterized in that: - the blank part is a section of the blank extending outwardly from a body of the blank. 13. A process for manufacturing a piece of pulverized metal infiltrated with metal, characterized in that the process comprises: compacting a pulverized metal to form a tablet; forming an infiltrating blank from a forged metal sheet, the blank has a positioning element that is suitable for engaging a corresponding positioning element in the tablet; placing the infiltrating blank in contact with the tablet in such a way that the insertion element of the blank engages the corresponding positioning element in the tablet; and sintering the tablet at a temperature sufficient to form a sintered tablet with a matrix having pores and melting the forged metal in such a way that molten forged metal infiltrates the pores. The process according to claim 13, characterized in that: the pulverized metal is selected from iron, iron alloys and mixtures thereof; and the forged metal is selected from copper and copper alloys. 15. The process according to claim 14, characterized in that: the forged metal sheet has a thickness of less than 1 millimeter. 16. The process according to claim 13, characterized in that: the infiltrating blank is formed by means of a selected method of stamping, forming fine preliminary pieces, and laser cutting. The process according to claim 13, characterized in that: the blank part is a section of the blank that extends outwardly from a body of the blank. 18. A process of manufacturing a piece of pulverized metal infiltrated with metal, characterized in that the process comprises: compacting a pulverized metal to form a tablet; sintering the tablet at a temperature sufficient to form a sintered tablet with a matrix having pores; forming an infiltrating blank from a sheet of forged metal, the blank has a positioning element which is suitable for engaging a corresponding positioning element in the sintered tablet; placing the infiltrating blank in contact with the sintered tablet in such a way that the inserting element of the blank engages the corresponding positioning element in the sintered tablet; and melting the forged metal in such a way that the molten forged metal infiltrates the pores of the sintered tablet; The process according to claim 18, characterized in that: the pulverized metal is selected from iron, iron alloys and mixtures thereof; and the forged metal is selected from copper and copper alloys. The process according to claim 19, characterized in that: the forged metal sheet has a thickness of less than 1 t millimeter. 21. The process according to claim 18, characterized in that: the infiltrating blank is formed by means. of a selected method of stamping, forming fine preliminary pieces and laser cutting. 22. The process according to claim 18, characterized in that: the element for placing the blank is a section of the blank that extends outward from a body of the blank.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US60/542,271 | 2004-02-04 |
Publications (1)
Publication Number | Publication Date |
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MXPA06008798A true MXPA06008798A (en) | 2006-12-13 |
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