JP5940058B2 - Manufacturing method of powder metallurgy steel - Google Patents

Description

Field of Invention

Those concerning the way for the production of powder metallurgical steel by powder metallurgy techniques.

Background of the Invention

In the prior art, cylindrical bars made of HSS or HSS-E high speed tool steel for producing cutting tools are produced by rolling or drawing.

  Heretofore, manufacturing blanks for making tools from HSS or HSS-E has been done by rolling or stretching the steel in repeated processing cycles. Such processing steps require expensive equipment and complicated processes, and are time consuming and expensive.

  In contrast, manufacturing a blank from cemented carbide or cermet can be done with much cheaper equipment and less complicated processes. The blank can be produced from cemented carbide or cermet by performing a sintering process after the extrusion process. Related production methods are described, for example, in documents US 2,422,994, DE 36 01 385 A1, EP 465 946 A1, EP 1 017 527 B1, EP-A-0 340 495, EP-A-0 458 774, WO-A-92. / 22390 or US-A-4 779 440.

  Advantageously, the extrusion process can produce a continuous bar. This continuous bar is advantageous for making drilling tools, milling machines, reamers or counterbore tools. This is because the raw material (green compact / green mold) can already be formed into a desired cylindrical shape by extrusion. This cylindrical shape can be considered as an ideal starting point for manufacturing drilling tools, milling machines, reamers or counterboring tools.

  It is also advantageous that the extrusion process can be arranged, for example, in an extruded path within the extruded rod, by simply expanding the extrusion nozzle already during the extrusion process. These internal paths are utilized in the finished tool to allow refrigerant and / or lubricant to pass through the tool and to the member performing the cutting action of the tool.

Thus, the challenge is a powder metallurgy steel, Ru near the point which makes it possible to obtain easily from high-speed tool steel HSS or HSS-E.

This problem is solved by the method for producing powder metallurgy steel according to claim 1.

The method for producing powder metallurgical steel according to the present invention (in particular, high-speed tool steel such as HSS or HSS-E) is characterized in that steel powder having a certain predetermined structure is first generated. The steel powder is mixed with a binder such as wax or paraffin to produce a deformable raw material mass having plasticity. This raw material mass can be immediately subjected to a forming process by appropriately selecting the particle size and / or particle distribution of the steel powder. In this way, it is possible to produce a blank having any complex three-dimensional shape for steel components without interrupting the process.

The original structure is formed when sintering a blank that has been previously subjected to a special step to remove the binder. That is, in order to accelerate the extrusion process, the steel particles having a substantially spherical shape are melted together and closely bonded. Thereby, a high-density and high-strength steel member can be obtained. The internal structure of the steel powder particles is substantially preserved, which results in predictable material properties. It has been shown that the pressure generated by the nozzle during extrusion is already sufficient to produce blanks consisting of a mass of steel / binder raw material. This blank has sufficient density and strength after the sintering process. Of course, the structure can be further improved by performing a HIP (high temperature isostatic pressing) process before, during or after the sintering process .

In order to better prepare the raw material mass for the forming process, the shape of the powder particles is homogenized into the steel powder during and / or prior to the mixing process with the binder. subjected to processing for.

According to the structure of claim 1 , the steel powder is subjected to a classification treatment before being mixed. Thus, the steel powder, a given particle size and / or particle size distribution is fed to the mixing process, the strength of the structure of the steel, it is possible to influence not good.

Since the steel powder is obtained by grinding and grinding the steel particles, the initial structure of the steel powder can be freely selected regardless of the powder production process.

  If the steel powder is further mixed with a metal binder such as cobalt, the material properties of the produced steel can be affected in a wider range.

In particular, in order to supply the high-density material, the blank, prior to the sintering process, during the process, or after the said processing, a HIP (hot isostatic pressing).

  It is particularly advantageous to perform a heat treatment, for example a hardening treatment, on the blank while a sintering treatment is being carried out to control the steel structure. This is done by executing an appropriate temperature / time management program that can be selected according to material technical standards as required.

According to the manufacturing method of powder metallurgy according to the present invention, it is possible to perform continuous manner extrusion processing deformable mass having plasticity, yet ensures a very good structural density of the steel material It is possible. Thus, deformable mass having plasticity, the extruder having a Bruno nozzle, is extruded into a continuous rod. The bar is then cut to the required dimensions. In this way, blanks can be produced very efficiently.

  According to the present invention, powder metallurgy steel can be easily obtained. Powdered steel is processed with the addition of binder, as in the manufacture of cemented carbide. Thereafter, the powdered steel containing the binder is extruded and sintered.

  Further advantageous configurations of the invention are the subject of other dependent claims.

  According to an exemplary embodiment of the present invention, there is additionally provided a method using cobalt as a metal binder.

  In a further embodiment according to the present invention there is provided a method wherein the pressing step is performed by an extruder having a nozzle. This makes it possible to extrude the raw material mass into a continuous bar.

According to the implementation mode of the present invention, during extrusion, a method of partially provided with at least one internal passage is provided. The internal path is for introducing refrigerant and / or lubricant into the rod.

  According to an exemplary embodiment of the present invention, a method is provided in which the internal path is at least partially configured in a spiral or straight line.

The following points are considered as significant advantages of the present invention. That is, it is possible to manufacture powder metallurgy steel easily and at low cost. As an initial material, a high - speed tool steel such as HSS or HSS-E is used . The powder may be obtained by spraying a melted steel or obtained by grinding. The method for producing powder metallurgical steel according to the present invention does not require large-scale production equipment. Therefore, compared with the prior art, it becomes possible to hold down the cost concerning production. Moreover, according to the manufacturing method of the powder metallurgy steel which concerns on this invention, it becomes possible to achieve high productivity compared with the manufacturing method of a prior art.

  Individual features can of course be combined between each feature. As a result, it is possible to partially achieve advantageous effects that exceed the total of the effects obtained from the individual features.

  Further details and advantages of the invention will be described with reference to the embodiments shown in the drawings.

FIG. 4 is a diagram for explaining a method step according to the present invention. These are figures which show the nozzle for extruding the continuous stick | rod by powder metallurgy.

  In the prior art, it is known to use powdered steel to produce powder metallurgy steel. This steel is typically a highly alloyed steel and can contain, for example, 0.46% carbon and 13% chromium. In this case, the powdered steel is compressed by repeated rolling. A tool can then be generated from the resulting mass. During the initial rolling process, the coolant path can be arranged by drilling in the already partially compressed steel. Overall, this powder metallurgical steel manufacturing method requires high costs for manufacturing equipment. Moreover, the manufacturing method according to this prior art takes a long time.

FIG. 1 shows the course of a method for producing powder metallurgical steel according to the invention, in particular a high speed tool steel such as HSS or HSS- E . In that case, first, steel powder is produced | generated in a 1st method process. The steel powder preferably has a previously selected structure, for example a cast high-speed working steel, or a structure of high-speed working steel that has already been greatly deformed.

  Subsequent mixing with a binder such as paraffin or wax results in a deformable raw material mass having plasticity, which can be further processed directly in the molding process. Variations are indicated by broken lines. Accordingly, the steel powder is further mixed with a metal binder such as cobalt.

  During mixing with the binder and / or prior to mixing with the binder, the steel powder is subjected to a homogenization treatment in the form of powder particles, for example in a ball mill. The corners of the powder particles are removed in this way, and the particles become nearly spherical, which facilitates the subsequent molding process.

Furthermore, it is possible and advantageous that the steel powder is subjected to a classification treatment before mixing with the binder, and the steel powder having a predetermined particle size and / or particle size distribution can be subjected to a mixing treatment. .

Mass so resulting raw material, in turn, in press extruder unit, it is molded into a blank having a predetermined three-dimensional shape, as a result, the blank having an arbitrarily complex three-dimensional structure is created.

The binder is removed at a selected temperature during the subsequent sintering, but prior to that. Then the actual sintering process takes place, at which time the steel structure is finally produced. Blank, prior to sintering, during or after, Keru received an HIP (hot isostatic pressing) process. This process is indicated by broken lines in FIG.

  Similarly, the blank can also be selected such that it undergoes a heat treatment, such as a hardening process, during the sintering process for control of the steel structure. At that time, the sintering facility performs a predetermined temporally controlled temperature profile, so that the steel finally has the desired structural quality.

Steel powder is obtained by grinding and grinding steel particles.

  The plastically deformable mass is subjected to continuous extrusion, in particular, when the plastically deformable mass is relatively low compressed by an extruder having a nozzle (102), the continuous bar It can be seen that a high quality steel part can be produced from HSS or HSS-E.

  Blanks (compact / green) produced as a steel / binder mixture produced in the extrusion step can be processed in a manner similar to the production of cemented carbide or cermet. Processing by an extruder (which may be equipped with a nozzle for extrusion) and subsequent sintering steps make it possible to produce powder metallurgy steel easily, quickly and advantageously. The extrusion shape during extrusion, which is a continuous bar, is also advantageous because it already has the rough shape of a drilling tool, milling machine, reamer or counterbore tool. That is, according to the present invention, powdered steel, such as tungsten carbide, is treated and processed as an initial material for producing cemented carbide (adding a binder such as cobalt).

  According to the present invention, it is possible to produce using an extrusion process, and it is even more convenient to easily form an internal path in the extruded bar. This internal path, in particular, its dimensions (diameter, circular or elliptical cross section) is not significantly changed by further processing steps, for example sintering. Compared with this, the change of the said dimension may arise in the process by rolling of a prior art. Therefore, it is possible to ensure high accuracy in the production of the internal path of powder metallurgy steel.

  FIG. 1 shows an example of a nozzle for extruding a continuous bar. Here, a mass of raw material is pushed into the nozzle through the inflow openings 103, 104. The inflow openings 103 and 104 may have an annular surface. According to the invention, the raw material mass comprises powdered steel. The steel may be a high alloy and may have at least one additional metal binder (eg, cobalt). The raw material masses merge at region 105, and a plurality of internal channels 101 can be formed that are twisted into the extruded raw material mass, for example, by continuously rotating bars 107. . Thereafter, a continuous bar 106 having an internal passage 101 can be discharged from the nozzle 102. If the bar 107 is not rotating and stopped, a continuous bar 106 with a linear internal path can be formed.

  Such extrusion nozzles or related nozzles that can be used are known, for example, the following documents: US 2,422,994, DE 36 01 385 A1, EP 465 946 A1, EP 1 017 527 B1, EP-A- 0 340 495, EP-A-0 458 774, WO-A-92 / 22390, or US-A-4 779 440. These disclosures are expressly incorporated herein by reference.

The present invention thus implements a method for producing powder metallurgical steel. The method includes the steps of producing a steel powder Jo Tokoro structure, is mixed with binder powder of the steel, the predetermined forming a mass of deformable raw material having plasticity, the mass of the raw materials A step of forming a blank having a three-dimensional shape, a step of sintering the blank, and the like .

  Note that the term “comprising” does not exclude other components or other processing steps. Similarly, the term “a” does not exclude a plurality of components and a plurality of steps.

  The symbols used here are used only for the purpose of improving the ease of understanding, and should not be interpreted in a limited way. The scope of protection of the present invention is set forth in the appended claims.

101 Internal path 102 Nozzle 103 Inflow opening 104 Inflow opening 105 Mixing area 106 Extruded rod 107 Bar

Claims (5)

In a production method for producing HSS or HSS-E high speed tool steel with powder metallurgy steel:
Producing steel powder having a predetermined steel structure by grinding and grinding steel particles ;
A step of classifying process the steel powder to the steel powder of predetermined particle size and / or particle size distribution,
Mixing a binder with the steel powder having a predetermined particle size and / or particle size distribution in order to form a deformable raw material mass having plasticity;
Before or during the step of mixing the binder with the steel powder, the powder particle shape is homogenized by removing the corners of the powder particle of the steel powder so that the shape of the powder particle becomes substantially spherical. The process of
Receiving mass of the raw material to the extrusion, for forming a continuous rod, the step of mass of the plasticity of the raw material is molded pressed out by the extruder having a nozzle (102),
A step of sintering a blank formed by cutting the continuous bar , and
A method for producing powder metallurgical steel, comprising: a step of subjecting the blank to HIP (high temperature isostatic pressing) before, during or after the step of sintering the blank . The method of claim 1 , wherein in the step of mixing a binder with the steel powder, the steel powder is mixed with a cobalt binding metal. During the process of sintering process the blanks, A method according to claim 1 or 2 characterized by having a step of performing heat treatment of hardening treatment the blank. In the step of mass of the plasticity of the raw material is extruded, at least in part, of the refrigerant and / or lubricant, the interior path for guiding into the continuous rods (101), formed by The method according to any one of claims 1 to 3 , wherein: The method according to claim 4 , characterized in that the internal path (101) is at least partly configured in a spiral or straight line.

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