JP5819503B1 - Method for manufacturing lost wax mold for powder metallurgy that is layered with 3D printer - Google Patents

Abstract

In the conventional powder metallurgy method, it takes a lot of cost and time to form a green compact, especially for a small variety of products. In addition, the dust during the molding process made the workplace environment worse. Using a 3D printer having a tank that can be filled with paraffin equipped with a heat-retaining heater, a melted paraffin having a melting point of 5 ° C. lower than that of the paraffin granulating the raw material powder is supplied to a predetermined position. In addition, it adheres to the shape and cross section of each layer, and at the same time, it is locally cooled with air supplied from a compressor or air cooled by heat exchange to harden paraffin, and lost wax for use in compacting in powder metallurgy The mold is layered. This mold is filled with the mixed powder of the material, pressed into a green compact, and sintered to obtain the material. [Selection figure] None

Description

  The present invention relates to cemented carbide, cermet, ceramics, powder high speed steel, solid lubricant, heavy alloy, Cu-W alloy, Ti alloy, Co-based alloy, diamond-copper sintered material for heat sink, produced by powder metallurgy. The present invention relates to a sintered machine component material, a magnetic material, and a green compact molding method thereof.

  Cemented carbide, cermet, ceramics, high-speed steel powder, solid lubricant, heavy alloy, Cu-W alloy, Ti alloy, Co-base alloy, diamond-copper sintered material for heat sink, sintering machine For component materials and magnetic materials, blended powders obtained by mixing and pulverizing the respective raw material powders are subjected to cold or warm press molding with a mold, and then molded into a predetermined shape as necessary. A raw material is obtained by heating and sintering in air, gas atmosphere, or vacuum atmosphere to produce a predetermined solid (alloy or the like).

  In order to obtain the shape by powder metallurgy, it is necessary to press-mold cold or warm, so a mold is always required first. Many of the molds are so-called molds made of an alloy such as cemented carbide or die steel.

  Inevitably, in the case of mass production, the operation efficiency of the mold is good, but in the case of multi-product small-quantity production, if the mold is manufactured each time, the cost tends to be broken due to an increase in the mold cost.

  Then, after press-molding with a simple-shaped die, machining with a machine tool is performed, and the approximate shape is heated and sintered in the air, gas atmosphere, or vacuum atmosphere to obtain a predetermined solid (alloy) Etc.) to obtain the material.

  However, since it is originally a powder, machining with a machine tool generates dust and tends to cause a deterioration of the work environment. In addition to the cost of machining, there is a cost to prevent health problems. ing.

  On the other hand, there is a technique called rapid prototyping (RP) that has been attracting attention in recent years. This technology calculates the cross-sectional shape sliced in the stacking direction based on data describing the surface of one three-dimensional shape as a collection of triangles (industry standard format in the optical modeling field: STL format), and the shape is made of resin, etc. This is a technology that forms, laminates, and forms the shape.

  According to the classification of the Japan RP Industry Association, there are four methods: (1) stereolithography, (2) thin plate lamination, (3) melt deposition, and (4) powder fixing. This has become famous as a 3D printer.

  According to this method, since an approximate shape can be formed without using a mold and without machining, development on a national scale has been performed. However, all methods of 3D printers use cemented carbide, cermet, ceramics, powdered high speed steel, solid lubricant, heavy alloy, Cu-W alloy, Ti alloy, Co-based alloy, heat sink diamond obtained by powder metallurgy. -A predetermined alloy or the like that can substitute for a copper sintered material, a sintered machine component material, or a magnetic material is not obtained.

  The reason is that there is non-uniformity due to the laminated interface and the laminated portion in the case of lamination, and it still takes time to solve this.

  On the other hand, there is a method called a lost wax method in which a mold is made using a low melting point material such as paraffin (wax) to obtain an approximately shaped molded body. However, it is not widely used because a mold for lost wax has to be made, trial and error is required, and it takes time and cost to obtain a lost wax mold.

  Therefore, the present inventors decided to develop a new technique for an efficient mold in a large variety of small-quantity production. First, attention was paid to the melt volume method in the 3D printer.

  The conventional technology that is going to be performed by a 3D printer is to make a final shaped object in any technology. As mentioned above, this technology takes time to develop.

  Therefore, the present inventors have come up with the idea of making a mold with a 3D printer. However, when making a mold with a relatively inexpensive 3D printer, only a low-strength resin can be made. Here, the present inventors considered making a lost wax mold with a 3D printer.

  Paraffin used for lost wax has a low melting point, so it melts at several tens of degrees Celsius, but easily solidifies at room temperature, so the printing speed with a 3D printer is efficient. Moreover, paraffin is inexpensive.

  In addition, 3D printers can be controlled by computer, and can be reused by dissolving paraffin, melting powder, and re-granulating. An approximate shape (near net shape) can be obtained. Paraffin can also be recovered during production during sintering.

  That is, by creating a lost wax mold with a 3D printer, human beings can obtain a low-cost mold that is flexible and recyclable for the first time in history.

  A lost wax mold made with a 3D printer is filled with powder by a method such as pouring the powder, and then isotropically pressed with a cold isostatic press to obtain a press-molded body. In addition, even if it is not a cold isostatic press, according to a shape, you may press using other methods, such as a uniaxial compression press.

  The lost wax mold can basically be used as a mold as it is, but if strength is required, a fixed outer mold of stainless steel or carbon may be prepared and reinforced.

  After pressing, the paraffin is also pressurized at the same time, so it cannot be easily separated from the powder compact as it is, but can be easily separated by heating.

  Paraffins Wax-115, Paraffinin Wax-120, Paraffinin Wax-125, Paraffinin Wax-130, Paraffinin Wax-135, Paraffinin Wax-140, ParaffinWax-150, ParaffinWax-150, manufactured by Nippon Seiwa Co., Ltd. -155 is suitable, but it is not limited to these as long as it has an equivalent melting point and penetration (one of the scales of hardness measurement).

  Paraffin may be separated and then sintered, or may be separated and recovered during the sintering process.

  Here, since the powder used can be basically a powder produced by a conventional powder metallurgy method, this method can be applied immediately and obtained by a method such as a normal mold press. Those with the same characteristics can be made.

  By carrying out the method of the present invention, compared to conventional powder metallurgy, the cost and time required for compacting can be significantly reduced, and the generation of dust in the workplace environment can also be reduced. .

  Using a 3D printer with a tank that can be filled with paraffin (Paraffin Wax-115) equipped with a warming heater, while supplying melted paraffin to a predetermined position, it adheres to the shape and cross section of each layer, and at the same time from the compressor The paraffin was solidified by local cooling with supplied air, and a lost wax mold was layered.

  Using a 3D printer with a tank that can be filled with paraffin (Paraffin Wax-115) fitted with a thermal heater, melted paraffin adheres to the shape of the cross section of each layer while dripping the melted paraffin into a thread from a thin nozzle at a predetermined position. At the same time, it was locally cooled with air supplied from a compressor to harden the paraffin, and a lost wax mold was layered.

  Using a 3D printer with a tank that can be filled with paraffin (Paraffin Wax-115) fitted with a warming heater, melted paraffin is ejected from a head like a inkjet printer from a thin nozzle to a predetermined position. At the same time as adhering to the shape of the cross section, it was locally cooled with air supplied from a compressor and heat-exchanged and cooled to solidify the paraffin, and a lost wax mold was layered.

  The lost wax mold obtained in each of Examples 1, 2, and 3 was filled with granulated powder of WC-15% Co cemented carbide (granulated with Paraffin Wax-125), and a paraffin lid was placed thereon. Heated and sealed. This was pressed with a cold isostatic press.

The pressed lost wax mold is heated to 50 ° C., and only the lost wax paraffin is recovered. The near net shape green compact is taken out and filled in a vacuum debinding sintering furnace at 1360 ° C. Sintering was performed for 1 hr to prepare a cemented carbide.

  The reason for changing the type of Paraffin Wax between cemented carbide granulated powder and lost wax mold is to use a lost wax mold that melts at a lower temperature to prevent collapse of the pressed green compact.

  Separately, the pressed lost wax mold was filled in a vacuum debinder sintering furnace as it was, and sintered at 1360 ° C. for 1 hr to prepare a near net shape cemented carbide.

  Each of the obtained cemented carbides has characteristics equivalent to those produced by the conventional manufacturing method, and this method proved to be practical.

  Lost wax mold that is layered and molded in the same manner as in Examples 1, 2, and 3, for cermet, ceramics, high-speed steel powder, solid lubricant, heavy alloy, Cu-W alloy, Ti alloy, Co-based alloy, heat sink Filled with powder of diamond-copper sintered material and magnetic material (hereinafter referred to as solid such as alloy), covered and formed as it is by cold isostatic pressing, and near-net shape of alloy etc. by a predetermined method Could be solid.

  After sintering, the solids such as alloys obtained have properties equivalent to those produced by conventional manufacturing methods, and this method proved to be very practical.

  The material production method according to the present invention enables the use of a low-cost recycling type adapted to a small variety of products, contributes to resource saving, energy saving, acceleration of new development, and accelerates the development of industry. is there.

Claims (4)

  Using a 3D printer with a tank that can be filled with paraffin equipped with a warming heater, while supplying melted paraffin having a melting point of 5 ° C. lower than that of the paraffin granulating the raw material powder to a predetermined position, layer by layer At the same time as adhering to the shape of the cross section, it is locally cooled with air supplied from the compressor or air cooled by heat exchange to harden the paraffin, and the lost wax mold for use in compacting in powder metallurgy is laminated Obtained by the method of modeling, after filling this lost wax mold with powder, by cold isostatic pressing, to obtain a green compact for powder metallurgy, a lost wax mold containing this green compact, A method of powder metallurgy in which paraffin is recovered after deparaffinization by heating, followed by main sintering.   Using a 3D printer with a tank that can be filled with paraffin equipped with a warming heater, melted paraffin with a melting point of 5 ° C lower than that of the paraffin granulating the raw material powder is dripped in a string from a thin nozzle at a predetermined position. However, it adheres to the shape of the cross section of each layer at the same time, and at the same time, it is locally cooled with air supplied from a compressor or air cooled by heat exchange to solidify paraffin, and lost for use in compacting in powder metallurgy A wax mold is obtained by a layered manufacturing method, and after filling the lost wax mold with powder, cold isostatic pressing is performed to obtain a green compact for powder metallurgy, including this green compact. A method of powder metallurgy, in which a lost wax mold is deparaffinized by heating to recover paraffin, followed by main sintering.   Using a 3D printer with a tank that can be filled with paraffin equipped with a warming heater, melted paraffin having a melting point of 5 ° C. lower than that of the paraffin granulating the raw material powder is placed in a predetermined position from a thin nozzle to the inkjet printer. In this way, while being ejected from the head, it adheres to the shape and cross section of each layer at the same time, and at the same time, locally cooled with air supplied from the compressor or air cooled by heat exchange to solidify the paraffin, A lost wax mold for use in molding is obtained by the method of layered modeling, and after filling the lost wax mold with powder, cold isostatic pressing is performed to obtain a green compact for powder metallurgy, The lost wax mold containing this green compact is deparaffinized by heating to recover the paraffin, followed by main sintering. The method of the end metallurgy.   A method for performing any one of claims 1 to 3 by reusing the recovered paraffin obtained by any one of claims 1 to 3.