A method for improving the processing yield of tungsten-molybdenum sintered products

Abstract

The present invention provides a method for improving the processing yield rate of tungsten-molybdenum sintered products. According to three-dimensional digital modeling and simulation of pressing and sintering process, combined with the particle size, loose ratio and other characteristics of tungsten-molybdenum materials, the powder filling size and powder car size of the pressed green sheets of different batches of raw materials are determined, and the compression performance of the raw materials used for the pressed green sheets is judged by weighing the unit weight of the pressed green sheets, thereby reducing the processing allowance and improving the product yield rate. For large-scale special-shaped products, the tap density of the tungsten-molybdenum powder raw materials is digitally modeled, and the unit weight of the pressed green sheets after preliminary processing is deducted from the powder filling weight. The volume of the pressed green sheets can be obtained by three-dimensional modeling, and the density formula of the pressed green sheets is: unit weight÷volume of the pressed green sheets=density of the pressed green sheets. The digital modeling and simulation of the sintering process are finally used to accurately adjust the powder car processing technology of the pressed green sheets. The tungsten-molybdenum products made by the powder metallurgy method have a size and shape qualification rate of nearly 100% after implementation, and the utilization rate of the raw materials is improved, thereby reducing the cost and improving the product qualification rate.

Description

Technical Field

[0001] The invention relates to the field of processing tungsten-molybdenum sintered products, and in particular to a method for improving the processing yield of tungsten-molybdenum sintered products. Background Art

[0002] The market price of tungsten and molybdenum raw materials has always been at a high level. Among major tungsten and molybdenum product manufacturers, how to reduce the input of raw materials and thus reduce production costs has become the primary task and problem. General production companies have always designed the size of compacting molds and powder carts based on production experience, but this has very high requirements for the performance of tungsten and molybdenum powder raw materials and the pressure stability of the press. Once one of these factors changes, the product will have a high quality risk, thereby reducing the processing yield of tungsten and molybdenum sintered products. Therefore, we made a change and proposed a method to improve the processing yield of tungsten and molybdenum sintered products. Summary of the invention

[0003] The purpose of the present invention is to solve the problems raised by the existing background technology and to achieve the above invention purpose. The present invention provides the following technical solutions: a method for improving the processing yield of tungsten-molybdenum sintered products, comprising the following steps: S1, querying the pressing performance parameters of tungsten-molybdenum powder raw materials: particle size, particle size distribution, bulk ratio, and tap density;

[0004] S2, digital modeling and simulation of the pressing process, design of the mold and determination of the powder size and powder weight;

[0005] S3. Calculation of green compact density: After compaction, the green compact pre-powder is machined into a regular shape, the turning powder is weighed, the unit weight of the green compact is calculated, the volume is calculated by modeling, and the density of the green compact is calculated by the green compact density formula: unit weight ÷ green compact volume = green compact density;

[0006] S4. Based on the fact that the unit weight before and after sintering remains unchanged, V1*ρ billet = V2*ρ finished product, digital modeling and simulation of the sintering process are carried out to determine the powder car process. This will greatly improve the dimensional accuracy of the sintered furnace; S5. Based on the three-dimensional software simulation of shrinkage, the corresponding shrinkage ratio of the compacts with different densities is determined;

[0007] S6, measuring the density of the green compact, judging the density of the green compact by weighing the unit weight, and then adjusting the size by a given process;

[0008] S7. For large products, after the pressing is completed, the outer shape is first turned into a regular shape, and the turning powder is weighed. The weight of the powder is subtracted from the unit weight of the turning powder, i.e., the unit weight of the compact after preliminary processing. The density of the compact is obtained by the density formula of the compact: unit weight ÷ volume of the compact = density of the compact;

[0009] S8. According to the fact that the unit weight remains unchanged before and after sintering shrinkage, V1*ρ billet = V2*ρ finished product, the sintering shrinkage value is determined by the formula, and then fine powder processing is carried out to finally determine the sintered furnace size accuracy.

[0010] As the preferred technical solution of the present invention, S9, mold design, tungsten-molybdenum processed crucible products, large specifications, low yield. Mold design is particularly important. The key to controlling the amount of powder is the bottom size D of the mold. According to digital modeling and cold pressing process simulation, combined with the performance parameters of tungsten-molybdenum powder raw materials, the design size calculation formula is:

[0011] D=((powder car outer diameter - D1) / 2+3)*1.9*2+D1-10

[0012] The powder loading size is ((outer diameter of the powder car-D1) / 2+3)*1.9*2+ D1+20. The invention is put into practice in product production, and the yield rate of raw materials is high.

[0013] As a preferred technical solution of the present invention, before the three-dimensional software simulation in S5, three-dimensional modeling is performed according to the size and shape of the tungsten-molybdenum sintered product, and force analysis is performed after the three-dimensional modeling is completed.

[0014] As a preferred technical solution of the present invention, in the process of pressing the green sheet in S6, the green sheet is pressed and formed by a cold isostatic press according to the size and shape of the product.

[0015] As a preferred technical solution of the present invention, the spindle speed during the turning process in S7 is 800-1200 r / min.

[0016] As a preferred technical solution of the present invention, in S7, a ceramic tool is selected as the turning tool (tungsten and molybdenum processing is generally an alloy tool or a diamond tool, and the tool type is not required) and cutting is performed for 15 to 30 minutes under the conditions of f=0.6 to 5.5 mm / r, ap=4 to 6 mm, and vσ=120 to 160 m / min.

[0017] As a preferred technical solution of the present invention, the S8 fine powder turning process uses a fine turning tool to finish the tungsten-molybdenum sintered product to the required accuracy by correcting the tool tooth profile and tool pitch.

[0018] As a preferred technical solution of the present invention, in the step five of mold processing, the cavity surface of the mold is finely processed by a CNC milling machine, the rotation speed of the CNC milling machine is 2500r / min to 3000r / min, and the processing allowance is 0.1mm to 0.3mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In the scheme of the present invention: according to the three-dimensional software simulation shrinkage, the corresponding shrinkage ratio of the green compact with different densities is determined, the density of the green compact is measured, and the size of the green compact density is judged by weighing the unit weight, and then the size is adjusted by a given process. For large products, after the pressing is completed, the outer shape is first turned into a regular shape, and the turning powder is weighed. The powder weight is subtracted from the turning powder, that is, the unit weight of the green compact after preliminary processing. The density of the green compact is obtained by the density formula of the green compact: unit weight ÷ volume of the green compact = density of the green compact. According to the unit weight before and after sintering shrinkage, V1*ρ green compact = V2*ρ finished product, the sintering shrinkage value is determined by the formula, and then the fine powder is processed, and the sintering furnace size accuracy is finally determined. The processed crucible tungsten and molybdenum products have larger specifications and lower yields. Mold design is also particularly important. The method of controlling the amount of powder is the bottom size D of the mold. After actual production, the raw material yield is high, and the size qualification rate after product sintering is close to 100%. The raw material utilization rate is greatly improved, which effectively reduces the production cost and improves the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart provided for the present invention;

[0022] Figure 2 A simulation diagram of the sintering process provided by the present invention;

[0023] Figure 3 A simulation diagram of the sintering process provided by the present invention;

[0024] Figure 4 A simulation diagram of the pressing process provided by the present invention;

[0025] Figure 5 This is a simulation diagram of the pressing process provided by the present invention. DETAILED DESCRIPTION

[0026] To make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiment is a specific implementation of the present invention and is not limited to all embodiments.

[0027] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein can be combined with each other. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0029] Example 1: Please refer to Figure 1-5 ,A method for improving the processing yield of tungsten-molybdenum sintered products, S1, query the pressing performance parameters of tungsten-molybdenum powder raw materials: particle size, particle size distribution, bulk ratio, tap density;

[0030] S2, digital modeling and simulation of the pressing process, design of the mold and determination of the powder size and powder weight;

[0031] S3. Calculation of green compact density: After compaction, the green compact pre-powder is machined into a regular shape, the turning powder is weighed, the unit weight of the green compact is calculated, the volume is calculated by modeling, and the density of the green compact is calculated by the green compact density formula: unit weight ÷ green compact volume = green compact density;

[0032] S4. Based on the fact that the unit weight before and after sintering remains unchanged, V1*ρ billet = V2*ρ finished product, digital modeling and simulation of the sintering process are carried out to determine the powder car process. This will greatly improve the dimensional accuracy of the sintered furnace; S5. Based on the three-dimensional software simulation of shrinkage, the corresponding shrinkage ratio of the compacts with different densities is determined;

[0033] S6, measuring the density of the green compact, judging the density of the green compact by weighing the unit weight, and then adjusting the size by a given process;

[0034] S7. For large products, after the pressing is completed, the outer shape is first turned into a regular shape, and the turning powder is weighed. The weight of the powder is subtracted from the unit weight of the turning powder, i.e., the unit weight of the compact after preliminary processing. The density of the compact is obtained by the density formula of the compact: unit weight ÷ volume of the compact = density of the compact;

[0035] S8. According to the fact that the unit weight remains unchanged before and after sintering shrinkage, V1*ρ billet = V2*ρ finished product, the sintering shrinkage value is determined by the formula, and then fine powder processing is carried out to finally determine the sintered furnace size accuracy.

[0036] S9. Mold design. Tungsten and molybdenum processed crucible products have large specifications and low yield. Mold design is particularly important. The key to controlling the amount of powder is the bottom size D of the mold. According to digital modeling and cold pressing process simulation, combined with the performance parameters of tungsten and molybdenum powder raw materials, the design size calculation formula is:

[0037] D=((powder car outer diameter - D1) / 2+3)*1.9*2+D1-10

[0038] The powder loading size is ((outer diameter of the powder car-D1) / 2+3)*1.9*2+ D1+20. The invention is put into practice in product production, and the yield rate of raw materials is high.

[0039] Before the three-dimensional software simulation in S5, three-dimensional modeling is performed according to the size and shape of the tungsten-molybdenum sintered product, and force analysis is performed after the three-dimensional modeling is completed.

[0040] In the process of pressing the green sheet in S6, the green sheet is pressed and shaped by a cold isostatic press according to the size and shape of the product.

[0041] During the turning process in S7, the spindle speed is 800-1200 r / min.

[0042] In S7, a ceramic tool is selected as the turning tool (tungsten and molybdenum processing generally uses alloy tools and diamond tools, and the tool type is not required) and cutting is performed for 15 to 30 minutes under the conditions of f=0.6 to 5.5 mm / r, ap=4 to 6 mm, and vσ=120 to 160 m / min.

[0043] The S8 fine powder turning process uses a fine turning tool to process the tungsten-molybdenum sintered product to the required accuracy by correcting the tool tooth profile and tool pitch.

[0044] In the step 5 of mold processing, the cavity surface of the mold is finely processed by a CNC milling machine, the rotation speed of the CNC milling machine is 2500r / min to 3000r / min, and the processing allowance is 0.1mm to 0.3mm.

[0045] Example 2: Please refer to Figure 1 , a method for improving the processing yield of tungsten-molybdenum sintered products, S5, according to the three-dimensional software simulation shrinkage, determine the corresponding shrinkage ratio of the compact with different densities;

[0046] S6, measuring the density of the green compact, judging the density of the green compact by weighing the unit weight, and then adjusting the size by a given process;

[0047] S7. After the large products are pressed, the outer shape is first turned into a regular shape, and the turning powder is weighed. The weight of the powder is subtracted from the unit weight of the turning powder, that is, the unit weight of the compact after preliminary processing. The density of the compact is calculated by the density formula of the compact: unit weight ÷ volume of the compact = density of the compact. In S7, the turning tool is a ceramic tool (tungsten and molybdenum processing is generally an alloy tool, a diamond tool, and the tool type can be omitted) and the cutting is performed for 15 to 30 minutes under the conditions of f=0.6~5.5mm / r, ap=4~6mm, and vσ=120~160m / min.

[0048] S8. According to the fact that the unit weight remains unchanged before and after sintering shrinkage, V1*ρ billet = V2*ρ finished product, the sintering shrinkage value is determined by the formula, and then fine powder processing is carried out to finally determine the sintered furnace size accuracy.

[0049] S9. Mold design. Tungsten and molybdenum processed crucible products have large specifications and low yield. Mold design is particularly important. The key to controlling the amount of powder is the bottom size D of the mold. According to digital modeling and cold pressing process simulation, combined with the performance parameters of tungsten and molybdenum powder raw materials, the design size calculation formula is:

[0050] D=((powder car outer diameter - D1) / 2+3)*1.9*2+D1-10

[0051] The powder loading size is ((outer diameter of the powder car-D1) / 2+3)*1.9*2+ D1+20. The invention is put into practice in product production, and the yield rate of raw materials is high.

[0052] Before the three-dimensional software simulation in S5, three-dimensional modeling is performed according to the size and shape of the tungsten-molybdenum sintered product, and force analysis is performed after the three-dimensional modeling is completed. In S6, during the process of pressing the blank, the product is stamped and formed by a punch according to the size and shape of the product, and a secondary stamping is performed when the density of the pressed blank is measured and there is an error. In S8 fine powder turning, the fine turning tool fine machining is used to cumulatively process the tungsten-molybdenum sintered product to the required accuracy by correcting the tool tooth profile and tool pitch. In step five, in mold processing, the cavity surface of the mold is finely machined by a CNC milling machine. The speed of the CNC milling machine is 2500r / min to 3000r / min, and the machining allowance is 0.1mm to 0.3mm.

[0053] During the use of the present invention, S5, according to the three-dimensional software simulation shrinkage, determine the corresponding shrinkage ratio of the green compacts with different densities; S6, measure the density of the green compact, judge the size of the green compact density by weighing the unit weight, and then adjust the size by a given process; S7, for large products, after the pressing is completed, first turn the outer shape into a regular shape, weigh the turning powder, and subtract the unit weight of the turning powder, i.e. the green compact after preliminary processing, from the weight of the powder, and calculate the density of the green compact by the density formula of the green compact: unit weight÷the volume of the green compact=the density of the green compact; in S7, the spindle speed during the turning process is 800-1200r / min. In S7, the turning tool is selected as a ceramic tool and cuts for 15-30min under the conditions of f=0.6-5.5mm / r, ap=4-6mm, and vσ=120-160m / min. S8, according to the unit weight before and after sintering shrinkage remains unchanged, V1*ρ billet = V2*ρ finished product, the sintering shrinkage value is determined by the formula, and then the fine powder car processing is carried out to finally determine the sintering furnace size accuracy. Step 5, mold processing, the crucible tungsten and molybdenum products are processed, the specifications are large, and the yield rate is low. Mold design is also particularly important. The method to control the amount of powder is the bottom size D of the mold. The design size calculation formula is D=((powder car outer diameter-D1) / 2+3)*1.9*2+D1-10. The powder size is ((powder car outer diameter-D1) / 2+3)*1.9*2+ D1+20. After actual production, the raw material yield rate is high. Before the three-dimensional software simulation in S5, three-dimensional modeling is carried out according to the size and shape of the tungsten and molybdenum sintered products, and the force analysis is carried out after the three-dimensional modeling is completed. In S6, during the process of pressing the blank, the product is stamped by a punch according to the size and shape of the product, and the density of the pressed blank is measured and a secondary stamping is performed when there is an error. In the S8 fine powder turning process, the fine turning tool fine machining will process the tungsten-molybdenum sintered products to the required accuracy by correcting the tool tooth profile and tool pitch. In step 5, the mold cavity surface is finely machined by a CNC milling machine in the mold processing. The speed of the CNC milling machine is 2500r / min to 3000r / min, and the machining allowance is 0.1mm to 0.3mm.

[0054] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A method for improving the processing yield of tungsten and molybdenum sintered products, characterized in that: The following steps are involved: S1. Check the pressing performance parameters of tungsten and molybdenum powder raw materials: particle size, particle size distribution, bulk ratio, and tap density; S2, digital modeling and simulation of the pressing process, design of the mold and determination of the powder size and powder weight; S3. Calculation of green compact density: After compaction, the green compact pre-powder is machined into a regular shape, the turning powder is weighed, the unit weight of the green compact is calculated, the volume is calculated by modeling, and the density of the green compact is calculated by the green compact density formula: unit weight ÷ green compact volume = green compact density; S4. Based on the fact that the unit weight before and after sintering remains unchanged, V1*ρ billet = V2*ρ finished product, digital modeling and simulation of the sintering process are carried out to determine the powder car process; thereby greatly improving the sintering furnace dimensional accuracy; S5. Determine the corresponding shrinkage ratio of the compacts with different densities according to the shrinkage simulation using the three-dimensional software; S6, measuring the density of the green compact, judging the density of the green compact by weighing the unit weight, and then adjusting the size by a given process; S7. For large products, after the pressing is completed, the outer shape is first turned into a regular shape, and the turning powder is weighed. The weight of the powder is subtracted from the unit weight of the turning powder, i.e., the unit weight of the compact after preliminary processing. The density of the compact is obtained by the density formula of the compact: unit weight ÷ volume of the compact = density of the compact; S8. According to the fact that the unit weight remains unchanged before and after sintering shrinkage, V1*ρ billet = V2*ρ finished product, the sintering shrinkage value is determined by the formula, and then fine powder processing is performed to finally determine the sintered furnace size accuracy; S9, the bottom size D of the mold is calculated based on digital modeling and cold pressing process simulation, combined with the performance parameters of tungsten and molybdenum powder raw materials. The design size calculation formula is: D=((powder car outer diameter - D1) / 2+3)*1.9*2+D1-10 The powder loading size is ((powder car outer diameter-D1) / 2+3)*1.9*2+ D1+20.

2. A method for improving the processing yield of tungsten and molybdenum sintered products according to claim 1, characterized in that: Before the three-dimensional software simulation in S5, three-dimensional modeling is performed according to the size and shape of the tungsten-molybdenum sintered product, and force analysis is performed after the three-dimensional modeling is completed.

3. A method for improving the processing yield of tungsten and molybdenum sintered products according to claim 2, characterized in that: In the process of pressing the green sheet in S6, the green sheet is pressed and shaped by a cold isostatic press according to the size and shape of the product.

4. A method for improving the processing yield of tungsten and molybdenum sintered products according to claim 3, characterized in that: During the turning process in S7, the spindle speed is 800-1200 r / min.

5. A method for improving the processing yield of tungsten and molybdenum sintered products according to claim 4, characterized in that: In the S7, a ceramic cutting tool is selected as the turning tool and cutting is performed for 15 to 30 minutes under the conditions of f=0.6 to 5.5 mm / r, ap=4 to 6 mm, and vσ=120 to 160 m / min.

6. A method for improving the processing yield of tungsten and molybdenum sintered products according to claim 5, characterized in that: The S8 fine powder turning process uses a fine turning tool to process the tungsten-molybdenum sintered product to the required accuracy by correcting the tool tooth profile and tool pitch.

7. A method for improving the processing yield of tungsten and molybdenum sintered products according to claim 6, characterized in that: In the step 5 of mold processing, the cavity surface of the mold is finely processed by a CNC milling machine, the rotation speed of the CNC milling machine is 2500r / min to 3000r / min, and the processing allowance is 0.1mm to 0.3mm.

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