Hard alloy blank barge burning process

Abstract

The invention discloses a hard alloy blank burning process, the blank is of a high cylinder structure with a step on the outer side, the burning process comprises the following steps: step 1, the blank is decomposed into the high cylinder structure without the step and a step structure with a through hole in the middle, and the inner diameter of the through hole is larger than the diameter of the outer circle of the high cylinder; step 2, firstly pressing into a high cylinder structure without steps, presintering the product to 1350 DEG C, preserving heat for 30-50 minutes, and cooling to obtain a sintered blank; 3, pressing to form a step structure with a through hole in the middle, wherein the inner diameter of the through hole is 1.05-1.06 times of the diameter of the outer circle of the high-cylinder sintered blank; and 4, after the unsintered blank in the step 3 and the sintered blank in the step 2 are assembled, the assembled blank and the sintered blank are placed on the same graphite plate, the graphite plate is put into a degumming and sintering integrated furnace to be sintered, and finally the high cylinder structure with the steps is obtained. The production efficiency and the powder utilization rate are improved.

Description

Technical Field

[0001] The invention relates to the technical field of cemented carbide manufacturing, in particular to a cemented carbide blank sintering process. Background Art

[0002] In the prior art, in processing high-cylinder cemented carbide products with steps, the usual approach is to first make a cemented carbide cylinder, and then machine the upper layer of the cylinder to shape it into a high-cylinder cemented carbide product with steps. However, this approach has the following disadvantages: low powder utilization, long processing cycle, and is not conducive to mass production.

[0003] The information disclosed in the above background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0004] In view of the above existing defects, the present invention aims to provide a cemented carbide blank sintering process. Through the new cemented carbide unsintered blank and cemented carbide sintered blank sintering process, the production problem is solved, the production efficiency is improved, and the powder utilization rate is improved.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A sintering process for a cemented carbide blank, wherein the blank is a high cylinder structure with steps on the outside, and the sintering process comprises the following steps:

[0007] Step 1: decomposing the blank into a high cylinder structure without steps and a step structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high cylinder;

[0008] Step 2: first press into a high cylinder structure without steps, and pre-sinter the product to 1300-1400℃, keep warm for 30-50min, and cool to obtain a sintered blank;

[0009] Step 3: Pressing the mold into a stepped structure with a through hole in the middle, wherein the inner diameter of the through hole is 1.05-1.06 times the outer diameter of the high-tube sintered blank;

[0010] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high-tube structure with steps.

[0011] Furthermore, the cemented carbide is a cemented carbide with a cobalt / nickel content of higher than 10% by mass.

[0012] Furthermore, the cemented carbide is a medium-high cobalt / nickel grade of YG10-YG25.

[0013] Furthermore, the height of the high tube is 280-350 mm.

[0014] Furthermore, the thickness of the high tube is 14-17 mm.

[0015] Furthermore, the inner diameter of the high cylinder is 210-220 mm.

[0016] Furthermore, the height of the step is 30-40 mm.

[0017] Furthermore, the thickness of the step is 60-80 mm.

[0018] Furthermore, the sintering process of the integrated sintering furnace is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1300-1350°C for vacuum sintering; keep warm for 1.5-2 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at a temperature of 1350-1450°C, and keep warm for 1-1.5 hours; (4) after the argon protection sintering is completed, cool naturally.

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

[0020] The invention enables the powder utilization rate to reach 100% under the premise that the hardness and strength of the stepped high-tube product meet the requirements, saves production costs compared with the conventional method, and has a production efficiency much higher than the conventional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : A schematic diagram of the exploded structure of a high-tube cemented carbide with a step according to an embodiment of the present invention;

[0022] Figure 2 : An assembly structure diagram of the stepped high cylinder cemented carbide before sintering in an embodiment of the present invention;

[0023] Figure 3 : A structural diagram of the stepped high-tube cemented carbide after sintering in an embodiment of the present invention;

[0024] In the figure, 1-high tube; 2-step; 3-graphite plate. DETAILED DESCRIPTION

[0025] In order to explain the technical content, purpose and effect of the present invention in detail, the following is explained in combination with embodiments and accompanying drawings. In the description of this embodiment, it should be understood that the terms indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0026] Example 1

[0027] A sintering process for a cemented carbide blank, wherein the blank is a high tube structure with steps on the outside, the cemented carbide is of YG10 grade, the height of the high tube 1 is 280 mm, the thickness of the high tube 1 is 14 mm, and the inner diameter of the high tube 1 is 210 mm.

[0028] like Figure 3 As shown, the calcination process comprises the following steps:

[0029] Step 1: Decompose the blank into a high tube 1 structure without steps and a step 2 structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high tube 1, the height of the step 2 is 30 mm, and the thickness of the step 2 is 60 mm;

[0030] Step 2: first press into a high cylinder 1 structure without steps, and pre-sinter the product to 1350°C, keep warm for 30 minutes, and cool to obtain a sintered blank;

[0031] Step 3: Pressing the step 2 structure with a through hole in the middle, the inner diameter of the through hole is 1.05 times the outer diameter of the sintered billet of the high cylinder 1, that is, 250 mm;

[0032] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate 3 and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high-tube structure with steps.

[0033] The integrated furnace sintering process in this embodiment is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1300°C for vacuum sintering; keep warm for 2 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at 1350°C, and keep warm for 1.5 hours; (4) after the argon protection sintering is completed, cool naturally.

[0034] Example 2

[0035] A sintering process for a cemented carbide blank, wherein the blank is a high tube structure with steps on the outside, the cemented carbide is of YG12 grade, the height of the high tube 1 is 350 mm, the thickness of the high tube 1 is 17 mm, and the inner diameter of the high tube 1 is 220 mm.

[0036] like Figure 3 As shown, the calcination process comprises the following steps:

[0037] Step 1: Decompose the blank into a high tube 1 structure without steps and a step 2 structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high tube 1, the height of the step 2 is 40 mm, and the thickness of the step 2 is 80 mm;

[0038] Step 2: first press into a high cylinder 1 structure without steps, and pre-sinter the product to 1350°C, keep warm for 50 minutes, and cool to obtain a sintered blank;

[0039] Step 3: Press it into a step 2 structure with a through hole in the middle, the inner diameter of the through hole is 1.06 times the outer diameter of the sintered billet of the high tube 1, that is, 269 mm.

[0040] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate 3 and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high-tube structure with steps.

[0041] The integrated furnace sintering process in this embodiment is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1350°C for vacuum sintering; keep warm for 1.5 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at 1450°C, and keep warm for 1 hour; (4) after the argon protection sintering is completed, cool naturally.

[0042] Example 3

[0043] A sintering process for a cemented carbide blank, wherein the blank is a high tube structure with steps on the outside, the cemented carbide is YG15 grade, the height of the high tube 1 is 300 mm, the thickness of the high tube 1 is 15 mm, and the inner diameter of the high tube 1 is 220 mm.

[0044] like Figure 3 As shown, the calcination process comprises the following steps:

[0045] Step 1: Decompose the blank into a high tube 1 structure without steps and a step 2 structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high tube 1, the height of the step 2 is 35 mm, and the thickness of the step 2 is 70 mm;

[0046] Step 2: first press into a high cylinder 1 structure without steps, and pre-sinter the product to 1350°C, keep warm for 40 minutes, and cool to obtain a sintered blank;

[0047] Step 3: Pressing the step 2 structure with a through hole in the middle, the inner diameter of the through hole is 1.05 times the outer diameter of the high tube 1 sintered blank, that is, 262.5 mm;

[0048] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate 3 and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high-tube structure with steps.

[0049] The integrated furnace sintering process in this embodiment is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1330°C for vacuum sintering; keep warm for 1.7 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at 1400°C, and keep warm for 1.3 hours; (4) after the argon protection sintering is completed, cool naturally.

[0050] Example 4

[0051] A sintering process for a cemented carbide blank, wherein the blank is a high tube structure with steps on the outside, the cemented carbide is of YG20 grade, the height of the high tube 1 is 320 mm, the thickness of the high tube 1 is 16 mm, and the inner diameter of the high tube 1 is 215 mm.

[0052] like Figure 3 As shown, the calcination process comprises the following steps:

[0053] Step 1: Decompose the blank into a high tube 1 structure without steps and a step 2 structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high tube 1, the height of the step 2 is 35 mm, and the thickness of the step 2 is 65 mm;

[0054] Step 2: first press into a high cylinder 1 structure without steps, and pre-sinter the product to 1350°C, keep warm for 35 minutes, and cool to obtain a sintered blank;

[0055] Step 3: Pressing the step 2 structure with a through hole in the middle, the inner diameter of the through hole is 1.06 times the outer diameter of the high tube 1 sintered blank, that is, 262 mm;

[0056] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate 3 and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high tube 1 structure with steps.

[0057] The integrated furnace sintering process in this embodiment is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1340°C for vacuum sintering; keep warm for 1.6 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at 1420°C, and keep warm for 1.2 hours; (4) after the argon protection sintering is completed, cool naturally.

[0058] Example 5

[0059] A sintering process for a cemented carbide blank, wherein the blank is a high tube 1 structure with steps on the outside, the cemented carbide is YG25 grade, the height of the high tube is 290 mm, the thickness of the high tube is 15 mm, and the inner diameter of the high tube is 216 mm.

[0060] like Figure 3As shown, the calcination process comprises the following steps:

[0061] Step 1: Decompose the blank into a high cylinder structure without steps and a step 2 structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high cylinder, the height of the step 2 is 36 mm, and the thickness of the step 2 is 68 mm;

[0062] Step 2: first press into a high cylinder structure without steps, and pre-sinter the product to 1350°C, keep warm for 37 minutes, and cool to obtain a sintered blank;

[0063] Step 3: Pressing the mold into a step 2 structure with a through hole in the middle, the inner diameter of the through hole is 1.05 times the outer diameter of the high tube sintered blank, that is, 261 mm;

[0064] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate 3 and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high-tube structure with steps.

[0065] The integrated furnace sintering process in this embodiment is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1310°C for vacuum sintering; keep warm for 1.8 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at 1420°C, and keep warm for 1.2 hours; (4) after the argon protection sintering is completed, cool naturally.

[0066] Example 6

[0067] A sintering process for a cemented carbide blank, wherein the blank is a high tube structure with steps on the outside, the cemented carbide is of YG18 grade, the height of the high tube 1 is 350 mm, the thickness of the high tube 1 is 14 mm, and the inner diameter of the high tube 1 is 210 mm.

[0068] like Figure 3 As shown, the calcination process comprises the following steps:

[0069] Step 1: Decompose the blank into a high tube 1 structure without steps and a step 2 structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high tube 1, the height of the step 2 is 30 mm, and the thickness of the step 2 is 60 mm;

[0070] Step 2: first press into a high cylinder 1 structure without steps, and pre-sinter the product to 1350°C, keep warm for 30 minutes, and cool to obtain a sintered blank;

[0071] Step 3: Pressing the step 2 structure with a through hole in the middle, the inner diameter of the through hole is 1.05 times the outer diameter of the sintered billet of the high cylinder 1, that is, 250 mm;

[0072] Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate 3 and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high tube 1 structure with steps.

[0073] The integrated furnace sintering process in this embodiment is as follows: (1) first fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1300°C for vacuum sintering; keep warm for 1.8 hours; (3) fill with argon gas at the end of vacuum sintering, perform argon protection sintering at 1350°C, and keep warm for 1.3 hours; (4) after the argon protection sintering is completed, cool naturally.

[0074] Experimental example: The step-high-tube cemented carbide products prepared in Examples 1-6 were subjected to tensile strength and hardness tests. The test results are shown in the following table:

[0075] sample Hardness HRC StrengthMpa Grain size μm Example 1 91 3342 1.2 Example 2 90.5 3282 1.2 Example 3 91 3390 1.2 Example 4 91 2850 1.2 Example 5 90 3026 1.4 Example 6 90.2 3120 1.4

[0076] The present invention is to first split the high-tube cemented carbide product into a high tube 1 and a step 2. First, make the high tube and pre-burn the product to give it a certain strength and hardness. The second step: make the unburned blank of the step part and install it on the same graphite plate at the same time as the high tube, with a designed support amount of 5-6%. Cemented carbide support amount: Since cemented carbide belongs to liquid phase sintering and is sensitive to sintering temperature, a graphite ring is placed in the inner hole of the annular product. The outer circle of the graphite ring can prevent the cemented carbide from shrinking freely and play a role in fixing the inner hole size. This is the origin of graphite support. The calculation formula is: support amount % = {graphite ring outer circle - (blank inner hole / shrinkage coefficient)} / graphite ring outer circle. The present invention uses the high tube as a graphite ring, which can achieve the same effect as a graphite ring support. The basis for the 5-6% expansion amount is the results obtained from multiple test data. When the expansion amount is less than 5%, local non-fitting between products is likely to occur. When the expansion amount is greater than 6%, the indentation on the contact surface of the blank will be too deep, which is not good for high-tube products.

[0077] Calculation method for the inner hole of product 2#: take the outer circle of product 1# as the basic size, (basic size / (1+0.05-0.06))*shrinkage coefficient = the size of the inner hole of product 2# before sintering. After the size of the inner hole of product 2# is determined, the size of the outer circle of product 2# before sintering can be calculated based on the shrinkage coefficient and product margin.

[0078] The present invention is suitable for high cobalt / nickel grades in YG10-YG25, but not for grades with cobalt / nickel content less than 10%, because grades with cobalt / nickel content less than 10% have less bonding phase, which is not conducive to bonding between products and the sintering process is uncontrollable. The present invention enables the powder utilization rate to reach 100% under the premise that the hardness and strength of the stepped high-tube product meet the requirements, saving production costs and reducing losses compared with conventional methods.

[0079] Although the present invention has been described in detail above with specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A cemented carbide blank sintering process, characterized in that: The blank is a high tube structure with steps on the outside, and the sintering process includes the following steps: Step 1: decomposing the blank into a high cylinder structure without steps and a step structure with a through hole in the middle, wherein the inner diameter of the through hole is larger than the outer diameter of the high cylinder; Step 2: first press into a high cylinder structure without steps, and pre-sinter the product to 1300-1400℃, keep warm for 30-50min, and cool to obtain a sintered blank; Step 3: Pressing the mold into a stepped structure with a through hole in the middle, wherein the inner diameter of the through hole is 1.05-1.06 times the outer diameter of the high-tube sintered blank; Step 4: After assembling the unfired blank of step 3 and the fired blank of step 2, place them on the same graphite plate and put them into a debonding and sintering integrated furnace for sintering, and finally obtain a high-tube structure with steps.

2. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The cemented carbide is a cemented carbide with a cobalt / nickel content of more than 10% by mass.

3. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The cemented carbide is of medium to high cobalt / nickel grade YG10-YG25.

4. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The height of the high tube is 280-350mm.

5. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The thickness of the high tube is 14-17 mm.

6. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The inner diameter of the high cylinder is 210-220 mm.

7. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The height of the step is 30-40 mm.

8. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The thickness of the step is 60-80 mm.

9. The process for sintering a cemented carbide blank according to claim 1, characterized in that: The sintering process of the integrated sintering furnace is as follows: (1) firstly fill the furnace with vacuum; (2) increase the temperature by 100°C every 10 minutes to 1300-1350°C for vacuum sintering; and keep the temperature for 1.5-2 hours; (3) fill argon gas in the later stage of vacuum sintering, and carry out argon protection sintering at a temperature of 1350-1450°C for 1-1.5 hours; (4) after the argon protection sintering is completed, cool naturally.

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