Die assembly and synthesis cavity for producing multi-grain superhard material sintered body

Abstract

The utility model provides a die assembly and a synthesis cavity for producing a multi-grain superhard material sintered body. The die assembly comprises an upper graphite die, a lower graphite die, a middle graphite die and a separation graphite sheet, each graphite mold is provided with a plurality of hole cavities used for containing cutter blanks, and the multiple hole cavities are distributed in a concentric circle mode with the circle center of the corresponding graphite mold as the center; when the specifications of the hole cavities in the upper graphite mold, the middle graphite mold and the lower graphite mold are consistent, the shapes of two adjacent circles of hole cavities in the same layer of mold are different; when the shapes of the two adjacent circles of pore cavities in the same layer of mold are the same, the shape specification of the pore cavity in the upper graphite mold is consistent with that of the pore cavity in the lower graphite mold, and the specification of the pore cavity in the middle graphite mold is different from that of the pore cavity in the upper graphite mold. According to the mold assembly, the distribution trend of temperature and pressure in the synthesis cavity can be reasonably utilized, and the synthesis qualification rate of the superhard blade is increased.

Description

Technical Field

[0001] The utility model relates to the field of superhard material synthesis equipment. Specifically, it relates to a mold assembly and a synthesis cavity for producing multiple superhard material sintered compacts. Background Art

[0002] Currently, the synthesis of superhard material blades is usually carried out by filling superhard material powder into a graphite mold, compacting it, assembling it with other accessories, and then loading it into pyrophyllite for high-temperature and high-pressure synthesis. The usual assembly structure includes a synthesis cavity, a conductive steel sheet, a pressure transmission medium, a heating element, and a graphite tube. When the conductive steel sheet transmits current to the graphite tube, the graphite tube contacts the heating element to make it heat up. However, this heating method has uneven temperature and pressure fields in the cavity, resulting in uneven sintering tissue structure.

[0003] To solve the above problems, the utility model patent with the authorization announcement number CN111013492B discloses a superhard material synthesis cavity and a method for synthesizing superhard materials. The superhard material synthesis cavity includes a central heating element, an upper cavity and a lower cavity arranged at the upper and lower ends of the central heating element for placing superhard material raw materials for synthesis; and a first conductive steel cap and a second conductive steel cap arranged on both sides of the central heating element through the upper cavity and the lower cavity. This superhard material synthesis cavity can effectively reduce the uneven distribution of the temperature field in the synthesis cavity, reduce the problems of high temperature at the edge and low temperature in the central region of the cavity, and large temperature gradient, which plays an important role in improving the quality of superhard materials. However, this device needs to change the internal structure of the existing superhard material synthesis cavity, lacks universality and will additionally increase production costs. Summary of the Utility Model

[0004] In order to rationally utilize the internal temperature and pressure distribution trend of the synthesis cavity without changing the internal structure of the existing superhard material synthesis cavity to improve the synthesis qualification rate of superhard blades, the technical solution adopted by the utility model is: a mold assembly for producing multiple superhard material sintered compacts, including an upper graphite mold at the top layer, a lower graphite mold at the bottom layer, and a middle graphite mold clamped between the upper graphite mold and the lower graphite mold. Separation graphite sheets are respectively arranged on the upper and lower surfaces of the middle graphite mold;

[0005] A plurality of cavities for placing tool blanks are respectively formed on the upper graphite mold, the middle graphite mold, and the lower graphite mold. The plurality of cavities are arranged in concentric circles with the center of each graphite mold as the center;

[0006] When the cavity specifications on the upper graphite mold, the middle graphite mold, and the lower graphite mold are the same, the shapes of adjacent two circles of cavities in the same layer of molds are different;

[0007] When the shapes of two adjacent circles of holes in the same layer of the mold are the same, the hole cavity specifications on the upper graphite mold are consistent with those on the lower graphite mold, and the hole cavity specifications on the middle graphite mold are different from those on the upper graphite mold.

[0008] Based on the above, when the hole cavity specifications on the upper graphite mold, the middle graphite mold, and the lower graphite mold are the same, the shapes of the outer ring of hole cavities in the same layer of the mold are all triangular or all rhombic, and the shapes of the inner ring of hole cavities in the same layer of the mold are all circular or all octagonal.

[0009] Based on the above, when the shapes of two adjacent circles of holes in the same layer of the mold are the same, the holes on the upper graphite mold and the holes on the lower graphite mold are all triangular or all rhombic, and the holes on the middle graphite mold are all circular or all octagonal.

[0010] The present utility model also provides a synthesis cavity including the above-mentioned mold assembly, which includes a pyrophyllite outer shell. Composite liners are respectively arranged at the upper and lower ends of the pyrophyllite outer shell. A dolomite tube is inlaid inside the pyrophyllite outer shell. A carbon paper tube is filled inside the dolomite tube, and the mold assembly is arranged inside the carbon paper tube;

[0011] End graphite sheets are respectively covered at the upper and lower ends of the mold assembly, and alloy sheets that fit the inner side of the composite liner are arranged at the outer ends of the end graphite sheets;

[0012] The composite liner includes a conductive steel cap with a bottom that fits the alloy sheet. A pyrophyllite ring is sleeved at the outer end of the conductive steel cap, and a dolomite ring is sleeved at the inner end of the conductive steel cap.

[0013] Based on the above, dolomite blocks that fit the alloy sheet are also arranged inside the conductive steel cap.

[0014] Based on the above, in the mold assembly, the upper graphite mold, the middle graphite mold, and the lower graphite mold have the same thickness.

[0015] The present utility model has substantial features and progress compared with the prior art. Specifically, for the synthesis cavity for producing multiple superhard material sintered bodies provided by the present utility model, by analyzing the internal temperature and pressure distribution of the existing superhard material synthesis cavity, the tool types that require higher pressure or higher temperature are arranged in the outer ring of the mold, and the tool types that require lower pressure or lower temperature are arranged in the inner ring of the mold.

[0016] Meanwhile, either alone or simultaneously, by adopting the upper, middle, and lower interlayer methods, the mold with a lower-pressure or lower-temperature tool type is clamped between two molds with a higher-pressure or higher-temperature tool type, thereby effectively utilizing the slightly lower temperature and pressure in the central region of the graphite mold. Without changing the internal structure of the existing superhard material synthesis cavity, the internal temperature and pressure distribution trend of the synthesis cavity is reasonably utilized to improve the synthesis qualification rate of superhard blades, significantly reducing the phenomena of unqualified density and hardness of superhard tools. At the same time, the synthesis cavity provided by the present invention has universality and does not additionally increase the production cost. Description of the Drawings

[0017] Figure 1 It is a schematic cross-sectional view of the synthesis cavity for producing multi-grain superhard material sintered bodies provided by the present utility model.

[0018] Figure 2 It is a schematic structural view of the outer mold in the synthesis cavity for producing multi-grain superhard material sintered bodies provided by the present utility model.

[0019] Figure 3 It is a schematic structural view of the inner mold in the synthesis cavity for producing multi-grain superhard material sintered bodies provided by the present utility model.

[0020] Figure 4 It is a schematic structural view of each layer of the mold in the synthesis cavity for producing multi-grain superhard material sintered bodies provided in Embodiment 2 of the present utility model.

[0021] In the figure: 1, pyrophyllite outer shell; 2, dolomite tube; 3, dolomite ring; 4, pyrophyllite ring; 5, conductive steel cap; 6, carbon paper tube; 7, dolomite block; 8, alloy sheet; 9, middle graphite mold; 10, separating graphite sheet; 11, upper graphite mold; 12, lower graphite mold; 13, end graphite sheet; 14, mold matrix; 15, rhombic cavity; 16, circular cavity. Detailed Embodiments

[0022] The technical solutions of the present utility model will be further described in detail below through specific embodiments.

[0023] Embodiment 1

[0024] This embodiment provides a mold assembly for producing multi-grain superhard material sintered bodies. As Figure 1 , Figure 2 , Figure 3 shown, it includes an upper graphite mold 11 at the top layer, a lower graphite mold 12 at the bottom layer, and a middle graphite mold 9 clamped between the upper graphite mold 11 and the lower graphite mold 12. Separating graphite sheets 10 are respectively arranged on the upper and lower surfaces of the middle graphite mold 9.

[0025] On the mold bases 14 of the upper graphite mold 11, the middle graphite mold 9, and the lower graphite mold 12, a plurality of cavities for placing tool blanks are respectively provided. The plurality of cavities are arranged in concentric circles with the center of each graphite mold as the center.

[0026] In this embodiment, the cavities on the upper graphite mold and the lower graphite mold are both rhombus-shaped, forming rhombus-shaped cavities 15, and the cavities on the middle graphite mold are all circular, forming circular cavities 16. Specifically, the rhombus-shaped cavities are used to place 80-degree C-type tool blanks. The circular cavities are used to place R-type tool blanks.

[0027] Embodiment 2

[0028] This embodiment provides a mold assembly for producing multiple superhard material sintered bodies. The main difference from Embodiment 1 is that in this embodiment, as Figure 1 and Figure 4 shown, the cavity specifications on the upper graphite mold, the middle graphite mold, and the lower graphite mold are the same. The outer ring cavities in the same layer of molds are all rhombus-shaped, and the inner ring cavities in the same layer of molds are all circular.

[0029] Embodiment 3

[0030] This embodiment provides a synthesis cavity including the mold assembly described in Embodiment 1 or Embodiment 2. As Figure 1 shown, it includes a pyrophyllite outer shell 1, and composite liners are respectively provided at the upper and lower ends of the pyrophyllite outer shell 1. A dolomite tube 2 is inlaid inside the pyrophyllite outer shell 1, a carbon paper tube 6 is filled inside the dolomite tube 2, and the mold assembly is arranged inside the carbon paper tube 6.

[0031] End graphite sheets 13 are respectively covered at the upper and lower ends of the mold assembly. Alloy sheets 8 that fit with the inner sides of the composite liners are provided at the outer ends of the end graphite sheets 13.

[0032] The composite liner includes a conductive steel cap 5 whose bottom fits with the alloy sheet 8. A pyrophyllite ring 4 is sleeved at the outer end of the conductive steel cap 5, and a dolomite ring 3 is sleeved at the inner end of the conductive steel cap 5.

[0033] Specifically, dolomite blocks 7 that fit with the alloy sheets are further provided inside the conductive steel cap 5. In the mold assembly, the upper graphite mold, the middle graphite mold, and the lower graphite mold have the same thickness.

[0034] Comparative Example 1

[0035] This comparative example provides a synthesis cavity for producing multiple superhard material sintered bodies. The main difference from Embodiment 3 is that in this comparative example, as Figure 1 andFigure 2 As shown, the cavity shapes of the upper graphite mold 11, the middle graphite mold 9, and the lower graphite mold 12 in the mold assembly are all rhombic.

[0036] The mold assemblies and synthesis cavities provided in Example 1, Example 2, Comparative Example 1, and Example 3 were respectively used to actually synthesize multiple superhard materials, and the qualification rates were respectively tested. The specific operation steps are as follows:

[0037] The prepared cubic boron nitride mixture was loaded into a steel tool mold and pressed multiple times, each time for 10 to 15 s, to obtain pre-pressed sintered bodies of different tool shapes. The pre-pressed sintered bodies of corresponding shapes were placed into the cavities of the corresponding graphite molds. The thickness of the graphite molds was 7.5 cm, and separator graphite sheets of the same shape were respectively padded on the upper and lower surfaces. From the inside to the outside, first, the three-layer graphite molds were wrapped with end graphite sheets, and the upper and lower ends were closely attached to alloy sheets. Then, the outer layer was wrapped with a composite liner. The upper and lower parts of the composite liner were pyrophyllite rings, conductive steel caps, and dolomite rings. Then, a carbon paper tube, a dolomite tube, and a pyrophyllite outer shell were sleeved on the outermost layer. After the assembly was completed, it was placed into a six-sided top press for synthesis. 10 pieces were continuously synthesized, and the sintered bodies were processed into finished tools, and the density and hardness were tested. The test results are shown in the following table. It can be seen from the table that compared with Comparative Example 1, the mold assembly and synthesis cavity provided by the present invention can rationally utilize the internal temperature and pressure distribution trend of the synthesis cavity without changing the internal structure of the existing superhard material synthesis cavity, and improve the synthesis qualification rate of superhard blades.

[0038] Table 1. Tool specifications and qualification rates in the synthesis cavity

[0039]

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: still modifications can be made to the specific implementation manners of the present invention or equivalent replacements can be made to some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A mold assembly for producing multi-grain superhard material sintered compacts, characterized in that: It includes an upper graphite mold located at the top layer, a lower graphite mold located at the bottom layer, and a middle graphite mold clamped between the upper graphite mold and the lower graphite mold. Separation graphite sheets are respectively arranged on the upper and lower surfaces of the middle graphite mold. A plurality of cavities for placing tool blanks are respectively formed on the upper graphite mold, the middle graphite mold, and the lower graphite mold. The plurality of cavities are arranged in concentric circles with the center of their respective graphite mold as the center. When the cavity shape specifications on the upper graphite mold, the middle graphite mold, and the lower graphite mold are the same, the shapes of adjacent two circles of cavities in the same layer of mold are different. When the shapes of adjacent two circles of cavities in the same layer of mold are the same, the cavity shape specifications on the upper graphite mold are the same as those on the lower graphite mold, and the cavity specifications on the middle graphite mold are different from the cavity shape specifications on the upper graphite mold.

2. The mold assembly for producing a plurality of superhard material sintered compacts according to claim 1, characterized in that: When the cavity shape specifications on the upper graphite mold, the middle graphite mold, and the lower graphite mold are the same, the outer circle cavities in the same layer of mold are all triangular or all rhombic, and the inner circle cavities in the same layer of mold are all circular or all octagonal.

3. The mold assembly for producing multiple superhard material sintered compacts according to claim 1, characterized in that: When the shapes of adjacent two circles of cavities in the same layer of mold are the same, the cavities on the upper graphite mold and the lower graphite mold are all triangular or all rhombic, and the cavities on the middle graphite mold are all circular or all octagonal.

4. A synthetic cavity comprising the mold assembly according to any one of claims 1 to 3, characterized in that: It includes a pyrophyllite outer shell. Composite lining tubes are respectively arranged at the upper and lower ends of the pyrophyllite outer shell. A dolomite tube is inlaid inside the pyrophyllite outer shell. A carbon paper tube is filled inside the dolomite tube, and the mold assembly is arranged inside the carbon paper tube. End graphite sheets are respectively covered at the upper and lower ends of the mold assembly. Alloy sheets that fit with the inner side of the composite lining tube are arranged at the outer ends of the end graphite sheets. The composite lining tube includes a conductive steel cap with the bottom fitting with the alloy sheet. A pyrophyllite ring is sleeved at the outer end of the conductive steel cap, and a dolomite ring is sleeved at the inner end of the conductive steel cap.

5. The synthetic cavity according to claim 4, wherein: A dolomite block that fits with the alloy sheet is further arranged inside the conductive steel cap.

6. The synthetic cavity according to claim 4 or 5, characterized in that: In the mold assembly, the upper graphite mold, the middle graphite mold, and the lower graphite mold have the same thickness.

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