Graphite tool for sintering hard alloy long pipe with step inside

Abstract

The utility model discloses a graphite tool for sintering a hard alloy long pipe with steps inside. The graphite tool comprises a stepped graphite core, a plurality of arc graphite flakes, a graphite core rod and an annular graphite core, the plurality of arc graphite flakes surround the graphite core rod to form a complete cylinder, the stepped graphite core is placed in an inner hole of one end, with steps, of a product, and the annular graphite core is placed in an inner hole of the other end, without steps, of the product; by means of the optimized and improved design of the graphite tool, the graphite tool is suitable for sintering of a thin-wall inner-step-structure long pipe with the inner hole with the two ends small and the middle large, the problems of product ellipse, bending and the like caused by the influence of the height and the self weight of a workpiece are solved, graphite cores can be separated and separated more smoothly, and the service life of the graphite core is prolonged. And therefore, the beneficial effects that the application range of the graphite tool to sintered products is widened, and the sintering quality is further improved are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of sintering tooling for alloy long tubes, and more specifically, to a graphite tooling for sintering hard alloy long tubes with internal steps. Background Art

[0002] As an important powder metallurgy processing method, the liquid-phase sintering of tubular alloys has extensive applications in the field of materials science.

[0003] Liquid-phase sintering refers to the sintering process in which powders or compacts with at least two components are sintered in a state where a liquid phase is formed. In the preparation of tubular alloys, the liquid-phase sintering technology forms a dense tubular alloy structure by introducing a low-melting-point alloy component as the liquid phase and co-sintering it with high-melting-point alloy powders. This technology can significantly improve the densification and performance of the sintered body and is suitable for the preparation of high-performance tubular alloy materials.

[0004] Hard alloy is an alloy material made from refractory metal hard compounds and binder metals through powder metallurgy processes, and has a series of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance, and corrosion resistance. In particular, its high hardness and wear resistance remain basically unchanged even at a temperature of 500 °C and still have high hardness at 1000 °C.

[0005] However, during the liquid-phase sintering process of thin-walled long tubular hard alloys, due to the influence of the height and self-weight of the workpiece, problems such as inner hole ovality and workpiece bending will occur. Especially for products with a higher binder phase, problems such as ovality and bending are particularly obvious, and the dimensions are difficult to control, resulting in a low product qualification rate. Currently, existing sintering tooling for thin-walled long tubes such as CN219632604U, this tubular hard alloy sintering graphite core rod, the fixing mechanism reduces problems such as inner hole ovality and workpiece bending caused by the influence of the height and self-weight of the workpiece inside. However, this type of structural tooling still cannot be applied to the sintering of thin-walled inner stepped structure long tubes with small ends and a large middle in the inner hole. Summary of the Utility Model

[0006] In view of the above technical problems in the related art, the present utility model proposes a graphite tooling for sintering hard alloy long tubes with internal steps, which can overcome the above-mentioned deficiencies of the prior art.

[0007] To achieve the above technical objectives, the technical solution of the present utility model is realized as follows:

[0008] A graphite tooling for sintering hard alloy long tubes with internal steps;

[0009] The graphite tooling for sintering the hard alloy long tube with steps inside includes a stepped graphite core, several arc graphite sheets, a graphite core rod, and a ring graphite core; several of the arc graphite sheets surround the graphite core rod to form a complete cylinder, the stepped graphite core is placed in the inner hole at one end of the product with steps, and the ring graphite core is placed in the inner hole at the other end of the product without steps.

[0010] Further, the stepped graphite core includes a large-diameter part of the stepped graphite core, a small-diameter part of the stepped graphite core, and an inner-hole part of the stepped graphite core. The arc graphite sheet includes a stepped part of the arc graphite sheet, a protruding ring part of the arc graphite sheet, and an inner-hole part of the arc graphite sheet. The graphite core rod includes an outer-circle part of the graphite core rod and an inner-hole part of the graphite core rod. The ring graphite core includes an outer-circle part of the ring graphite core and an inner-hole part of the ring graphite core. The product is a hard alloy long tube, and a first inner cavity section, a second inner cavity section, a third inner cavity section, and a fourth inner cavity section are formed inside the hard alloy long tube.

[0011] Further, the diameter of the cylindrical hole formed by enclosing the inner-hole parts of multiple arc graphite sheets is smaller than the diameter of the cylindrical hole of the third inner cavity section, and the difference between the two is twice the coating thickness.

[0012] Further, the total horizontal length of the stepped graphite core is D1, the horizontal length of the large-diameter part of the stepped graphite core is E1, the outer diameter of the large-diameter part of the stepped graphite core is φA1, the outer diameter of the small-diameter part of the stepped graphite core is φB1, and the diameter of the inner-hole part of the stepped graphite core is φC1;

[0013] The total horizontal length of the arc graphite sheet is E2, the horizontal length of the stepped part of the arc graphite sheet is D2, the cross-sectional width of the arc graphite sheet is C2, the outer diameter of the cylinder formed by enclosing multiple arc graphite sheets is φB2, the diameter of the cylindrical hole formed by enclosing the inner-hole parts of multiple arc graphite sheets is φA2, and the difference between the radius of the cylinder formed by enclosing multiple arc graphite sheets and the radius of the cylindrical hole formed by enclosing the inner-hole parts of multiple arc graphite sheets is F2;

[0014] The total horizontal length of the graphite core rod is C3, the outer diameter of the outer-circle part of the graphite core rod is φA3, and the diameter of the inner-hole part of the graphite core rod is φB3;

[0015] The total horizontal length of the ring graphite core is C4, the outer diameter of the outer-circle part of the ring graphite core is φB4, and the diameter of the inner-hole part of the ring graphite core is φA4;

[0016] The transverse length of the first inner cavity section is L1, the diameter of the cylindrical hole of the first inner cavity section is φD, the transverse length of the second inner cavity section is L2, the diameter of the cylindrical hole of the second inner cavity section is φA, the transverse length of the third inner cavity section is L3, the diameter of the cylindrical hole of the third inner cavity section is φB, the transverse length of the fourth inner cavity section is L4, and the diameter of the cylindrical hole of the fourth inner cavity section is φC.

[0017] Further, the outer area after the assembly of the stepped graphite core, multiple arc graphite sheets (2), graphite core rod (3) and ring graphite core (4) is uniformly coated with a coating for hard alloy sintering, and the coating thickness of the coating for hard alloy sintering is x , and 0.1 ≤ x ≤ 0.5.

[0018] Further, D1 = L1 + L2,

[0019] E1 = L1,

[0020] φA1 = φD - x * 2,

[0021] φB1 = φA - x * 2,

[0022] E2 = L3 - 20 * 2 + 5,

[0023] D2 = L3 - 20 * 2,

[0024] φB2 = φB - x * 2;

[0025] C3 = L3 - 20 * 2 + F2,

[0026] φA3 = φA2,

[0027] C4 = L4,

[0028] φA4 = φC - x * 2,

[0029] And C1 > A2 > B3 = A4.

[0030] Further, the diameter of the inner hole part of the arc graphite sheet is the same as the diameter dimension of the outer circular part of the graphite core rod.

[0031] Further, a wide step of 3 - 7 mm is reserved between the step part and the protruding ring part of the arc graphite sheet of the arc graphite sheet.

[0032] Further, the stepped graphite core, multiple arc graphite sheets, graphite core rod and ring graphite core are all made of high-purity graphite.

[0033] Advantages of the present utility model: Through the optimized and improved design of the product of the present utility model, the graphite tooling is applicable to the sintering of long tubes with a thin-walled internal stepped structure where the inner hole is small at both ends and large in the middle, and problems such as ovality and bending of the product caused by the influence of the height and self-weight of the workpiece are avoided. The separation and ejection of the graphite core are more smooth, thereby achieving the beneficial effects that the applicable range of the graphite tooling for sintered products is increased and the sintering quality is further improved. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 is a side view of a cemented carbide long tube of a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model;

[0036] Figure 2 is a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model Figure 1 sectional view along line A-A;

[0037] Figure 3 is a front view of a stepped graphite core of a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model;

[0038] Figure 4 is a side view of an arc-shaped graphite sheet of a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model;

[0039] Figure 5 is a front view of an arc-shaped graphite sheet of a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model;

[0040] Figure 6 is a front view of a graphite core rod of a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model;

[0041] Figure 7 is a front view of a ring-shaped graphite core of a graphite tooling for sintering a cemented carbide long tube with internal steps according to an embodiment of the present utility model;

[0042] In the figure: 1. stepped graphite core; 101. large circular part of the stepped graphite core; 102. small circular part of the stepped graphite core; 103. inner hole part of the stepped graphite core; 2. arc-shaped graphite sheet; 201. stepped part of the arc-shaped graphite sheet; 202. protruding ring part of the arc-shaped graphite sheet; 203. inner hole part of the arc-shaped graphite sheet; 3. graphite core rod; 301. outer circular part of the graphite core rod; 302. inner hole part of the graphite core rod; 4. circular graphite core; 401. outer circular part of the circular graphite core; 402. inner hole part of the circular graphite core; 5. hard alloy long tube; 501. first inner cavity section; 502. second inner cavity section; 503. third inner cavity section; 504. fourth inner cavity section. Detailed implementation mode

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0044] It should be understood that in the description of the embodiments of the present invention, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying 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 to the embodiments of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "several" means two or more, unless otherwise specifically defined.

[0045] As Figures 1-7 shown, a graphite tooling for sintering a hard alloy long tube with steps inside according to an embodiment of the present invention includes a stepped graphite core 1, a plurality of arc-shaped graphite sheets 2, a graphite core rod 3, and a circular graphite core 4; the plurality of arc-shaped graphite sheets 2 surround the graphite core rod 3 to form a complete cylinder, the stepped graphite core 1 is placed in the inner hole at one end of the product with steps, and the circular graphite core 4 is placed in the inner hole at the other end of the product without steps.

[0046] According to a graphite tooling for sintering a cemented carbide long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the stepped graphite core 1 includes a stepped graphite core large circle part 101, a stepped graphite core small circle part 102, and a stepped graphite core inner hole part 103. The arc graphite sheet 2 includes an arc graphite sheet step part 201, an arc graphite sheet protruding ring part 202, and an arc graphite sheet inner hole part 203. The graphite core rod 3 includes a graphite core rod outer circle part 301 and a graphite core rod inner hole part 302. The circular ring graphite core 4 includes a circular ring graphite core outer circle part 401 and a circular ring graphite core inner hole part 402. The product is a cemented carbide long tube 5, and a first inner cavity section 501, a second inner cavity section 502, a third inner cavity section 503, and a fourth inner cavity section 504 are formed inside the cemented carbide long tube 5.

[0047] According to a graphite tooling for sintering a cemented carbide long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the diameter of the cylindrical hole formed by enclosing a plurality of the arc graphite sheet inner hole parts 203 is smaller than the diameter of the cylindrical hole of the third inner cavity section 503, and the difference between the two is 0.36 mm.

[0048] According to a graphite tooling for sintering a cemented carbide long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the total horizontal length of the stepped graphite core 1 is D1, the horizontal length of the stepped graphite core large circle part 101 is E1, the outer diameter of the stepped graphite core large circle part 101 is φA1, the outer diameter of the stepped graphite core small circle part 102 is φB1, and the diameter of the stepped graphite core inner hole part 103 is φC1;

[0049] The total horizontal length of the arc graphite sheet 2 is E2, the horizontal length of the arc graphite sheet step part 201 is D2, the cross-sectional width of the arc graphite sheet 2 is C2, the outer diameter of the cylinder formed by enclosing a plurality of the arc graphite sheets 2 is φB2, the diameter of the cylindrical hole formed by enclosing a plurality of the arc graphite sheet inner hole parts 203 is φA2, and the difference between the radius of the cylinder formed by enclosing a plurality of the arc graphite sheets 2 and the radius of the cylindrical hole formed by enclosing a plurality of the arc graphite sheet inner hole parts 203 is F2;

[0050] The total horizontal length of the graphite core rod 3 is C3, the outer diameter of the graphite core rod outer circle part 301 is φA3, and the diameter of the graphite core rod inner hole part 302 is φB3;

[0051] The total horizontal length of the circular ring graphite core 4 is C4, the outer diameter of the circular ring graphite core outer circle part 401 is φB4, and the diameter of the circular ring graphite core inner hole part 402 is φA4;

[0052] The transverse length of the first inner cavity section 501 is L1, the diameter of the cylindrical hole of the first inner cavity section 501 is φD, the transverse length of the second inner cavity section 502 is L2, the diameter of the cylindrical hole of the second inner cavity section 502 is φA, the transverse length of the third inner cavity section 503 is L3, the diameter of the cylindrical hole of the third inner cavity section 503 is φB, the transverse length of the fourth inner cavity section 504 is L4, and the diameter of the cylindrical hole of the fourth inner cavity section 504 is φC.

[0053] According to a graphite tooling for sintering a hard alloy long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the outer region after the assembly of the stepped graphite core 1, multiple arc graphite sheets 2, a graphite core rod 3, and a ring graphite core 4 is uniformly coated with a coating for sintering hard alloy, and the coating thickness of the coating for sintering hard alloy is 0.18 mm.

[0054] According to a graphite tooling for sintering a hard alloy long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the diameter of the inner hole part 203 of the arc graphite sheet of the arc graphite sheet 2 is the same as the diameter dimension of the outer circular part 301 of the graphite core rod of the graphite core rod 3.

[0055] According to a graphite tooling for sintering a hard alloy long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, a wide step of 3 - 7 mm is reserved between the step part 201 and the protruding ring part 202 of the arc graphite sheet of the arc graphite sheet 2.

[0056] According to a graphite tooling for sintering a hard alloy long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the longitudinal height of the wide step is 5 mm.

[0057] According to a graphite tooling for sintering a hard alloy long tube with steps inside according to an embodiment of the present invention, in a specific embodiment, the stepped graphite core 1, multiple arc graphite sheets 2, the graphite core rod 3, and the ring graphite core 4 are all made of high-purity graphite.

[0058] In order to facilitate the understanding of the above technical solution of the present invention, the above technical solution of the present invention will be described in detail below through specific usage methods.

[0059] When in specific use, a graphite tooling for sintering a hard alloy long tube with steps inside according to the present invention includes a stepped graphite core 1, multiple arc graphite sheets 2, a graphite core rod 3, and a ring graphite core 4; and all the above component materials are high-purity graphite. Multiple arc graphite sheets 2 surround the graphite core rod 3 to form a complete cylinder, the stepped graphite core 1 is placed in the stepped inner hole of the product, and the ring graphite core 4 is placed in the non-stepped inner hole at the other end of the product.

[0060] In component stepped graphite core 1:

[0061] The total transverse length of the stepped graphite core 1 is D1;

[0062] The transverse length of the large circular part 101 of the stepped graphite core is E1;

[0063] The outer diameter of the large circular part 101 of the stepped graphite core is φA1;

[0064] The outer diameter of the small circular part 102 of the stepped graphite core is φB1;

[0065] The diameter of the inner hole part 103 of the stepped graphite core is φC1.

[0066] In component arc graphite sheet 2:

[0067] The total transverse length of the arc graphite sheet 2 is E2;

[0068] The transverse length of the step part 201 of the arc graphite sheet is D2;

[0069] The cross-sectional width of the arc graphite sheet 2 is C2;

[0070] The outer diameter of the cylinder formed by enclosing multiple arc graphite sheets 2 is φB2;

[0071] The diameter of the cylindrical hole formed by enclosing the inner hole parts 203 of multiple arc graphite sheets is φA2;

[0072] The difference between the radius of the cylinder formed by enclosing multiple arc graphite sheets 2 and the radius of the cylindrical hole formed by enclosing the inner hole parts 203 of multiple arc graphite sheets is F2.

[0073] In component graphite core rod 3:

[0074] The total transverse length of the graphite core rod 3 is C3;

[0075] The outer diameter of the outer circular part 301 of the graphite core rod is φA3;

[0076] The diameter of the inner hole part 302 of the graphite core rod is φB3;

[0077] In component ring-shaped graphite core 4:

[0078] The total transverse length of the ring-shaped graphite core 4 is C4;

[0079] The outer diameter of the outer circular part 401 of the ring-shaped graphite core is φB4;

[0080] The diameter of the inner hole part 402 of the ring-shaped graphite core is φA4;

[0081] In component hard alloy long tube 5:

[0082] The transverse length of the first inner cavity section 501 is L1;

[0083] The cylindrical hole diameter of the first inner cavity section 501 is φD;

[0084] The transverse length of the second inner cavity section 502 is L2;

[0085] The cylindrical hole diameter of the second inner cavity section 502 is φA;

[0086] The transverse length of the third inner cavity section 503 is L3;

[0087] The cylindrical hole diameter of the third inner cavity section 503 is φB;

[0088] The transverse length of the fourth inner cavity section 504 is L4;

[0089] The cylindrical hole diameter of the fourth inner cavity section 504 is φC;

[0090] The above dimensions in the hard alloy long tube 5 of the component are all alloy state dimensions after sintering densification.

[0091] The default dimension unit in the following dimension relationships is millimeter.

[0092] Among them, the dimensional relationship between φB2 and φB is: B2 = φB - 0.18 * 2; and there is a wide step of 3 - 7 mm reserved between the arc graphite sheet step part 201 and the arc graphite sheet protruding ring part 202 of the arc graphite sheet 2. In a preferred embodiment, the setting parameter of the wide step is 5 mm. It can be fixed with a rolling belt, which is convenient for coating the boat. The diameter of the inner hole part 203 of the arc graphite sheet 2 of the arc graphite sheet 2 is the same as the diameter of the outer circular part 301 of the graphite core rod 3 of the graphite core rod 3, and the length needs to support the product as much as possible, but it is necessary to ensure that the product will not touch the side of the graphite core after shrinkage. Considering that the graphite core 1 will move during the sintering process of the product, a safety distance of 15 - 25 mm is currently reserved. The number of cut arcs of the arc graphite sheet 2 needs to consider that the maximum width of the arc graphite sheet 2 after cutting needs to be less than the inner diameter of one end of the product to ensure that the graphite core can be smoothly removed, and there needs to be an arc graphite sheet 2 with parallel cut parts, which is convenient for the separation of the graphite core after sintering; that is: the dimension of C2 is less than φC or φD.

[0093] In a preferred embodiment of the present invention, the number of the arc graphite sheets 2 is three, and the three arc graphite sheets 2 together enclose a cylinder.

[0094] The graphite cores at both ends include: a stepped graphite core 1 and a ring-shaped graphite core 4, and their specific designs are as follows:

[0095] φA1 = φD - 0.18 * 2; φB1 = φA - 0.18 * 2; D1 = L1 + L2; E1 = L1; φA4 = φC - 0.18 * 2; C4 = L4; The inner hole sizes of multiple graphite cores need to have a certain gradient from one end of the product to the other end (the difference between adjacent two is more than 5 mm), which is convenient for the graphite cores to be removed after sintering. That is: φC1 ≥ φA2 + 5 ≥ φA4 + 5.

[0096] The principle of loading the graphite cores into the boat is as follows:

[0097] The stepped graphite core 1, multiple arc graphite sheets 2, graphite core rod 3 and ring graphite core 4 processed as required are assembled, and the areas in direct contact with the product are evenly brushed with the coating for hard alloy sintering, and the coating thickness is between 0.1 - 0.5, to prevent the product from directly contacting the graphite parts during the sintering process and causing carburization. Place the product on the V-shaped groove plate, then place multiple arc graphite sheets 2 in the middle position of the inner hole groove of the product, measure the distance from the end face of the graphite core to the edge of the groove, and make the distances at both ends the same (the distance is about 20 mm). Finally, place the stepped graphite core 1 and graphite core rod 3 of the assembly in the smaller holes at both ends of the product, and the graphite cores will move together with the shrinkage of the product during the sintering process.

[0098] In a specific embodiment of the present utility model, the sintering object is a hard alloy long tube 5,

[0099] The specific design and dimensional relationship of the boat assembly are as follows:

[0100] Stepped graphite core 1:

[0101] D1 = L1 + L2 = 20 + 25 = 45;

[0102] E1 = L1 = 20;

[0103] φA1 = φD - 0.18 * 2 = 55 - 0.36 = 54.64;

[0104] φB1 = φA - 0.18 * 2 = 49.64;

[0105] φC1 = 30.

[0106] Arc graphite sheet 2:

[0107] E2 = L3 - 20 * 2 + 5 = 130 - 40 + 5 = 95;

[0108] D2 = L3 - 20 * 2 = 130 - 40 = 90;

[0109] φB2 = φB - 0.18 * 2 = 55 - 0.36 = 54.64; F2 = 5;

[0110] φA2 = 20.

[0111] Graphite core rod 3:

[0112] C3 = L3 - 20 * 2 + 5 = 130 - 40 + 5 = 95;

[0113] φA3 = φA2 = 20;

[0114] φB3 = 10.

[0115] Annular graphite core 4:

[0116] C4 = L4 = 30;

[0117] φA4 = φC - 0.18 * 2 = 50 - 0.36 = 49.64;

[0118] φA4 = 10.

[0119] The method for assembling the boat and loading the green compact into the boat is as follows:

[0120] 1) Complete the assembly of each component processed as required, and evenly brush the coating for carbide sintering on the area in direct contact with the product, with the coating thickness being 0.18 mm.

[0121] 2) Place the product on the V-groove plate, then place the arc graphite sheet 2 and the graphite core rod 3 in the middle position of the inner hole groove of the product, measure the distance from the end face of the graphite core to the edge of the groove, and make the distances at both ends the same (the distance is about 20 mm). Finally, place the stepped graphite core 1 and the annular graphite core 4 in the smaller holes at both ends of the product.

[0122] The inspection of the sintered blank of the graphite tooling for sintering a long carbide tube with an internal stepped structure having a small diameter at both ends and a large diameter in the middle as described in the product of the present utility model is as follows:

[0123] After the product is sintered and taken out of the furnace, inspect the inner hole size of the blank shaft, and the range is 0.3 mm, and the effect is good.

[0124] In summary, by means of the above technical solutions of the present utility model, through the optimized and improved design of the product of the present utility model, the graphite tooling is made suitable for sintering a long tube with a thin-walled inner stepped structure having a small diameter at both ends and a large diameter in the middle, and problems such as ovality and bending of the product caused by the influence of the height and self-weight of the workpiece are avoided, and the separation and removal of the graphite core are more smooth. Furthermore, the beneficial effects of improving the applicable range of the graphite tooling for sintered products and further improving the sintering quality are achieved.

[0125] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A graphite tooling for sintering a cemented carbide long tube with internal steps, characterized in that: The invention comprises a stepped graphite core (1), a plurality of arc graphite sheets (2), a graphite core rod (3) and a circular graphite core (4); the plurality of arc graphite sheets (2) surround the graphite core rod (3) to form a completed cylinder; the stepped graphite core (1) is placed in the inner hole of one end of the product with a step, and the circular graphite core (4) is placed in the inner hole of the other end of the product without a step.

2. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 1, characterized in that: The step graphite core (1) comprises a step graphite core large circular portion (101), a step graphite core small circular portion (102) and a step graphite core inner hole portion (103); the arc graphite sheet (2) comprises an arc graphite sheet step portion (201), an arc graphite sheet protruding ring portion (202) and an arc graphite sheet inner hole portion (203); the graphite core rod (3) comprises a graphite core rod outer circular portion (301) and a graphite core rod inner hole portion (302); the annular graphite core (4) comprises an annular graphite core outer circular portion (401) and an annular graphite core inner hole portion (402); the product is a cemented carbide long tube (5); a first inner cavity segment (501), a second inner cavity segment (502), a third inner cavity segment (503) and a fourth inner cavity segment (504) are formed inside the cemented carbide long tube (5).

3. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 2, characterized in that: The diameter of the cylindrical hole formed by the multiple arc graphite sheet inner hole portions (203) is smaller than the diameter of the cylindrical hole of the third inner cavity section (503), and the difference between the two is twice the thickness of the coating.

4. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 2, characterized in that: The total transverse length of the stepped graphite core (1) is D1, the transverse length of the large circular portion (101) of the stepped graphite core is E1, the outer diameter of the large circular portion (101) of the stepped graphite core is φA1, the outer diameter of the small circular portion (102) of the stepped graphite core is φB1, and the diameter of the inner hole portion (103) of the stepped graphite core is φC1; The total transverse length of the arc graphite sheet (2) is E2, the transverse length of the arc graphite sheet step portion (201) is D2, the cross-sectional width of the arc graphite sheet (2) is C2, the outer diameter of the cylinder enclosed by the plurality of arc graphite sheets (2) is φB2, the diameter of the cylindrical hole enclosed by the plurality of inner hole portions (203) of the arc graphite sheets is φA2, and the difference between the radius of the cylinder enclosed by the plurality of arc graphite sheets (2) and the radius of the cylindrical hole enclosed by the plurality of inner hole portions (203) of the arc graphite sheets is F2; The total transverse length of the graphite core rod (3) is C3, the outer diameter of the outer circular portion (301) of the graphite core rod is φA3, and the diameter of the inner hole portion (302) of the graphite core rod is φB3; The total transverse length of the annular graphite core (4) is C4, the outer diameter of the outer circular portion (401) of the annular graphite core is φB4, and the diameter of the inner hole portion (402) of the annular graphite core is φA4; The transverse length of the first inner cavity section (501) is L1, and the diameter of the cylindrical hole of the first inner cavity section (501) is φD; the transverse length of the second inner cavity section (502) is L2, and the diameter of the cylindrical hole of the second inner cavity section (502) is φA; the transverse length of the third inner cavity section (503) is L3, and the diameter of the cylindrical hole of the third inner cavity section (503) is φB; the transverse length of the fourth inner cavity section (504) is L4, and the diameter of the cylindrical hole of the fourth inner cavity section (504) is φC.

5. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 4, characterized in that: The outer area of ​​the assembled stepped graphite core (1), the plurality of arc graphite sheets (2), the graphite core rod (3) and the annular graphite core (4) is evenly coated with a hard alloy sintering coating, and the coating thickness of the hard alloy sintering coating is x , and 0.1≤ x ≤0.

5.

6. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 5, characterized in that: D1=L1+L2, E1=L1, φA1=φD- x *2, φB1=φA- x *2, E2=L3-20*2+5, D2=L3-20*2, φB2=φB- x *2; C3=L3-20*2+F2, φA3=φA2, C4=L4, φA4=φC- x *2, And C1>A2>B3=A4.

7. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 2, characterized in that: The diameter of the inner hole portion (203) of the circular graphite sheet (2) is the same as the diameter of the outer circle portion (301) of the graphite core rod (3).

8. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 2, characterized in that: A step with a width of 3-7 mm is reserved between the circular-arc graphite sheet step portion (201) and the circular-arc graphite sheet protruding ring portion (202) of the circular-arc graphite sheet (2).

9. The graphite tooling for sintering a cemented carbide long tube with internal steps according to claim 1, characterized in that: The stepped graphite core (1), the plurality of circular arc graphite sheets (2), the graphite core rod (3) and the circular graphite core (4) are all made of high-purity graphite.

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