A hole rod with V-shaped groove and its preparation method and application

Abstract

A hole rod with a V-shaped groove and its preparation method and application, comprising the following preparation steps: mixing and ball-milling 87-95 parts of WC, 5-12 parts of Co, 0-1 parts of other carbide inhibitors and molding agents by weight, spray drying to form a mixture; adding 3%-9% of a plasticizer by weight to the mixture, stirring and kneading for 50-90 minutes, extruding and drying to form a hole rod blank with a V-shaped groove in the cross section, wherein the two sides of the V-shaped groove of the hole rod blank with the V-shaped groove are asymmetric structures; placing the two groove edges of the V-shaped groove hole rod of the hole rod blank with the V-shaped groove sideways against the groove wall of the boat dish, and sintering to form a cemented carbide hole rod with a V-shaped groove. The hole rod (gun drill) with a V-shaped groove prepared by the method of the present invention has high strength and hardness, and can solve the deformation of the cemented carbide gun drill during the sintering process.

Description

Technical Field

[0001] The invention belongs to the technical field of hard alloy product preparation, and in particular relates to a hole rod and a preparation method and application thereof. Background Art

[0002] Carbide gun drill is an effective deep hole processing tool with a wide range of processing, from mold steel, glass fiber, Teflon and other plastics to deep hole processing of high-strength alloys (such as P20 and chromium-nickel-inconel alloy). In deep hole processing with strict tolerance and surface roughness requirements, carbide gun drill can ensure the dimensional accuracy, position accuracy and straightness of the hole.

[0003] However, due to the asymmetric structure of cemented carbide gun drills, the shrinkage during the sintering process is inconsistent, which will often cause bending and twisting deformation during the sintering process of the gun drill. The straightness of the cemented carbide gun drill cannot be guaranteed, and the processing accuracy after being processed into a tool cannot be guaranteed.

[0004] Previously, the sintering method of gun drills was to place them flat in a boat. However, during the sintering process in this way, the gun drill was affected by the non-stacking shrinkage process, and the parallelism of the two sides of the V-shaped groove was often poor, and the straightness of the sintered product was poor.

[0005] Ensuring the straightness of the finished product after gun drilling is sintered can effectively improve the machining accuracy of the tool, but there is currently no effective method to solve the bending and twisting deformation caused by the asymmetric structure. Patent No. CN113528918A discloses a low-cobalt high-strength cemented carbide and its preparation method, providing technical inspiration for preparing cemented carbide using WC and Co through ball milling, spray drying, pressing blanks and sintering, but the molding method involved in this method is pressing molding, which is not suitable for the molding of rods with V-grooved holes.

[0006] Therefore, seeking a preparation method to correct the straightness of the gun drill has great practical significance for improving the quality consistency of the tool and improving the machining accuracy of the workpiece. Summary of the invention

[0007] The technical problem to be solved by the present invention is the distortion and bending deformation caused by the uneven shrinkage of the gun drill during the sintering process, and the shortcomings and defects mentioned in the above background technology are overcome to provide a hole rod with a V-groove and a preparation method and application thereof.

[0008] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0009] A method for preparing a hole rod with a V-shaped groove comprises the following preparation steps:

[0010] (1) mixing 87-95 parts by weight of WC, 5-12 parts by weight of Co, and 0-1 parts by weight of other carbide inhibitors and molding agents, ball milling, and spray drying to form a mixture;

[0011] (2) adding 3% to 9% by weight of a plasticizer to the mixture, stirring and kneading for 50 to 90 minutes, extruding and drying to form a hole rod dry blank with a V-groove in the cross section, wherein the two sides of the V-groove of the hole rod dry blank with the V-groove are asymmetrical structures;

[0012] (3) The two groove edges of the V-grooved hole rod of the V-grooved hole rod dry blank are placed sideways against the groove wall of the boat dish, and sintered to form a cemented carbide hole rod with a V-grooved hole rod.

[0013] Preferably, when placed on its side, the V-groove edges of the hole rod dry blank with V-grooves are in contact with the groove walls of the boat respectively, the contact point between the V-groove edge at the larger end of the hole structure and the groove wall of the boat is lower, and the contact point between the V-groove edge at the smaller end of the hole structure and the groove wall of the boat is higher.

[0014] Preferably, a circular hole is provided on both sides of the V-shaped groove of the cross section of the hole rod blank with the V-shaped groove, and the circular hole on one side has a larger diameter than that on the other side.

[0015] Preferably, the V-groove edge of the hole rod blank with a V-groove at the end with a larger diameter of the circular hole in the cross section is in line contact with the lower end of the boat groove wall, and the V-groove edge at the end with a smaller diameter of the circular hole in the cross section is in line contact or point contact with the upper end of the boat groove wall and does not exceed the top of the boat groove.

[0016] When the sintering shrinks violently, the conventional placement method is to place the product with the V-notch facing upwards. When the sintering shrinks, the product shrinks freely in the boat. The asymmetric structure will cause inconsistent shrinkage processes between the large hole end and the small hole end, and the internal stress during the forming process will also be uneven, resulting in twisting and bending deformation of the cemented carbide hole rod after sintering.

[0017] The present invention adopts a method of placing the dry blank lying inside a boat, so that the V-groove edge of one end of the large hole is in line contact with the lower part of the boat groove wall, and the V-groove edge of one end of the small hole is in line contact or point contact with the upper end of the boat groove wall and does not exceed the top of the boat groove. The size of the V-groove hole rod dry blank is larger than the alloy size. During the sintering process, this placement method ensures that the center of gravity of the dry blank is at a lower position during the sintering process, and as it shrinks during the sintering process, the center of gravity moves downward in space. In addition, there is line contact between the V-groove edge of the large hole end and the boat groove wall. When the dry blank shrinks, it gradually approaches the bottom of the boat groove, and the V-groove fits with the boat groove wall, ensuring the stability of the center of gravity and preventing more serious distortion due to unstable center of gravity.

[0018] Preferably, during the ball milling process in step (1), the ball-to-material ratio is 3:1 to 5:1, the amount of ball milling medium alcohol added is 300 ml / kg to 450 ml / kg, and the ball milling time is 35 to 55 h.

[0019] Preferably, the stirring and kneading in step (2) is carried out at a temperature of 20 to 80° C. and for a time of 50 to 90 minutes.

[0020] Preferably, the extrusion molding in step (2) is specifically: extrusion molding to form a wet billet, drying the wet billet at a temperature of 100 to 150° C. and keeping the temperature for 100 to 500 hours to form a dry billet with a V-groove hole rod.

[0021] Preferably, the sintering in step (3) is high-temperature sintering in a sintering furnace at a temperature of 1400-1450°C.

[0022] Under the same technical concept, the present invention also provides a hole rod with a V-shaped groove, which is prepared by a method for preparing a hole rod with a V-shaped groove.

[0023] Under the same technical concept, the present invention also provides an application of a hole rod with a V-shaped groove, wherein the hole rod with a V-shaped groove is used in a gun drill.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a method for preparing a hole rod with a V-groove. The V-groove hole rod is mostly an asymmetric structure. If the V-groove is placed upward during sintering, the product shrinks freely in the boat during sintering shrinkage. The asymmetric structure will cause the shrinkage process at both ends of the V-groove to be inconsistent, and the internal stress during the molding process is also uneven, and the cemented carbide hole rod after sintering is twisted and bent. The present invention ensures that the center of gravity is stable at the lower end during the sintering process by placing the dry blank lying on its side in the boat, reducing more serious distortion caused by unstable center of gravity. The hole rod (gun drill) with a V-groove prepared by the method of the present invention has high strength and hardness, and can solve the deformation of the cemented carbide gun drill during the sintering process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 The rod with two holes in Example 1 is lying sideways in the boat;

[0028] Figure 2The comparative example 1 is a flat lying mode of the rod with two holes in the boat;

[0029] Figure 3 The side-lying mode of the rod with waist-shaped holes in the boat according to Example 2;

[0030] Figure 4 This is a simulation diagram of the side-lying mode of the two-hole rod in the boat according to Example 1. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0032] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0034] Embodiment 1:

[0035] Add grinding balls according to the ball-to-material ratio of 4:1 to WC weight percentage 93%, Co weight percentage 6%, Cr3C2 weight percentage 1% and molding agent, add alcohol according to 350ml / kg, ball mill for 55h, dry into a mixture, add 7% plasticizer to the mixture, mix at 55℃ for 80min, cool and then form by extrusion, heat the formed wet blank to 140℃, keep warm for 200h, remove the plasticizer inside after drying, and obtain a dry blank with two-hole rod, then drill the dry blank as shown in Figure 1 , 4 Placed on its side, the V-groove edge of the V-groove hole rod blank is in close contact with the boat dish groove wall, the V-groove edge at one end of the large hole is in line contact with the lower part of the boat dish groove wall, and the V-groove edge at one end of the small hole is in line contact or point contact with the upper end of the boat dish groove wall, and does not exceed the top of the boat dish groove; after sintering at 1450℃, check the parallelism of the two groove edges of the V-groove hole rod of the side-lying sintered product <0.1mm, the pass rate is 96%, the straightness of the outer circle of the V-groove hole rod of the side-lying sintered product is <0.2mm, the pass rate is 99%, the Vickers hardness is 1650Mpa, and the strength is 2300Mpa.

[0036] Embodiment 2:

[0037] Add grinding balls according to the ball-to-material ratio of 4:1 to WC weight percentage 93%, Co weight percentage 6%, Cr3C2 weight percentage 1% and molding agent, add alcohol according to 350ml / kg, ball mill for 55h, dry into a mixture, add 7% plasticizer to the mixture, mix at 55℃ for 80min, cool and then form by extrusion, heat the formed wet blank to 140℃, keep warm for 200h, remove the plasticizer inside after drying, and obtain a dry blank with waist-shaped hole rod, then drill the dry blank as shown in Figure 2 Placed on its side, the V-groove edge of the V-groove hole rod dry blank is in contact with the boat dish groove wall, the contact point of the V-groove edge at the larger end of the hole structure and the boat dish groove wall is lower, and the contact point of the V-groove edge at the smaller end of the hole structure and the boat dish groove wall is higher, and does not exceed the top of the boat dish groove; after sintering at 1450℃, the parallelism of the two groove edges of the V-groove hole rod of the side-lying product is checked to be <0.1mm, and the pass rate is 97%, the straightness of the outer circle of the V-groove hole rod of the side-lying product is <0.2mm, and the pass rate is 100%, the Vickers hardness is 1650MPa, and the strength is 2300Mpa.

[0038] Embodiment 3:

[0039] Add grinding balls to WC (87%), Co (12%), Cr3C2 (1%) and a molding agent at a ball-to-material ratio of 3:1, add alcohol at 450 ml / kg, ball-mill for 40 hours, and dry into a mixture. Add 9% plasticizer to the mixture, mix at 90°C for 60 minutes, cool and then form by extrusion. Heat the formed wet blank to 150°C for 100 hours. After drying, remove the plasticizer inside to obtain a dry blank with two holes. Then drill the side of the dry blank with a gun. When placed lying down, the V-groove edge of the V-groove hole rod dry blank is in close contact with the boat dish groove wall, the V-groove edge at one end of the large hole is in line contact with the lower part of the boat dish groove wall, and the V-groove edge at one end of the small hole is in line contact or point contact with the upper end of the boat dish groove wall, and does not exceed the top of the boat dish groove; after sintering at 1400℃, the parallelism of the two groove edges of the V-groove hole rod of the side-lying product is checked to be <0.1mm, and the pass rate is 96%, the straightness of the outer circle of the V-groove hole rod of the side-lying product is <0.2mm, and the pass rate is 99%, the Vickers hardness is 1650MPa, and the strength is 3000Mpa.

[0040] Embodiment 4:

[0041] Add grinding balls with a weight percentage of 95% WC, 4.8% Co, 0.2% Cr3C2 and a molding agent at a ball-to-material ratio of 5:1, add alcohol at 300ml / kg, ball-mill for 35h, dry into a mixture, add 3% plasticizer to the mixture, mix at 20℃ for 50min, cool and then form by extrusion, heat the formed wet billet to 100℃, keep warm for 500h, remove the internal plasticizer after drying, and then place the gun-drilled dry billet on its side. The V-groove edge of the V-groove hole rod blank is in close contact with the boat groove wall, the V-groove edge at one end of the large hole is in line contact with the lower part of the boat groove wall, and the V-groove edge at one end of the small hole is in line contact or point contact with the upper end of the boat groove wall, and does not exceed the top of the boat groove; after sintering at 1410℃, the parallelism of the two groove edges of the V-groove hole rod of the side-lying sintered product is checked to be <0.1mm, and the qualified rate is 96%, the straightness of the outer circle of the V-groove hole rod of the side-lying sintered product is <0.2mm, and the qualified rate is 98%, the Vickers hardness is 1650MPa, and the strength is 2200Mpa.

[0042] Embodiment 5:

[0043] Add grinding balls to WC (90.2%), Co (9%), Cr3C2 (0.8%) and a molding agent at a ball-to-material ratio of 3:1, add alcohol at 400 ml / kg, ball-mill for 50 hours, and dry into a mixture. Add 5% plasticizer to the mixture, mix at 75°C for 70 minutes, cool and then form by extrusion. Heat the formed wet blank to 120°C for 300 hours. After drying, remove the plasticizer inside. Then place the gun-drilled dry blank on its side. The V-groove edge of the V-groove hole rod blank is in close contact with the boat groove wall, the V-groove edge at one end of the large hole is in line contact with the lower part of the boat groove wall, and the V-groove edge at one end of the small hole is in line contact or point contact with the upper end of the boat groove wall, and does not exceed the top of the boat groove; after sintering at 1445℃, the parallelism of the two groove edges of the V-groove hole rod of the side-lying sintered product is checked to be <0.1mm, and the qualified rate is 97%, and the straightness of the outer circle of the V-groove hole rod of the side-lying sintered product is <0.2mm, and the qualified rate is 98%, the Vickers hardness is 1650MPa, and the strength is 2800Mpa.

[0044] Comparative Example 1:

[0045] The remaining steps are the same as those in Example 1. Figure 2 The product was sintered lying flat, and the pass rate of the parallelism of the two groove sides of the V-groove hole rod of the inspected product was <0.1mm, and the pass rate was 63%, and the pass rate of the straightness of the outer circle of the V-groove hole rod was <0.2mm, and the pass rate was 66%.

[0046] Comparative Example 2:

[0047] The remaining steps are the same as those in Example 2. The product is sintered flat. The parallelism of the two groove sides of the V-groove hole rod of the product sintered flat is checked to be <0.1mm, and the pass rate is 65%. The straightness of the outer circle of the V-groove hole rod of the product sintered flat is <0.2mm, and the pass rate is 69%.

[0048] Comparative Example 3:

[0049] The remaining steps are the same as those in Example 3. The product is sintered flat. The parallelism of the two groove sides of the V-groove hole rod of the product sintered flat is checked to be <0.1mm, and the pass rate is 63%. The straightness of the outer circle of the V-groove hole rod of the product sintered flat is <0.2mm, and the pass rate is 66%.

[0050] Comparative Example 4:

[0051] The remaining steps are the same as those in Example 4. The product is sintered flatly. The parallelism of the two groove sides of the V-groove hole rod of the product sintered flatly is checked to be <0.1mm, and the pass rate is 62%. The straightness of the outer circle of the V-groove hole rod of the product sintered flatly is <0.2mm, and the pass rate is 64%.

[0052] Comparative Example 5:

[0053] The remaining steps are the same as those in Example 5. The product is sintered flatly. The parallelism of the two groove sides of the V-groove hole rod of the product sintered flatly is checked to be <0.1mm, and the pass rate is 65%. The straightness of the outer circle of the V-groove hole rod of the product sintered flatly is <0.2mm, and the pass rate is 65%.

[0054] Comparing Examples 1-5 and Comparative Examples 1-5 respectively, under the same conditions, different placement methods are adopted, and the qualified rate of the side-lying sintering gun drill is significantly improved.

Claims

1. A method for preparing a hole rod with a V-groove, characterized in that: The method comprises the following preparation steps: (1) Mixing WC 87-95 parts, Co 5-12 parts, Cr3C20-1 parts and a molding agent in a weight ratio, ball milling, and spray drying to form a mixture; (2) adding 3% to 9% by weight of a plasticizer to the mixture, stirring and kneading for 50 to 90 minutes, extruding and drying to form a perforated rod blank with a V-groove cross section, wherein both sides of the V-groove of the perforated rod blank with the V-groove are asymmetrical structures; (3) placing the two groove edges of the V-grooved hole rod of the V-grooved hole rod dry blank in contact with the groove wall of the boat dish and sintering to form a cemented carbide V-grooved hole rod; A circular hole is respectively arranged on both sides of the V-groove of the cross section of the hole rod blank with the V-groove, and the circular hole on one side has a larger diameter than that on the other side; when the hole rod blank with the V-groove is placed on its side, the V-groove edges of the hole rod blank with the V-groove are respectively in contact with the groove wall of the boat, and in its asymmetric structure, the contact point of the V-groove edge at the larger end of the circular hole and the groove wall of the boat is lower, and the contact point of the V-groove edge at the smaller end of the circular hole and the groove wall of the boat is higher.

2. The preparation method according to claim 1, characterized in that The V-groove edge of the hole rod blank with a V-groove at the end with a larger diameter of the cross-sectional circular hole is in line contact with the lower end of the boat groove wall, and the V-groove edge at the end with a smaller diameter of the cross-sectional circular hole is in line contact or point contact with the upper end of the boat groove wall and does not exceed the top of the boat groove.

3. The preparation method according to claim 1, characterized in that: In the ball milling process of step (1), the ball-to-material ratio is 3:1-5:1, the amount of ball milling medium alcohol added is 300 ml / kg-450 ml / kg, and the ball milling time is 35-55 h.

4. The preparation method according to claim 1, characterized in that: The stirring and mixing in step (2) is carried out at a temperature of 20 to 80° C. and for a time of 50 to 90 minutes.

5. The preparation method according to claim 1, characterized in that: The extrusion molding in step (2) is specifically as follows: extrusion molding forms a wet billet, and the wet billet is dried at a temperature of 100-150° C. for a heat preservation time of 100 h-500 h to form a dry billet with a hole rod having a V-shaped groove.

6. The preparation method according to claim 1, characterized in that: The sintering in step (3) is high-temperature sintering in a sintering furnace at a temperature of 1400-1450°C.

7. A hole rod with a V-shaped groove, characterized in that: The V-groove hole rod prepared by the preparation method according to any one of claims 1 to 6 has a parallelism of the two groove sides of ≤0.1mm, a straightness of the outer circle of the V-groove hole rod of ≤0.2mm, a Vickers hardness of ≥1650Mpa, and a bending strength of ≥2200MPa.

8. An application of a hole rod with a V-groove, characterized in that: The hole rod with V-shaped groove is used in gun drilling.

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