Hard alloy tool bit with transition material

Abstract

The hard alloy tool bit with the transition material comprises a tool apron made of low-carbon alloy steel and a tool nose part brazed on the tool apron, an arc-shaped surface welded with the tool nose part is arranged on the tool apron, the section of the tool nose part is in a fan shape, and the fan shape is matched with the arc-shaped surface; the tool nose part made of the hard alloy material comprises a rear tool face, a front tool face, an arc welding face, a tool nose face and two side tool faces. The width of the tool nose surface is t, and t is 0.2 mm; the arc welding surface is matched with the arc-shaped surface; the tool apron further comprises a tool apron rear face, a tool apron front face, two tool apron side faces and a welding face. The arc-shaped face is arranged between the tool apron front face and the tool apron rear face. The welding surface corresponds to the tooth holder of the base body; the tool bit has the beneficial effects that through vacuum brazing of the tool nose part and the tool apron, the use amount of hard alloy is reduced, the tool bit cost is reduced, and the welding strength of the tool nose part and the tool apron is improved through vacuum brazing.

Description

Technical Field

[0001] This application relates to the technical field of cemented carbide inserts, and particularly to a cemented carbide insert with a transition material. Background Art

[0002] Cemented carbide has high hardness, strength, wear resistance and corrosion resistance, and is known as the "industrial teeth". It is an important material for manufacturing cutting tools and wear-resistant parts, and is widely used in military, aerospace, machining, metallurgy, oil drilling, mining tools, electronic communication, construction and other fields.

[0003] In the sawing field, the components directly acting on the material for cutting are mainly divided into two categories: circular saw blades and saw blades. Among them, the cemented carbide circular saw blade is integrally circular and thin. The outermost end of the circular blade is evenly distributed with cutting teeth, and the cutting teeth have tooth tips and cutting edges. When the saw blade is driven to rotate by a cutting device, the tip and the cutting edge cut the cutting material. The material of the cutting teeth is cemented carbide, which has high hardness and high brittleness. The saw blade consists of a long strip-shaped saw body and cutting teeth welded on the tooth seats of the saw body, and is driven by a sawing machine or manually, and cuts the material by reciprocating along the length direction of the saw body.

[0004] Although the cutting movement methods of the saw blade and the saw blade are different, the basic cutting principles are the same, and the cutting tooth materials used are the same, both of which are cemented carbide materials.

[0005] Currently, all saw blades and saw blades all use cemented carbide materials with the entire insert being integral. The main processing procedures are brazing, tempering, and tooth grinding. Brazing is to braze several inserts and the substrate into one body. Among them, the insert is made of cemented carbide material, and according to different requirements, the material and structural dimensions have been standardized and serialized, and can be selected by saw blade manufacturers. The substrate is designed and processed into different structures and dimensions according to the actual situation, especially the tooth seats on the outside of the substrate. Then, each insert is ground. Each conventional insert needs to be ground on 4 surfaces: two side surfaces, one front surface, and one back surface. Through the grinding of the four surfaces, the tip and the main and secondary cutting edges are formed.

[0006] The welding of cemented carbide and matrix steel can only adopt the brazing process at present, and only professional welding equipment - the special welding tooth machine for alloy saw blades can be used for processing. This greatly restricts the production of alloy saw blades, and they can only be processed and manufactured by professional alloy saw blade manufacturers. This poses a great obstacle to the use of cemented carbide products with special structures in some special usage scenarios. The so-called special usage scenarios often involve special structures and dimensions, small demand quantities, or even single pieces, and require short-time delivery, etc. In these cases, it is difficult for alloy saw blade manufacturers to accept orders. If the limitations of the brazing process can be solved by using general welding processes, it will create good conditions for the scope of use of cemented carbide. General welding processes here refer to welding processes with a high penetration rate in general mechanical factories, such as argon arc welding and laser welding.

[0007] Poor welding quality. Since the professional welding tooth machine is an open-type welding, oxide impurities in the weld seam are inevitable, reducing the quality of the weld seam. The direct manifestation is low fatigue strength, which directly affects the service life of the saw blade. Since vacuum welding requires positioning the tool tip and the matrix and then putting them into a vacuum furnace together, not only does the size of the matrix itself occupy a large space, but the positioning tooling on the outside of the matrix will occupy an even larger space. And the furnace chamber of the vacuum furnace is small, resulting in a small loading capacity and too high a cost. Therefore, no manufacturer uses vacuum brazing for alloy saw blades.

[0008] For saw blades, the rotational speed during operation can reach 12,000 rpm, and the stress it receives is high-frequency alternating stress. Just looking at the stress value, it is not large. Therefore, the main cause of weld failure is fatigue failure, and the fatigue source is mainly oxide inclusions and pores caused by oxidation in the weld seam, because appearance defects such as unfilled weld seams and undercut are easy to observe and control.

[0009] The oxide film formed during the brazing process has a serious destructive effect on the weld strength. It not only reduces the wettability of cemented carbide to the filler metal but also forms tissue defects, which has a great impact on the brazing strength. According to the research results, there are 5 film-removing mechanisms for vacuum brazing, which have a significant effect on improving the brazing quality.

[0010] The overall tool tip (tooth) causes a huge waste of cemented carbide materials. The size of the tool tip of an alloy saw blade is generally 5 - 20 mm in length and 2 - 6 mm in thickness. The actual cutting part is only the tool tip and the main and secondary cutting edges near the tool tip, and the size of this part is generally 2 - 3 mm. The other parts of the tool tip are only for facilitating processing and manufacturing and do not contribute to the cutting performance.

[0011] Cemented carbide is a powder metallurgy product sintered from carbides of high-hardness refractory metals (usually tungsten carbide WC) and cobalt (Co) or nickel (Ni), etc. It has many excellent properties, such as high hardness, wear resistance, high strength and toughness, and is widely used in many fields such as machinery, automobiles, and electronics. Among them, the largest amount is used in cutting tools and armor-piercing bullets. It is not only an important industrial resource but also an important strategic resource.

[0012] In addition, cobalt is the main bonding phase of cemented carbide. As a scarce and expensive metal, its global reserves are extremely limited. The global cobalt reserves are 4.5 million tons. Experts predict that according to the current consumption rate, it can only be reused for another 50 years.

[0013] In summary, it is urgent to reduce the consumption of cemented carbide.

[0014] The application number is 201921462577.9, and the name is an alloy circular saw blade with a scraper, which discloses a circular saw blade body. The surface of the circular saw blade body is provided with cutting teeth. Drainage grooves are opened at the top and bottom of the circular saw blade body. An installation groove is opened on the left side of the inner wall of the drainage groove, and a scraper is arranged inside the drainage groove; this saw blade fails to strengthen the tooth seat and has the technical problem of low strength mentioned above. The application number is 202110359340.3; the name is a cemented carbide circular saw blade, which includes a saw blade body and a cutter head. Tooth-shaped protrusions are evenly distributed on the outer edge of the saw blade body. A cutter head seat is arranged on the upper part of each tooth-shaped protrusion. The side surface of the cutter head seat is a side end wall. The side end wall and the cutter head are in contact and arranged side by side in the thickness direction of the saw blade body. The side end wall and the cutter head are fixed together by screws; the cutter head is fixed to the tooth seat of the base body by screws, which reduces the strength of the tooth seat on the base body, and the tooth seat is more likely to break. Summary of the Invention

[0015] The purpose of this application is to solve the shortcomings existing in the prior art, and provide a cemented carbide cutter head with a transition material, which can not only fully ensure the welding strength and welding quality between the tool tip and the tool seat. The tempering after welding the tool tip and the tool seat can be carried out at above 400 °C, so that the welding stress between the tool tip and the tool seat is fully released. Further ensuring the welding strength, it can also reduce the consumption of cemented carbide and reduce costs.

[0016] To achieve the above purpose, a cemented carbide cutter head with a transition material is provided, which includes a tool seat made of carbon alloy steel and a tool tip brazed on the tool seat. The tool seat is provided with an arc surface for welding with the tool tip. The cross-section of the tool tip is fan-shaped, and the fan shape is adapted to the arc surface.

[0017] Furthermore, the tip part of the cemented carbide material includes a flank face, a rake face, an arc welding face, a tip face and two side cutting faces; the width of the tip face is t, and the t is 0.2 mm; the arc welding face is adapted to the arc face. The width of the tip face is 0.2 mm because when forming the tip of a line, tooth grinding is required. If the tip face is too small, it is easy to cause an incomplete tip. If the tip face is too large, the amount of tooth grinding required is too large, affecting efficiency.

[0018] Furthermore, the tool holder further includes a rear surface of the tool holder corresponding to the flank face, a front surface of the tool holder corresponding to the rake face, two side surfaces of the tool holder corresponding to the side cutting faces respectively, and a welding surface welded to the base body. The arc face is arranged between the front surface and the rear surface of the tool holder; the welding surface corresponds to the tooth seat of the base body; the welding surface includes a circumferential welding surface and a radial welding surface.

[0019] Furthermore, there is an arc transition between the circumferential welding surface and the radial welding surface. The arc transition can avoid dead corners at this position of the tooth seat of the base body. After welding, stress concentration is likely to occur, causing the base body to break and tooth loss.

[0020] Furthermore, the arc face and the arc welding face are fixed by vacuum brazing. Using vacuum brazing can avoid oxidation of the weld seam and improve the welding strength.

[0021] Furthermore, a chamfer β is provided between the circumferential welding surface and the front surface of the tool holder; the β is -20 degrees. The setting of the chamfer β is to reduce the weight of the tool holder as much as possible while ensuring the strength of the tool holder.

[0022] Furthermore, the radius of the arc welding face is R1, and the R1 is not less than 2 mm; the determination of R1 is based on making the tip part as large as possible. If it is too small, the strength is insufficient; if it is too large, it wastes materials.

[0023] The distance between the intersection line of the arc welding face and the flank face and the radial welding surface is T, and the T is not less than 1.5 mm. The setting of T is to ensure the strength of the part on the tool holder closest to the tip part. The set value of 1.5 mm is determined based on experience accumulated during work.

[0024] The beneficial effects of this application are: 1. The tip of the tool head vacuum brazed to the tool holder is free of impurities, pores, and oxidation, and the welding is firm. Vacuum brazing can not only improve the strength of the weld seam, but more importantly, the stability and reliability of the weld seam quality are improved. This fully ensures the welding strength and quality between the tip of the tool head and the tool holder. After welding the tip of the tool head to the tool holder, tempering can be carried out at a temperature above 400 °C to fully release the welding stress between the tip and the tool holder, further ensuring the welding strength. The hardness of the tool holder will be lower than HRC40. Since the tool holder is welded to one side of the tooth groove on the outer edge of the base body, it has no impact on the stiffness of the base body, but instead improves the toughness of the weld area. The setting of T1 is to ensure the strength of the part on the tool holder closest to the tip of the tool head, and the set data is determined based on the experience accumulated during work.

[0025] The size of the tool head formed after welding the tip of the tool head to the tool holder is the same as that of the existing tool head, which is to ensure the universality of the tool head of this application and the existing standard tool head. Under the condition that all processing technologies and equipment remain unchanged, replacing the existing standard tool head with the tool head of this application can minimize the usage amount of cemented carbide materials. The setting of R is to ensure the strength of the tool head of this application. If R is too small, the welding area of the tooth tip will be too small. Since the strength of the end of the weld seam is affected, it is difficult to achieve stability, and the comprehensive strength cannot be guaranteed.

[0026] The selection of the tool holder material as carbon alloy steel is determined by considering comprehensive factors such as the mechanical properties (such as hardness) of the base body, weldability, procurement convenience, and economy. In actual work, it is not limited to these materials. However, it is preferred to use the same material for the tool holder and the base body to improve the welding performance between the tool holder and the base body.

[0027] After the tool head is welded, string polishing and sandblasting are used to remove the oxide scale, which is the simplest, most economical and effective method. At the same time, it has a further effect of releasing the welding stress of the weld seam.

[0028] This tool head structure expands the application range of the tool head, enabling the welding of the tool head not to be limited to the brazing process and ensuring the welding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following further describes this application in conjunction with the drawings and embodiments; Figure 1 is a schematic structural diagram of this application; Figure 2 is a three-dimensional structural diagram of this application; Figure 3 is a schematic structural diagram of the tip of the tool head; Figure 4 is a schematic structural diagram of the tooth seat; Figure 5 is a schematic structural diagram of the tool head and the base body after welding and grinding the teeth; LEGEND DESCRIPTION: 1 - Tool holder, 11 - Radial welding surface, 12 - Circumferential welding surface, 13 - Front surface of the tool holder, 14 - Arc surface, 15 - Rear surface of the tool holder; 2 - Tool tip, 21 - Rear cutting face, 22 - Front cutting face, 23 - Arc welding surface, 24 - Side cutting face, 25 - Tool tip face. Specific embodiments

[0030] This part will describe in detail the specific embodiments of the present application. The preferred embodiments of the present application are shown in the drawings. The role of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present application, but it should not be construed as a limitation on the protection scope of the present application.

[0031] Embodiment 1

[0032] Refer to Figures 1 - 5 , A cemented carbide tool tip with a transition material, comprising a tool holder 1 made of carbon alloy steel and a tool tip 2 brazed on the tool holder 1. The tool holder 1 is provided with an arc surface 14 for welding with the tool tip 2. The cross-section of the tool tip 2 is fan-shaped, and the fan shape is adapted to the arc surface 14. The selection of the material of the tool holder 1 should consider being close to or the same as the material of the base body, which is convenient for better welding performance when the tool holder 1 is welded to the tooth seat of the base body, ensuring the welding strength and reducing the welding stress. We have preferably selected several low-carbon alloy steels with good welding performance, such as 30CrMo, 40Cr, 40CrMo, etc., as the first choice for the tool holder 1.

[0033] As Figure 3 shown, the tool tip 2 made of cemented carbide material includes a rear cutting face 21, a front cutting face 22, an arc welding surface 23, a tool tip face 25 and two side cutting faces 24; the width of the tool tip face 25 is t, and the t is 0.2 mm; the arc welding surface 23 is adapted to the arc surface 14. The width of the tool tip face 25 is for being able to machine a complete tool tip during the subsequent gear grinding process. If the width is less than 0.2 mm, it is not easy to machine a complete tool tip, affecting the cutting performance of the saw blade. If the width is too large, the machining amount during gear grinding is too large, affecting the efficiency of gear grinding and wasting the grinding wheel.

[0034] As Figure 5 shown, after the tool tip is welded to the base body, gear grinding is carried out. After gear grinding, the tool tip face 25 becomes a linear tool tip; it is convenient for cutting; As Figure 4As shown, the tool holder 1 further includes a rear surface 15 of the tool holder corresponding to the rear cutting surface 21, a front surface 13 of the tool holder corresponding to the front cutting surface 22, two side surfaces of the tool holder corresponding to the side cutting surfaces 24 respectively, and a welding surface welded to the base body. An arc surface 14 is arranged between the front surface 13 and the rear surface 15 of the tool holder; the welding surface corresponds to the tooth seat of the base body; the welding surface includes a circumferential welding surface 12 and a radial welding surface 11.

[0035] There is an arc transition between the circumferential welding surface 12 and the radial welding surface 11. There is also an arc transition at this position of the tooth seat, which can avoid stress concentration at this position during welding and reduce the risk of tooth loss during saw blade cutting.

[0036] The arc surface 14 and the arc welding surface 23 are fixed by vacuum brazing. The tip 2 and the tool holder 1 are vacuum brazed, which can avoid the appearance of oxide films in the weld seam, improve the weld quality, increase the welding strength compared with the current open welding (that is, welding in the air), and prevent the tip 2 from falling off during cutting.

[0037] A chamfer β is provided between the circumferential welding surface 12 and the front surface 13 of the tool holder; the β is 15 - 20 degrees. If this angle is too large, it will affect the strength of the tool holder 1, and if it is too small, it will be meaningless. Choosing 18 degrees is the most reasonable; in this way, without affecting the strength of the tool holder 1, the weight of the tool tip can be reduced.

[0038] Embodiment 2

[0039] As Figure 1 shown, The difference between this embodiment and Embodiment 1 is that The radius of the arc welding surface 23 is R1, and the R1 is not less than 2 mm; if the radius R1 is too small, the volume of the tip 2 is small, which affects the strength of the tip 1. If the radius is too large, it is not conducive to cost reduction. The arc-shaped welding surface can increase the length of the welding surface, thereby ensuring as large a welding area as possible, ensuring the welding strength, and preventing the tip 2 from falling off the tool holder 1.

[0040] The distance between the intersection line of the arc welding surface 23 and the rear cutting surface 21 and the radial welding surface 11 is T, and the T is not less than 1.5 mm; the determination of the distance T takes into account the connection strength between the tool holder 1 and the tip 2. If this distance is too small, the rear surface 15 of the tool holder is too weak, and during saw blade cutting, the tool holder 1 is prone to deformation, resulting in tooth breakage. When ensuring that the size of the tip 2 is sufficient, the larger the width of the rear surface 15 of the tool holder, the better.

[0041] Embodiment 3

[0042] The difference between this embodiment and Embodiment 1 is that After the current integral cemented carbide cutting tips are welded to the substrate, intermediate temperature tempering cannot be carried out. Once the tempering temperature exceeds 280 °C, two problems occur: the substrate discolors severely - oxidized, and the hardness of the substrate decreases. Tempering after welding is to eliminate welding stress. Since cemented carbide is a powder metallurgy product with WC as the hard phase and Co as the bonding phase, and the proportion of WC is over 90%, and its linear expansion coefficient is only half of that of low-carbon steel. When the cemented carbide is brazed to the substrate of this kind of steel, great thermal stress will be generated in the joint, resulting in cracking of the joint. Therefore, timely tempering is required, but the current tempering temperature below 280 °C cannot completely release the welding stress.

[0043] Intermediate temperature tempering at 280 °C after welding is only suitable for brazing with a silver content in the filler metal of over 16%. Currently, most manufacturers use silver-free welding wires to reduce costs. If the tempering temperature after welding is still 280 °C, there is a high risk of tooth loss. Practice has proved that a tempering temperature of 420 °C after welding is relatively ideal and economical.

[0044] Before brazing with the cutting tip, the substrate needs to go through quenching and tempering processes to improve the mechanical properties of the substrate. The tempering temperature is about 400 °C, and the hardness is generally HRC40 - 48. The main materials used are 65Mn and 75Cr1.

[0045] The requirement for the hardness of the substrate is not for the strength of the substrate, but to ensure the stiffness in the circumferential direction of the substrate. Only with sufficient circumferential stiffness of the substrate can the saw blade be prevented from undergoing unstable deformation during use. The methods to ensure the circumferential stiffness of the substrate are, one is to increase the thickness of the substrate, and the other is to improve the mechanical properties of the substrate. The simplest manifestation is to increase the hardness of the substrate. Increasing the thickness of the substrate not only increases the manufacturing cost of the saw blade, but also increases the consumption of the cutting object and the energy consumption, so it is unacceptable. Therefore, only the hardness of the substrate can be ensured.

[0046] For the cutting tip with the tool holder brazed by vacuum brazing process, there are no impurities, pores, no oxidation, and the welding is firm. Vacuum brazing can not only improve the strength of the weld, but more importantly, improve the stability and reliability of the weld quality. This fully ensures the welding strength and quality between the cutting tip and the tool holder. After welding between the cutting tip and the tool holder, tempering can be carried out at over 400 °C to fully release the welding stress between the cutting tip and the tool holder, further ensuring the welding strength. After tempering, the hardness of the tool holder will be lower than HRC40. Since the tool holder is welded on one side of the tooth groove at the outer edge of the substrate, it has no influence on the stiffness of the substrate, but instead improves the toughness of the weld area.

[0047] The embodiments of the present application have been described in detail above in conjunction with the accompanying drawings. However, the present application is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present application within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A cemented carbide tool head with transition material, characterized in that: The invention comprises a knife seat (1) made of carbon alloy steel and a knife tip portion (2) brazed on the knife seat (1); the knife seat (1) is provided with an arc surface (14) welded to the knife tip portion (2); the knife tip portion (2) has a fan-shaped cross section, and the fan shape is matched with the arc surface (14).

2. A cemented carbide tool head with transition material according to claim 1, characterized in that: The tip portion (2) of the cemented carbide material comprises a rear blade surface (21), a front blade surface (22), an arc welding surface (23), a tip surface (25), and two side blade surfaces (24); the tip surface (25) has a width t, and t is 0.2 mm; the arc welding surface (23) is compatible with the arc surface (14).

3. A cemented carbide tool head with transition material according to claim 2, characterized in that: The tool holder (1) further comprises a tool holder rear face (15) corresponding to the back tool face (21), a tool holder front face (13) corresponding to the front tool face (22), two tool holder side faces corresponding to the side tool faces (24) respectively, and a welding face welded to the base body, wherein the arcuate face (14) is arranged between the tool holder front face (13) and the tool holder rear face (15); the welding face corresponds to the tooth seat of the base body; and the welding face comprises a circumferential welding face (12) and a radial welding face (11).

4. A cemented carbide tool head with transition material according to claim 3, characterized in that: There is a circular arc transition between the circumferential welding surface (12) and the radial welding surface (11).

5. The cemented carbide tool head with transition material according to claim 3, characterized in that: The arc surface (14) and the circular arc welding surface (23) are fixed by vacuum brazing.

6. The cemented carbide tool head with transition material according to claim 3, characterized in that: A chamfer β is provided between the circumferential welding surface (12) and the front face (13) of the knife seat; the β is 15-20 degrees.

7. The cemented carbide tool head with transition material according to claim 3, characterized in that: The radius of the circular arc welding surface (23) is R1, and R1 is not less than 2 mm; the distance between the intersection line of the circular arc welding surface (23) and the back knife surface (21) and the radial welding surface (11) is T, and T is not less than 1.5 mm.

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