Hob cutter ring and preparation method thereof

Abstract

The invention provides a preparation method of a hobbing cutter ring, and relates to the technical field of metal matrix composites.The preparation method comprises the following steps that firstly, a prefabricated body is prepared, and the prefabricated body is a high-toughness steel prefabricated body of a grid structure; (2) the prefabricated body is placed on the cutting edge part of a hob cutter ring mold, then molten metal of high-hardness wear-resistant steel is poured into the hob cutter ring mold, the root part of a hob cutter is filled with the molten metal of the high-hardness wear-resistant steel, meanwhile, the prefabricated body is wrapped, the molten metal of the high-hardness wear-resistant steel is infiltrated into the grid structure of the prefabricated body, and a rough blank of the hob cutter ring is obtained; and (3) heat treatment and machining are conducted on the rough blank of the hob cutter ring, and the hob cutter ring is obtained. The high-hardness wear-resistant steel can ensure the high hardness of the surface of the hob cutter ring, and the grid structure high-toughness steel can absorb impact energy and effectively block crack propagation of the high-hardness wear-resistant steel, so that the (fracture) toughness of the hob cutter ring is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal-based composite materials, and in particular relates to a hob cutter ring and a preparation method thereof. Background Art

[0002] As a key component of the key equipment for the full-section construction of underground rock tunnel (hole) projects, the hob is widely used in comprehensive excavation operations such as railways, highway tunnels, coal mine tunnels, urban underground passages, and hydropower and water conservancy tunnels. Its core components include the cutter body, cutter ring, retaining ring, sealing assembly, bearing system, spindle and end cover, etc. Among them, the cutter ring is the core and vulnerable component, which often faces challenges such as poor wear resistance, chipping, breakage and falling off, which directly affects the construction efficiency and cost. Regular inspection, replacement and maintenance of the cutter is not only time-consuming and labor-intensive, but also significantly increases the project cost and prolongs the construction period. According to data analysis, the cost of the hob accounts for about 1 / 5 to 1 / 3 of the total project cost, and the replacement of the cutter ring due to wear is as high as 80%, highlighting its heavy loss. Therefore, it is necessary to improve the service performance and service life of the cutter ring. Among them, the hob cutter ring includes the blade part and the blade root part. At present, the life of the hob cutter ring is mainly closely related to its blade part.

[0003] There is an inherent contradiction between the hardness and toughness of materials, and it is difficult to have both. As a result, a single material cutter ring is difficult to meet the requirements of high hardness and toughness at the same time, thus causing fracture or rapid wear problems. At present, there are three main methods to improve the life of the blade of the hob cutter ring: one is to enhance durability by adding a wear-resistant layer to the existing cutter ring, but the thickness of the high-hardness wear-resistant layer is limited, and the wear-resistant layer peels off layer by layer, resulting in the cutter ring being unable to fully withstand long-term friction and wear; the second is to use high-wear-resistant materials to replace traditional materials. Although wear resistance can be improved, fracture toughness is poor; the third is to adopt a composite structure design, the inner ring is forged with high-toughness alloy steel, and the outer ring is cast with high-hardness wear-resistant steel. When casting, the high-hardness wear-resistant steel of the outer ring is usually cast first, and then the high-toughness steel of the inner ring is cast to combine the inner and outer layers. However, due to the different expansion coefficients between the inner and outer ring alloys, they shrink in their respective directions, resulting in poor bonding between the inner and outer rings. The joint is prone to cracking during cooling, resulting in a reduced service life of the cutter ring and a low yield rate.

[0004] In summary, the cutting edge of the hob cutter ring prepared by the existing method has the problems of difficulty in achieving both high wear resistance and high toughness, and poor bonding strength between the composite materials. Summary of the invention

[0005] Therefore, the present invention provides a hob cutter ring and a preparation method thereof to solve the problem in the prior art that the cutting edge of the hob cutter ring is difficult to have both high wear resistance and high toughness.

[0006] In order to solve the above problems, the present invention provides a method for preparing a hob cutter ring, comprising the following steps:

[0007] Step 1) preparing a preform, wherein the preform is a high-toughness steel preform with a grid structure;

[0008] Step 2) placing the preform on the blade of a hob cutter ring mold, and then pouring molten metal of high-hardness wear-resistant steel into the hob cutter ring mold, so that the molten metal of high-hardness wear-resistant steel fills the root of the hob cutter tool, wraps the preform, and infiltrates into the grid structure of the preform, to obtain a rough hob cutter ring blank;

[0009] Step 3) heat treating and processing the rough cutter ring blank to obtain the cutter ring.

[0010] Further, in the step 1):

[0011] The preparation steps of the preform include: melting high-toughness steel to obtain high-toughness steel melt, then injecting the high-toughness steel melt into a mold, and obtaining the preform after cooling; preferably, the mold is a ring-shaped ceramic mold with a grid structure; and / or

[0012] The preform is a cylindrical steel mesh; and / or

[0013] The high-toughness steel has a room temperature impact toughness greater than 10 J / cm 2 Pearlite / ferrite dual phase steel; and / or

[0014] The high-toughness steel is one or more of 20 steel, 42CrMo steel, 35CrMo steel, 4Cr5MoSiV steel or 40CrNiMo steel.

[0015] Further, in the step 2), placing the preform on the blade portion of the hob cutter ring mold comprises:

[0016] Placing two or three of the preforms on the cutting edge of a hob cutter ring mold in parallel to the cutting edge direction;

[0017] Preferably, the distance between two adjacent preforms among the two or three preforms is 1 / 5 to 1 / 3 of the width of the blade.

[0018] Furthermore, the thickness of the preform is 5 to 8 mm; and / or

[0019] The pore diameter of the grid structure is 15 to 20 mm.

[0020] Furthermore, in the step 2), before pouring the molten metal of hard wear-resistant steel into the hob cutter ring mold, the step further includes:

[0021] The temperature of the hob cutter ring mold is raised to 100-250° C. and preheated for 1-2 hours.

[0022] Furthermore, in the step 2), the hardness of the high-hardness wear-resistant steel is HRC68 or above; and / or

[0023] The carbon content of the high-hardness wear-resistant steel is 3-4.5wt%; and / or

[0024] The alloy content of high hardness and wear-resistant steel is 30-40wt%.

[0025] Furthermore, in the step 2), the molten metal of hard wear-resistant steel is poured into the hob cutter ring mold by centrifugal casting;

[0026] Preferably, the centrifugal casting temperature is 1520-1550°C;

[0027] Preferably, the initial centrifugal speed of centrifugal casting is 550-700 r / min, and the final centrifugal speed is 1300-1500 r / min.

[0028] Furthermore, in the step 3), the heat treatment includes: sequentially performing annealing treatment and normalizing treatment on the rough cutter ring blank;

[0029] The annealing treatment includes: heating the rough cutter ring blank to 300-500° C. and then keeping the temperature for 3-5 hours;

[0030] The normalizing treatment includes: heating the annealed hob cutter ring to 1000-1100°C and then keeping it warm for 2.5-3.5 hours.

[0031] On the other hand, the present invention further provides a hob cutter ring, the hob cutter ring comprises a blade portion and a blade root portion, the blade root portion is a base area, and the blade portion is a composite area;

[0032] The matrix area is high-hardness wear-resistant steel, and the microstructure of the matrix area includes martensite, austenite and carbide; the carbide includes VC and M7C3; the volume fraction of martensite is 40-50%, the volume fraction of austenite is 7-10%, the volume fraction of VC is 20-30%, and the volume fraction of M7C3 is 15-20%;

[0033] The composite zone is a composite zone formed by high-toughness steel and high-hardness wear-resistant steel; wherein the high-toughness steel is a high-toughness steel preform with a grid structure; the microstructure of the composite zone includes pearlite, ferrite and carbide.

[0034] Furthermore, the hardness of the hob cutter ring is 68-70HRC and the impact toughness is 7-10J / cm 2 ; Compressive strength 2760~2780MPa.

[0035] Preferably, the hob cutter ring is obtained by any of the preparation methods described above.

[0036] The present invention provides a hob cutter ring and a preparation method thereof, which have the following beneficial effects:

[0037] 1. The present invention prepares a preform, places the preform on the blade part of a hob cutter ring mold, then pours molten metal of high-hardness wear-resistant steel into the hob cutter ring mold so that the molten metal of high-hardness wear-resistant steel wraps the preform to obtain a rough hob cutter ring, and then heat treats and processes the rough hob cutter ring to obtain a hob cutter ring; wherein the preform is a high-toughness steel preform with a grid structure, and the preform is in the shape of a shell of the blade part of the hob cutter ring; based on the above method, the present invention has a hob cutter ring blade part The interior of the hob cutter is preformed with high-toughness steel with a grid structure, and then high-hardness wear-resistant steel is used as a matrix to wrap the high-toughness steel. The high-hardness wear-resistant steel can ensure the high hardness of the surface of the blade of the hob cutter ring, and the high-toughness steel with a grid structure can absorb impact energy and effectively block the crack expansion of the high-hardness wear-resistant steel, thereby improving the (fracture) toughness of the hob cutter ring. At the same time, the high-toughness steel with a grid structure is used as a preform, which increases the contact area of ​​the metallurgical bonding between the two materials (i.e., high-hardness wear-resistant steel and high-toughness steel), thereby improving the bonding ability between the two.

[0038] 2. Furthermore, the present invention adopts centrifugal casting to pour the molten metal of high-hardness and wear-resistant steel. On the one hand, under the action of centrifugal force, it helps the high-hardness and wear-resistant steel to flow fully, so that it can fully wrap the high-toughness steel preform, and helps the high-hardness and wear-resistant steel and the high-toughness structural steel preform to fully infiltrate and form a metallurgical bond, further enhancing the bonding force between the high-hardness and wear-resistant steel and the high-toughness steel, thereby avoiding cracking at the joint; on the other hand, centrifugal casting causes the microstructure of the high-hardness and wear-resistant steel of the hob cutter ring to change in a gradient manner (i.e., from the core to the outer layer of the hob cutter ring, the carbides become increasingly finer and more dispersed), and the carbides in the high-hardness and wear-resistant steel are finely and dispersedly distributed on the surface of the hob cutter ring, thereby enhancing the second phase strengthening effect, and since the fine carbide grains can enhance the fine grain strengthening, the second phase strengthening and the fine grain strengthening work synergistically to ensure the high hardness and excellent wear resistance of the alloy surface; at the same time, a higher rotation speed also causes the carbides in the outer layer of the high-hardness and wear-resistant steel to be more finely and dispersedly distributed, thereby avoiding cracks formed by carbide aggregation. At the same time, under the action of greater centrifugal force, the pearlite and ferrite grains inside the high-toughness steel are refined to 0.5-1.0μm, further improving the toughness of the high-toughness steel.

[0039] 3. On the other hand, the present invention provides a hob cutter ring, which is obtained by the above-mentioned preparation method, and the hob cutter ring includes a blade portion and a blade root portion, the blade root portion is a matrix area, and the blade portion is a composite area; wherein the matrix area is high-hardness wear-resistant steel, and the microstructure of the matrix area includes martensite, austenite and carbide; the composite area is a composite area formed by high-toughness steel and high-hardness wear-resistant steel; wherein the high-toughness steel is a grid structure, and the microstructure of the high-toughness steel includes ferrite and pearlite; the microstructure of the high-hardness wear-resistant steel includes martensite, Austenite and carbide; therefore, the microstructure of the composite zone includes ferrite, pearlite and carbide; the high-toughness steel with a grid structure can effectively block the expansion of cracks in high-hardness and wear-resistant steel, thereby improving the fracture toughness of the hob cutter ring; the ferrite and pearlite dual-phase structure of high-toughness steel has excellent toughness, which can effectively hinder the expansion of cracks and improve the fracture toughness of the cutter ring; the martensitic matrix and multi-scale carbides of high-hardness and wear-resistant steel can improve the hardness and strength of the hob cutter ring, and further improve the wear resistance of the cutter ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0041] Figure 1 A schematic diagram of the structure of a hob cutter ring prepared in Example 1 of the present invention;

[0042] Figure 2 This is a microstructure morphology of the hob cutter ring prepared in Example 2 of the present invention;

[0043] Figure 3 A schematic diagram comparing the compressive strength and impact toughness of the hob cutter rings prepared in Example 3 and Example 1 of the present invention;

[0044] Figure 4 A schematic diagram comparing the compressive strength and impact toughness of the hob cutter rings prepared in Example 4 and Example 1 of the present invention;

[0045] Figure 5 A schematic diagram comparing the compressive strength and wear resistance of the hob cutter rings prepared in Example 5 and Example 1 of the present invention;

[0046] Figure 6 This is a microstructure image of a hob cutter ring prepared in Example 6 of the present invention;

[0047] Figure 7 A schematic diagram showing a comparison of the wear resistance of the hob cutter rings prepared in Example 6 and Example 1 of the present invention;

[0048] Figure 8 is a schematic diagram of a grid structure in the present invention;

[0049] Fig. 9 A schematic diagram of a hob cutter ring prepared according to the present invention. DETAILED DESCRIPTION

[0050] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0051] A method for preparing a hob cutter ring comprises the following steps:

[0052] Step 1) melting high-toughness steel to obtain high-toughness steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a shell (ring) of the blade portion of a hob cutter ring, and obtaining a ring-shaped preform having a grid structure after cooling;

[0053] The preform is a cylindrical steel mesh; the high-toughness steel has a room temperature impact toughness greater than 10J / cm 2 Pearlite / ferrite dual-phase steel; preferably, the high-toughness steel is one or more of 20 steel, 42CrMo steel, 35CrMo steel, 4Cr5MoSiV steel or 40CrNiMo steel; the pore diameter of the grid structure is 15 to 20 mm;

[0054] Step 2) placing two or three (two or three layers) preforms parallel to the blade direction on the blade portion of the hob cutter ring mold, and heating the hob cutter ring mold to 100-250° C., preheating for 1-2 hours, and then pouring molten metal of high-hardness wear-resistant steel into the hob cutter ring mold by centrifugal casting, so that the molten metal of high-hardness wear-resistant steel fills the root of the hob cutter tool, wraps the preform, and infiltrates into the grid structure of the preform, to obtain a rough hob cutter ring blank;

[0055] Among them, the spacing between two adjacent preforms in the two or three preforms is 1 / 5 to 1 / 3 of the blade width; the thickness of the preform is 5 to 8 mm; the height of the preform varies with the blade size of the hob cutter ring; the hardness of the high-hardness wear-resistant steel is above HRC68; the carbon content of the high-hardness wear-resistant steel is 3 to 4.5 wt%; the alloy content of the high-hardness wear-resistant steel is 30 to 40 wt%; the temperature of the centrifugal casting is 1520 to 1550° C.; preferably, the initial centrifugal speed of the centrifugal casting is 550 to 700 r / min, and the final centrifugal speed is 1300 to 1500 r / min;

[0056] Step 3) heat treating and processing the rough cutter ring blank to obtain the cutter ring;

[0057] Among them, the heat treatment includes: annealing and normalizing the rough blank of the hob cutter ring in sequence; removing the internal stress of centrifugal casting by annealing, and adjusting the microstructure of the cutting edge of the cutter ring by normalizing; wherein, the annealing treatment includes: heating the rough blank of the hob cutter ring to 300-500°C, and then keeping it warm for 3-5 hours; the normalizing treatment includes: heating the annealed hob cutter ring to 1000-1100°C, and then keeping it warm for 2.5-3.5 hours.

[0058] Among them, during centrifugal casting, the centrifugal speed during centrifugal casting is adjusted according to the Konstantinov formula, and the specific formula is:

[0059]

[0060] Where: n is the centrifugal speed of the mold (i.e. the mold used for pouring) (r / min); r0 is the inner surface radius of the casting (hob cutter ring) (m); γ is the density of the liquid metal (N / m 3 ). Gravity refers to the force of gravity per unit volume of a substance.

[0061] The hob cutter ring of the present invention comprises a blade portion and a blade root portion, wherein the blade root portion is a base area and the blade portion is a composite area. Figure 1 As shown; wherein the matrix area is high-hardness wear-resistant steel, the composite area is formed by high-toughness steel and high-hardness wear-resistant steel, wherein the high-toughness steel is a high-toughness steel preform with a grid structure (i.e. Figure 1 mesh high-toughness steel in the preform); the mesh structure of the preform is as follows Figure 8 As shown, the hob cutter ring containing the preform is obtained as Fig. 9 As shown, it can be seen that the preform is a cylindrical steel mesh. In the above method, the multi-layer preform (two or three layers) refers to a plurality of preforms of different diameters; the multi-layer preform is placed on the blade part of the hob cutter ring mold parallel to the blade direction, which means that a plurality of preforms of different diameters are mounted on the blade part of the hob cutter ring mold according to the change of the blade diameter.

[0062] Based on the above method, a grid-structured high-toughness steel is used as a preform inside the hob cutter ring, and then a high-hardness wear-resistant steel is used as a matrix to wrap the high-toughness steel, wherein the high-hardness wear-resistant steel can ensure the high hardness of the surface of the hob cutter ring, and the grid-structured high-toughness steel can absorb impact energy and effectively block the crack propagation of the high-hardness wear-resistant steel, thereby improving the (fracture) toughness of the hob cutter ring; at the same time, the grid-structured high-toughness steel is used as a preform, which increases the contact area of ​​the metallurgical bonding between the two materials (i.e., high-hardness wear-resistant steel and high-toughness steel), thereby improving the bonding ability between the two.

[0063] The present invention adopts centrifugal casting to pour the molten metal of high-hardness wear-resistant steel. On the one hand, under the action of centrifugal force, it helps the high-hardness wear-resistant steel to fully flow, so that it fully wraps the high-toughness steel preform, and helps the high-hardness wear-resistant steel and the high-toughness structural steel preform to fully infiltrate and form a metallurgical bond, further improving the bonding force between the high-hardness wear-resistant steel and the high-toughness steel, thereby avoiding cracking at the joint; on the other hand, centrifugal casting causes the organization of the high-hardness wear-resistant steel of the hob cutter ring to change in a gradient, and the carbides in the high-hardness wear-resistant steel are finely dispersed and distributed on the surface of the hob cutter ring, thereby improving the second phase strengthening effect, and because the carbide grains are fine, the fine grain strengthening can be improved, and the second phase strengthening and the fine grain strengthening work synergistically to ensure the high hardness and excellent wear resistance of the alloy surface; at the same time, the higher speed also promotes the carbides of the outer layer of the high-hardness wear-resistant steel to be more finely dispersed, thereby avoiding cracks formed by the aggregation of carbides. At the same time, under the action of a greater centrifugal force, the pearlite and ferrite grains inside the high-toughness steel are refined, further improving the toughness of the high-toughness steel.

[0064] Among them, if there are more layers of high-toughness steel (more than 3 layers), the high-toughness steel preform will occupy most of the volume of the cutter ring mold. Therefore, during centrifugal casting, it will hinder the flow of high-hardness wear-resistant steel, resulting in a decrease in the bonding strength of the two metals and defects such as holes in the high-hardness wear-resistant steel; when the number of layers of high-toughness steel is one, the impact absorption work on the blade is insufficient, so the impact toughness is low; the spacing between two adjacent high-toughness steel preforms is small, and it is impossible to effectively promote the high-hardness wear-resistant steel to fill the preform, which reduces the bonding force between the two. If the spacing is too large, the high-toughness steel network density is small, and the high-toughness steel content in the unit space near the surface of the hob cutter ring is small. If the amount is insufficient, the barrier effect on cracks is reduced, and the fracture toughness of the hob cutter ring is not significantly improved; if the thickness of the preform is small, the high-toughness steel will be severely burned when casting the high-hardness and wear-resistant steel (centrifugal casting), and a stable toughness skeleton (grid structure) cannot be formed. At the same time, the high-toughness steel preform melts into the high-hardness and wear-resistant steel, resulting in its component segregation, coarsening the structure, and reducing the compressive strength and wear resistance of the hob cutter ring; if the thickness of the preform is too large, the preform occupies a large space, and has a greater barrier effect on the flow and filling of the high-hardness and wear-resistant steel, resulting in more void defects in the alloy and insufficient bonding ability between the high-hardness and wear-resistant steel and the high-toughness steel.

[0065] On the other hand, the present invention also provides a hob cutter ring, the hob cutter ring comprises a blade portion and a blade root portion, the blade root portion is a base area, and the blade portion is a composite area;

[0066] The matrix area is high-hardness wear-resistant steel, and the microstructure of the matrix area includes martensite, austenite and carbide; the carbide includes VC and M7C3; the volume fraction of martensite is 40-50%, the volume fraction of austenite is 7-10%, the volume fraction of VC is 20-30%, and the volume fraction of M7C3 is 15-20%;

[0067] The composite zone is a composite zone formed by high-toughness steel and high-hardness wear-resistant steel; the microstructure of the composite zone includes pearlite, ferrite and carbide; wherein the grain size of pearlite is 0.5-1.0 μm; the grain size of ferrite is 0.5-1.0 μm.

[0068] Furthermore, the hardness of the hob cutter ring is 68-70HRC; the impact toughness is 7-10J / cm 2 ;Compressive strength 2760~2780MPa;

[0069] Preferably, the hob cutter ring is obtained by any of the above-mentioned preparation methods.

[0070] The invention is further described below with reference to specific embodiments and comparative examples.

[0071] Example 1

[0072] This embodiment provides a method for preparing a hob cutter ring, which specifically includes the following steps:

[0073] Step 1) smelting 20 steel to obtain 20 steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a shell of the blade portion of a hob cutter ring, and obtaining a preform after cooling;

[0074] Wherein, in terms of mass percentage, the composition of 20 steel includes: C: 0.2wt%, Si: 0.25wt%, Mn: 0.55wt%, S: 0.02wt%, P: 0.02wt%, Cr: 0.1wt%, Ni: 0.1wt%, Cu: 0.15wt%, and the balance is Fe; the thickness of the preform is 6mm; the height of the preform varies with the blade size of the hob cutter ring; the pore diameter of the grid structure is 18mm;

[0075] Step 2) Fix the blade of the hob cutter ring mold with three preforms parallel to the blade direction, and heat the hob cutter ring mold to 150° C., preheat for 1 hour, and then pour the molten metal of high hardness and wear-resistant steel into the hob cutter ring mold by centrifugal casting, so that the molten metal of high hardness and wear-resistant steel fills the root of the hob cutter tool and wraps the preform at the same time, and infiltrates into the grid structure of the preform to obtain a rough hob cutter ring blank;

[0076] Among them, the spacing between two adjacent preforms in the three preforms is 1 / 4 of the blade width; in terms of mass percentage, the components of the high-hardness wear-resistant steel include: C: 3.5wt%, V: 9.2wt%, Mo: 3wt%, Si: 1.5wt%, Mn: 0.5wt%, Ni: 2.6wt%, N: 0.1wt%, W: 2.6wt%, Al: 0.8wt%, Co: 1.2wt%, Nb: 0.6wt%, and the balance is Fe; the hardness of the high-hardness wear-resistant steel is HRC68; the alloy content of the high-hardness wear-resistant steel is 35wt%; the temperature of centrifugal casting is 1530°C; the initial centrifugal speed of centrifugal casting is 550r / min, and the final centrifugal speed is 1400r / min;

[0077] Step 3) After the centrifuge is stopped, the rough cutter ring blank is taken out and annealed at 350° C. for 4 hours; then the rough cutter ring blank after annealing is normalized at 1000° C. for 3 hours, and then processed to obtain the cutter ring.

[0078] The structure of the hob cutter ring prepared in this embodiment is as follows Figure 1 shown.

[0079] Example 2

[0080] This embodiment provides a method for preparing a hob cutter ring, which specifically includes the following steps:

[0081] Step 1) smelting 42CrMo high-toughness steel to obtain 42CrMo high-toughness steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a blade shell of a hob cutter ring, and obtaining a preform after cooling;

[0082] Among them, the composition of 42CrMo high-toughness steel includes, by mass percentage: C: 0.4wt%, Si: 0.2wt%, Mn: 0.6wt%, S: 0.03wt%, P: 0.03wt%, Cr: 0.95wt%, Ni: 0.030wt%, Cu: 0.020wt%, Mo: 0.2wt%, and the balance is Fe; the thickness of the preform is 7mm; the height of the preform varies with the blade size of the hob cutter ring; the pore diameter of the grid structure is 18mm;

[0083] Step 2) Fix the blade of the hob cutter ring mold with three preforms parallel to the blade direction, and heat the hob cutter ring mold to 120°C, preheat for 1.5 hours, and then pour the molten metal of high hardness and wear-resistant steel into the hob cutter ring mold by centrifugal casting, so that the molten metal of high hardness and wear-resistant steel fills the root of the hob cutter tool and wraps the preform at the same time, and infiltrates into the grid structure of the preform to obtain a rough hob cutter ring;

[0084] Among them, the spacing between two adjacent preforms in the three (three-layer) preforms is 1 / 4 of the blade width; in terms of mass percentage, the components of the high-hardness wear-resistant steel include: C: 3.5wt%, V: 9.2wt%, Mo: 3wt%, Si: 1.5wt%, Mn: 0.5wt%, Ni: 2.6wt%, N: 0.1wt%, W: 2.6wt%, Al: 0.8wt%, Co: 1.2wt%, Nb: 0.6wt%, and the balance is Fe; the hardness of the high-hardness wear-resistant steel is above HRC68; the alloy content of the high-hardness wear-resistant steel is 38wt%; the temperature of centrifugal casting is 1530°C; the initial centrifugal speed of centrifugal casting is 550r / min, and the final centrifugal speed is 1400r / min;

[0085] Step 3) After the centrifuge is stopped, the rough cutter ring blank is taken out and annealed at 300° C. for 3.5 hours; then the rough cutter ring blank after annealing is normalized at 1100° C. for 2.5 hours, and then processed to obtain the cutter ring.

[0086] The microstructure morphology of the hob cutter ring prepared in this embodiment is as follows: Figure 2 As shown, it can be found that the high-hardness wear-resistant steel and the high-toughness steel of the hob cutter ring prepared in this embodiment are metallurgically bonded, and there is no defect in the interface, which shows that the bonding force between the two is good. At the same time, the hob cutter ring of this embodiment is destroyed, and the grid structure of the high-toughness steel inside the hob cutter ring can be directly observed, indicating that the preform of the high-toughness steel can exist intact inside the hob cutter ring, ensuring the fracture toughness of the hob cutter ring.

[0087] Embodiments 1 and 2 are preferred embodiments that adopt the essential features and preferred technical features of the present invention, and the following embodiments are embodiments that adopt the essential features and non-preferred technical features.

[0088] Example 3

[0089] This embodiment provides a method for preparing a hob cutter ring, which specifically includes the following steps:

[0090] Step 1) smelting 20 steel to obtain 20 steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a shell of the blade portion of a hob cutter ring, and obtaining a preform after cooling;

[0091] Wherein, in terms of mass percentage, the composition of 20 steel includes: C: 0.2wt%, Si: 0.25wt%, Mn: 0.55wt%, S: 0.02wt%, P: 0.02wt%, Cr: 0.1wt%, Ni: 0.1wt%, Cu: 0.15wt%, and the balance is Fe; the thickness of the preform is 6mm; the height of the preform varies with the blade size of the hob cutter ring; the pore diameter of the grid structure is 18mm;

[0092] Step 2) Fixing a preform to the blade of the hob cutter ring mold parallel to the blade direction, and heating the hob cutter ring mold to 150° C., preheating for 1 hour, and then pouring high-hardness wear-resistant steel molten metal into the hob cutter ring mold by centrifugal casting, so that the high-hardness wear-resistant steel molten metal fills the root of the hob cutter tool, wraps the preform, and infiltrates into the grid structure of the preform, to obtain a rough hob cutter ring blank;

[0093] Wherein, the composition of the high hardness wear-resistant steel includes, by mass percentage: C: 3.5wt%, V: 9.2wt%, Mo: 3wt%, Si: 1.5wt%, Mn: 0.5wt%, Ni: 2.6wt%, N: 0.1wt%, W: 2.6wt%, Al: 0.8wt%, Co: 1.2wt%, Nb: 0.6wt%, and the balance is Fe; the hardness of the high hardness wear-resistant steel is HRC69; the alloy content of the high hardness wear-resistant steel is 35wt%; the temperature of centrifugal casting is 1530°C; the initial centrifugal speed of centrifugal casting is 550r / min, and the final centrifugal speed is 1400r / min;

[0094] Step 3) After the centrifuge is stopped, the rough cutter ring blank is taken out and annealed at 350° C. for 4 hours; then the rough cutter ring blank after annealing is normalized at 1000° C. for 3 hours, and then processed to obtain the cutter ring.

[0095] The compressive strength and impact toughness of the hob cutter ring prepared in this embodiment and in Example 1 are compared. Figure 3 As shown in the figure, it can be seen that the compressive strength and impact toughness of the hob cutter ring of this embodiment are both low. This is because the high-toughness steel preform of this embodiment has only one layer (i.e., one), and the impact absorption work of the blade is insufficient. Therefore, its impact toughness is significantly lower than that of Example 1, and the impact toughness is only 5 J / cm 2 .

[0096] Example 4

[0097] This embodiment provides a method for preparing a hob cutter ring, which specifically includes the following steps:

[0098] Step 1) smelting 20 steel to obtain 20 steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a shell of the blade portion of a hob cutter ring, and obtaining a preform after cooling;

[0099] Wherein, in terms of mass percentage, the composition of 20 steel includes: C: 0.2wt%, Si: 0.25wt%, Mn: 0.55wt%, S: 0.02wt%, P: 0.02wt%, Cr: 0.1wt%, Ni: 0.1wt%, Cu: 0.15wt%, and the balance is Fe; the thickness of the preform is 6mm; the height of the preform varies with the blade size of the hob cutter ring; the pore diameter of the grid structure is 18mm;

[0100] Step 2) Fix the blade of the hob cutter ring mold with three preforms parallel to the blade direction, and heat the hob cutter ring mold to 150° C., preheat for 1 hour, and then pour the molten metal of high hardness and wear-resistant steel into the hob cutter ring mold by centrifugal casting, so that the molten metal of high hardness and wear-resistant steel fills the root of the hob cutter tool and wraps the preform at the same time, and infiltrates into the grid structure of the preform to obtain a rough hob cutter ring blank;

[0101] Among them, the spacing between two adjacent preforms in the three preforms is 1 / 6 of the width of the blade; in terms of mass percentage, the components of the high-hardness wear-resistant steel include: C: 3.5wt%, V: 9.2wt%, Mo: 3wt%, Si: 1.5wt%, Mn: 0.5wt%, Ni: 2.6wt%, N: 0.1wt%, W: 2.6wt%, Al: 0.8wt%, Co: 1.2wt%, Nb: 0.6wt%, and the balance is Fe; the hardness of the high-hardness wear-resistant steel is HRC68; the alloy content of the high-hardness wear-resistant steel is 35wt%; the temperature of centrifugal casting is 1530°C; the initial centrifugal speed of centrifugal casting is 550r / min, and the final centrifugal speed is 1400r / min;

[0102] Step 3) After the centrifuge is stopped, the rough cutter ring blank is taken out and annealed at 350° C. for 4 hours; then the rough cutter ring blank after annealing is normalized at 1000° C. for 3 hours, and then processed to obtain the cutter ring.

[0103] The compressive strength and impact toughness of the hob cutter ring prepared in this embodiment and in Example 1 are compared. Figure 4 As shown in the figure, since the spacing between two adjacent high-toughness steel preforms in this embodiment is small, the high-toughness steel cannot effectively promote the high-hardness wear-resistant steel to fill the preform, causing its bonding strength to decrease. Therefore, the impact toughness and compressive strength of the hob cutter ring in this embodiment are both low, with a compressive strength of only 2200MPa and an impact toughness of only 4J / cm 2 .

[0104] Example 5

[0105] This embodiment provides a method for preparing a hob cutter ring, which specifically includes the following steps:

[0106] Step 1) smelting 20 steel to obtain 20 steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a shell of the blade portion of a hob cutter ring, and obtaining a preform after cooling;

[0107] Wherein, in terms of mass percentage, the composition of 20 steel includes: C: 0.2wt%, Si: 0.25wt%, Mn: 0.55wt%, S: 0.02wt%, P: 0.02wt%, Cr: 0.1wt%, Ni: 0.1wt%, Cu: 0.15wt%, and the balance is Fe; the thickness of the preform is 2mm; the height of the preform varies with the blade size of the hob cutter ring; the pore diameter of the grid structure is 18mm;

[0108] Step 2) Fix the blade of the hob cutter ring mold with three preforms parallel to the blade direction, and heat the hob cutter ring mold to 150° C., preheat for 1 hour, and then pour the molten metal of high hardness and wear-resistant steel into the hob cutter ring mold by centrifugal casting, so that the molten metal of high hardness and wear-resistant steel fills the root of the hob cutter tool and wraps the preform at the same time, and infiltrates into the grid structure of the preform to obtain a rough hob cutter ring blank;

[0109] Among them, the spacing between two adjacent preforms in the three preforms is 1 / 4 of the width of the blade; in terms of mass percentage, the components of the high-hardness wear-resistant steel include: C: 3.5wt%, V: 9.2wt%, Mo: 3wt%, Si: 1.5wt%, Mn: 0.5wt%, Ni: 2.6wt%, N: 0.1wt%, W: 2.6wt%, Al: 0.8wt%, Co: 1.2wt%, Nb: 0.6wt%, and the balance is Fe; the hardness of the high-hardness wear-resistant steel is HRC69; the alloy content of the high-hardness wear-resistant steel is 35wt%; the temperature of centrifugal casting is 1530°C; the initial centrifugal speed of centrifugal casting is 550r / min, and the final centrifugal speed is 1400r / min;

[0110] Step 3) After the centrifuge is stopped, the rough cutter ring blank is taken out and annealed at 350° C. for 4 hours; then the rough cutter ring blank after annealing is normalized at 1000° C. for 3 hours, and then processed to obtain the cutter ring.

[0111] Comparison of the impact toughness and wear resistance of the hob cutter rings prepared in this embodiment and in Example 1 Figure 5 As shown, since the thickness of the high-toughness steel preform in this embodiment is relatively small, the high-toughness steel is severely burned when casting the high-hardness wear-resistant steel (centrifugal casting), and a stable toughness skeleton cannot be formed. At the same time, the high-toughness steel preform is melted into the high-hardness wear-resistant steel, resulting in its component segregation, coarsening of the structure, and reducing its compressive strength and wear resistance.

[0112] Example 6

[0113] This embodiment provides a method for preparing a hob cutter ring, which specifically includes the following steps:

[0114] Step 1) smelting 20 steel to obtain 20 steel melt, then injecting the high-toughness steel melt into a ceramic mold having a grid structure and being in the shape of a shell of the blade portion of a hob cutter ring, and obtaining a preform after cooling;

[0115] Wherein, in terms of mass percentage, the composition of 20 steel includes: C: 0.2wt%, Si: 0.25wt%, Mn: 0.55wt%, S: 0.02wt%, P: 0.02wt%, Cr: 0.1wt%, Ni: 0.1wt%, Cu: 0.15wt%, and the balance is Fe; the thickness of the preform is 6mm; the height of the preform varies with the blade size of the hob cutter ring; the pore diameter of the grid structure is 18mm;

[0116] Step 2) Fix the blade of the hob cutter ring mold with three preforms parallel to the blade direction, and heat the hob cutter ring mold to 150° C., preheat for 1 hour, and then pour the molten metal of high hardness and wear-resistant steel into the hob cutter ring mold by centrifugal casting, so that the molten metal of high hardness and wear-resistant steel fills the root of the hob cutter tool and wraps the preform at the same time, and infiltrates into the grid structure of the preform to obtain a rough hob cutter ring blank;

[0117] Among them, the spacing between two adjacent preforms in the three preforms is 1 / 4 of the width of the blade; in terms of mass percentage, the components of the high-hardness wear-resistant steel include: C: 3.5wt%, V: 9.2wt%, Mo: 3wt%, Si: 1.5wt%, Mn: 0.5wt%, Ni: 2.6wt%, N: 0.1wt%, W: 2.6wt%, Al: 0.8wt%, Co: 1.2wt%, Nb: 0.6wt%, and the balance is Fe; the hardness of the high-hardness wear-resistant steel is HRC69; the alloy content of the high-hardness wear-resistant steel is 35wt%; the temperature of centrifugal casting is 1530°C; the initial centrifugal speed of centrifugal casting is 450r / min, and the final centrifugal speed is 1000r / min;

[0118] Step 3) After the centrifuge is stopped, the rough cutter ring blank is taken out and annealed at 350° C. for 4 hours; then the rough cutter ring blank after annealing is normalized at 1000° C. for 3 hours, and then processed to obtain the cutter ring.

[0119] The organizational morphology of the hob cutter ring prepared in this embodiment is as follows Figure 6 As shown, it can be seen that cracks and holes appear at the junction of high-toughness steel and high-hardness wear-resistant steel; the wear resistance of the hob cutter ring prepared in this embodiment is compared with that prepared in Example 1. Figure 7As shown, due to the slow rotation speed of centrifugal casting in this embodiment, a large number of defects such as voids exist in the high-hardness wear-resistant steel. At the same time, insufficient molten liquid flow will also lead to a decrease in the bonding strength between high-hardness wear-resistant steel and high-toughness steel. Therefore, the wear resistance of the hob cutter ring is significantly reduced.

[0120] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a hob cutter ring, characterized in that: The following steps are involved: Step 1) preparing a preform, wherein the preform is a high-toughness steel preform with a grid structure; Step 2) placing the preform on the blade of a hob cutter ring mold, and then pouring molten metal of high-hardness wear-resistant steel into the hob cutter ring mold, so that the molten metal of high-hardness wear-resistant steel fills the root of the hob cutter tool, wraps the preform, and infiltrates into the grid structure of the preform, to obtain a rough hob cutter ring blank; Step 3) heat treating and processing the rough cutter ring blank to obtain the cutter ring.

2. The method for preparing a hob cutter ring according to claim 1, characterized in that: In the step 1): The preparation steps of the preform include: melting high-toughness steel to obtain high-toughness steel melt, then injecting the high-toughness steel melt into a mold, and obtaining the preform after cooling; preferably, the mold is a ring-shaped ceramic mold with a grid structure; and / or The preform is a cylindrical steel mesh; and / or The high-toughness steel has a room temperature impact toughness greater than 10 J / cm 2 Pearlite / ferrite dual phase steel; and / or The high-toughness steel is one or more of 20 steel, 42CrMo steel, 35CrMo steel, 4Cr5MoSiV steel or 40CrNiMo steel.

3. The method for preparing a hob cutter ring according to claim 1, characterized in that: In the step 2), placing the preform on the blade portion of the hob cutter ring mold comprises: Placing two or three of the preforms on the cutting edge of a hob cutter ring mold in parallel to the cutting edge direction; Preferably, the distance between two adjacent preforms among the two or three preforms is 1 / 5 to 1 / 3 of the width of the blade.

4. The method for preparing a hob cutter ring according to any one of claims 1 to 3, characterized in that: The thickness of the preform is 5 to 8 mm; and / or The pore diameter of the grid structure is 15 to 20 mm.

5. The method for preparing a hob cutter ring according to claim 1, characterized in that: In the step 2), before pouring the molten metal of hard wear-resistant steel into the hob cutter ring mold, the method further includes: The temperature of the hob cutter ring mold is raised to 100-250° C. and preheated for 1-2 hours.

6. The method for preparing a hob cutter ring according to claim 1, characterized in that: In the step 2), the hardness of the high-hardness wear-resistant steel is HRC68 or above; and / or The carbon content of the high-hardness wear-resistant steel is 3-4.5wt%; and / or The alloy content of high hardness and wear-resistant steel is 30-40wt%.

7. The method for preparing a hob cutter ring according to any one of claims 1 to 6, characterized in that: In the step 2), the molten metal of hard wear-resistant steel is poured into the hob cutter ring mold by centrifugal casting; Preferably, the centrifugal casting temperature is 1520-1550°C; Preferably, the initial centrifugal speed of centrifugal casting is 550-700 r / min, and the final centrifugal speed is 1300-1500 r / min.

8. The method for preparing a hob cutter ring according to claim 1, characterized in that: In the step 3), the heat treatment includes: sequentially performing annealing treatment and normalizing treatment on the rough cutter ring blank; The annealing treatment includes: heating the rough cutter ring blank to 300-500° C. and then keeping the temperature for 3-5 hours; The normalizing treatment includes: heating the annealed hob cutter ring to 1000-1100°C and then keeping it warm for 2.5-3.5 hours.

9. A hob cutter ring, characterized in that: The hob cutter ring includes a blade portion and a blade root portion, the blade root portion is a base area, and the blade portion is a composite area; The matrix area is high-hardness wear-resistant steel, and the microstructure of the matrix area includes martensite, austenite and carbide; the carbide includes VC and M7C3; the volume fraction of martensite is 40-50%, the volume fraction of austenite is 7-10%, the volume fraction of VC is 20-30%, and the volume fraction of M7C3 is 15-20%; The composite zone is a composite zone formed by high-toughness steel and high-hardness wear-resistant steel; wherein the high-toughness steel is a high-toughness steel preform with a grid structure; the microstructure of the composite zone includes pearlite, ferrite and carbide; wherein the grain size of the pearlite is 0.5 to 1.0 μm; the grain size of the ferrite is 0.5 to 1.0 μm.

10. The rolling cutter ring according to claim 9, characterized in that: The hardness of the hob cutter ring is 68-70HRC; the impact toughness is 7-10J / cm 2 ;Compressive strength 2760~2780MPa; Preferably, the hob cutter ring is obtained by the preparation method described in any one of claims 1 to 8.

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