A kind of knife shaft quenching method and quenching device

Abstract

The present invention relates to the technical field of induction quenching, and in particular to a quenching method and a quenching device for a knife shaft, wherein the quenching method comprises the following steps: step S1: grinding the inner wall of the groove and the hole; step S2: filling the groove and the hole with conductive clay; step S3: drying and shaping; step S4: induction quenching; step S5: removing the conductive clay, wherein the raw materials of the conductive clay include kaolin, metal powder, water, stainless steel chopped fibers and graphite, and the resistivity of the conductive clay is less than or equal to 0.1Ω·m, and the thermal conductivity is greater than or equal to 2W / m·K. The process of the present invention is simple and easy to operate, does not require covering holes or grooves, reduces the generation of quenching cracks, and can ensure that the sharp corners of the edges of the grooves or holes are well treated, thereby ensuring the quenching effect.

Description

Technical Field

[0001] The invention relates to the technical field of induction quenching, and in particular to a knife shaft quenching method and a quenching device. Background Art

[0002] The material of the knife shaft is mainly 42CrMo. The surface of the knife shaft is required to have high hardness and high wear resistance. The hardness needs to reach 55HRC. It is usually quenched by continuous scanning with a circular sensor. The shaft body usually has an oil groove, an oil filling hole and a shoulder flange. The oil groove, the oil filling hole and the shoulder flange edge form a sharp angle of about 90°. Due to the sharp angle effect of induction heating, the temperature here rises too quickly, which is prone to overheating and causes cracking after quenching.

[0003] In the 2003 issue of Mechanical Worker, Qin Xinhong et al. recorded in "Experiences in Preventing Cracks from Induction Quenching of Grooves" that using copper keys or asbestos ropes to plug grooves can prevent induction quenching cracks in parts with grooves; and the patent document with application number 201610699939.0 discloses a method for preventing quenching cracks in the tool shaft, which mainly involves coating aluminate cement in the keyway of the tool shaft to cover the sharp corners, preventing the quenching liquid from cooling the sharp corners during the water injection process, and effectively reducing the cooling rate of the sharp corners.

[0004] The above methods can weaken the cooling section of induction quenching to reduce the probability of induction cracks, but this also results in the oil groove, oil filling hole and shoulder flange hole edge not being quenched, and good heat treatment cannot be achieved. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a tool shaft quenching method and a quenching device, which can reduce the generation of quenching cracks and ensure that the sharp corners of the groove or hole edge are better processed.

[0006] The technical solution adopted by this application to solve this technical problem is:

[0007] A knife shaft quenching method comprises the following steps:

[0008] Step S1: grinding the groove of the cutter shaft and the inner wall of the hole;

[0009] Step S2: Fill the grooves and holes with conductive glue;

[0010] Step S3: drying and shaping;

[0011] Step S4: using a high-frequency quenching device to perform induction quenching on the knife shaft;

[0012] The raw materials of the conductive mortar include kaolin, metal powder, water, stainless steel chopped fibers and graphite. The resistivity of the conductive mortar is less than or equal to 0.1Ω·m, and the thermal conductivity is greater than or equal to 2W / m·K.

[0013] After the conductive glue is filled, induced current and heat can be generated in the induction coil, sharing the current at the sharp corners of the grooves and holes, making the current distribution relatively dispersed instead of concentrated at the sharp corners, reducing the sharp corner effect, and preventing the quenching liquid from accumulating when the quenching liquid is sprayed. The temperature at the sharp corner is lowered to be close to other positions, and the temperature difference between the sharp corner and other parts is small, that is, the sharp corner is also quenched normally.

[0014] Furthermore, in step S2, the mass ratio of kaolin, metal powder, water, stainless steel chopped fibers and graphite is (40-46): (25-30): (14-19): (5-10): (5-8), wherein 0.1% carboxymethyl cellulose is dissolved in water, and the conductive putty is in a paste or wet soil state.

[0015] The conductive glue in the technical solution has a certain resistivity and magnetic permeability, and can generate an induced current when induction heating is performed in the induction coil, thereby eliminating the sharp corner effect during the quenching process.

[0016] Furthermore, in the step S2, the conductive glue is completely filled in the grooves and holes or at least filled to 10 mm, taking the cylindrical surface where the outer wall of the knife shaft is located as a reference.

[0017] Furthermore, in the step S3, the shaping is to polish the surface of the conductive adhesive so that it is on the same cylindrical surface as the outer wall of the blade shaft.

[0018] Furthermore, in step S4, the cooling rate during quenching is 55-60°C / s.

[0019] The above method has a very outstanding effect on grooves and holes, but it is subject to certain limitations when quenching protruding ridges such as shoulders on shafts. Because when applying conductive putty on the shoulders and then reshaping them, the conductive putty needs to be reshaped to a specific shape and be uniform. It is difficult to control the protruding parts using manual operation. Although mechanical operation can achieve a certain effect of covering the shoulders and reducing cooling, it cannot achieve the same effect of eliminating sharp corners as for grooves and holes, nor can it achieve the same quenching effect. Therefore, the above method has relatively poor effect on protruding shoulders. In order to achieve the quenching effect on the shoulders and not be affected by the sharp corner effect, the quenching equipment needs to be improved.

[0020] A tool shaft quenching device comprises a quenching machine and an induction heater, wherein the quenching machine has a quenching liquid tank, the induction heater has an induction coil, the induction coil is located in the upper part of the quenching liquid tank, and also comprises an adjustment mechanism;

[0021] The regulating mechanism comprises:

[0022] A plurality of magnetizers, each of which is a tubular body with a "C"-shaped cross section and a side opening, and each of which is spaced apart and sleeved on the induction coil, and each of which is provided with an adjustment rod;

[0023] An adjusting ring, wherein a plurality of slidable joint balls are arranged on the adjusting ring, the plurality of joint balls correspond to the adjusting rods one by one, and each of the joint balls is sleeved on the corresponding adjusting rod;

[0024] The lifting control mechanism comprises a connecting rod and a lifter, wherein the connecting rod is connected to an adjusting ring, and the output end of the lifter is connected to the connecting rod. When the output end of the lifter is lifted up and down, the adjusting ring drives the magnetic conductor to rotate on the induction coil.

[0025] The magnetizer is rotatable, and under the regulation of the lifting control mechanism, the magnetizer can limit and regulate the distribution state of the magnetic flux lines, so that the induced current at the shaft shoulder is concentrated on the cylindrical surface of the shaft and the annular surface of the shaft shoulder.

[0026] Furthermore, the magnetic conductor is a columnar body formed by stacking a plurality of “C”-shaped ferromagnetic materials.

[0027] Furthermore, the central angle of the "C"-shaped opening of the magnetic conductor is 40°-60°.

[0028] Furthermore, the sum of the arc lengths of the plurality of magnetic conductors on the induction coil is equal to half the length of the induction coil.

[0029] Furthermore, an insulating layer is provided outside the magnetic conductor, and a high temperature resistant material with capillary pores is provided outside the insulating layer, which has the effect of cooling the silicon steel sheet.

[0030] Specifically, the high temperature resistant material with capillary pores is asbestos cloth.

[0031] Furthermore, the magnetic conductor is composed of a plurality of stacked silicon steel sheets, and each of the silicon steel sheets has an insulating layer outside.

[0032] Beneficial Effects

[0033] 1. The present invention uses conductive glue to fill the grooves and holes, thereby eliminating the sharp corner effect after the conductive glue fills the grooves and holes. At the same time, because the edges of the grooves and holes are not covered, a normal quenching state can be obtained there.

[0034] 2. The present invention improves the quenching device to make its magnetic field distribution adjustable and the current position adjustable, which is beneficial to the induction heating of the shaft shoulder and can also eliminate the sharp corner effect to a certain extent. The knife shaft quenching device of the present invention can complete the quenching of the knife shaft at one time with the conductive clay, and the sharp corners of the oil groove, oil filling hole and shoulder flange can also obtain better quenching effect.

[0035] 3. The adjustment mechanism of the present invention has a special structure, which facilitates the adjustment and use of the magnetic conductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of a knife shaft quenching device of the present invention;

[0037] Figure 2 It is a schematic diagram of the positional relationship between the adjustment mechanism and the induction coil of the present invention;

[0038] Figure 3 It is a front view of the adjustment mechanism and the induction coil of the present invention;

[0039] Figure 4 The present invention Figure 2 A magnified view of part A;

[0040] Figure 5 It is a schematic diagram of the connection between the magnetic conductor, the connecting rod and the joint ball of the present invention;

[0041] Figure 6 yes Figure 5 B-B sectional view;

[0042] Figure 7 It is a diagram showing the quenching state of the shoulder of the knife shaft of the present invention.

[0043] The numbers in the attached drawings are: 1. conductive clay; 2. quenching machine; 3. induction heater; 4. clamping end; 5. driving mechanism; 6. quenching liquid tank; 7. induction coil; 8. water spray ring; 9. water pipe; 10. water spray hole; 11. magnetic conductor; 12. adjusting rod; 13. adjusting ring; 14. joint ball; 15. filling material; 16. connecting rod; 17. lifter; 18. insulating layer; 19. high temperature resistant material with capillary pores. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] A knife shaft quenching method comprises the following steps:

[0046] Step S1: grinding the groove of the cutter shaft and the inner wall of the hole;

[0047] Step S2: Use the conductive glue 1 to fill the grooves and holes and compact them;

[0048] Step S3: drying in an incubator at 70°C, and grinding with 120-200 grit sandpaper until the conductive glue and the cylindrical surface are on the same surface;

[0049] Step S4: using a high-frequency quenching device to perform induction quenching on the knife shaft;

[0050] Step S5: using a wire brush to remove the conductive glue 1;

[0051] Among them, the raw materials of the conductive mud 1 include kaolin, metal powder, water, stainless steel chopped fibers and graphite. The main components in the conductive mud are not sintered during the quenching process. The resistivity of the conductive mud 1 is less than or equal to 0.1Ω·m, and the thermal conductivity is greater than or equal to 2W / m·K.

[0052] The present invention uses conductive glue 1 as a filler to fill the grooves and holes. Because it has a conductive effect, current and heat will be generated inside it during induction heating, which reduces the sharp corner effect of the grooves and hole edges. The grooves and hole edges will not be overburned due to current accumulation. At the same time, because the conductive glue 1 fills the grooves and holes, the quenching liquid is avoided from being retained here, and an excessively fast cooling rate will not be generated, thereby reducing the generation of quenching cracks. In addition, the edges of the grooves and sharp corners can also be quenched instead of being covered like the prior art, which can ensure that the sharp corners of the grooves or hole edges are better quenched.

[0053] In step S2, the mass ratio of kaolin, metal powder, water, stainless steel chopped fibers and graphite is (40-46): (25-30): (14-19): (5-10): (5-8), wherein 0.1% carboxymethyl cellulose is dissolved in water, and the conductive putty is in a paste or wet soil state.

[0054] The kaolin and metal powder are ground to a particle size of less than or equal to 200 meshes, the metal powder includes but is not limited to copper powder, iron powder and zinc powder, preferably iron powder, and the length of the stainless steel chopped fibers is 0.5-1.5 mm.

[0055] Kaolin mainly plays a filling and bonding role. In the short time of induction quenching process, kaolin will not be sintered, which is convenient for cleaning. It can be cleaned with a wire brush. The addition of iron powder can make the conductive putty have a certain conductive effect on the one hand, and on the other hand, it can also make the conductive putty have a certain paramagnetism, so that after the conductive putty is filled, it can generate induced current during induction heating and eliminate the sharp corners of grooves and holes. Stainless steel chopped fibers can improve the electrical conductivity and thermal conductivity on the one hand, and increase the adhesion of the conductive putty on the other hand. Graphite has excellent thermal conductivity and thermal conductivity.

[0056] The above formula can change the resistivity of the conductive paste by adjusting the proportion of each component.

[0057] The production method of conductive glue is as follows:

[0058] In the first step, water and kaolin are mixed into a slurry;

[0059] In the second step, graphite and metal powder are added to the slurry in the first step to mix into a paste;

[0060] The third step is to add stainless steel chopped fibers into the paste of the second step to obtain a premix;

[0061] The fourth step is to use a mixing device to homogenize the premixed material in the third step.

[0062] To avoid overburning due to insufficient filling depth, in step S2, based on the cylindrical surface where the outer wall of the knife shaft is located, the conductive glue should be completely filled in the grooves and holes or at least filled by 10 mm, that is, the filling depth is greater than the quenching depth.

[0063] In step S3, during the shaping, in order to eliminate sharp corners, the conductive putty cannot produce a depression lower than the cylindrical surface of the knife shaft, but in order to avoid contact between the conductive putty and the induction coil, the conductive putty cannot protrude from the cylindrical surface of the knife shaft. Therefore, it is most appropriate to use it on the same cylindrical surface. The grinding sandpaper mesh number is 120-200 to avoid more prominent scratches.

[0064] In step S4, the cooling rate during quenching is 55-60°C / s.

[0065] Embodiment 1:

[0066] The conductive glue comprises, by mass percentage, 43 parts of kaolin, 25 parts of iron powder, 7 parts of stainless steel chopped fibers, 7 parts of graphite, and 18 parts of water, wherein 0.1% of carboxymethyl cellulose is dissolved in the water.

[0067] Embodiment 2:

[0068] The conductive glue comprises, by mass percentage, 46 parts of kaolin, 27 parts of iron powder, 6 parts of stainless steel chopped fibers, 5 parts of graphite, and 16 parts of water, wherein 0.1% of carboxymethyl cellulose is dissolved in the water.

[0069] Embodiment three:

[0070] The conductive glue comprises, by mass percentage, 40 parts of kaolin, 30 parts of iron powder, 10 parts of stainless steel chopped fibers, 5 parts of graphite, and 15 parts of water, wherein 0.1% of carboxymethyl cellulose is dissolved in the water.

[0071] Embodiment 4:

[0072] The conductive glue comprises, by mass percentage, 40 parts of kaolin, 30 parts of iron powder, 8 parts of stainless steel chopped fibers, 8 parts of graphite, and 14 parts of water, wherein 0.1% of carboxymethyl cellulose is dissolved in the water.

[0073] Embodiment five:

[0074] The conductive glue comprises, by mass percentage, 45 parts of kaolin, 25 parts of iron powder, 5 parts of stainless steel chopped fibers, 6 parts of graphite, and 19 parts of water, wherein 0.1% of carboxymethyl cellulose is dissolved in the water.

[0075] The above five embodiments were made into conductive pastes, pressed into blocks with a flat tool at room temperature, dried and shaped into cubes with a side length of 1 cm and rods with a length of 120 mm and a diameter of 5 mm. Performance tests were performed according to the national standard GB / T351-2019 for the measurement of resistivity of metal materials and the GB / T3651-2008 for the measurement of thermal conductivity of metals at high temperatures. The results are as follows:

[0076] Table 1: Test results of conductive paste prepared in various embodiments

[0077]

[0078] The conductive glue obtained in the above embodiments was used to fill the grooves and holes of the knife shaft respectively. The knife shaft filled in each embodiment was dried in an insulation box at 60-70°C for 2h. After drying, 10 knife shafts without processing defects were selected in the embodiment, and quenched after shaping. The quenching parameters were the same. One knife shaft in each embodiment one and five was cracked, and both were cracked in the holes, and the grooves were not cracked. The knife shafts in the other embodiments were not cracked.

[0079] In the prior art, when the grooves and holes are directly quenched without any measures, the cracking ratio is about 30%. When the grooves are plugged with copper keys or copper tubes, basically no quenching cracking can be achieved. However, the copper tubes or copper keys are easily deformed after quenching and are not easy to remove. After removal, the copper tubes or copper keys are easily scrapped, and the one-time cost is high. Asbestos ropes are relatively easy to fill and remove, but asbestos ropes cannot eliminate the problem of sharp corners being easy to overheat. Asbestos ropes have capillaries that are easy to absorb water, causing water to accumulate in the capillaries. During quenching and cooling, when the quenching liquid spray has moved to another position, the accumulated quenching liquid still has a strong cooling effect on the grooves or holes, resulting in large internal stress, and the grooves and holes are easy to deform. In the prior art, when copper tubes or copper keys are used for filling, the holes or grooves need to be protruded, which are easy to contact with the induction coil, resulting in a short circuit. In order to prevent the short circuit problem, the induction coil needs to increase its diameter, and the heating efficiency is low. The present invention has a better quenching effect because the conductive glue does not protrude and will not contact the induction coil.

[0080] Although the conductive putty of the present invention has a certain gap in performance with that of steel in terms of electrical conductivity and thermal conductivity, it can eliminate current accumulation at sharp corners to a certain extent, and reduce the generation of internal stress without affecting the cooling rate. Therefore, the above method has a very outstanding effect on grooves and holes. However, it is not convenient for protruding ridges such as shoulders, because when the conductive putty is applied to the shoulder and then reshaped, the conductive putty needs to be reshaped to a specific shape and be uniform. It is difficult to control the protruding parts by manual operation. Although mechanical operation can achieve a certain coverage of the shoulder and reduce cooling effects, it cannot eliminate sharp corners and achieve the quenching effect of general cylindrical surfaces like grooves and holes. Therefore, the above method is not applicable to protruding shoulders. In order to enable the shoulder to achieve the quenching effect and not be affected by the sharp corner effect, the quenching equipment needs to be improved.

[0081] like Figure 1 and Figure 2 As shown, a tool shaft quenching device includes a quenching machine 2 and an induction heater 3. The quenching machine 2 has a clamping end 4, and a driving mechanism 5 is connected to the clamping end 4 for clamping the tool shaft and rotating it up and down. The induction heater 3 is used to induction heat the surface of the tool shaft. The quenching machine 2 has a quenching liquid tank 6. The induction heater 3 has an induction coil 7 and a water spray ring 8. The water spray ring 8 is located above the induction coil 7. The water spray ring 8 is connected to a plurality of water pipes 9. The peripheral wall of the water spray ring 8 is arranged with annular water spray holes 10. The induction coil 7 is located on the upper part of the quenching liquid tank 6. The cross section of the induction coil 7 is circular. An adjusting mechanism is also included.

[0082] like Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the regulating mechanism includes:

[0083] A plurality of magnetizers 11 are provided, each of which is a tubular body with a "C"-shaped cross section and a side opening. The plurality of magnetizers 11 are sleeved on the induction coil 7 at intervals, and each of the magnetizers 11 is provided with an adjusting rod 12;

[0084] An adjusting ring 13, on which a plurality of slidable joint balls 14 are arranged, and the plurality of joint balls 14 are arranged at intervals. For positioning, a filling material 15 is provided between each two adjacent joint balls 14. The filling material 15 is a material filled in the adjusting ring 13, located between two adjacent joint balls 14, and having a certain strength, and is mainly used to limit the movement of the joint balls 14, including but not limited to arc-shaped columnar metal materials, concrete or ceramic materials that can solidify (solidify) after filling. The plurality of joint balls 14 correspond to the adjusting rods 12 one by one, and each joint ball 14 is sleeved on the corresponding adjusting rod 12;

[0085] The lifting control mechanism includes a connecting rod 16 and a lifter 17. The connecting rod 16 is connected to the adjusting ring 13. The output end of the lifter 17 is connected to the connecting rod 16. When the output end of the lifter 17 is lifted up and down, the adjusting ring 13 drives the magnet 11 to rotate on the induction coil. The rotation guides the magnet 11 to rotate around the copper conductor tube forming the induction coil 7.

[0086] The magnetic conductor 11 is one of the frequently used matching parts of the induction coil 7. Its main function is to concentrate the current on the induction coil 7 at a specific position. For example, when heating the inner hole, the magnetic conductor 11 is used to concentrate the current more on the outer side of the induction coil 7, so that it is closer to the inner wall of the inner hole, thereby improving the heating efficiency. In the present invention, the magnetic conductor 11 is used to limit the distribution of magnetic lines of force and change the position of high-frequency current. When heating the shaft shoulder and the cylindrical surface of the shaft, the magnetic conductor 11 is used to be rotatable on the induction coil to achieve the effect of changing the current position and adjusting the distribution of magnetic lines of force. This effect can make the induced current concentrate on the connection between the shaft shoulder and the cylindrical surface of the shaft when the induction coil 7 is located near the shaft shoulder, such as Figure 7 As shown, the current at the position of the magnetizer 11 on the induction coil 7 is close to the opening of the magnetizer 11, and the magnetic flux lines are also denser here. The opening is toward the connection between the shoulder and the cylindrical surface of the knife shaft, and the heating efficiency of this connection is improved. At the same time, the opening of the magnetizer 11 is not toward the sharp corner of the shoulder. Due to the limitation of the magnetizer 11, the current is less near the surface of the shoulder, and the magnetic flux lines are less distributed, which avoids overheating due to current accumulation at the sharp corner, weakens the sharp corner effect of the shoulder, and achieves a certain quenching effect.

[0087] The magnetic conductor 11 is a columnar body formed by stacking “C”-shaped ferromagnetic materials.

[0088] The central angle of the "C"-shaped opening of the magnetic conductor 11 is 40°-60°, which can better limit the current flow position and the magnetic field direction.

[0089] The sum of the arc lengths of the plurality of magnetic conductors 11 on the induction coil is equal to half the length of the induction coil 7 applied to the induction heating portion.

[0090] like Figure 6 The shown magnetic conductor 11 is provided with an insulating layer 18 outside, and a high temperature resistant material 19 with capillary pores is provided outside the insulating layer 18. Specifically, the high temperature resistant material 19 with capillary pores is asbestos cloth.

[0091] The magnetic conductor 11 is composed of a plurality of stacked silicon steel sheets, each of which has an insulating layer 18 on the outside. The edges of the silicon steel sheets are connected to asbestos cloth, which is made into a tubular body. The silicon steel sheets are connected to the inner wall of the tubular body made of asbestos cloth at intervals. When the magnetic conductor is connected to the induction coil 7, the ends of two adjacent silicon steel sheets close to the central axis of the induction coil are in contact, and one of the silicon steel sheets is connected to the adjusting rod 12.

[0092] When the quenching liquid is sprayed, the asbestos cloth can absorb water through its capillaries, and the water then enters between two adjacent silicon steel sheets, thereby cooling the magnetizer 11 and ensuring that the temperature of the magnetizer 11 does not rise too much.

[0093] The knife shaft quenching device of the present invention basically performs quenching according to the process parameters of the prior art. As for the grooves and holes, since they are filled with conductive glue, there is no need to change the parameter settings. Only the induction heating time at the shaft shoulder needs to be slightly extended.

Claims

1. A knife shaft quenching method, characterized in that: The following steps are involved: Step S1: grinding the groove of the cutter shaft and the inner wall of the hole; Step S2: Fill the groove and the hole with conductive glue (1); Step S3: drying and shaping; Step S4: using a high-frequency quenching device to perform induction quenching on the knife shaft; The raw materials of the conductive mortar (1) are: kaolin, metal powder, water, stainless steel chopped fibers, graphite and carboxymethyl cellulose; the resistivity of the conductive mortar (1) is less than or equal to 0.1Ω·m, and the thermal conductivity is greater than or equal to 2W / m·K; The mass ratio of kaolin, metal powder, water, stainless steel chopped fibers and graphite is (40-46): (25-30): (14-19): (5-10): (5-8), wherein, by mass percentage, 0.1% carboxymethyl cellulose is dissolved in water, and the conductive glue is in a paste or wet mud state; A tool shaft quenching device is also provided, which is applied to the tool shaft quenching method described above, and comprises a quenching machine tool (2) and an induction heater (3), wherein the quenching machine tool (2) has a quenching liquid tank (6), and the induction heater (3) has an induction coil (7), and the induction coil (7) is located on the upper part of the quenching liquid tank (6), and is characterized in that it also comprises an adjustment mechanism, and the adjustment mechanism comprises: A magnetizer (11), wherein there are a plurality of magnetizers (11), each of the plurality of magnetizers (11) is a tubular body with a "C"-shaped cross section and a side opening, the plurality of magnetizers (11) are sleeved on the induction coil (7) at intervals, and each of the magnetizers (11) is provided with an adjustment rod (12); An adjustment ring (13), wherein a plurality of slidable joint balls (14) are provided on the adjustment ring (13), the plurality of joint balls (14) correspond to the adjustment rods (12) one by one, and each of the joint balls (14) is sleeved on a corresponding adjustment rod (12); The lifting control mechanism comprises a connecting rod (16) and a lifter (17), wherein the connecting rod (16) is connected to an adjusting ring (13), and an output end of the lifter (17) is connected to the connecting rod (16). When the output end of the lifter (17) moves up and down, the adjusting ring (13) drives the magnetic conductor (11) to rotate on the induction coil (7).

2. The knife shaft quenching method according to claim 1, characterized in that: In the step S2, the conductive glue is filled in the grooves and holes to a depth of at least 10 mm, taking the cylindrical surface where the outer wall of the knife shaft is located as a reference.

3. The knife shaft quenching method according to claim 1, characterized in that: In the step S4, the cooling rate during quenching is 55°C / s-60°C / s.

4. The knife shaft quenching method according to claim 1, characterized in that: The magnetizer (11) of the knife shaft quenching device is a columnar body formed by stacking a plurality of "C"-shaped ferromagnetic materials, the central angle of the "C"-shaped opening of the magnetizer (11) is 40°-60°, and the sum of the arc lengths occupied by the plurality of magnetizers (11) on the induction coil (7) is equal to half the length of the induction coil (7).

5. The knife shaft quenching method according to claim 1, characterized in that: An insulating layer (18) is provided outside the magnetic conductor (11) of the knife shaft quenching device.

6. The knife shaft quenching method according to claim 5, characterized in that: A high temperature resistant material (19) having capillary pores is provided outside the insulating layer (18) of the knife shaft quenching device.

7. The knife shaft quenching method according to claim 6, characterized in that: The high temperature resistant material (19) having capillary pores is asbestos cloth.

8. The knife shaft quenching method according to claim 5, characterized in that: The magnetic conductor (11) of the blade shaft quenching device is composed of a plurality of stacked silicon steel sheets, and each of the silicon steel sheets has an insulating layer (18) outside.

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