Inductor for heat treatment of large-diameter roller and heat treatment method

Abstract

The invention provides an inductor for large-diameter roller heat treatment and a heat treatment method, and belongs to the technical field of large-diameter roller heat treatment. The inductor comprises two connecting plates and an induction coil which are connected with each other, and the two connecting plates are connected with the power frequency heating device and the frequency heating device respectively. The heat treatment method for the large-diameter roller comprises the following steps: connecting an inductor with a quenching machine tool, and placing the large-diameter roller to be subjected to heat treatment in an induction coil; starting a power frequency heating device to perform diathermanous heating on the large-diameter roller; the medium-frequency heating device is started to heat the large-diameter roller; and the large-diameter roller is immersed in the quenching salt bath to be cooled, and heat treatment of the large-diameter roller is completed. According to the method, diathermanous heating is conducted on the steel plate through the power frequency heating device, then the surface temperature of the steel plate is increased and kept through the intermediate frequency heating device, and finally cooling is conducted through the salt bath to achieve thorough quenching; and the whole heat treatment process is simplified, so that the heat treatment cost of the large-diameter roller is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of large direct roller heat treatment, and relates to an inductor for large diameter roller heat treatment and a heat treatment method. Background Art

[0002] The main bearing of the shield machine bears axial force, radial force and overturning load during the engineering excavation process. Among them, the roller is an important component of the bearing operation, and its mechanical properties are very high. Generally, the surface hardness and the core temperature are greater than 55HRC. Therefore, it is necessary to heat treat the roller to form a martensitic hardened layer to improve the overall hardness and wear resistance. At present, the main heat treatment of the roller is the integral salt tank quenching, that is, the roller raw material is heated to the austenitizing temperature in the heating furnace, and then the whole roller is immersed in the salt tank to cool. It is cooled at a certain speed to form a complete martensitic roller. However, this traditional heat treatment method has a long cycle time, especially the slow heating process of the heating furnace. In addition, the operation is complicated. In order to prevent decarburization on the roller surface during the heating process, a certain atmosphere needs to be maintained in the furnace, involving a series of steps such as gas pipeline control, feeding, and furnace loading. In addition, the entire heating is suitable for mass production, the cost is high, and it is not suitable for processing single parts. Summary of the invention

[0003] The purpose of the present invention is to provide an inductor and a heat treatment method for large diameter rollers, so as to improve the efficiency of the heat treatment method for large rollers, simplify the heat treatment method, and reduce the cost of heat treatment. In order to solve the problems of slow heating speed, complex operation and high cost in traditional integral furnaces.

[0004] The present invention provides an inductor for heat treatment of a large-diameter roller, comprising a connecting plate and an induction coil connected to each other, wherein the connecting plate is connected to a busbar of a quenching machine through a connecting hole, and the induction coil is sleeved on the large-diameter roller;

[0005] The connecting plate is provided with two pieces, one of which is used to be connected with the industrial frequency heating device, and the other connecting plate is used to be connected with the medium frequency heating device.

[0006] Optionally, the induction coil is configured as a spiral structure formed by bending a circular copper tube.

[0007] Optionally, a gap of 2 mm-30 mm is provided between the induction coil and the large-diameter roller.

[0008] Optionally, the two connecting plates are fixedly connected to the two ends of the induction coil by welding.

[0009] In addition to the above structure, the induction coil can also be configured as: including a first coil and a second coil, the first coil and the second coil are both configured as a spiral structure formed by bending a round copper tube, the first coil and the second coil are spirally connected to each other, one connecting plate is connected to the first coil by welding, and the other connecting piece is connected to the second coil by welding.

[0010] Optionally, the first coil is connected to the power frequency heating device, and a gap of 10 mm to 30 mm is provided between the first coil and the large diameter roller;

[0011] The second coil is connected to the medium frequency heating device, and a gap of 2mm-5mm is arranged between the second coil and the large diameter roller.

[0012] The present invention also provides a large diameter roller heat treatment method, comprising the following steps:

[0013] Step 1: Connect the connecting plate in the inductor for heat treatment of large diameter rollers as described above to the quenching machine, and place the large diameter roller to be heat treated in the induction coil;

[0014] Step 2: Start the power frequency heating device to perform heat diathermy heating on the large diameter roller;

[0015] Step 3: Start the medium frequency heating device to heat the large diameter roller, so as to control the surface depth of the large diameter roller to 930°C-970°C;

[0016] Step 4: Maintain the surface temperature of the large diameter roller at 930°C-970°C by immersing it in a quenching salt bath for cooling, and keep the temperature at 100°C-160°C for 20min-30min, and then cool the large diameter roller to room temperature by air cooling to complete the heat treatment of the large diameter roller.

[0017] Optionally, when the large diameter roller is heated by the industrial frequency heating device, the industrial frequency is set to 40 Hz-60 Hz and the heating temperature is set to 870°C-950°C.

[0018] Optionally, when the large diameter roller is heated by the medium frequency heating device, the medium frequency frequency is set to 1000-2000 Hz.

[0019] Optionally, the quenching salt component in the quenching salt tank is set to nitrate.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention provides an inductor for heat treatment of large diameter rollers, wherein the induction coil is connected to an industrial frequency heating device and an intermediate frequency heating device respectively through two connecting pieces, so that the large diameter roller is heated through the industrial frequency heating device, and the surface of the large diameter roller is heated again and kept warm through the intermediate frequency heating device, so as to achieve through hardening of the large diameter roller.

[0022] (2) The present invention provides a large diameter roller heat treatment method, which first uses an industrial frequency heating device to heat the roller through the heat, then uses a medium frequency heating device to increase the surface temperature and keep it warm, and finally cools it in a salt tank to achieve quenching; the overall heat treatment process is simplified to effectively reduce the heat treatment cost of large diameter rollers.

[0023] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 It is a schematic diagram of the structure of an inductor for heat treatment of a large diameter roller in an embodiment of the present invention.

[0026] in:

[0027] 1. Induction coil, 2. Large diameter roller, 3. Connecting plate. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present invention more clear and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. It should be noted that the drawings of the present invention are all simplified and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the implementation of the present invention; the "number" mentioned in the present invention is not limited to the specific number in the examples in the accompanying drawings; the directions or positional relationships indicated by "front", "middle", "back", "left", "right", "up", "down", "top", "bottom", "middle", etc. mentioned in the present invention are based on the directions or positional relationships shown in the drawings of the present invention, and do not indicate or imply that the devices or components referred to must have a specific direction, nor can they be understood as limitations on the present invention.

[0029] See also Figure 1 As shown, the inductor for heat treatment of large diameter rollers provided by the present invention comprises a connecting plate 3 and an induction coil 1 which are connected to each other. The connecting plate 3 is connected to the bus of the quenching machine through a connecting hole, and the induction coil 1 is sleeved on the large diameter roller 2.

[0030] Preferably, the induction coil 1 is configured to be a spiral structure formed by bending a circular copper tube, and the pitch of the spiral structure is preferably configured to be equal to the diameter of the circular copper tube.

[0031] Further preferably, a gap of 2 mm-30 mm is provided between the induction coil 1 and the large-diameter roller 2 .

[0032] Preferably, the connecting plates 3 are provided with two pieces, and the two connecting plates 3 are respectively fixedly connected to the two ends of the induction coil 1 by welding.

[0033] Further preferably, one of the connecting plates 3 is used to connect to an industrial frequency heating device, and the other connecting plate 3 is used to connect to an intermediate frequency heating device, so as to achieve industrial frequency heating or intermediate frequency heating of the induction coil 1 .

[0034] In addition to the above structure, the induction coil 1 can also be configured as: including a first coil and a second coil, the first coil and the second coil are both configured as a spiral structure formed by bending a round copper tube, the first coil and the second coil are spirally connected to each other, and the two connecting plates 3 are respectively fixedly connected to the first coil and the second coil by welding.

[0035] Preferably, the first coil is connected to the industrial frequency heating device, the second coil is connected to the medium frequency heating device, and a gap of 10mm-30mm is provided between the first coil and the large diameter roller, and a gap of 2mm-5mm is provided between the second coil and the large diameter roller.

[0036] Furthermore, the method for heat treating a large diameter roller using the above-mentioned sensor specifically comprises the following steps:

[0037] Step 1: Connect the connecting plate in the inductor for heat treatment of large diameter rollers as described above to the quenching machine, and place the large diameter roller to be heat treated in the induction coil;

[0038] Step 2: Start the power frequency heating device to perform heat diathermy heating on the large diameter roller;

[0039] Step 3: Start the medium frequency heating device to heat the large diameter roller, so as to control the surface depth of the large diameter roller to 930°C-970°C;

[0040] Step 4: Maintain the surface temperature of the large diameter roller at 930°C-970°C by immersing it in a quenching salt tank for cooling, and keep the temperature at 160°C for 30 minutes, and then cool the large diameter roller to room temperature by air cooling to complete the heat treatment of the large diameter roller.

[0041] Preferably, when the large diameter roller is heated by the industrial frequency heating device, the industrial frequency is set to 40 Hz-60 Hz and the heating temperature is set to 870°C-950°C.

[0042] Preferably, when the large diameter roller is heated by the medium frequency heating device, the medium frequency frequency is set to 1000-2000 Hz.

[0043] Preferably, the quenching salt component in the quenching salt tank is set to nitrate.

[0044] Embodiment 1:

[0045] Assume that the material of the large diameter roller is GCr15SiMn and the diameter is 60;

[0046] The power frequency was set to 55 Hz, the gap between the induction coil and the large diameter roller was set to 15 mm, and the temperature was heated to 890 °C;

[0047] The intermediate frequency was set to 250 Hz, the gap between the induction coil and the large diameter roller was set to 3 mm, and the temperature was heated and kept at 950°C;

[0048] The large diameter roller kept at 950°C is placed in a quenching salt bath and cooled to 160°C for 30 minutes, and then cooled to room temperature by air cooling to achieve through quenching of the large diameter roller.

[0049] Embodiment 2:

[0050] Assume that the material of the large diameter roller is GCr15SiMn and the diameter is 70;

[0051] The power frequency was set to 45 Hz, the gap between the induction coil and the large diameter roller was set to 20 mm, and the temperature was heated to 880°C;

[0052] The intermediate frequency was set to 270 Hz, the gap between the induction coil and the large diameter roller was set to 2.5 mm, and the temperature was heated and kept at 965°C;

[0053] The large diameter roller kept at 965°C is placed in a quenching salt bath and cooled to 155°C for 30 minutes, and then air-cooled to room temperature to achieve through quenching of the large diameter roller.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An inductor for heat treatment of large diameter rollers, characterized in that: It comprises a connecting plate (3) and an induction coil (1) which are connected to each other, wherein the connecting plate (3) is connected to a busbar of a quenching machine tool through a connecting hole, and the induction coil (1) is sleeved on a large-diameter roller (2); The connecting plate (3) is provided in two pieces, wherein one connecting plate (3) is used to be connected to the industrial frequency heating device, and the other connecting plate (3) is used to be connected to the medium frequency heating device.

2. The inductor for heat treatment of large diameter rollers according to claim 1, characterized in that: The induction coil (1) is configured as a spiral structure formed by bending a circular copper tube.

3. The inductor for heat treatment of large diameter rollers according to claim 2, characterized in that: A gap of 2 mm to 30 mm is provided between the induction coil (1) and the large-diameter roller (2).

4. The inductor for heat treatment of large diameter rollers according to claim 3, characterized in that: The two connecting plates (3) are respectively fixedly connected to the two ends of the induction coil (1) by welding.

5. The inductor for heat treatment of large diameter rollers according to claim 1, characterized in that: The induction coil (1) comprises a first coil and a second coil, the first coil and the second coil are both arranged as spiral structures formed by bending a round copper tube, the first coil and the second coil are spirally connected to each other, one connecting plate (3) is connected to the first coil by welding, and the other connecting piece (3) is connected to the second coil by welding.

6. The inductor for heat treatment of large diameter rollers according to claim 5, characterized in that: The first coil is connected to the power frequency heating device, and a gap of 10mm-30mm is provided between the first coil and the large diameter roller; The second coil is connected to the medium frequency heating device, and a gap of 2mm-5mm is arranged between the second coil and the large diameter roller.

7. A large diameter roller heat treatment method, characterized in that: The following steps are involved: Step 1, connecting the connecting plate in the inductor for heat treatment of large diameter rollers as described in any one of claims 1 to 6 to a quenching machine, and placing the large diameter roller to be heat treated in the induction coil; Step 2: Start the power frequency heating device to perform heat diathermy heating on the large diameter roller; Step 3: Start the medium frequency heating device to heat the large diameter roller, so as to control the surface depth of the large diameter roller to 930°C-970°C; Step 4: Maintain the surface temperature of the large diameter roller at 930°C-970°C by immersing it in a quenching salt bath for cooling, and keep the temperature at 100°C-160°C for 20min-30min, and then cool the large diameter roller to room temperature by air cooling to complete the heat treatment of the large diameter roller.

8. The large diameter roller heat treatment method according to claim 7, characterized in that: When the large diameter roller is heated by the industrial frequency heating device, the industrial frequency is set to 40Hz-60Hz and the heating temperature is set to 870℃-950℃.

9. The large diameter roller heat treatment method according to claim 7, characterized in that: When the large diameter roller is heated by the medium frequency heating device, the medium frequency frequency is set to 1000-2000 Hz.

10. The large diameter roller heat treatment method according to claim 8 or 9, characterized in that: The quenching salt component in the quenching salt tank is set to be nitrate.

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