Machining method for floating ring of main bearing of heading machine

Abstract

The invention provides a heading machine main bearing floating ring machining method, and belongs to the technical field of heading machine main bearing machining. Comprising the following steps: roughly turning the floating ring forging; carrying out heat treatment on the floating ring subjected to rough turning; the floating ring subjected to low-temperature tempering treatment is subjected to primary finish turning; carrying out vibration aging treatment on the floating ring; second-time finish turning is conducted; after finish turning of the floating ring is completed, elliptic deformation of the floating ring is corrected in a thermal correction mode; and the floating ring subjected to second-time finish turning is subjected to fine grinding, and machining of the floating ring is completed. The method is mainly characterized in that in the heat treatment process, quenching coupling gaps and quenching parameters are strictly controlled, and the quenching internal stress of the two end faces of the floating ring is balanced; in the machining process, a vibration aging mode is adopted for releasing the machining internal stress of the floating ring, and deformation in the machining process is effectively reduced; aiming at the problem of radial elliptical deformation of the floating ring, a correction method for applying thermal stress is provided for control.

Description

Technical Field

[0001] The invention belongs to the technical field of main bearing processing of a tunnel boring machine, and relates to a method for processing a floating ring of a main bearing of a tunnel boring machine. Background Art

[0002] The main bearing of the tunnel boring machine is the core component of the tunnel boring machine, mainly composed of inner / outer rings, floating rings, and gear rings. The floating ring is the most important component of the main bearing. Both ends need to be quenched. The hardened layer depth is required to be more than 7mm and the hardness is required to be more than 58HRC. The processing and manufacturing are difficult. The processing of the floating ring requires rough turning, quenching, fine turning, grinding and other processes. The larger the diameter, the more difficult it is to control the accuracy and the greater the difficulty of processing and manufacturing. The main problems in the processing and manufacturing of the floating ring are the large warping deformation of the rear end face after quenching, the large radial elliptical deformation, and the large warping deformation caused by stress release during processing. Excessive warping deformation after quenching will make it difficult to ensure the uniformity of the plane accuracy and the depth of the plane hardened layer. After ensuring the plane accuracy, the depth of the hardened layer may not meet the requirements. If the depth of the hardened layer is increased, the risk of quenching deformation and quenching cracking will also increase accordingly, and the processing difficulty will be greater. The large elliptical deformation after quenching will result in no processing allowance for the inner and outer diameters and difficulty in assembly. The large warping deformation caused by stress release during processing will make it impossible to ensure the plane accuracy, workpiece thickness, and hardened layer depth, resulting in the scrapping of the workpiece. Summary of the invention

[0003] In order to effectively release the quenching internal stress of the floating ring of the main bearing of the tunnel boring machine and control the processing accuracy, the present invention proposes a method for controlling the processing deformation of the floating ring of the main bearing of the tunnel boring machine.

[0004] The present invention provides a method for machining a floating ring of a main bearing of a tunnel boring machine, comprising the following steps: Step 1: Rough turning the floating ring forging; Step 2: Heat treat the floating ring after rough turning; the specific process is as follows: S2.1. The floating ring after rough turning is arranged between the first quenching inductor and the second quenching inductor which are arranged in a vertical direction and spaced from each other, and a gap a is set between the first quenching inductor and the upper end surface of the floating ring and between the second quenching inductor and the lower end surface of the floating ring; S2.2, respectively heating the first quenching inductor and the second quenching inductor, and controlling the heating temperature to 800° C.-900° C., so as to perform quenching treatment on the surface of the floating ring after rough turning; S2.3. Within 4 hours after the quenching is completed, the floating ring after quenching is subjected to low temperature tempering treatment; Step 3: Perform the first fine turning on the floating ring after low temperature tempering treatment, so as to remove 0.5mm of the margin on the upper and lower end surfaces of the floating ring and control the machining margin of the inner and outer diameters of the floating ring within 1mm; Step 4: Evenly pad the floating ring after the first fine turning with elastic material between the high support of the machine tool used for fine turning the floating ring, and perform vibration aging treatment on the floating ring; Step 5: Perform a second finish turning on the floating ring after vibration aging treatment; Step 6: After the floating ring is fine-turned, the elliptical deformation of the floating ring is corrected by thermal correction; Step 7: Fine-grind the floating ring after the second fine turning to complete the processing of the floating ring.

[0005] Furthermore, after rough turning the floating ring forging, the rough turning thickness dimension tolerance of the floating ring is controlled within 0.3 mm.

[0006] Furthermore, the setting method of the gap a is: Assuming the thickness of the floating ring after rough turning is h, and the opening width of the quenching sensor is d, then a=(dh) / 2.

[0007] Furthermore, after quenching the upper and lower end faces of the floating ring after rough turning, the radial warping deformation of the floating ring after quenching is controlled within 0.5 mm, and the full circle runout error of the floating ring after quenching is controlled within 0.3 mm.

[0008] Furthermore, when the floating ring after quenching is subjected to low temperature tempering treatment, the tempering temperature is controlled to be 150°C-180°C, the tempering time is controlled to be 5 hours-6 hours, and the heating rate is controlled to be 20°C / hour-25°C / hour.

[0009] Furthermore, when the floating ring is subjected to vibration aging treatment after the first fine turning, the parameters are set as follows: the vibration frequency adopts the resonance frequency, and the vibration time is set to 15min-20min.

[0010] Furthermore, after the floating ring after the vibration aging treatment is subjected to a second fine turning, the deformation of the floating ring is controlled within 0.2 mm.

[0011] Furthermore, the correction process parameters are: heating temperature 250°C-350°C, heating time 3-6s, coupling gap 2-3mm, and no cooling.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention combines previous data and experience to propose a method for machining a floating ring of a main bearing of a tunnel boring machine. The main invention lies in strictly controlling the quenching coupling gap and quenching parameters during the heat treatment process to balance the quenching internal stress of the two end faces of the floating ring; during the machining process, it is proposed to use vibration aging to release the internal stress of the floating ring, thereby effectively reducing the deformation during the machining process; in order to solve the problem of radial elliptical deformation of the floating ring, it is proposed to use a correction method of applying thermal stress to control it.

[0013] (2) The present invention strictly controls the thickness tolerance of the floating ring forging during rough turning, thereby effectively ensuring the gap between the floating ring and the quenching induction device, thereby balancing the internal stresses on the two end faces during the quenching process, effectively adjusting the hardness and strength of the floating ring, and improving the deformation of the floating ring after quenching.

[0014] (3) In order to eliminate the influence of internal stress release on the size and precision of the floating ring during machining, mechanical aging stress relief is used to release the stress inside the floating ring during machining, thereby achieving the purpose of controlling the size and precision stability of the workpiece.

[0015] (4) In order to eliminate the ellipse in the machining process, after the workpiece is finished turning, the elliptical deformation of the workpiece is corrected by thermal correction. A special correction sensor is used on the quenching machine to heat the corresponding position of the inner diameter and apply thermal stress to the workpiece to achieve the purpose of correcting the elliptical deformation of the workpiece.

[0016] 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

[0017] 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: Figure 1 It is a schematic diagram of the quenching induction device and the floating ring connected to each other in an embodiment of the present invention.

[0018] in: 1. First quenching sensor, 2. Floating ring, 3. Second quenching sensor. DETAILED DESCRIPTION

[0019] 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. Example

[0020] A method for machining a floating ring of a main bearing of a tunnel boring machine provided by the present invention comprises the following steps: Step 1: Rough turn the floating ring forging, and control the rough turn thickness tolerance of the floating ring within 0.3mm; Step 2: Heat treat the floating ring after rough turning; the specific process is as follows: S2.1. Set the rough-turned floating ring and the quenching induction device relative to each other with clearance fit; for details, see Figure 1 As shown, a first quenching inductor 1 and a second quenching inductor 3 are respectively arranged at the upper end and the lower end of the floating ring after rough turning, and a gap a is provided between the first quenching inductor 1 and the upper end surface of the floating ring 2 and between the second quenching inductor 3 and the lower end surface of the floating ring 2; S2.2, respectively heat the first quenching inductor and the second quenching inductor, and control the heating temperature to 800°C-900°C, so as to quench the surface of the floating ring after rough turning, and ensure that the hardened layer depth and internal stress of the upper end face and the lower end face of the floating ring after quenching are consistent, so as to balance the internal stress of the floating ring after quenching; S2.3. Within 4 hours after quenching, the floating ring after quenching shall be subjected to low temperature tempering treatment to reduce the internal stress caused by quenching, adjust the hardness and strength of the floating ring, and improve the processing performance of the floating ring; Step 3: Perform the first fine turning process on the floating ring that has been subjected to low temperature tempering treatment, so as to remove 0.5mm of the margin from both the upper and lower end surfaces of the floating ring and control the machining margin of the inner and outer diameters of the floating ring within 1mm; Step 4: Evenly pad elastic materials (such as rubber, pads, rigid springs, etc.) between the floating ring after the first fine turning and the high support of the machine tool used for fine turning the floating ring, and perform vibration aging treatment on the floating ring; Step 5: Perform a second fine turning on the floating ring after vibration aging treatment to remove 0.2mm-0.5mm of the upper end face, lower end face, inner diameter and outer diameter of the floating ring, so as to achieve uniform removal of the machining allowances on the upper end face and lower end face of the floating ring, gradually release the quenching internal stress of the floating ring, and control the deformation of the floating ring within 0.2mm; Step 6. After the floating ring is fine-turned, the elliptical deformation of the floating ring is corrected by thermal correction. A special correction sensor is used on the quenching machine to heat the corresponding position of the inner diameter to apply thermal stress to the floating ring to achieve the purpose of correcting the elliptical deformation of the floating ring. The correction process parameters are: heating temperature of about 300°C, heating time of 3-6s, coupling gap of 2-3mm, and no cooling.

[0021] Step 7. Fine grinding is performed on the floating ring after the second fine turning to remove 0.1-0.3mm of allowance from the upper end face, lower end face, inner diameter and outer diameter of the floating ring, so as to achieve uniform removal of the machining allowance from the upper end face and lower end face of the floating ring, and gradually release the quenching internal stress of the floating ring, so that the shape and position tolerance of the floating ring is controlled within the design requirements, and the processing of the floating ring is completed.

[0022] Furthermore, the setting rules of the gap a between the first quenching sensor and the upper end surface of the floating ring and between the second quenching sensor and the lower end surface of the floating ring are as follows: Assuming the thickness of the floating ring after rough turning is h, and the opening width of the quenching sensor is d, then a=(dh) / 2.

[0023] Furthermore, the gap a between the first quenching sensor and the upper end face of the floating ring and between the second quenching sensor and the lower end face of the floating ring can also be specifically set to 1-1.5mm. Through experiments, when the coupling gap is less than 1mm, there is a risk of the sensor contacting the workpiece and causing a short circuit due to the deformation of the workpiece and the sensor during processing; when the coupling gap is greater than 1.5mm, it is not conducive to the heating of the raceway and has a certain impact on the quenching hardness of the workpiece and the depth of the hardened layer. Therefore, the coupling gap is controlled to 1-1.5mm.

[0024] Furthermore, after quenching the upper and lower end faces of the floating ring after rough turning, the radial warping deformation of the outer surface and the internal structure of the floating ring after quenching is controlled within 0.5mm, and the full circle runout error of the floating ring after quenching is controlled within 0.3mm.

[0025] Furthermore, when the floating ring after quenching is subjected to low temperature tempering, the tempering temperature is controlled to be 150°C-180°C, the tempering time is controlled to be 5 hours-6 hours, and the heating rate is controlled to be 20°C / hour-25°C / hour. Preferably, a tempering furnace is used to perform low temperature tempering on the floating ring after quenching.

[0026] Furthermore, when the floating ring is subjected to vibration aging treatment after the first fine turning, the parameters are set as follows: the vibration frequency adopts the resonance frequency (the workpieces of different sizes are determined according to the vibration aging instrument test), the vibration time is 15min-20min, and the dynamic stress is determined according to the vibration aging instrument test.

[0027] Experimental example:

[0028] Table 1: Deformation of floating ring under different quenching conditions

[0029] As shown in Table 1, the double-end quenching method with strict control of the quenching sensor gap has a good effect on controlling the full circle runout and warping deformation of the workpiece.

[0030] Table 2: Residual stress on workpiece surface under different tempering process conditions

[0031] The residual stress unit in Table 2 is MPa, and the minus sign indicates that the surface residual stress is compressive stress. When the temperature is low and the tempering time is short, the residual stress on the workpiece surface is not eliminated significantly; when the temperature is high and the tempering time is long, the residual stress on the workpiece surface is eliminated better, but the high temperature and long time will have a certain impact on the hardness of the workpiece, and the processing cost is high. Therefore, the tempering temperature of the workpiece is set to 150℃-180℃, and the tempering time is controlled to 5-6h. Under the condition of ensuring the hardness of the workpiece, the residual stress of the workpiece is eliminated and the deformation of the workpiece is controlled.

[0032] Table 3: Workpiece deformation control under different vibration conditions

[0033] As shown in Table 3, after adding vibration aging, the surface stress of the workpiece is reduced, the deformation of the workpiece during processing is small, and the deformation control has a better effect.

[0034] 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. A method for machining a floating ring of a main bearing of a tunnel boring machine, characterized in that: The following steps are involved: Step 1: Rough turning the floating ring forging; Step 2: Heat treat the floating ring after rough turning; the specific process is as follows: S2.

1. The floating ring after rough turning is arranged between the first quenching inductor and the second quenching inductor which are arranged in a vertical direction and spaced from each other, and a gap a is set between the first quenching inductor and the upper end surface of the floating ring and between the second quenching inductor and the lower end surface of the floating ring; S2.2, respectively heating the first quenching inductor and the second quenching inductor, and controlling the heating temperature to 800° C.-900° C., so as to perform quenching treatment on the surface of the floating ring after rough turning; S2.

3. Within 4 hours after the quenching is completed, the floating ring after quenching is subjected to low temperature tempering treatment; Step 3: Perform the first fine turning on the floating ring after low temperature tempering treatment, so as to remove 0.5mm of the margin on the upper and lower end surfaces of the floating ring and control the machining margin of the inner and outer diameters of the floating ring within 1mm; Step 4: Evenly pad the floating ring after the first fine turning with elastic material between the high support of the machine tool used for fine turning the floating ring, and perform vibration aging treatment on the floating ring; Step 5: Perform a second finish turning on the floating ring after vibration aging treatment; Step 6: After the floating ring is fine-turned, the elliptical deformation of the floating ring is corrected by thermal correction; Step 7: Fine-grind the floating ring after the second fine turning to complete the processing of the floating ring.

2. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 1, characterized in that: After rough turning of the floating ring forging, the rough turning thickness dimension tolerance of the floating ring is controlled within 0.3mm.

3. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 1 or 2, characterized in that: The setting method of gap a is: Assuming the thickness of the floating ring after rough turning is h, and the opening width of the quenching sensor is d, then a=(dh) / 2.

4. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 3, characterized in that: After quenching the upper and lower end faces of the floating ring after rough turning, the radial warping deformation of the floating ring after quenching is controlled within 0.5mm, and the full circle runout error of the floating ring after quenching is controlled within 0.3mm.

5. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 4, characterized in that: When the floating ring after quenching is subjected to low temperature tempering treatment, the tempering temperature is controlled to be 150°C-180°C, the tempering time is controlled to be 5 hours-6 hours, and the heating rate is controlled to be 20°C / hour-25°C / hour.

6. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 4 or 5, characterized in that: When the floating ring is subjected to vibration aging treatment after the first fine turning, the parameters are set as follows: the vibration frequency adopts the resonance frequency, and the vibration time is set to 15min-20min.

7. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 6, characterized in that: After the second fine turning of the floating ring after vibration aging treatment, the deformation of the floating ring is controlled within 0.2mm.

8. The method for machining the floating ring of the main bearing of a tunnel boring machine according to claim 7, characterized in that: The correction process parameters are: heating temperature 250℃-350℃, heating time 3-6s, coupling gap 2-3mm, and no cooling.

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