Machining method for controlling deformation of roller neck of slender roller

Abstract

The invention discloses a machining method for controlling deformation of a roller neck of a slender roller. The machining method comprises turning machining and grinding machining. Hardening and tempering and first-time stress relief are further included before turning; secondary stress removal is carried out after turning and before grinding; a clamping mode of clamping and jacking is adopted in turning, a three-jaw self-centering chuck in a machine tool spindle box is used for clamping the left end of the slender roller, the right end of the slender roller is jacked by an elastic live center, and an open steel wire ring is padded between the three-jaw self-centering chuck and the slender roller. According to the machining method, a whole-process standardized machining method including quenching and tempering heat treatment, turning machining, grinding machining and the like is formulated for the slender roller, a method for controlling deformation of the roller neck of the slender roller is formulated for each working procedure, and the problem of deformation of the roller neck of the slender roller caused by factors such as gravity and thermal deformation can be effectively solved by adopting the machining method; the machining quality and the machining efficiency are greatly improved, and the defects of an existing machining technology are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of machining, and in particular relates to a machining method for controlling the deformation of a roll neck of a slender roller. Background Art

[0002] At present, the demand for high-end plates at home and abroad is increasing, especially the precision requirements for the roller neck position as the reference surface are getting higher and higher.

[0003] However, in the process of machining slender rollers (aspect ratio > 11), due to the combined effects of cutting force, gravity and top clamping force, it is easy to cause the roller neck to bend and deform, affecting the dimensional accuracy and surface quality of the product.

[0004] At present, conventional methods to solve the above problems include: increasing machining allowance, tensioning device, center frame support and stress relief, etc.; however, on the one hand, these methods can only alleviate the deformation problem, on the other hand, these methods have low machining efficiency and the effect is not obvious, especially they need to rely on the personal experience of the operator.

[0005] At present, there is no literature report on the standardized processing of slender roller necks.

[0006] Chinese patent document CN102259194A discloses a method for machining a slender shaft, which performs segmented cutting on both ends of the slender shaft, thereby improving the surface machining quality.

[0007] On the one hand, the document only involves turning processing and is still not comprehensive enough; on the other hand, the segmented cutting processing method adopted in the document will produce a large runout tolerance, and multiple segmented grinding processes are required to ensure the processing accuracy. Not only is the processing cycle long, but it also requires high technical capabilities of the operator, which is difficult to meet production requirements. Summary of the invention

[0008] The object of the present invention is to solve the above-mentioned problem and provide a processing method for controlling the deformation of the roll neck of an elongated roller.

[0009] The technical solution to achieve the purpose of the present invention is: a processing method for controlling the deformation of the neck of a slender roller, including turning and grinding; before the turning process, it also includes tempering and the first stress relief; after the turning process and before the grinding process, it also includes a secondary stress relief.

[0010] The tempering is well furnace tempering, and the tempering quenching temperature is 880-920°C; the first stress relief is to use a well furnace to heat to 500-550°C, keep warm for 4-5 hours, and then cool the furnace to below 300°C before taking out of the furnace.

[0011] The turning process adopts a clamping method of one clamp and one push, using a three-jaw self-centering chuck in the machine tool spindle box to clamp the left end of the slender roller, and the right end of the slender roller is supported by an elastic live center, and an open wire ring is inserted between the three-jaw self-centering chuck and the slender roller; during turning, a tool rest is arranged on the opposite side of the turning tool processing position, so that the turning tool and the tool rest move synchronously on the lathe guide rail and press against the outer circle of the roller neck of the slender roller.

[0012] The process parameters of the turning process are as follows: the back cutting depth of rough turning is 1-2mm, the feed rate of rough turning is 0.3-0.4mm / r, and the cutting speed of rough turning is 30-40m / min; the back cutting depth of semi-finishing turning is 0.5-1mm, the feed rate of semi-finishing turning is 0.2-0.3mm / r, and the cutting speed of semi-finishing turning is 30-40m / min.

[0013] The front angle γ of the turning tool is 15°, the main deflection angle Kr is 60-75°, and the positive edge inclination angle λ is 3-10°.

[0014] The secondary stress relief heats the elongated roller to 640-660° C., keeps the temperature for 4-5 hours, then slowly cools it, and then air cools it.

[0015] The process parameters of the grinding process are as follows: the rough grinding cutting depth is 0.008-0.01 mm, the rough grinding longitudinal feed speed is 1.3-1.5 m / min, and the rough grinding slender roller speed is 140-160 r / min; the semi-fine grinding cutting depth is 0.006-0.008 mm, the semi-fine grinding longitudinal feed speed is 1.0-1.5 m / min, and the semi-fine grinding slender roller speed is 120-140 r / min; the fine grinding cutting depth is 0.003-0.006 mm, the fine grinding longitudinal feed speed is 0.5-1.0 m / min, and the fine grinding slender roller speed is 100-120 r / min.

[0016] The grinding wheel used in the grinding process is made of brown corundum or white corundum abrasive, the grinding wheel particle size is 40-50 grains, the grinding wheel hardness is K or L grade, and the grinding wheel structure is 6-8.

[0017] The grinding wheel used in the grinding process is concave in the middle.

[0018] The present invention has positive effects: the present invention has formulated a standardized processing method for the entire process of slender rollers, including tempering heat treatment, turning processing, grinding processing, etc., and a method for controlling the deformation of the slender roller neck has been formulated for each process. The processing method of the present invention can effectively solve the problem of deformation of the slender roller neck caused by factors such as gravity and thermal deformation, greatly improve the processing quality and processing efficiency, and make up for the shortcomings of the existing processing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the turning process of the present invention. DETAILED DESCRIPTION

[0020] (Example 1) The processing method for controlling the deformation of the neck of the slender roller of this embodiment comprises the following steps: S1, quenching and tempering and first stress relief.

[0021] S11. In order to reduce the tempering deformation of the slender roller, the well furnace is used for tempering, and the tempering quenching temperature is 900±10℃.

[0022] For slender rollers with a roller diameter of D>100mm, the tempering and quenching time (min) = D×1.2min / mm.

[0023] For a slender roller with a roller body diameter D≤100mm, the tempering and quenching time (min) = (D+15mm)×1.2min / mm.

[0024] After quenching and tempering, high temperature tempering is adopted, and the temperature is 630~640℃.

[0025] S12, straighten the slender roller after furnace tempering; if there is deformation, secondary high-temperature tempering is required, the temperature is 30-40°C lower than step S11, the time is 4-8h, and then air-cooled; if there is no deformation, directly proceed to step S13.

[0026] S13. For the first stress relief annealing, use a well furnace to heat to 500-550°C, keep warm for 4-5 hours, then cool to below 300°C and take out of the furnace.

[0027] S2, turning processing, details are as follows: S21. First, repair the center hole of the roller body. The center hole is the processing reference of the slender roller. After the tempering treatment, the center hole will be deformed. Therefore, it is necessary to repair the center hole first so that its 60° taper hole and roundness meet the standard requirements.

[0028] S22, then, use a clamping method of one clamp and one top, see Figure 1 .

[0029] Use the three-jaw self-centering chuck 2 in the machine tool spindle box to clamp the left end of the slender roller 1, and check whether the roller body runout meets the requirements.

[0030] The right end of the elongated roller 1 is supported by an elastic live center 3 (installed on the tailstock of the lathe, not shown in the figure). The use of the elastic live center can allow the workpiece to stretch freely after being heated, thereby reducing its bending deformation due to heat.

[0031] At the same time, an open wire ring 4 is inserted between the three-jaw self-centering chuck 2 and the slender roller 1, which can shorten the axial contact length between the three-jaw self-centering chuck 2 and the slender roller 1, eliminate over-positioning during installation, and reduce bending deformation.

[0032] S23. Next, during turning, a tool rest 6 is arranged on the opposite side of the processing position of the turning tool 5, so that the turning tool 5 and the tool rest 6 move synchronously on the lathe guide rail and press against the outer circle of the workpiece. This can offset the influence of the radial cutting force, make the force more uniform during turning, and make the turning process smoother, avoiding deformation and vibration.

[0033] The process parameters of the turning processing in this embodiment are as follows: the back cutting depth of rough turning is 1.5mm, the feed rate of rough turning is 0.35mm / r, and the cutting speed of rough turning is 35m / min; the back cutting depth of semi-finishing turning is 0.75mm, the feed rate of semi-finishing turning is 0.25mm / r, and the cutting speed of semi-finishing turning is 35m / min.

[0034] In addition, in order to reduce the bending deformation caused by turning the slender shaft, the cutting force generated during turning is required to be as small as possible. Among the geometric angles of the tool, the rake angle, main deflection angle and cutting edge inclination angle have the greatest influence on the cutting force.

[0035] ① Under the premise of ensuring that the turning tool has sufficient strength, the rake angle of the tool is increased as much as possible. In this embodiment, the rake angle is 15°.

[0036] ② With the increase of the main deflection angle, the radial cutting force decreases significantly. When the main deflection angle Kr is between 60 and 75°, the proportional relationship of the cutting force is relatively reasonable.

[0037] ③ The positive edge inclination angle λ of the tool is between 3 and 10°, which can make the chips flow to the surface to be processed.

[0038] S3. Secondary stress relief.

[0039] After the turning process is completed, the hardness of the slender roller needs to be tested. If the hardness exceeds the technical requirements, it needs to be tempered in time to avoid tempering after the finished product to increase the deformation.

[0040] If the hardness meets the technical requirements, secondary stress relief is carried out. The slender roller is heated to 650±5℃, kept warm for 4 to 5 hours, and then slowly cooled and then air-cooled to remove the residual stress caused by machining, deformation processing, heat treatment, etc.

[0041] S4, grinding process, details are as follows: S41. First, fine-tune the center hole and grind it on a grinder for a while to adjust the tightness of the workpiece between the centers.

[0042] S42. Then, place a bracket at the roller neck to increase the rigidity of the workpiece; at the same time, set a micrometer in the horizontal and vertical directions of the bracket so that the runout of the workpiece during grinding can be intuitively understood.

[0043] S43. Next, during the grinding process, the processing sequence should be improved. The "secondary gear outer circle" should be fine-ground first, and then the "outer circle with high precision requirements" should be fine-ground. Before fine-grinding, the machine should be operated without feed, and fine-grinding should be performed when the system is in a stable state.

[0044] During the grinding process, sufficient grinding fluid containing extreme pressure cooling additives is supplied in a spraying manner to improve the cooling conditions of the slender roller.

[0045] The grinding process parameters of this embodiment are as follows: the rough grinding cutting depth is 0.009mm, the rough grinding longitudinal feed speed is 1.4m / min, and the rough grinding elongated roller speed is 150r / min. The semi-finishing grinding cutting depth is 0.007mm, the semi-finishing grinding longitudinal feed speed is 1.2m / min, and the semi-finishing grinding elongated roller speed is 130r / min. The fine grinding cutting depth is 0.005mm, the fine grinding longitudinal feed speed is 0.8m / min, and the fine grinding elongated roller speed is 110r / min.

[0046] The grinding wheel material used in this embodiment is brown corundum abrasive, the grinding wheel grit is 40 grains, the grinding wheel hardness is K grade, and the grinding wheel structure is No. 7.

[0047] The grinding wheel used in this embodiment is concave in the middle, which can reduce the contact area between the grinding wheel and the workpiece and reduce the self-excited vibration of the slender roller during rotation.

[0048] Dressing the grinding wheel can improve its sharpness to reduce grinding resistance. The lateral feed of the grinding wheel should be smaller than the lateral cutting force. If necessary, the grinding resistance can be reduced by correcting the grinding wheel and reducing its width.

[0049] S44. After the fine grinding process is completed, the size and shape of all fine roller necks are inspected, and the super fine grinding process is carried out after the inspection is correct.

[0050] For workpieces with obvious deformation, the center hole is re-done, and other gears are ground and corrected based on the bearing gear. After grinding to the finished size, measure and confirm.

Claims

1. A processing method for controlling the deformation of a slender roller neck, comprising turning and grinding; characterized in that: The turning process also includes tempering and a first stress relief before the turning process; and the second stress relief is also included after the turning process and before the grinding process.

2. The processing method for controlling the deformation of the roll neck of an elongated roller according to claim 1, characterized in that: The tempering is well furnace tempering, and the tempering quenching temperature is 880-920°C; the first stress relief is to use a well furnace to heat to 500-550°C, keep warm for 4-5 hours, and then cool the furnace to below 300°C before taking out of the furnace.

3. The processing method for controlling the deformation of the roll neck of an elongated roller according to claim 1, characterized in that: The turning process adopts a clamping method of one clamp and one push, using a three-jaw self-centering chuck (1) in the machine tool spindle box to clamp the left end of the slender roller (1), and the right end of the slender roller (1) is supported by an elastic live center (3), and an open wire ring (4) is inserted between the three-jaw self-centering chuck (2) and the slender roller (1); during the turning process, a tool holder (6) is arranged on the opposite side of the processing position of the turning tool (5), so that the turning tool (5) and the tool holder (6) move synchronously on the lathe guide rail and press against the outer circle of the roller neck of the slender roller (1).

4. The processing method for controlling the deformation of the roll neck of an elongated roller according to claim 3, characterized in that: The process parameters of the turning process are as follows: the back cutting depth of rough turning is 1-2mm, the feed rate of rough turning is 0.3-0.4mm / r, and the cutting speed of rough turning is 30-40m / min; the back cutting depth of semi-finishing turning is 0.5-1mm, the feed rate of semi-finishing turning is 0.2-0.3mm / r, and the cutting speed of semi-finishing turning is 30-40m / min.

5. The processing method for controlling the deformation of the roll neck of an elongated roller according to claim 3, characterized in that: The front angle γ of the turning tool (5) is 15°, the main deflection angle Kr is 60-75°, and the positive edge inclination angle λ is 3-10°.

6. The processing method for controlling the deformation of the neck of an elongated roller according to claim 1, characterized in that: The secondary stress relief heats the elongated roller to 640-660° C., keeps the temperature for 4-5 hours, then slowly cools it, and then air cools it.

7. The processing method for controlling the deformation of the neck of an elongated roller according to claim 1, characterized in that: The process parameters of the grinding process are as follows: the rough grinding cutting depth is 0.008-0.01 mm, the rough grinding longitudinal feed speed is 1.3-1.5 m / min, and the rough grinding slender roller speed is 140-160 r / min; the semi-fine grinding cutting depth is 0.006-0.008 mm, the semi-fine grinding longitudinal feed speed is 1.0-1.5 m / min, and the semi-fine grinding slender roller speed is 120-140 r / min; the fine grinding cutting depth is 0.003-0.006 mm, the fine grinding longitudinal feed speed is 0.5-1.0 m / min, and the fine grinding slender roller speed is 100-120 r / min.

8. The processing method for controlling the deformation of the neck of an elongated roller according to claim 1, characterized in that: The grinding wheel used in the grinding process is made of brown corundum or white corundum abrasive, the grinding wheel particle size is 40 to 50 grains, the grinding wheel hardness is K or L grade, and the grinding wheel structure is 6 to 8; the grinding wheel used in the grinding process is concave in the middle.

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