A processing technology of a large-size 86CrMoV7 steel embossing roller

Abstract

The present application relates to a kind of large specification 86CrMoV7 steel kind embossing roller processing technology, roller body processing method: roller body quenching and tempering piece-frame position-rough boring inner hole-half precision turning-outer circle grinding-magnetic exploration-double frequency quenching+tempering-precision turning frame position-precision boring inner hole-precision turning and shaft head hot mounting;Shaft head processing method: shaft head quenching and tempering piece-precision turning and roller body hot mounting.Processing method is adopted after roller body hollow double frequency quenching and then hot mounting, selects reasonable process parameter, solves the precision control problem of fit length and total length, avoids the quality problems such as quenching crack, deformation, uneven hardness easily appeared in hollow double frequency quenching process, effectively guarantees product quality, satisfies user demand.

Description

Technical Field

[0001] This invention belongs to the field of embossing roller processing technology, and in particular relates to a processing technology for large-size 86CrMoV7 steel embossing rollers that can avoid quality problems such as quenching cracks, deformation, and uneven hardness that occur during the hollow double-frequency quenching process of high carbon steel, and effectively ensure product quality. Background Technology

[0002] Currently, in the production of large-size finished embossing rollers, embossing rollers are high-end paper embossing equipment in China. This product consists of a roller body and a shaft head heat-fitted together. The roller body is a hollow part made of 86CrMoV7 material with a high C content of 0.8~0.9 (m / %). The finished roller body specifications are φD×φd×L, with a surface hardness requirement of HRC64-66, requiring surface quenching treatment. The shaft head steel is 42CrMo. The shaft head and roller body are heat-fitted together with a radial interference of 0.3~0.4mm and a mating length L1 (0, +0.2)mm. In the early trial production process, a process of heat-fitting the shaft head and roller body followed by double-frequency quenching was adopted. During quenching, the axial elongation of the roller body varied from 10 to 20mm. Due to the different expansion coefficients of the shaft head and roller body, it was impossible to accurately guarantee the roller body length L±0.5mm and the mating length L1 (0, +0.2)mm between the roller body and shaft head during precision machining after quenching. To solve this problem, it is necessary to optimize the process and select reasonable process parameters to address the issue of fit length. This is used to resolve quality problems such as quenching cracks, deformation, and uneven hardness that are prone to occur during the hollow double-frequency quenching of high-carbon steel, thereby ensuring product quality and meeting user needs. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a processing technology for large-size 86CrMoV7 steel embossing rollers that can avoid quality problems such as quenching cracks, deformation, and uneven hardness during the hollow double-frequency quenching process of high carbon steel, and effectively ensure product quality.

[0004] The objective of this invention is achieved as follows:

[0005] A processing technology for large-size 86CrMoV7 steel embossing rolls, which meets product precision requirements by selecting reasonable process parameters and employing a method of hollow roller body double-frequency quenching followed by hot mounting, is achieved through the following steps:

[0006] Step 1) The first step in the machining process of the roller body is as follows: Heat treatment of the roller body – frame position – rough boring of the inner hole – semi-finish turning – grinding of the outer diameter – magnetic detection – dual-frequency quenching + tempering – finish turning of the frame position – finish boring of the inner hole – finish boring of the bore – hot fitting of the roller body and shaft head; the specific steps are as follows:

[0007] Step 1.1) Chassis position: Clamp the roller body heat treatment part on the lathe using a two-top and one-clamp method. Machine a 200mm long outer circle at 500mm from each end of the workpiece to make it a deep hole boring position. The surface roughness at the position should be ≤Ra3.2μm, and the end faces of both ends should be flat and polished.

[0008] Step 1.2) Rough boring of the inner hole: Clamp the workpiece on the deep hole boring machine, and after finding that the outer diameter runout at both ends is ≤0.2mm, rough bore the inner hole to φ(d-10)±0.1mm;

[0009] Step 1.3) Semi-finish turning: First, in order to ensure the quality of hollow double-frequency quenching and avoid quenching crack defects, the size and shape of the roller body before quenching are designed to prevent quenching cracks. The length of the roller body is designed to be 20×45°mm at both ends, all sharp edges are rounded to R3~R15mm, the surface roughness is ≤Ra1.6μm, and tool marks are not allowed.

[0010] Secondly, when semi-finishing the outer diameter on the lathe, use the inner hole as the reference for positioning, adjust the wall thickness difference of the roller body to within ≤0.2mm, semi-finish turn the outer diameter to ΦD(+0.4, +0.5)mm, flatten the end face on the center rest, machine a 20mm×45° taper and fillet R15mm, and round the inner hole to R3mm; turn the workpiece around and flatten the other end, ensuring that the total length L+100mm is 50mm longer than the finished length L at both ends by the length of the quenched soft strip, machine a 45° taper and fillet R15mm, round the inner hole to R3mm, and polish the chamfers and R15mm at both ends to a surface roughness ≤Ra1.6μm;

[0011] Step 1.4) Grinding the outer diameter: After semi-finish turning the outer diameter, a grinding process is added. The outer diameter is ground to ΦD(0, +0.1) mm on the two centers of the outer diameter grinding machine. The surface roughness of the outer surface is ≤Ra0.8μm to ensure the uniformity of hardness after quenching and reduce quenching stress, and avoid quenching cracks.

[0012] Step 1.5): Magnetic detection: Transfer the roller to the magnetic detector and perform magnetic detection on the outer surface of the roller. The surface must be free of defects to avoid quenching cracks during quenching.

[0013] Step 1.6) Dual-frequency quenching: Design and manufacture special tooling to connect the hollow roller body to the tooling. Then, vertically erect the workpiece and tooling together on a 50 / 250HZ dual-frequency quenching equipment. Turn on the quenching equipment and rotate the roller body at a speed of 20-40 r / min. After preheating at 380±10℃ and holding at a uniform temperature for ≥8h, quench at a quenching temperature of 890-900℃. During quenching, the roller body descends at a speed of 0.8-1.0 mm / s. To avoid quenching cracks, reduce the quenching water pressure to 0.08-0.09 MPa. After quenching, continue cooling in the water tank for 60±10 min to complete the quenching process. Then, transfer the roller body to a tempering furnace for tempering at a tempering temperature of 190±10℃ and a holding time of ≥16h to complete the dual-frequency quenching process. The surface hardness of the roller body is tested to be HRC64-66.

[0014] Step 1.7) Precision turning position: Clamp and support the lathe, adjust the total wall thickness difference to within 0.2mm, and precision turn 200mm long outer circles at 300mm from both ends of the workpiece to obtain the deep hole boring position. Control the roundness at the position to ≤0.02mm and the roughness to ≤Ra6.3μm to reduce error replication and ensure the accuracy of the inner hole; install the center rest, evenly distribute the length allowance at both ends, and flatten the end face to ensure the total length L±0.5mm;

[0015] Step 1.8): Precision boring of the inner hole: Clamp the workpiece on the deep hole boring machine, measure the runout at two locations of the support position to be ≤0.1mm, then clamp the workpiece, precision bore the inner hole Φd±0.1mm, the workpiece rotation speed n=20-40r / min, and the feed rate of the boring bar along the workpiece axis direction f=60-80mm / min;

[0016] Step 1.9) Precision boring: Clamp and align the workpiece on the lathe. After measuring the runout of the workpiece at the chuck and the position of the support, clamp the workpiece. Precision bore the inner hole of the hot fitting hole of the shaft head from one end of the workpiece, Φ(d+10)(0, -0.05)mm, with a length L(0, +0.2)mm. Turn the workpiece around and precision bore the inner hole of the other end, Φ(d+10)(0, -0.05)mm, with a boring length L(0, +0.2)mm.

[0017] Step 2) The shaft head machining process is as follows: Shaft head tempering part - precision turning - hot fitting with roller body. The specific steps are as follows: After clamping and aligning the shaft head tempering part on the lathe, precision turn it. Turn the part that is hot fitted with the roller body to Φ (d+10) (+0.30, +0.35) mm and the length L (0, +0.2) mm.

[0018] Step 3) The hot fitting process is as follows: The roller body is placed in the heating furnace and heated to 140±10℃. The hot fitting temperature should be lower than the roller body tempering temperature. The roller body is then lifted out of the heating furnace and placed on the platform. The shaft head is hot-fitted into the roller body to ensure the assembly length L (0, +0.1) mm.

[0019] The technical effects of this invention are as follows: By adopting the process of hollow double-frequency quenching of the roller body followed by hot fitting, and by selecting reasonable process parameters, the problem of precision control of the fitting length and total length is solved. This avoids quality problems such as quenching cracks, deformation, and uneven hardness that are prone to occur during hollow double-frequency quenching, effectively ensuring product quality and meeting user needs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the embossing roller of the present invention.

[0021] Figure 2 This is a schematic diagram of the pre-quenching processing of the roller body according to the present invention.

[0022] Figure 3 This is a schematic diagram of the pre-heat loading process after surface quenching of the roller body according to the present invention.

[0023] Figure 4 This is a schematic diagram of the precision machining of the shaft head before hot fitting according to the present invention.

[0024] Figure 5 This is a schematic diagram of the hollow quenching process of the roller body according to the present invention.

[0025] The figure shows: 1. Shaft head; 2. Roller body; 3. Lower fixing block; 4. Fastening screw; 5. Adjusting screw; 6. Lower support plate; 7. Mandrel; 8. Upper support plate; 9. Upper fixing block; 10. Roller body; 11. Connecting plate. Detailed Implementation

[0026] Example 1: A processing technology for large-size 86CrMoV7 steel embossing rolls: By selecting reasonable process parameters and using a method of hollow roller body double-frequency quenching followed by hot mounting, the product precision requirements are met. This is achieved through the following steps:

[0027] Step 1) The machining process for roller body 2 is as follows: Heat treatment of roller body components—carriage position—rough boring of inner hole—semi-finish turning—grinding of outer diameter—magnetic detection—dual-frequency quenching + tempering—finish turning of carriage position—finish boring of inner hole—finish boring of bore—heat fitting of roller body and shaft head; Specific steps are as follows:

[0028] Step 1.1) Chassis position: Clamp the roller body heat treatment part on the lathe using a two-top and one-clamp method. Machine a 200mm long outer circle at 500mm from each end of the workpiece to make it a deep hole boring position. The surface roughness at the position should be ≤Ra3.2μm, and the end faces of both ends should be flat and polished.

[0029] Step 1.2) Rough boring of the inner hole: Clamp the workpiece on the deep hole boring machine, and after finding that the outer diameter runout at both ends is ≤0.2mm, rough bore the inner hole to φ524±0.1mm;

[0030] Step 1.3) Semi-finish turning: First, to ensure the quality of hollow double-frequency quenching and avoid quenching crack defects, the dimensions and shape of the roller body before quenching are designed to prevent quenching cracks. The two ends of the roller body are designed to be 20mm × 45°, all sharp edges are rounded to R3~R15mm, the surface roughness is ≤Ra1.6μm, and tool marks are not allowed; Second, when semi-finish turning the outer diameter on the lathe, the inner hole Φ524mm is used as the reference for positioning, and the wall thickness difference along the entire length of the roller body is adjusted to ≤0.2mm, and the outer diameter is semi-finish turned to Φ65. 6.4~Φ656.5mm (leaving a grinding allowance of about 0.5mm), flatten the end face with the center rest, machine a 20mm×45° taper and a fillet radius of R15mm, and round the inner hole with a radius of R3mm; turn the workpiece around and machine the other end flat, ensuring a total length of 3900±2mm (compared to the finished length of 3800mm, with an additional 50mm of hardened soft strip length at each end), machine a 45° taper and a fillet radius of R15mm, round the inner hole with a radius of R3mm, and polish the chamfers and R15mm at both ends until the surface roughness is ≤Ra1.6μm;

[0031] Step 1.4) Grinding the outer diameter: After semi-finish turning the outer diameter, a grinding process is added. The outer diameter is ground to Φ656~Φ656.1 mm on an outer cylindrical grinding machine with two centers. The surface roughness of the outer surface is ≤Ra0.8μm to ensure the uniformity of hardness after quenching and reduce quenching stress, and avoid quenching cracks.

[0032] Step 1.5): Magnetic detection: Transfer the roller to the magnetic detector and perform magnetic detection on the outer surface of the roller. The surface must be free of defects to avoid quenching cracks during quenching.

[0033] Step 1.6) Dual-frequency quenching + tempering: Design and manufacture a special tooling, which mainly consists of a mandrel 7, an upper fixing block 9, a lower fixing block 3, fastening screws 4, an upper support plate 8, a lower support plate 6, adjusting screws 5, and a connecting plate 11. The upper and lower fixing blocks and the upper and lower support plates are all composed of semicircles, facilitating easy assembly and disassembly. The special tooling design is implemented according to the following steps:

[0034] Step 1.6.1) The upper fixed block 9, the lower fixed block 3, the upper support plate 8, and the lower support plate 6 are all two halves of a semicircle. The inner hole of the roller body fits with the spindle 7. The outer circles of the upper support plate 8 and the lower support plate 6 have two steps. The smaller outer circle is machined to fit with the inner hole of the spindle 7. The gap between the inner holes of the upper support plate 8 and the lower support plate 6 and the spindle 7 plus the gap between the smaller outer circle and the inner hole of the roller body is greater than the shrinkage of the roller body.

[0035] Step 1.6.2): ​​Insert the mandrel 7 into the inner hole of the roller body 10, and clamp the lower fixing block 3 into the groove of the mandrel 7. Secure it firmly with the fastening screws 4. Insert the lower support plate 6 into the roller body and make it close to the roller body and the lower fixing block 3. Use the adjusting screws 5 to lift the lower support plate 6 and make it close to the inner hole of the roller body. Connect the lower support plates 6 together with the connecting plate 11. The upper support plate 8 is installed in the same way as the lower support plate 6. Secure the upper fixing block 9 to the mandrel 7 with the fastening screws 4, leaving a shrinkage gap with the upper support plate 8.

[0036] Step 1.6.3) After quenching, loosen the fastening screws 4 and adjusting screws 5 that connect the upper fixing block 9, the lower fixing block 3, the upper support plate 8, and the lower support plate 6. The entire fixture will then be detached, and the mandrel 7 can be removed.

[0037] Before quenching, the hollow roller body 10 is connected to a special tooling. Then, the workpiece and the tooling are vertically erected on a 50 / 250HZ dual-frequency quenching equipment. The quenching equipment is turned on and the roller body is rotated at a speed of 20-40 r / min. After preheating at 380±10℃ and holding at a uniform temperature for ≥8h, the roller body is quenched at a temperature of 890-900℃. During quenching, the roller body descends at a speed of 0.8-1.0 mm / s. To avoid quenching cracks, the quenching water pressure is reduced to 0.08-0.09 MPa. After quenching, the roller body is further cooled in a water tank for 60±10 min to complete the quenching process. Then, the roller body is transferred to a tempering furnace for tempering at a temperature of 190±10℃ and a holding time of ≥16h to complete the dual-frequency quenching process. The surface hardness of the roller body is tested to be HRC64-66.

[0038] Step 1.7) Precision turning position: On the lathe, with one clamp and one support, adjust the total wall thickness difference to within 0.2mm, and precision turn 200mm of the outer diameter at 300mm from both ends of the workpiece to obtain the deep hole boring position. Control the roundness at the position to ≤0.02mm and the roughness to ≤Ra6.3μm to reduce error replication and ensure the accuracy of the inner hole; install the center rest, evenly distribute the length allowance at both ends, and flatten the end face to ensure a total length of 3800±0.5mm;

[0039] Step 1.8): Precision boring of the inner hole: Clamp the workpiece on the deep hole boring machine, measure the runout at two locations of the support position to be ≤0.1mm, then clamp the workpiece, precision bore the inner hole Φd±0.1mm, the workpiece rotation speed n=20-40r / min, and the feed rate of the boring bar along the workpiece axis direction f=60-80mm / min;

[0040] Step 1.9) Precision boring: Clamp and align the workpiece on the lathe. After measuring the runout of the workpiece at the chuck and the position of the support, clamp the workpiece. Precision bore the inner hole of the hot fitting hole of the shaft head from one end of the workpiece to Φ544 (0, -0.05) mm, with a length of 460 (0, +0.2) mm. Turn the workpiece around and precision bore the inner hole of the other end to Φ544 (0, -0.05) mm, with a boring length of 460 (0, +0.2) mm.

[0041] Step 2) The machining process of shaft head 1 is as follows: Shaft head tempering part - precision turning - hot fitting with roller body. The specific steps are as follows: After clamping and aligning the shaft head blank tempering part on the lathe, precision turn it. The part that is hot fitted with the roller body is turned to Φ544 (+0.30, +0.35) mm and the length is 460 (0, +0.2) mm.

[0042] Step 3) The hot fitting process is as follows: The roller body is placed in the heating furnace and heated to 140±10℃. The hot fitting temperature should be lower than the roller body tempering temperature. Then the roller body is lifted out of the heating furnace and placed on the platform. The shaft head is hot fitted into the roller body to ensure the assembly length is 460 (0, +0.2) mm.

Claims

1. A processing technology for large-size 86CrMoV7 steel embossing rollers, characterized in that, By selecting appropriate process parameters and employing a method of hollow roller body double-frequency quenching followed by hot mounting, the product precision requirements are met. This is achieved through the following steps: Step 1) The first step in the machining process of the roller body is as follows: Heat treatment of the roller body – frame position – rough boring of the inner hole – semi-finish turning – grinding of the outer diameter – magnetic detection – dual-frequency quenching + tempering – finish turning of the frame position – finish boring of the inner hole – finish boring of the bore – hot fitting of the roller body and shaft head; the specific steps are as follows: Step 1.1) Chassis position: Clamp the roller body heat treatment part on the lathe using a two-top and one-clamp method. Machine a 200mm long outer circle at 500mm from each end of the workpiece to make it a deep hole boring position. The surface roughness at the position should be ≤Ra3.2μm, and the end faces of both ends should be flat and polished. Step 1.2) Rough boring of the inner hole: Clamp the workpiece on the deep hole boring machine, and after finding that the outer diameter runout at both ends is ≤0.2mm, rough bore the inner hole to φ(d-10)±0.1mm; Step 1.3) Semi-finish turning: First, to ensure the quality of hollow double-frequency quenching and avoid quenching crack defects, the dimensions and shape of the roller body before quenching are designed to prevent quenching cracks. The two ends of the roller body length are designed to be 20mm × 45°, all sharp edges are rounded to R3~R15mm, the surface roughness is ≤Ra1.6μm, and tool marks are not allowed; Second, when semi-finish turning the outer diameter on the lathe, the inner hole is used as the reference for positioning, and the wall thickness difference along the entire length of the roller body is adjusted to be ≤0.2mm. Finish-machine the outer diameter to ΦD (+0.4, +0.5) mm, flatten the end face with the center rest, machine a 20 mm × 45° taper and fillet R15 mm, and round the inner hole to R3 mm; turn the workpiece around and machine the other end flat, ensuring that the total length L + 100 mm is 50 mm longer than the finished length L at both ends by adding the length of the quenched soft strip, machine a 45° taper and fillet R15 mm, round the inner hole to R3 mm, and polish the chamfers and R15 mm at both ends until the surface roughness is ≤ Ra1.6 μm; Step 1.4) Grinding the outer diameter: After semi-finish turning the outer diameter, a grinding process is added. The outer diameter is ground to ΦD(0, +0.1) mm on the two centers of the outer diameter grinding machine. The surface roughness of the outer surface is ≤Ra0.8μm to ensure the uniformity of hardness after quenching and reduce quenching stress, and avoid quenching cracks. Step 1.5): Magnetic detection: Transfer the roller to the magnetic detector and perform magnetic detection on the outer surface of the roller. The surface must be free of defects to avoid quenching cracks during quenching. Step 1.6) Dual-frequency quenching + tempering: Design and manufacture special tooling. Before quenching, connect the hollow roller to the tooling. Then, vertically stand the workpiece and tooling together on a 50 / 250HZ dual-frequency quenching machine. Turn on the quenching machine and rotate the roller at a speed of 20-40 r / min. After preheating at 380±10℃ and holding at a uniform temperature for ≥8h, quench at a temperature of 890-900℃. During quenching, the roller descends at a speed of 0.8-1.0 mm / s. To avoid quenching cracks, reduce the quenching water pressure to 0.08-0.09 MPa. After quenching, continue cooling in the water tank for 60±10 min to complete the quenching process. Then, transfer the roller to a tempering furnace for tempering at a temperature of 190±10℃ and a holding time of ≥16h to complete the dual-frequency quenching process. The surface hardness of the roller is tested to be HRC64-66. Step 1.7) Precision turning position: Clamp and support the lathe, adjust the total wall thickness difference to within 0.2mm, and precision turn 200mm long outer circles at 300mm from both ends of the workpiece to obtain the deep hole boring position. Control the roundness at the position to ≤0.02mm and the roughness to ≤Ra6.3μm to reduce error replication and ensure the accuracy of the inner hole; install the center rest, evenly distribute the length allowance at both ends, and flatten the end face to ensure the total length L±0.5mm; Step 1.8): Precision boring of the inner hole: Clamp the workpiece on the deep hole boring machine, measure the runout at two locations of the support position to be ≤0.1mm, then clamp the workpiece, precision bore the inner hole Φd±0.1mm, the workpiece rotation speed n=20-40r / min, and the feed rate of the boring bar along the workpiece axis direction f=60-80mm / min; Step 1.9) Precision boring: Clamp and align the workpiece on the lathe. After measuring the runout of the workpiece at the chuck and the position of the support, clamp the workpiece. Precision bore the inner hole of the hot fitting hole of the shaft head from one end of the workpiece, Φ(d+10)(0, -0.05)mm, with a length L(0, +0.2)mm. Turn the workpiece around and precision bore the inner hole of the other end, Φ(d+10)(0, -0.05)mm, with a boring length L(0, +0.2)mm. Step 2) The shaft head machining process is as follows: Shaft head tempering part - precision turning - hot fitting with roller body. The specific steps are as follows: After clamping and aligning the shaft head tempering part on the lathe, precision turn it. Turn the part that is hot fitted with the roller body to Φ (d+10) (+0.30, +0.35) mm and the length L (0, +0.2) mm. Step 3) The hot fitting process is as follows: The roller body is placed in the heating furnace and heated to 140±10℃. The hot fitting temperature should be lower than the roller body tempering temperature. The roller body is then lifted out of the heating furnace and placed on the platform. The shaft head is hot-fitted into the roller body to ensure the assembly length L (0, +0.1) mm.

2. The processing technology for a large-size 86CrMoV7 steel embossing roller according to claim 1, characterized in that, In the dual-frequency quenching and tempering process of step 1.6), a special tooling is designed and manufactured. The specific method is as follows: The special tooling mainly consists of a mandrel (7), an upper fixing block (9), a lower fixing block (3), fastening screws (4), an upper support plate (8), a lower support plate (6), adjusting screws (5), and a connecting plate (11). The upper and lower fixing blocks and the upper and lower support plates are all composed of half-circles. The design of the special tooling is achieved according to the following steps: Step 1.6.1) The upper fixed block (9), the lower fixed block (3), the upper support plate (8), and the lower support plate (6) are all two halves of a semicircle. The inner hole of the roller body is fitted with the spindle (7). The outer circles of the upper support plate (8) and the lower support plate (6) have two steps. The smaller outer circle is fitted with the inner hole of the spindle (7) and the gap between the inner hole of the upper support plate (8) and the lower support plate (6) and the spindle (7) plus the gap between the smaller outer circle and the inner hole of the roller body is greater than the shrinkage of the roller body. Step 1.6.2): ​​Insert the mandrel (7) into the inner hole of the roller body (10), and clamp the lower fixing block (3) into the groove of the mandrel (7). Secure it firmly with fastening screws (4). Insert the lower support plate (6) into the roller body and press it against the roller body and the lower fixing block (3). Use adjusting screws (5) to lift the lower support plate (6) and press it against the inner hole of the roller body. Connect the lower support plate (6) together with connecting plate (11). Install the upper support plate (8) in the same way as the lower support plate (6). Fix the upper fixing block (9) on the mandrel (7) with fastening screws (4) and leave a shrinkage gap with the upper support plate (8). Step 1.6.3) After quenching, loosen the fastening screws (4) and adjusting screws (5) connecting the upper fixing block (9), the lower fixing block (3), the upper support plate (8), and the lower support plate (6). The entire fixture will then be detached, and the mandrel (7) can be removed.

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