A tooth profile machining process for a large output pinion shaft

Abstract

The application relates to a gear profile machining process of a large output gear shaft, which comprises the following process steps: forging, normalizing, rough turning, ultrasonic flaw detection, drilling, sawing, rough gear milling, quenching and tempering, shot blasting, secondary ultrasonic flaw detection, finish turning and finish gear milling, wherein the sawing step adopts a scheme of pre-machining the gear profile before quenching and tempering and finish machining the gear after heat treatment, a rotary table sawing tool is used to realize gear cutting machining, and most of the machining allowance is efficiently removed; after the gear is sawed, a vertical machining center coarsely mills the gear in one stroke according to a gear profile diagram, removes high and sharp points of the gear after the gear cutting, and also makes the gear allowance consistent to ensure the consistency of the hardness after the heat treatment. The application improves the gear cutting efficiency, reduces the production cost, and improves the economic reliability of the gear profile machining of the large output gear shaft.

Description

Technical Field

[0001] This invention relates to the field of gear shaft tooth profile machining technology, and in particular to a tooth profile machining process for large output gear shafts, mainly used for rough machining of large module tooth profiles. Background Technology

[0002] Rough machining of large-module gear teeth using hobbing or milling machines and cutting tools is expensive, and domestic manufacturers generally lack the necessary equipment. In many cases, the module of a large-module gear tooth far exceeds the machining limit of domestic machine tools and the manufacturing limit of the corresponding hobs. In such situations, the preferred machining method is usually to mill the entire gear shape using a machining center (either vertical or horizontal). Another method is wire EDM, where a 2D gear shape is generated using Kisssoft, and then cut according to this shape. However, existing machining methods have the following problems: Because large-module tooth profiles have a large machining allowance, the cutting time to mill the entire tooth groove is long, and the tool wear is relatively severe. While production plans can be arranged to ensure machining cycles for single or small-piece production, it is impossible to complete the machining cycle for mass production with a limited number of machine tools. The machining cycle for each piece is long, the machining efficiency is low, and the machining cost is high. Furthermore, if wire EDM is used, the machining cycle will be even longer, making it even less suitable for mass production of such large-module tooth profiles. Therefore, how to economically and reliably solve the machining of such parts and improve machining efficiency is currently a key research and improvement direction. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a tooth profile machining process for large output gear shafts, which solves the disadvantages of large machining allowance and high cost of large module tooth profiles, and maximizes the economic reliability of machining while ensuring that the quality of the parts meets the requirements of the drawings.

[0004] The objective of this invention is achieved as follows: A machining process for the tooth profile of a large output gear shaft includes the following steps: forging, normalizing, rough turning, ultrasonic testing, drilling, sawing, rough milling, quenching and tempering, shot peening, secondary ultrasonic testing, finish turning, and finish milling. The sawing step includes the following specific steps: A toothed processing device is prepared, comprising a saw tooth fixture mounted on a vertical band saw. The vertical band saw includes a frame, a worktable and a band saw blade on the frame, and the saw tooth fixture mounted on the processing seat. The saw tooth fixture includes an upper saw tooth fixture plate, a lower saw tooth fixture plate, and a base plate arranged sequentially from top to bottom. The base plate is mounted on the worktable, the lower saw tooth fixture plate is detachably mounted on the base plate, and the upper saw tooth fixture plate is rotatably mounted on the lower saw tooth fixture plate. A center hole is provided at the center of the upper and lower saw tooth fixture plates for fitting the tooth shaft to be processed. The tooth shaft to be processed is detachably connected to the lower saw tooth fixture plate. A laser tracker is provided at the top of the frame of the vertical band saw. The colored laser emitted by the laser tracker forms a laser line on the tooth shaft to be processed. The laser tracker is positioned directly above the band saw blade, so that the laser tracker and the band saw blade are on the same axis, and the band saw blade cuts along the laser line. First, use a U-drill to drill equal-division relief holes at the tooth root position of the gear shaft to be machined. The diameter of the relief holes depends on the size of the tooth root fillet. Before sawing, check that the laser line is aligned with the saw blade and the tooling reference line, confirm that the tooling is clamped correctly, adjust the tracker so that the emitted colored laser coincides with the saw blade, and adjust the limit of the sawing machine according to the required feed stroke of the part. Mount the base plate on the workbench and align the laser tracking line with the marking line on the base plate. After the upper plate, ball bearings, and lower plate of the sawing fixture are assembled, they are then connected to the right end of the base plate via keys and screws. The positional relationship between the two is ensured by the screws. After assembly, the upper plate can be easily rotated manually. At this time, the gear shaft to be processed is placed on the upper plate of the fixture, and the positioning pin is inserted to limit the circumferential movement of the gear shaft to be processed. At this time, the laser line, saw blade, base plate marking line, and the left tooth surface of the tooth being cut are on the same straight line. After cutting one tooth, rotate one adjacent hole angle and repeat inserting the positioning pin until all the left tooth surfaces of all batches of gear shafts are cut. Move the entire sawing fixture assembly, including the upper plate, ball bearings, and lower plate, to the left end of the base plate. At this point, the laser line, saw blade, base plate marking line, and the right tooth surface being sawed are all on the same straight line. Repeat the above steps to complete the processing of the right tooth surface of all parts.

[0005] Furthermore, the marking lines on the base plate must ensure that there is a margin of >6mm on each side of the tooth surface.

[0006] Furthermore, the upper part of the lower plate of the sawtooth fixture is provided with a circular groove, the outer diameter of which matches the upper plate of the sawtooth fixture, and the bottom of the upper plate of the sawtooth fixture is disposed in the circular groove.

[0007] Furthermore, the bottom surface of the upper plate of the sawtooth fixture is provided with an upper ball groove at each of the left and right ends, and the bottom surface of the circular groove is provided with a lower ball groove at each of the left and right ends. The position of the lower ball groove corresponds to the upper ball groove. When the upper plate of the sawtooth fixture is placed on the lower plate of the sawtooth fixture, the upper ball groove and the lower ball groove form a spherical groove. A ball is placed in the spherical groove, so that the upper plate of the sawtooth fixture can rotate.

[0008] Furthermore, each of the left and right ends of the circular groove is provided with a shaft hole for inserting bolts to fix the saw blade fixture lower plate to the base plate.

[0009] Furthermore, a connecting hole is provided on one side of the circular groove, and a through hole is provided on the machined gear shaft. A positioning pin is inserted into the through hole, and the bottom of the positioning pin is inserted into the connecting hole, so that the saw tooling lower plate and the machined gear shaft can be detachably connected.

[0010] Furthermore, the base plate is provided with a base plate marking line, which is on the same straight line as the laser line.

[0011] Compared with the prior art, the beneficial effects of the present invention are: The saw teeth of this invention utilize a rotatable upper and lower plate on the worktable of a vertical band saw. Dividing holes are provided on the machined tooth shaft. The band saw blade of the vertical band saw cuts along a laser line, with the laser line coinciding with the marking line on the same straight line. During cutting, the saw tooth position line on one side of the dividing hole is aligned with the marking line, thus achieving cutting along the saw tooth surface. After cutting the left saw tooth line, the machined tooth shaft is repositioned and the operation is repeated to complete the cutting on the right side. This improves cutting efficiency, reduces sawing costs, lowers production costs, reduces manual labor, and enhances the economic reliability of machining the tooth profile of large output tooth shafts. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the saw's left tooth surface in the processing device of the present invention.

[0013] Figure 2 for Figure 1 Top view.

[0014] Figure 3 for Figure 1 A schematic diagram of the sawtooth tooling in the diagram.

[0015] Figure 4 This is a schematic diagram of the right tooth surface of the processing device of the present invention.

[0016] Figure 5 for Figure 4 Top view.

[0017] Figure 6 for Figure 4A schematic diagram of the sawtooth tooling in the diagram.

[0018] Figure 7 This is a cross-sectional view of the upper plate of the sawtooth tooling of the present invention.

[0019] Figure 8 This is a cross-sectional view of the lower plate of the sawtooth tooling of the present invention.

[0020] Figure 9 This is a top view of the lower platen of the sawtooth tooling of the present invention.

[0021] Figure 10 This is a diagram showing the sawtooth pattern and drilling of the present invention.

[0022] in: Vertical band saw 1. Laser tracker 2. Band saw blade 3. Machined toothed shaft 4. Upper plate of saw tooth fixture 5. Upper groove of ball bearing 51. Lower plate of saw tooth fixture 6. Circular groove 61. Lower groove of ball bearing 62. Connecting hole 63. Positioning pin 7. Ball bearing 8. Base plate 9. Laser line 10. Base plate marking line 11. Implementation

[0023] To better understand the technical solution of the present invention, a detailed description will be provided below in conjunction with relevant illustrations. It should be understood that the specific embodiments described below are not intended to limit the specific implementation of the technical solution of the present invention, but are merely possible implementations of the technical solution of the present invention. It should be noted that the descriptions of the positional relationships of the components herein, such as component A being located above component B, are based on the relative positions of the components in the illustrations and are not intended to limit the actual positional relationships of the components. Example 1

[0024] See Figures 1-10 , Figure 1 A schematic diagram of a gear profile machining device for a large output gear shaft is shown. As illustrated, the gear profile machining process for a large output gear shaft according to the present invention includes the following steps: forging → normalizing → rough turning → ultrasonic testing → drilling → sawing → rough milling → tempering → shot peening → ultrasonic testing → finish turning → finish milling. Specifically, it includes the following: (1) Forging: The chemical composition of the forgings meets the requirements of JB / T6396-2006, and the material and heat treatment quality inspection shall be carried out in accordance with the MQ grade of ISO6336-5:2016; (2) Positive heat; (3) Rough turning: Follow the rough turning drawings; for parts with samples, follow the rough turning drawings for forgings with samples. (4) Ultrasonic testing: The ultrasonic testing quality level within 171mm below the gear tooth tip shall not be lower than the requirements of Class II in JB / T5000.15-2007, and the quality level of other parts shall not be lower than Class I. (5) Drilling: Drill holes 9-40 according to the drilling and sawing diagram; avoid drilling holes at the location of the toothed boat pattern (you can use the toothed template to tap the toothed boat pattern after drilling). (6) Saw teeth: Use a special tooth processing device and follow the drilling and sawing diagram; arrange the sawed toothed materials in order; ensure that the tooth surface has a single-sided allowance of >6mm; before sawing, check that the laser line is aligned with the saw blade and the tooling reference line, and confirm that the tooling is clamped correctly, and avoid sawing off-center or sawing too deep; The aforementioned tooth processing device includes a saw tooth fixture mounted on a vertical band saw 1. The vertical band saw 1 includes a frame, a worktable and a cutting assembly on the frame, and the cutting assembly includes a band saw blade 3. The band saw blade 3 moves to cut the toothed shaft 4 being processed on the worktable. The saw tooth fixture is mounted on the processing seat. The sawing fixture includes an upper sawing fixture plate 5, a lower sawing fixture plate 6, and a base plate 9 arranged sequentially from top to bottom. The upper sawing fixture plate 5 is an annular disc with a central hole for fitting the machined gear shaft 4. The bottom surface of the upper sawing fixture plate 5 has a ring of upper ball grooves 51. The lower sawing fixture plate 6 has a central hole that matches the central hole of the upper sawing fixture plate 5 for fitting the machined gear shaft 4. The upper part of the lower sawing fixture plate 6 has a circular groove 61, the outer diameter of which matches that of the upper sawing fixture plate 5. The bottom of the upper sawing fixture plate 5 is located within the circular groove 61, and the bottom surface of the circular groove 61 has a ring of lower ball grooves. The lower ball groove 62 corresponds to the upper ball groove 51. When the upper plate 5 of the sawing fixture is set on the lower plate 6 of the sawing fixture, the upper ball groove 51 and the lower ball groove 62 form a spherical groove. The ball 8 is set in the spherical groove, so that the upper plate 5 of the sawing fixture can rotate. The left and right ends of the circular groove 61 are respectively provided with shaft holes for inserting bolts to fix the lower plate 6 of the sawing fixture on the base plate 9. A connecting hole 63 is also provided on one side of the circular groove 61. The machined gear shaft 4 is provided with a through hole. A positioning pin 7 is inserted into the through hole. The bottom of the positioning pin 7 is inserted into the connecting hole 63, so that the lower plate 6 of the sawing fixture and the machined gear shaft 4 can be detachably connected. The vertical band saw 1 has a laser tracker 2 on the top of its frame. The colored laser emitted by the laser tracker 2 forms a laser line 10 on the machined gear shaft 4. The laser tracker 2 is positioned directly above the band saw blade 3, so that the laser tracker 2 and the band saw blade 3 are on the same axis. The band saw blade 3 cuts along the laser line 10. The base plate 9 is fixed on the worktable of the vertical band saw 1. The base plate 9 is provided with a base plate marking line 11, and the base plate marking line 11 and the laser line 10 are on the same straight line. (6.1) First, use a U-drill to drill equal-division relief holes at the tooth root position of the gear shaft to be machined. The diameter of the relief holes depends on the size of the tooth root fillet. (6.2) Then adjust the tracker to make the emitted colored laser coincide with the saw blade. Adjust the limit of the saw to see if it is reasonable according to the required feed stroke of the part, so as to prevent the saw blade from cutting too far during use and causing the part to be scrapped. (6.3) Install the base plate on the workbench and align the laser tracking line with the marking line on the base plate; (6.4) After the upper plate, ball bearings, and lower plate of the sawing fixture are assembled, they are then assembled with the base plate to the right end of the base plate by key and screw. The positional relationship between the two is ensured by the screw. After assembly, the upper plate can be easily rotated manually. At this time, the gear shaft to be processed is placed on the upper plate of the fixture, and the positioning pin is inserted to limit the circumferential movement of the gear shaft to be processed. At this time, the laser line, saw blade, base plate marking line, and the left tooth surface of the tooth being cut are on the same straight line. After cutting one tooth, rotate one adjacent hole angle and repeat inserting the positioning pin until all the left tooth surfaces of all batches of gear shafts are cut. (6.5) Move the sawing fixture assembly, including the upper plate, ball bearings, and lower plate, to the left end of the base plate. At this point, the laser line, saw blade, base plate marking line, and right tooth surface of the saw are on the same straight line. Repeat the above steps to complete the processing of the right tooth surface of all parts. (7) Rough milling: Position and clamp according to the rough milling process drawing, align the outer circle and tooth surface of the part, rough mill the tooth part, the single-sided allowance of the tooth surface and tooth root is >4mm, the roughness is Ra12.5; the tooth profiles at both ends and the remaining sharp edges are blunted with C2-2.5; the milling accuracy is checked by three coordinate measuring machines on the first piece; (8) Quenching and tempering: HBW 320-340; parts are mounted vertically in the furnace, and care is taken to control the deformation of the parts; (9) Shot blasting: Shot blasting shall meet the requirements of Sa2.5 grade in GB / T 8923.1-2011; (10) Ultrasonic testing: The ultrasonic testing quality level within 171mm below the gear tooth tip shall not be lower than the requirements of Class II in JB / T5000.15-2007, and the quality level of other parts shall not be lower than Class I. (11) Finish turning: The runout of the outer circles of the two ends of the center 240p6 and center 260p6 is ≤0.01. Finish turn the outer circle dimensions of the oil seals at both ends to center 260 (-0.06 / -0.10) and center 280 (-0.06 / -0.10). Roller 260f8 / center 280f8 to ensure a surface roughness Ra0.8; (12) Precision milling of teeth: 1. Find two relatively far-distance ground outer circle runout ≤0.01, align the tooth surface: precision mill the teeth (tooth profile modification), end face chamfer C1 finished product; verify the tooth profile accuracy on the first piece using a three-coordinate measuring machine; 2. Point holes, drill, tap P-direction view screw holes 4-M12, 2-M16 finished product, right end screw holes 2-M16, 4-M8 screw holes finished product, hole opening chamfer to the major diameter of the thread; (13) Final inspection, demagnetization, cleaning, oil sealing, and warehousing.

[0025] The gears in this invention all use quenched and tempered soft-tooth surface gears. Since the total tooth height is 2.25 or 2.4 times the module, and quenching and tempering presents a hardness gradient issue, to ensure that the final hardness of the entire tooth surface and tooth root meets the drawing requirements, the heat treatment cannot arbitrarily increase the hardness to guarantee the internal hardness requirements of the part, as increasing the hardness also increases the difficulty of machining. This invention plans the machining of such parts by pre-machining the tooth profile before quenching and tempering and then finishing the tooth portion after heat treatment. The specific process route is: forging → normalizing → rough turning → ultrasonic testing → drilling → sawing → rough milling → quenching and tempering → shot peening → ultrasonic testing → finish turning → finish milling.

[0026] This invention fully considers operability. The sawing lines on the left and right tooth surfaces are two parallel lines. Therefore, regardless of whether the left or right tooth surface is sawed, only the same locating pin position is needed to achieve equal circumferential indexing. If they are not parallel, two locating pin positions will be required, i.e., one pin hole position for sawing the left tooth surface and another pin hole position for sawing the right tooth surface. This will cause inconvenience to the operator and create the risk of confusion.

[0027] This invention uses a rotary table sawing fixture to cut the teeth, efficiently removing most of the machining allowance. After sawing, a vertical machining center performs a rough milling cut on the teeth according to the tooth profile diagram to remove the high and sharp points after cutting, which also ensures that the allowance of the teeth is consistent and guarantees the consistency of hardness after heat treatment.

[0028] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformations or substitutions fall within the scope of protection of the present invention.

Claims

1. A tooth profile machining process for a large output gear shaft, characterized in that, The process includes the following steps: forging, normalizing, rough turning, ultrasonic testing, drilling, sawing, rough milling, quenching and tempering, shot peening, secondary ultrasonic testing, finish turning, and finish milling. The sawing step includes the following specific steps: Prepare a toothed processing device, which includes a saw tooth fixture mounted on a vertical band saw (1). The vertical band saw (1) includes a frame, on which a worktable and a band saw blade (3) are mounted. The saw tooth fixture is mounted on the worktable. The saw tooth fixture includes an upper saw tooth fixture plate (5), a lower saw tooth fixture plate (6), and a base plate (9) arranged sequentially from top to bottom. The base plate (9) is mounted on the worktable. The lower saw tooth fixture plate (6) is detachably mounted on the base plate (9). The upper saw tooth fixture plate (5) is rotatably mounted on the lower saw tooth fixture plate (6). The upper plate (5) and lower plate (6) of the sawing fixture are provided with a central hole for fitting the toothed shaft (4) to be processed. The toothed shaft (4) to be processed is detachably connected to the lower plate (6). The top of the frame of the vertical band saw (1) is provided with a laser tracker (2). The colored laser emitted by the laser tracker (2) forms a laser line (10) on the toothed shaft (4) to be processed. The laser tracker (2) is set directly above the band saw blade (3) so that the laser tracker (2) and the band saw blade (3) are on the same axis. The band saw blade (3) cuts along the laser line (10). First, use a U-drill to drill equal-division relief holes at the tooth root position of the gear shaft to be machined. The diameter of the relief holes depends on the size of the tooth root fillet. Before sawing, check that the laser line is aligned with the saw blade and the tooling reference line, confirm that the tooling is clamped correctly, adjust the laser tracker (2) so that the emitted colored laser coincides with the saw blade, and adjust the limit of the sawing machine according to the required feed stroke of the part. Mount the base plate on the workbench and align the laser line with the marking line on the base plate. After the upper plate, ball bearings, and lower plate of the sawing fixture are assembled, they are then connected to the right end of the base plate via keys and screws. The positional relationship between the two is ensured by the screws. After assembly, the upper plate of the sawing fixture can be easily rotated manually. At this time, the gear shaft to be processed is placed on the upper plate of the sawing fixture, and the positioning pin is inserted to limit the circumferential movement of the gear shaft to be processed. At this time, the laser line, saw blade, base plate marking line, and the left tooth surface of the tooth being cut are on the same straight line. After cutting one tooth, rotate one adjacent hole angle and repeat inserting the positioning pin until all the left tooth surfaces of all batches of gear shafts are cut. Move the entire sawing fixture assembly, including the upper plate, ball bearings, and lower plate, to the left end of the base plate. At this point, the laser line, saw blade, base plate marking line, and the right tooth surface being sawed are on the same straight line. Repeat the above steps to complete the processing of all right tooth surfaces. The upper part of the sawtooth tooling lower plate (6) is provided with a circular groove (61), the outer diameter of the circular groove (61) matches the sawtooth tooling upper plate (5), and the bottom of the sawtooth tooling upper plate (5) is set in the circular groove (61); the bottom surface of the sawtooth tooling upper plate (5) is provided with a ring of ball upper groove (51), and the bottom surface of the circular groove (61) is provided with a ring of ball lower groove (62). The position of the ball lower groove (62) corresponds to the ball upper groove (51). When the sawtooth tooling upper plate (5) is set on the sawtooth tooling lower plate (6), the ball upper groove (51) and the ball lower groove (62) form a spherical groove, and a ball (8) is set in the spherical groove, so that the sawtooth tooling upper plate (5) can rotate; The base plate (9) is provided with a base plate marking line (11), and the base plate marking line (11) and the laser line (10) are on the same straight line.

2. The tooth profile machining process for a large output gear shaft according to claim 1, characterized in that: The marking lines on the base plate must have a margin of >6mm on each side of the tooth surface.

3. The tooth profile machining process for a large output gear shaft according to claim 1, characterized in that: The circular groove (61) has a shaft hole at each of its left and right ends, which is used to insert bolts to fix the saw blade fixture lower plate (6) on the base plate (9).

4. The tooth profile machining process for a large output gear shaft according to claim 1, characterized in that: A connecting hole (63) is provided on one side of the circular groove (61), and a through hole is provided on the machined gear shaft (4). A positioning pin (7) is inserted into the through hole, and the bottom of the positioning pin (7) is inserted into the connecting hole (63), so that the saw tooling lower plate (6) and the machined gear shaft (4) can be detachably connected.

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