1 Manufacturing of the scraper before scraping 2 Manufacturing of double arc negative rake angle scraping hob 2.1 Test of scraping hob negative rake angle According to the experience of involute scraping hob blade material, we chose Zigong hard The material of the alloy plant (code 726); because the blade of this material has good wear resistance and high strength, hardness and toughness.
Because the non-working part of the tooth root is small when the double circular arc gear meshes, the hob tooth top of the double arc carbide hob is inevitably involved in cutting. In the face of this reality, we have carried out some simple tests. .
1) Test workpiece: waste gear shaft, material 20CrNi2Mo; carburizing and quenching 58HRc; tooth outer diameter 240mm.
2) Test machine: C6303) Test tool: welding tool, blade material 726, tool nose radius R2, back angle 6, change the negative rake angle and cutting amount, interrupted cutting, test conditions.
We estimate that the cutting thickness of the scraper hob does not exceed 0.2mm, so the cutting depth t=0.2mm is selected, and the single-side cutting thickness is between 0.10.25mm, so the cutting amount is s=0.24mm.
From the table, the tool rake angle 15 is optimal, so the negative rake angle of the scraping hob is -15.
2.2 Blade welding Considering that there are not many blades during the trial production, it is uneconomical to order the blade with the shape of the coordinate point of the front blade surface. Therefore, the appropriate size of the involute scraping blade is selected, and the wire is cut into the same. Need to shape the residual blade (select m7, -30 front angle involute scraping hob blade, special model is T87073). After the welding surface is ground flat, the CNC wire is cut into a double-arc toothed blade with a 0.2 mm circumference of the front blade. The bottom projection is 55mm and is used for welding positioning.
Using 105 solder, high-frequency manual clamp welding, the welding temperature is gradually increased from low to high to 900 (allowing the blade to have a temperature diffusion time). If the temperature rises too fast, the blade will be cracked due to the large temperature difference between the blades and the increase in the amount. Immediately after the welding, 250260 tempering, the time is 35h, preferably with the furnace cooling, eliminating the welding stress. Based on our years of experience in welding involute carbide scraping hobs, this soldering and soldering method provides reliable soldering strength.
2.3 Precision grinding of the front edge of the hob To ensure the accuracy of the hob, the type of grinding machine imported from Germany AGW482 is used. The deviation value is e19.41mm, the deviation is controlled at 0.01mm; the adjacent error of the chip pocket is not more than 0.02. Mm, the cumulative error of the chip pocket is within 0.031mm; the surface roughness Ra0.4.
2.4 Tooth shovel grinding Because the tooth shape is shaped and shaped, in order to trim the grinding wheel shape to fully calibrate the hob tooth shape, we have selected synthetic diamond RVD, particle size 150, concentration 100, resin binder B. And forming special diamond grinding wheels. In order to facilitate the trimming, four kinds of grinding wheels, such as a circular arc, a convex arc, a concave arc and a transition arc, are respectively processed, and the corresponding arc shapes of the hob tooth shape are respectively processed.
The labeling order of the shovel order of each arc segment of the tooth shape, each label has a corresponding template, and the template controls the grinding surface based on the ground surface and is associated with each other. Finally, check the enlarged picture of the computer drawing on the projector. When the sample, tooth height, tooth thickness measurement, and projection inspection, all three types meet the requirements, the tooth shape is qualified.
2.5 Manufacturing precision m6 double arc carbide scraping hob manufacturing precision main items, required tolerances and actual test values.
3Rolling test m6 double arc hard alloy hob rolling test was carried out at Zhengzhou Machinery Research Institute. The gear material of the test piece was 20CrNi2Mo, the heat treatment hardness was 56HRc after carburizing and quenching, and the single side scraping amount was 0.15mm.
As a result of scraping, the cutter teeth have no desoldering and chipping; the length of one sharpening cutting is more than 80m, the maximum wear after the teeth is not more than 0.02mm; the tooth surface roughness of the workpiece is close to Ra0.8m.
Because the non-working part of the tooth root is small when the double circular arc gear meshes, the hob tooth top of the double arc carbide hob is inevitably involved in cutting. In the face of this reality, we have carried out some simple tests. .
1) Test workpiece: waste gear shaft, material 20CrNi2Mo; carburizing and quenching 58HRc; tooth outer diameter 240mm.
2) Test machine: C6303) Test tool: welding tool, blade material 726, tool nose radius R2, back angle 6, change the negative rake angle and cutting amount, interrupted cutting, test conditions.
We estimate that the cutting thickness of the scraper hob does not exceed 0.2mm, so the cutting depth t=0.2mm is selected, and the single-side cutting thickness is between 0.10.25mm, so the cutting amount is s=0.24mm.
From the table, the tool rake angle 15 is optimal, so the negative rake angle of the scraping hob is -15.
2.2 Blade welding Considering that there are not many blades during the trial production, it is uneconomical to order the blade with the shape of the coordinate point of the front blade surface. Therefore, the appropriate size of the involute scraping blade is selected, and the wire is cut into the same. Need to shape the residual blade (select m7, -30 front angle involute scraping hob blade, special model is T87073). After the welding surface is ground flat, the CNC wire is cut into a double-arc toothed blade with a 0.2 mm circumference of the front blade. The bottom projection is 55mm and is used for welding positioning.
Using 105 solder, high-frequency manual clamp welding, the welding temperature is gradually increased from low to high to 900 (allowing the blade to have a temperature diffusion time). If the temperature rises too fast, the blade will be cracked due to the large temperature difference between the blades and the increase in the amount. Immediately after the welding, 250260 tempering, the time is 35h, preferably with the furnace cooling, eliminating the welding stress. Based on our years of experience in welding involute carbide scraping hobs, this soldering and soldering method provides reliable soldering strength.
2.3 Precision grinding of the front edge of the hob To ensure the accuracy of the hob, the type of grinding machine imported from Germany AGW482 is used. The deviation value is e19.41mm, the deviation is controlled at 0.01mm; the adjacent error of the chip pocket is not more than 0.02. Mm, the cumulative error of the chip pocket is within 0.031mm; the surface roughness Ra0.4.
2.4 Tooth shovel grinding Because the tooth shape is shaped and shaped, in order to trim the grinding wheel shape to fully calibrate the hob tooth shape, we have selected synthetic diamond RVD, particle size 150, concentration 100, resin binder B. And forming special diamond grinding wheels. In order to facilitate the trimming, four kinds of grinding wheels, such as a circular arc, a convex arc, a concave arc and a transition arc, are respectively processed, and the corresponding arc shapes of the hob tooth shape are respectively processed.
The labeling order of the shovel order of each arc segment of the tooth shape, each label has a corresponding template, and the template controls the grinding surface based on the ground surface and is associated with each other. Finally, check the enlarged picture of the computer drawing on the projector. When the sample, tooth height, tooth thickness measurement, and projection inspection, all three types meet the requirements, the tooth shape is qualified.
2.5 Manufacturing precision m6 double arc carbide scraping hob manufacturing precision main items, required tolerances and actual test values.
3Rolling test m6 double arc hard alloy hob rolling test was carried out at Zhengzhou Machinery Research Institute. The gear material of the test piece was 20CrNi2Mo, the heat treatment hardness was 56HRc after carburizing and quenching, and the single side scraping amount was 0.15mm.
As a result of scraping, the cutter teeth have no desoldering and chipping; the length of one sharpening cutting is more than 80m, the maximum wear after the teeth is not more than 0.02mm; the tooth surface roughness of the workpiece is close to Ra0.8m.
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