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3 Rolling straightening method
In machining, rolling processing is often used to improve the surface hardness, fatigue strength and wear resistance of the workpiece, reduce the surface roughness of the workpiece, and prolong the service life of the workpiece. At the same time, in the process of rolling, the metal can be plastically deformed under the action of external force, and the internal stress is changed to straighten the shaft and rod workpiece with better rigidity.
In the process of rolling the workpiece, the rolled workpiece is bent by the unevenness of the surface layer under the action of an external force. The bending center of the rotation is high, the rolling pressure is large, and the plastic deformation is also large, so that the bending degree of the workpiece is further increased. This is especially true when using rigid rolling tools.
The method of rolling straightening is to check the radial runout of the workpiece after the first rolling of the workpiece, the recess is marked, and the recess of the workpiece is adjusted to the height of the center of the machine tool by the four-jaw chuck. , in proportion to the size of the workpiece bending, and then the second rolling, and then use the dial gauge and adjust the claws of the four-jaw chuck to correct the workpiece. Then use the dial gauge to check the bending condition. If it is also bent, use the above method to adjust the workpiece and perform the third rolling until the required straightness of the workpiece is reached. The length of the knife after the second time should be based on the specific circumstances, and it is not necessary to take the full course, but also to use the reverse knife.
Rolling straightening is generally done in the process of rolling the workpiece, which not only does not damage the surface of the workpiece, but also makes the outer surface of the workpiece relatively uniformly rolled, does not cause dead bends, and is easy to operate.
4 screw extrusion straightening method
For the larger diameter and longer length, there are several curved lead screws, which are squeezed and straightened, and the effect is very good.
(1) Working principle. The straightening tool is used to squeeze the surface of the screw bottom under the action of external force, so that the surface of the screw is plastically deformed and extends in the axial direction to change the internal stress state of the screw and make it straight.
(2) Straightening method. First, on the lathe or platform, measure the position and direction of the bending of the screw, and then place the curved recess upwards and the convex surface facing down to the metal pad, as shown in Figure 3-2(a). In the concave (200 ~ 300) mm range, use the special flat shovel and hand hammer shown in Figure 3-2 (b) to hit the screw bottom to deform the metal of the screw diameter to achieve the purpose of straightening. . During the entire straightening process, the bending is detected and the flat shovel is squeezed until the screw is straightened. This method is simple and easy to apply, not only for the size of the screw, but also for the straightening of the shaft blank, it is not easy to recover after straightening.
(3) Problems that should be noted. The size R of the special flat shovel for straightening should be greater than half of the diameter of the root of the screw, b is smaller than the width of the root, α is smaller than the angle of the tooth; the R section that is in contact with the workpiece should be ground out; after straightening, Use a file to level the extruded base.
Knowing the eccentricity e and the outer diameter Φ2 of the workpiece, the inner diameter Φ1, Φ1 = 2e + Φ2 of the clamp sleeve can be obtained. When the inner diameter of the processing fixture sleeve is Φ1, the inner hole accuracy must be paid attention to, so as not to affect the eccentricity dimension accuracy of the workpiece.
In machining, rolling processing is often used to improve the surface hardness, fatigue strength and wear resistance of the workpiece, reduce the surface roughness of the workpiece, and prolong the service life of the workpiece. At the same time, in the process of rolling, the metal can be plastically deformed under the action of external force, and the internal stress is changed to straighten the shaft and rod workpiece with better rigidity.
In the process of rolling the workpiece, the rolled workpiece is bent by the unevenness of the surface layer under the action of an external force. The bending center of the rotation is high, the rolling pressure is large, and the plastic deformation is also large, so that the bending degree of the workpiece is further increased. This is especially true when using rigid rolling tools.
The method of rolling straightening is to check the radial runout of the workpiece after the first rolling of the workpiece, the recess is marked, and the recess of the workpiece is adjusted to the height of the center of the machine tool by the four-jaw chuck. , in proportion to the size of the workpiece bending, and then the second rolling, and then use the dial gauge and adjust the claws of the four-jaw chuck to correct the workpiece. Then use the dial gauge to check the bending condition. If it is also bent, use the above method to adjust the workpiece and perform the third rolling until the required straightness of the workpiece is reached. The length of the knife after the second time should be based on the specific circumstances, and it is not necessary to take the full course, but also to use the reverse knife.
Rolling straightening is generally done in the process of rolling the workpiece, which not only does not damage the surface of the workpiece, but also makes the outer surface of the workpiece relatively uniformly rolled, does not cause dead bends, and is easy to operate.
4 screw extrusion straightening method
For the larger diameter and longer length, there are several curved lead screws, which are squeezed and straightened, and the effect is very good.
(1) Working principle. The straightening tool is used to squeeze the surface of the screw bottom under the action of external force, so that the surface of the screw is plastically deformed and extends in the axial direction to change the internal stress state of the screw and make it straight.
(2) Straightening method. First, on the lathe or platform, measure the position and direction of the bending of the screw, and then place the curved recess upwards and the convex surface facing down to the metal pad, as shown in Figure 3-2(a). In the concave (200 ~ 300) mm range, use the special flat shovel and hand hammer shown in Figure 3-2 (b) to hit the screw bottom to deform the metal of the screw diameter to achieve the purpose of straightening. . During the entire straightening process, the bending is detected and the flat shovel is squeezed until the screw is straightened. This method is simple and easy to apply, not only for the size of the screw, but also for the straightening of the shaft blank, it is not easy to recover after straightening.
(3) Problems that should be noted. The size R of the special flat shovel for straightening should be greater than half of the diameter of the root of the screw, b is smaller than the width of the root, α is smaller than the angle of the tooth; the R section that is in contact with the workpiece should be ground out; after straightening, Use a file to level the extruded base.
Knowing the eccentricity e and the outer diameter Φ2 of the workpiece, the inner diameter Φ1, Φ1 = 2e + Φ2 of the clamp sleeve can be obtained. When the inner diameter of the processing fixture sleeve is Φ1, the inner hole accuracy must be paid attention to, so as not to affect the eccentricity dimension accuracy of the workpiece.
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