Dwinauto's Mechanical Gear Stencil Cutting Machine
Date：2022/4/28 9:16:30 / Read： / Source：本站
Dwinauto's Mechanical Gear Stencil Cutting Machine
Formation of involutes and their properties
To draw an involute with a rope: from a cylinder (i.e. the base cylinder) a wound rope
Unfold, tie with a pencil to the end of the cord. Pull the rope taut (to make it a straight line) as it unfolds and the pencil will draw a circular involute. This means: All points on a straight line rolling on a circle (the so-called occurrence line) can describe the same involute. Therefore. The radius of the base circle, r, is determined by a single value in the involute period. The base point of the occurrence line on the base height is the center of curvature of the involute at the relevant point Y. Therefore, the tooth normal (= contact normal) is always in line with the base circle. cut.
In fact, the tooth profile is usually machined with a tool that has or can replicate the flat meshing tooth profile, where the flat meshing tooth gallery is a rack tooth profile with only straight teeth and trapezoidal teeth. The tool rolls with its pitch line on the machining pitch circle of the gear to be manufactured; the machining pitch circle can be the base circle, or a circle outside the base circle. While the tool is rolling, there is a cutting motion (shaping motion, milling motion, grinding motion) in the vertical direction of the graphic plane, that is to say, the cutting motion is completed in the direction of the tooth profile. At this time, the tooth profile is used as the cutting tool. generated by the envelope of the blade. The tooth top edge or the tooth top edge fillet of the tool also draws a "figure 8" involute (trochoid), forming the gear tooth root fillet. This trochoid is located outside the base circle, or is tangent to the involute; or (when the number of teeth is small) intersects with it, so there is an "undercut". www.dwinauto.com
The characteristics of open wire meshing are:
(1) Simple and economical machining can be performed with a hobbing tool with a straight edge profile.
(2) It can transmit the motion uniformly, even when the center distance deviates from the theoretical value (it can be imagined as: the contact normal must be tangent to the two base circles; it is like a very tight belt, from the One base circle wraps around the other base circle.
(3) Since the direction of the contact normal line does not change when the center distance is fixed, the meshing angle is also constant, and the meshing line is a straight line.
(4) The same tool can be used for all tooth numbers; it has the characteristics of group gears.
(5) When the number of teeth is the same, different tooth shapes and center distances can be obtained with the same tool through displacement.
(6) During meshing, the direction and magnitude of the tooth normal force (equal to the force on the bearing) remains the same as the direction of the contact normal (this is very important for low-vibration operation).
(7) For external meshing, the shape of the tooth profile is always convex (the closeness is poor, which is not good for contact stress, but it is good for processing), while for the internal gear, the shape of the tooth profile is concave (that is, in the When the gears are paired, the close condition is good).
(8) When the number of teeth is small (less than 10~30), the part of the tooth profile that is close to the base circle and the radius of curvature is small, the gear teeth are sometimes weakened due to undercutting, and the degree of coincidence is sometimes small. All in all, involute meshing has so many advantages that it is almost always used in machine manufacturing. www.dwinauto.com
Formation of involutes and their properties
To draw an involute with a rope: from a cylinder (i.e. the base cylinder) a wound rope
Unfold, tie with a pencil to the end of the cord. Pull the rope taut (to make it a straight line) as it unfolds and the pencil will draw a circular involute. This means: All points on a straight line rolling on a circle (the so-called occurrence line) can describe the same involute. Therefore. The radius of the base circle, r, is determined by a single value in the involute period. The base point of the occurrence line on the base height is the center of curvature of the involute at the relevant point Y. Therefore, the tooth normal (= contact normal) is always in line with the base circle. cut.
In fact, the tooth profile is usually machined with a tool that has or can replicate the flat meshing tooth profile, where the flat meshing tooth gallery is a rack tooth profile with only straight teeth and trapezoidal teeth. The tool rolls with its pitch line on the machining pitch circle of the gear to be manufactured; the machining pitch circle can be the base circle, or a circle outside the base circle. While the tool is rolling, there is a cutting motion (shaping motion, milling motion, grinding motion) in the vertical direction of the graphic plane, that is to say, the cutting motion is completed in the direction of the tooth profile. At this time, the tooth profile is used as the cutting tool. generated by the envelope of the blade. The tooth top edge or the tooth top edge fillet of the tool also draws a "figure 8" involute (trochoid), forming the gear tooth root fillet. This trochoid is located outside the base circle, or is tangent to the involute; or (when the number of teeth is small) intersects with it, so there is an "undercut". www.dwinauto.com
The characteristics of open wire meshing are:
(1) Simple and economical machining can be performed with a hobbing tool with a straight edge profile.
(2) It can transmit the motion uniformly, even when the center distance deviates from the theoretical value (it can be imagined as: the contact normal must be tangent to the two base circles; it is like a very tight belt, from the One base circle wraps around the other base circle.
(3) Since the direction of the contact normal line does not change when the center distance is fixed, the meshing angle is also constant, and the meshing line is a straight line.
(4) The same tool can be used for all tooth numbers; it has the characteristics of group gears.
(5) When the number of teeth is the same, different tooth shapes and center distances can be obtained with the same tool through displacement.
(6) During meshing, the direction and magnitude of the tooth normal force (equal to the force on the bearing) remains the same as the direction of the contact normal (this is very important for low-vibration operation).
(7) For external meshing, the shape of the tooth profile is always convex (the closeness is poor, which is not good for contact stress, but it is good for processing), while for the internal gear, the shape of the tooth profile is concave (that is, in the When the gears are paired, the close condition is good).
(8) When the number of teeth is small (less than 10~30), the part of the tooth profile that is close to the base circle and the radius of curvature is small, the gear teeth are sometimes weakened due to undercutting, and the degree of coincidence is sometimes small. All in all, involute meshing has so many advantages that it is almost always used in machine manufacturing. www.dwinauto.com
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