Spur Gears KHK Gears. Tooth Forms. This article is reproduced with the permission. Masao Kubota, Haguruma Nyumon, Tokyo Ohmsha, Ltd., 1. General Tooth Form. The tooth form of spur gears is normally shown as a plane curve on the cross section perpendicular to the shaft. Nv8skZZcUlw/maxresdefault.jpg' alt='Drawing Of Spur Gear In Autocad' title='Drawing Of Spur Gear In Autocad' />Therefore, instead of pitch cylinder, pitch circle is used. The contact point of the two pitch circles is called the pitch point. The pitch point is the point that the two pitch circles touch in rolling contact so that it is the spot that has no relative motion between the gears or, in other words, the instantaneous center of relative motion. In Figure 2. 1 where the pitch point is P, the contact point of the two gears is C, consider the common normal of the two tooth forms CN and the common tangent CT. Figure 2 1 Necessary Conditions Of Tooth Form Mechanics. In order for the two tooth forms not to separate or to run into each other as they rotate, there can be no relative motion in the direction of the common normal. That is, the velocity component must be equal. However, there is no problem if there is relative motion in the direction of the common tangent. That is, there can be a different velocity component, which is the sliding between the tooth forms and the difference of the velocity components, vs, is the relative sliding speed. Therefore, the relative motion at the contact point C is limited to the direction of the common tangent CT. However, as well known in kinematics, the instantaneous center of relative motion is in the straight line perpendicular to the direction of the relative motion. Therefore, The common normal CN at the contact point C of the two tooth forms must go through the contact point of the pitch circles, that is, the pitch point P instantaneous center. This is called the necessary conditions of tooth form mechanics which was attributed to Camus in 1. How To Break Into Windows Xp Account here. France and forms the foundation of tooth form theory. As long as a curve satisfies this condition, and the two tooth bodies do not interfere with each other, it can be used as a tooth form. Figure 2. 2 Cycloidal Curve. For example, as shown in Figure 2. O1 and O2 are externally touching, and when the circle Or. O2, rolls while contacting the two pitch circles at pitch point P, consider the traces F1 and F2 that a point C draw on the gears. The pitch point P is the instantaneous center of relative motion of the two pitch circles and circle Or. CP becomes the common normal of the traces F1  and F2. Puerto Rican Domino Games here. A Commerce spokesperson told Gizmodo the tweet was deleted out of an abundance of caution as the department was not clear it had received permission to post the. Drawing Of Spur Gear In Autocad' title='Drawing Of Spur Gear In Autocad' />TVET Skills Accreditation and Certification. Licensing of ITE TVET Courses TVET curriculum Training materials Assessment and exams Certification by ITE ITEES. This video explains how to draw an involute profiled teeth spur gear using AutoCAD. Its a graphical method by which you can draw almost correct involute. Issuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. Easily share your publications and get. Check design Software Free Download check design Top 4 Download Top4Download. Windows, Mac, iOS and Android computers and. Therefore, F1 and F2 satisfy the necessary conditions of the tooth form mechanics. As a result, F1 can be used as the tooth form outside of the pitch circle of gear 1 and similarly F2  for gear 2. It should be noted that when the radius of the rolling circle Or. O2, there is no interference. The curve F1 is called epicycloid while F2 is called hypocycloid. This kind of gear is called cycloidal gear. Similarly, think of rolling circle Or. O1, then we can obtain the tooth form inside pitch circle of gear 1, F1 hypocycloid and tooth form inside pitch circle of gear 2, F2 epicycloid. In general, using the pitch circle as the border, the tooth surface close to the toe of the tooth is called tooth face, and the tooth surface close to the heel, tooth flank. Drawing Of Spur Gear In Autocad' title='Drawing Of Spur Gear In Autocad' />Figure 2. Cycloidal Gear. The externally contacting cycloidal gears tooth face is epicycloids, and the tooth flank is cycloid. As the circle Or. Figure 2. 3, when the rolling circles diameter is equal to its internally contacting pitch circles radius, the hypocycloid that results becomes the diagonal straight line when less than the radius, concave in looking from the pitch point and convex when greater than the radius. The tooth form curve of a rack paired with a cycloidal gear is when the pitch circle becomes a straight line and is called the common cycloid. The trace point C may not always be on the rolling circle. When the point C is inside or outside of the rolling circle, the tooth form is called trochoid. In case of a cycloidal gear tooth form or a trochoidal tooth form, when the rolling circle and its internally contacting circle is matching, point C becomes the one sides equivalent to hypocycloid tooth form. This is called point tooth form. Next, if the circular arc with point C as its center concave or convex is used as the tooth form, the mating tooth form becomes the curve equidistant at radius equal to the arc with cycloidal or trochoidal arc of point C. Figure 2. 4 shows one kind of such gears when one side of the pair uses pins and called a pin gear. Drawing Of Spur Gear In Autocad' title='Drawing Of Spur Gear In Autocad' />Figure 2. One Kind Of Pin Gear. By generalizing the cycloidal and trochoidal gear forms, instead of a rolling circle, using any curve with its curvature greater than the interior contacting circle, regardless of the pitch circle, mutually meshing same system tooth forms can be obtained as the trace of the common contact point. Also, instead of the pitch circle, by considering arbitrary curves which are in mutually rolling contact as the pitch curves, their trace points lead to tooth forms of non circular gears. The aforementioned cycloidal and pin gears were often used in the early stages of gear development, but now they are very limited in their use such as in clocks, and general machine industries mainly use involute gears which are discussed next. Involute Tooth Form. An involute curve is produced by the trace of any point on a non stretchable string which is wound on a circle as it is unwound under tension. It is the involute of a circle. The following is the explanation of why this curve is suitable as a tooth form. Figure 2. 5 Involute Tooth Form. As shown in Figure 2. B1  diameter dg. B2  diameter dg. C CI or CII on the belt whose traces of the points F1  and F2 are clearly involute curves. If these are considered to be the tooth forms and if the points I1 and I2 are the points where the belt leaves the belt circles, then the straight lines CI1 and CI2  are, by the nature of involute curve, normal to respective tooth forms F1 and F2. If the intersection of the line I1 I2 and the center line O1 O2 is point P,O1. A gear drawing is a type of important technical reference required when designing machines. When a machine designer requires a gear when designing a new machine. PO2. P dg. 1 dg. Therefore,     O1. P 1  O2. P 2and point P is the pitch point. Thus, the necessary conditions of the tooth form mechanics are satisfied and point C is the contact point with its trace becoming a part of the straight line I1. PI2. Also, points I1 and I2, due to the nature of involute curve, are respectively the centers of curvature of the tooth forms F1 and F2, thus there will be no interference at contact points. The contours of these belt wheels, circles B1  and B2, are called base circles, the common tangent to the base circles, I1. PI2, is the line of action, and the angle  formed by the line of action and the common tangent of the pitch circles, PX, at the pitch point is called the pressure angle. If we assume the center distance O1. O2 is A and d. 1 and d. A,   d. 1 dg. 1 sec ,   d. The values of pressure angle  most commonly used are 2. The line of action indicates the direction of the force acting normal to the tooth surface. Ignoring friction force, if the transmitted torque of i wheel is Ti and the radius of pitch circle is Ri, then, the normal tooth surface load F is expressed as F Ti Ri  cos At the same time, this becomes the radial load on the axis. Therefore, with the same transmitted torque, the larger the pressure angle, the greater the normal force on the tooth surface and consequently on the shaft.