Gear and rack transmission is suitable for large stroke, high precision, and high torque transmission. In the field of CNC machine tools and automation, it is widely used. What are the advantages of belt transmission and trapezoidal screw transmission compared to traditional transmission methods? This article provides a brief analysis, taking the precision rack accuracy characteristics of Taiwan T-win as an example to compare and introduce traditional transmission methods.

(1) Due to the straight tooth profile of the rack, each point on the tooth profile has the same pressure angle and is equal to the inclination angle of the tooth profile. This angle is called the tooth profile angle, with a standard value of 20 °.

(2) Any straight line parallel to the tooth crest has the same tooth pitch and modulus.

(3) The straight line parallel to the tooth crest line and with a tooth thickness equal to the width of the tooth groove is called the indexing line (centerline), which is the reference line for calculating the size of the gear rack.

Introduce the method of eliminating errors in the teeth of precision rack shafts and the method of turning precision rack shafts, which is not only simple but also capable of eliminating errors. In order to overcome the inconvenience and often error prone phenomenon of machining the teeth of the rack and pinion shaft on lathes in the past, the method introduced in this article can be used to accurately eliminate cumulative errors and improve machining efficiency. In the past, when machining the teeth of the rack and pinion shaft on a lathe, a small drag plate was used to move one tooth pitch and cut one tooth. The number of grids on the micrometer clamp for each tooth pitch was calculated, which was a decimal and very troublesome, often prone to errors, and prone to cumulative errors in tooth pitch. In order to overcome the above phenomenon, the screw pitch of the small drag plate is changed to be the same as the pitch of the precision gear rack, and a thread of screw nut is added. This way, as long as the tooth pitch is moved slightly, the gear rack tip is ensured, and the drag plate screw rotates once, the tool accurately eliminates accumulated errors and improves processing efficiency.

Introduction to various technical indicators of gear racks

1. Determine the modulus m based on the load (refer to the value of m in the Mechanical Design Manual)

2. Determine the diameter D of the indexing circle of the driven gear, where D=m * z (where z is the number of teeth in the gear)

3. The number of teeth in a gear needs to be comprehensively considered based on the torque and structure of the load. When the torque is high, the number of teeth in the gear can be slightly larger, resulting in a larger gear diameter. Conversely, the diameter can be made smaller. Remember the key formula above: D=m * z, this is an important formula

4. After determining the diameter D of the gear rack's indexing circle, the circumference of the indexing circle diameter can be calculated, assuming L

5. L is the effective length of the rack. Considering the operation and installation of this rack, the actual length should generally be greater than L. The specific amount should be considered in the structural design.