When we design a threaded injection Mold, a straight rack is often used, and we can directly call it with an external hanger.
However, what if there is no plug-in or something goes wrong with the plug-in?
Or, don’t want to use external paintings, but want to understand the principles and parameters of painting racks. Now I will talk about how to draw a rack.
First draw the rack, you must first understand its main parameters (the same is true for gears).
- 1. Modulus (represented by m).
- 2. Pressure angle (indicated by a, the current general standard is 20 degrees).
- 3. The number of teeth (indicated by Z).
- 4. Diameter of the index circle (indicated by D).
Modulus = number of teeth/diameter of the index circle, the pressure angle is generally a standard value of 20 degrees, of course, other degrees can be used as needed.
Modulus, pressure angle, and number of teeth are the three basic parameters of gears. Of course, there are also tooth height, tooth thickness, and tooth pitch.
Tooth root height=1.25*modulus
In addition, please note that whether it is a gear or a rack, there must be a top clearance when they are matched, and don’t stick it too hard.
Drawing a rack is the same as a gear, but the diameter of the pitch circle of the rack is infinite.
Based on the previous information, I believe everyone will draw racks.
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