Design the pump casing of the gear pump model as a closed curve

The geometric model of the external gear pump was established, and the computer program for drawing a single gear was compiled by AutoLISP. In order to facilitate the drawing of the gear, the drawing gear dialog box is designed. When drawing a gear, simply type the draw gear command (Drawgear) on the command line and a dialog box will appear. Enter the known data according to the items in the dialog box to draw the required gear.
Draw a pair of meshing gears. Copy the drawn gears into two with the copy command, and then place the pair of gears at twice the pitch radius of the indexing circle. For the convenience of graphics processing, the two gears should be placed horizontally. Use the rotary command to adjust the two gears to the correct meshing position. Draw the pump body. The two gear tooth top circles are drawn with the center of the two gears as the center, and then the two outer common tangent lines of the two tooth top circles are drawn, and the intersection of the two tooth top and bottom circles is trimmed to form the inner surface curve of the pump casing. The purpose of establishing this model is to calculate the volume and volume change of each cavity in the gear pump. Therefore, the pump casing of the corrosion-resistant and wear-resistant mortar pump model is designed as a closed curve. This model construction is reasonable.
According to the accuracy requirement, the model of the oil pumping area is copied and the gear pump model is copied and placed at a certain interval. That is to say, the area of ​​the oil absorption area is calculated according to the angle of the gear and the volume change of the rotation angle is calculated. Place the geometric model of the gear pump. For example, to calculate the change of the volume of the suction chamber in the range of 36° rotation of the gear, the accuracy is taken to calculate the area of ​​the oil absorption area every time 1°, and the gear pump model is placed.