1.Screw air compressor host yin and yang rotor line characteristics

Twin screw air compressor is the contact line when the compressor's yin and yang rotor meshing, the two rotor tooth surface contact with each other to form a space curve.

The actual air compressor due to the presence of interdental gaps, the theoretical line of contact evolved into the actual gap zone, because the yin and yang screw tooth surface, the contact point in the line at this moment in the state of engagement, the screw tooth surface On the contact line along the smallest gap between the teeth. The most critical part in the screw compressor is a pair of intermeshing screw rotors. The intercept line of the rotor tooth surface perpendicular to the rotor axis is called the screw rotor line. As the rotor profile for helical movement to form the rotor's tooth surface, so again the rotor profile is called face profile or rotor profile. The rotor-and-rotor design of screw compressors meets the conjugate meshing law, where the common normal, passing through the contact point of the profile, must pass through the node, regardless of position.

In fact, the screw air compressor's tooth surface is mainly used for compressed gas, the use of the yin and yang two screw grooves and teeth intermesh to form a cavity, its yin and yang rotor does not contact between the two power transmission It is done by synchronizing the gear. In addition to the screw rotor tooth profile to meet the conditions of conjugation and ease of processing, it must have a good axial and transverse air tightness and larger volume and larger exhaust port. Therefore, the screw air compressor rotor profile usually point, straight line, cycloid, arc, ellipse and parabola and other multi-segment curve connected end to end composition; screw air compressor design, the most important is the design of the rotor line, Rotor profile basically determines the performance of the screw air compressor is good or bad.

2, screw yin and yang rotor meshing gap adjustment method

Screw air compressor screw installation gap ratio is controlled by the synchronous gear control. The main gear and the driven gear of the synchronous gear are respectively the male rotor and the female rotor with the same pitch circle. Since there is no adjustability between the driving gear and the male rotor after installation, they can be regarded as a whole gear; Ring and backlash ring gear are set in the hub, when the hub and the installation between the negative rotor position, the two ring gear with respect to the hub and the negative rotor is still adjustable.

For a particular gear pair, when the center distance is fixed, the gear meshing backlash is determined by the characteristics of the gear itself. Similarly, for a screw compressor yin and yang rotor meshing, ignoring the sliding bearing clearance on the center distance of minor effects, the total screw engagement gap should also be a certain value. In the maintenance process to adjust the screw clearance to maintain the negative rotor fixed, fine-tuning driven gear ring, its essence is to change the synchronous gear driven gear ring and the negative screw rotor circumferential positioning installation angle, so that the negative , The initial phase angle of the male screw is slightly changed, and the redistribution of chase-surface clearance and non-chase-surface clearance on the screw rotor node is realized.

According to theoretical analysis and practical maintenance experience summary, to make the screw installation clearance ratio reaches the specified range, the following adjustment of the driven ring gear as follows:

(1) Loosen the fastening bolt and dowel pin between the driven gear ring and the hub to make it flexible.

(2) Check the total gap of the tooth surface with a dial indicator or feeler gauge, closely contact the yin and yang rotor through the crank and accurately measure the total clearance of yin and yang rotor engagement.

(3) Calculate the value of chase clearance with the desired clearance ratio and total clearance, and then clamp the feeler with equal or similar value to chase clearance in the chase engagement area of the yin and yang rotor by the crank. During adjustment, use a copper rod to hit the screw on the synchronizing gear until the feeler is compressed.

(4) Turn the driven gear ring to the position just in engagement with the driving gear, taking care that the gear backlash must be completely vacant on one side of the engaging teeth and tighten the fastening bolt between the driven gear ring and the hub.

(5) Extracting the feeler between the yin and yang rotor, the gap at this time is the meshing clearance of the yin and yang rotor tooth surface. However, to be on the safe side, it is necessary to check the engagement of each part of the rotor gap.

Screw air compressor yin and yang rotor meshing the total gap larger, so the installation of clearance ratio adjustable range is larger. In general, the screw installation clearance ratio should be controlled at 08 ~ 12. In fact, high-speed air compressor operation, due to torsional deformation of the shaft and gear tooth surface wear and tear and other reasons, tend to narrow the surface clearance, non-chase clearance tends to Increase. In order to ensure the long-term reliable operation of the compressor, when repairing and assembling, the clearance of the chase face will be larger and the ratio of non-chase face clearance will be smaller so that the ratio of chase face and non-chase face gap falls between 1.0 and 1.2 Reasonable.

3, concluding remarks

The adjustment of screw air pressure tooth surface clearance is the most crucial step in the entire maintenance. It is directly related to the normal operation of the air compressor. It is a meticulous and difficult task, sometimes requiring repeated adjustment to meet the requirements. The method presented in the paper changes the traditional idea, using reverse thinking, giving the initial phase of the rotor in advance, and then adjusting the driven gear ring to close engagement with the driving gear and fastening with a fastening bolt. Under normal circumstances, this method can be directly satisfied screw clearance ratio, reducing the measurement gap and adjust the driven gear ring time, effectively reducing the inspection cycle.