Design strategy for low flow pulsation and low noise of FCB stainless steel gear

FCB stainless steel gear pump, as a fluid conveying equipment, has strict requirements for flow stability and operational quietness in chemical, food, medical and other areas. Due to the gear meshing characteristics, conservative gear pumps are prone to flow pulsation and mechanical noise. Therefore, it is necessary to achieve low pulsation and low noise operation goals through structural innovation, material optimization, and control technology upgrades.

1、 Optimization of gear geometric parameters

1. Improvement of tooth profile curve

Replace the standard involute tooth profile with an involute cycloid composite tooth profile. The involute segment determines the continuity of gear meshing, while the pendulum segment reduces meshing impact through circular arc transition. This composite tooth profile smoothly transitions from the tooth tip to the tooth root when the gear enters meshing, avoiding sudden pressure changes caused by rigid collisions. After a certain enterprise applied this tooth profile, the flow pulsation amplitude of the pump was significantly reduced, and the stability of the output fluid was improved.

2. Strategy for improving coincidence degree

By increasing the number of gear teeth or reducing the modulus, the coincidence degree can be improved. A better degree of coincidence means that the number of teeth participating in meshing increases, and the load distribution of a single pair of teeth becomes more uniform, which can weaken the periodic fluctuations of flow rate. It is necessary to balance the coincidence degree and gear strength to avoid insufficient bending strength of the tooth root due to too many teeth. In the renovation of a hydraulic system, increasing the number of gear teeth appropriately resulted in a significant decrease in the noise level of the pump.

3. Application of shaping technology

Perform shaping treatment on the gear end face and tooth orientation. End face modification can compensate for axial thermal deformation of gears and prevent flow fluctuations caused by changes in axial clearance; Tooth profile modification can improve the contact state of gear pairs and reduce vibration caused by edge contact. After a certain food processing enterprise adopted the tooth drum shape modification, the smooth operation of the pump was significantly improved, and the shear stress distribution of the conveyed liquid became more uniform.

2、 Optimization of structural dynamic characteristics

1. Pump body stiffness

Adopting an integral stainless steel pump body structure instead of a split type. The pump body cast as a whole has higher structural stiffness, which can control the vibration transmission caused by gear meshing. Install additional ribs at key parts of the pump body to further enhance local stiffness and avoid resonance phenomena. After a certain equipment supplier switched to using an integral pump body, the vibration amplitude of the pump was significantly reduced, and the noise radiation was controlled.

2. Optimization of bearing system

Choose high-precision angular contact ball bearings instead of ordinary rolling bearings. Angular contact bearings can simultaneously withstand radial and axial forces, reducing axial displacement of the gear shaft and minimizing flow pulsation caused by axial displacement. By optimizing the pre tightening force of the bearing, the bearing is in optimal working condition, extending its service life while reducing operating noise. The supporting pump of a certain instrument has achieved long-term stable operation through bearing upgrade.

3. Vibration isolation application

Install elastic vibration isolation components between the pump body and the installation base. Rubber isolation pads or metal spring isolators can isolate high-frequency vibrations and prevent them from being transmitted to the foundation. For demanding situations, active vibration isolation technology can be used to monitor vibration signals in real time through sensors, drive the actuator to generate reverse vibration, and achieve vibration cancellation. After the application of active vibration isolation system in a certain semiconductor production equipment, the impact of pump vibration on the process has been basically eliminated.

3、 Improved fluid dynamics performance

1. Improvement of suction chamber structure

Optimize the geometry of the suction chamber to reduce local resistance when fluid enters the gear chamber. Adopting a tapered suction pipeline to uniformly increase fluid velocity and avoid vortex generation due to sudden changes in flow velocity. Install a guide plate in the suction chamber to smoothly guide the fluid into the gear meshing area and reduce suction resistance. After the renovation of a certain chemical process pump, the suction performance has significantly improved and the cavitation phenomenon has been controlled.

2. Discharge chamber pressure balance

Discharge chamber pressure balancing mechanism to remove pressure shock caused by trapped oil phenomenon. By setting pressure relief slots or balance holes in the pump body, the trapped oil area is connected to the discharge chamber to balance pressure fluctuations. After adopting a balance hole in a certain hydraulic power unit, the amplitude of pressure pulsation in the discharge is significantly reduced, and the system stability is improved.

3. Fluid shear control

Optimize the matching relationship between gear speed and medium viscosity to reduce fluid shear stress. For high viscosity media, reducing the rotational speed appropriately can reduce shear heating and energy loss; For low viscosity media, it is necessary to reduce gear clearance and prevent internal leakage by improving machining accuracy. After adjusting the operating parameters of a certain lubrication system based on the characteristics of the medium, the pump speed significantly increased.

4、 Determination of assembly accuracy

1. Processing technology

Using CNC gear grinding technology to process gears, ensuring tooth profile accuracy and surface roughness. Good precision gears can reduce meshing errors and lower operating noise. Polish the pump body flow channel to reduce fluid resistance and minimize vortex generation. A certain equipment manufacturer has improved the processing accuracy to achieve industry-leading noise indicators for pumps.

2. Assembly process control

Strictly follow the cleaning assembly specifications to prevent impurities from entering the gear chamber. Use a torque wrench to control the tightening force of bolts and determine the connection of each component. After assembly, conduct no-load and load test runs, monitor vibration and noise indicators, and rework and adjust non-conforming products. A company with strict quality control has significantly improved the first pass rate of its products through meticulous assembly.

3. Dynamic balance correction

Perform dynamic balancing tests on gear components to eliminate vibrations caused by mass eccentricity. By installing balance weights on the gear end face and adjusting the mass distribution, the remaining unbalance is controlled within the allowable range. After implementing dynamic balance correction, a certain pump manufacturer significantly increased the critical speed of the pump and enhanced its operational stability.

The low flow pulsation and low noise of FCB stainless steel gear pump need to be optimized from multiple dimensions such as gear geometry, structural dynamics, fluid dynamics, and assembly. Through process improvement, it is possible to achieve good accuracy and low noise requirements for fluid transportation equipment in the region, promoting technological progress in the industry.