Abstract: This article elaborates on the basic methods and techniques for modeling and integrated simulation of cement brick making machines using relevant software. Based on the key structure of a certain type of cement brick making machine, combined with actual usage and finite element analysis results, the structural problems and reasons were analyzed, and structural improvement design was carried out.
Keywords: cement brick making machine; Modeling; Simulation; Structural improvement
1. Structure of cement brick making machine
Cement blocks are mainly molded by cement brick making machines and are widely used in industries and road and bridge engineering. The cement brick making machine is a strong pressure forming equipment, and its structure is shown in Figure 1.
Figure 1 Structure of Brick Making Machine
2. Modeling of Cement Brick Making Machine
The Pro/E module has rich functions, and we can use related functions such as rotation, stretching, and scanning to shape the structural components of cement brick machines and create various feature bodies. Simultaneously imitating a real cement brick machine for assembly, assembly is a process of establishing the position and connection relationship of components in the product based on the constraint relationship between components and pairing conditions, thereby positioning and effectively organizing the various components of the entire product. Pro/E software adopts a virtual assembly mode, which means that in assembly, the 3D model of the components uses the idea of reference sets, and is no longer simply copied into the assembly drawing, but is referenced assembly, thus simplifying the model information. Simultaneously using top-down, bottom-up, or hybrid assembly methods to maintain the geometric correlation of assembly components based on the main model can achieve automatic updating of assembly components. The assembled brick making machine is shown in Figure 1, and the exploded view is shown in Figure 2.
Figure 2 Explosion diagram of cement brick making machine
3. Integrated simulation
- Create a connecting rod. The difference between the definition of “connecting rod” in integrated simulation and the component “connecting rod” is that the connecting rod should be considered as a set of connected connecting rods, including synchronously moving components, which is beneficial for future analysis. Otherwise, there are too many calculation nodes and it is not easy.
- Create a connection method.The Pro/E module can truly correspond to the connection methods between components, providing over ten connection types through motion analysis, including rotating and moving pairs. After creating motion pairs using the Pro/E module, it is possible to simulate the relative motion between the limited links based on the constraint types and degrees of freedom of different types of motion pairs, enabling the mechanism to complete the predetermined actions according to the actual motion situation.
- Create motion driven. Pro/E adopts the STEP function in motion driving, which has a stepped characteristic and is in the form of ADAMS motion function. After defining the motion driver, open the software simulation environment, input the simulation steps and time, calculate through the solver, and finally achieve the motion simulation of the brick making machine.
Modeling and simulating cement brick making machines can reduce design costs, shorten research and development cycles, simplify the design process, and avoid major accidents in the manufacturing and use of equipment system devices.
Figure 3 Product Simulation Flowchart
4. Key structural improvement design
A certain company introduced a certain model of brick making machine from Germany in 2009, with a designed output of 65 million standard bricks per year. Due to the unreasonable structure of the transmission device and reducer in the upper mixing section, the phenomenon of component damage and oil leakage is becoming increasingly serious.
4.1 Problems in the structure
Through finite element analysis of its structure, it was found that its structure is unreasonable: (1) the active and driven shafts are longer, with more auxiliary support and large swing, resulting in poor concentricity; The load increases, the torque increases, and the force is uneven, resulting in severe oil stirring, temperature rise, severe gear wear and bite, and easy occurrence of high-speed shaft tooth tapping, bearing sleeve twisting, etc. The shaft structure is damaged, and the service life of the shaft is reduced. (2) The dual shaft transmission of the vacuum box is long, with many auxiliary support points, and axial positioning is carried out using bearing sleeves. It is often the case that the bearing sleeves are twisted and broken due to excessive torque. (3) Due to frequent directional changes in the hydraulic system, the valve suddenly opens and closes under high pressure, causing an instantaneous increase in pressure, which can easily lead to damage to the sealing device and leakage. (4) There is a blockage in the feeding position of the brick making machine. Upon inspection, it was found that the left and right ends of the front of the fabric bed are not in the same horizontal position.
4.2 Structural improvement plan
In response to the above situation, we have decided to dismantle and renovate the integrated gearbox and reducer. The plan is as follows:
- Separate the original split gear from the gearbox, connect the double shaft input end to the split gear, and connect the split gear with the reducer using a cross slider coupling. The crosshead coupling slider can self align within the specified range, transmit torque, ensure smooth operation, and reduce vibration.
- For the convenience of assembly and maintenance, the joint surface of the gearbox box is moved to the top of the box, and the gearbox is designed as a sub box surface mounted reducer. Splitting to a certain extent shortens the shaft and reduces the right fulcrum, thereby reducing the shaft swing, avoiding mutual wear between the shaft and groove walls, ensuring uniform force on the bearing gears, ensuring concentricity, and reducing the rate of bearing damage.
- The main measures for leakage prevention and control include: ① strictly controlling manufacturing and fitting accuracy, selecting Yx type with better sealing performance and less friction; ② Transform the shape of oil pipeline joints and flanges, strictly control the number of hydraulic valve joints, and reduce pipeline length.
- In structural design, in addition to calculating the bearing capacity of the masonry, the possible shear and additional tensile stresses should also be estimated to reduce bending deformation. For window openings with obvious stress concentration, reinforcement bars should be added, and the bottom sill of the window should be filled with solid masonry to ensure that the left and right ends are horizontal and avoid stagnation.
Figure 4 Improved reducer
Figure 5 Plan schematic diagram of the modified transmission device
5. epilogue
The entire implementation process started from December 2011 to April 2012, and there were no abnormal conditions during the trial run. Since taking on the production task and running until now, the completion has been good. The summary of the technical transformation results is as follows:
- The double axis auxiliary support is reduced, shortened compared to the same period last year, the rotation accuracy is improved, and shaking is reduced. The gear and bearing are well matched, with minimal wear, and the coaxiality is within the tolerance range.
- The sealing and lubrication conditions are good, and the mixing of pollutants such as mud, steam, and water has been effectively improved. There is no oil leakage, the lubrication is good, and vibration and noise are reduced.
- The transformation cost is relatively low, the operating equipment is normal, the production efficiency is significantly improved, and balanced production is achieved, solving practical problems for the company and creating great economic benefits.
