1. Requirements of CNC equipment for foundation
Among the actual manufacturers of CNC equipment, many equipment users ignore the requirements of the equipment installation environment. For heavy machine tools and precision machine tools, manufacturers generally provide users with basic machine tool foundation diagrams. , wait for the foundation to enter the stable stage, and then install the machine tool. Heavy-duty machine tools and precision machine tools must have a stable machine tool foundation, otherwise, the machine tool accuracy cannot be adjusted. It will change repeatedly even after adjustment. Some small and medium-sized CNC machine tools have no special requirements for the foundation. According to my country’s GB 50040-1996 “Code for Basic Design of Power Machines”, the following work should be done:
1. General requirements
- 1. During the basic design, the equipment manufacturer should provide the following information:
- (1) The Model, speed, power, specifications and outline dimensions of the equipment.
- (2) The center of gravity of the equipment and the position of the center of gravity.
- (3) Outline drawing of equipment base, auxiliary equipment, location of pipeline, size of pit, ditch, hole, thickness of grouting layer, location of anchor bolts and embedded parts, etc.
- (4) The disturbance force and disturbance force moment of the equipment and its direction.
- (5) The location of the foundation and the foundation drawing of the adjacent buildings.
- (6) Geological survey data and foundation dynamic experimental data of the construction site.
2. The equipment foundation is separated from the building foundation, superstructure and concrete floor.
3. When the pipeline and the machine are connected to produce large vibration, vibration isolation measures should be taken at the connection between the pipeline and the building.
4. When the vibration of the equipment foundation has a harmful effect on the adjacent personnel, precision equipment, instrumentation, factory production and buildings, isolation measures should be taken.
5. The equipment foundation design shall not produce harmful uneven settlement.
6. The setting of the equipment anchor bolts should meet the following requirements:
- (1) The embedded depth of anchor bolts with hooks should not be less than 20 times the diameter of the bolts, and the embedded depth of anchor bolts with anchor plates should not be less than 15 times the diameter of the bolts.
- (2) The distance between the axis of the anchor bolt and the edge of the foundation should not be less than 4 times the diameter of the bolt, and the distance between the edge of the reserved hole and the edge of the foundation should not be less than 100mm. When the requirements cannot be met, reinforcement measures should be taken.
- (3) The thickness of concrete under the bottom surface of the pre-embedded anchor bolts should not be less than 50mm. When it is a reserved hole, the net thickness of the concrete under the bottom surface of the hole should not be less than 100mm.
2.The following requirements should also be followed for CNC equipment:
1. Machine tools can be classified according to the following principles:
- (1) Medium and small machine tools refer to those with a single machine weighing less than 100kN.
- (2) Large-scale machine tools refer to those with a single machine weighing between 100 and 300 kN.
- (3) Heavy-duty machine tools refer to those with a single machine weighing between 300 and 1000kN.
2. When carrying out the basic design of CNC equipment, in addition to the above “general requirements”, the equipment manufacturer should also provide the following information:
- (1) Dimensions of the machine tool.
- (2) When the inclination and deformation of the foundation have an impact on the machining accuracy of the machine tool or the calculation of the foundation reinforcement, the distribution of the gravity of the machine tool and the workpiece to be processed, the gravity of the machine tool to move or the gravity of the workpiece to be moved and its movement range are still required.
3. Heavy and precision machine tools should be installed on separate foundations.
4. When performing a separate base installation, the following specifications should be observed:
- (1) The size of the base plane should not be smaller than the outline size of the support area of the machine tool, and should meet the dimensions required for installation, adjustment and maintenance.
- (2) The concrete thickness of the foundation shall comply with the concrete thickness (m) of the foundation of the metal cutting machine tool in Table 5-1
Table 5-1 Concrete Thickness of Metal Cutting Machine Tool Foundation (m)
- ①L in the table is the length (m) of the machine tool shape, and h is the height (m) of the machine tool, which are the dimensions provided in the machine tool sample and manual.
- ②The thickness of the foundation in the table refers to the concrete thickness of the load-bearing part under the base of the machine tool (for example, under the horn in the case of a horn).
5. For ordinary machine tools that have the requirement to improve processing accuracy, the concrete thickness in Table 5-1 can be increased by 5%~10%.
6. For the machining center series machine tools, the thickness of the foundation concrete can be used according to the type of combined machine tool, whichever has higher precision or longer shape, and adopts the same type of machine tool in Table 5-1.
7. When the foundation inclination and deformation have an influence on the machining accuracy of the machine tool, the deformation check should be carried out. When the deformation cannot meet the requirements, measures such as artificial reinforcement of the foundation or increase of the foundation stiffness should be taken.
8. For machine tools with high requirements on machining accuracy and a gravity above 500 kN, when the foundation is built on a weak foundation, it is advisable to take pre-compression and reinforcement measures for the foundation. The gravity of the preload can be 1.4 to 2.0 times the sum of the gravity of the machine tool and the maximum gravity of the workpiece, and it is distributed according to the actual load situation, and the preload gravity can be achieved in stages. The preload time can be determined according to the consolidation of the foundation.
9. Precision machine tools should be kept away from machine tools with large dynamic loads. The foundation of large, heavy machine tools or precision machine tools should be separated from the plant column foundation.
10. One of the following measures can be taken for the design of the foundation of the precision machine tool:
- (1) Vibration isolation ditch is set around the foundation. The depth of the vibration isolation ditch should be the same as that of the foundation, and the width should be 100mm. The vibration isolation ditch should be empty or filled with materials such as sponge and latex.
- (2) Paste vibration isolation materials such as foam plastic and polystyrene around the foundation.
- (3) Set joints around the foundation to separate from the concrete floor, and the joints should be filled with elastic materials such as asphalt and hemp.
- (4) When the machining accuracy of the precision machine tool is high, according to the environmental vibration conditions, additional vibration isolation measures can be taken on the foundation or the bottom of the machine tool.
The equipment management personnel of the equipment user and the personnel of the relevant institutions should cooperate with the basic designers to carry out the relevant basic design. For other numerical control equipment and precision equipment, more detailed information on the basic design can be found in GB 50040-1996 “Power Machine Fundamentals” Design Code” and GB 50037-1996 “Code for Design of Building Ground” two national standards. In short, the equipment foundation is the basis for the good work of the equipment in the subsequent stages and the realization of a high level of economic benefits.
2. Requirements for power supply of CNC equipment
The power supply is the energy support part that maintains the normal operation of the system. The direct result of its failure or failure is the shutdown of the system or the destruction of the entire system. In addition, the operation data, setting data and processing program of the CNC system are generally stored in the RAM memory. After the system is powered off, it is maintained by the backup battery or lithium battery of the power supply. Therefore, the downtime is relatively long, and the data loss may be caused by plugging in the power supply or the memory, making the system unable to operate.
At the same time, since the CNC equipment uses a three-phase AC 380V power supply, safety is also an important part of the pre-installation work of the CNC equipment. Based on the above reasons, the power supply used by the CNC equipment has the following requirements:
1. The voltage fluctuation of the power grid should be controlled between +10% and -15%, while the power supply in our country fluctuates greatly, the quality is poor, and there are hidden disturbances such as high-frequency pulses, plus human factors (such as sudden switch-offs). power outage, etc.). During the peak period of electricity, such as about an hour before going to work or off work during the day and at night, the deviation is often more than ±20%. Make the machine tool alarm and cannot work normally, and cause damage to the machine tool power system. Even lead to the loss of relevant parameter data and so on. This phenomenon has occurred in machine tools such as CNC machining centers or turning centers, and the frequency of occurrence is high, which should be paid attention to.
It is recommended to configure an AC voltage stabilized power supply system with automatic compensation adjustment function in a workshop where CNC machine tools are concentrated; a single CNC machine tool can be configured with an AC voltage stabilizer to solve the problem.
2. It is recommended to connect the mechanical and electrical equipment to a single power supply. If it is necessary to supply power to certain parts of electrical equipment (such as electronic circuits, electromagnetic clutches), these power sources should be taken as far as possible from devices (such as transformers, transducers, etc.) that form part of mechanical electrical equipment. For large and complex machines, including many machines that work together in a coordinated manner and occupy a large space, more than one induced power supply may be required, depending on the configuration of the site power supply.
Unless the mechanical electrical equipment uses a plug/socket to connect directly to the power source, it is recommended that the power cord be connected directly to the power terminal of the power disconnect switch. If this is not possible, a separate terminal block should be provided for the power cord.
The handle of the power cut-off switch should be easily accessible and should be installed between 0.6m and 1.9m above the easy-to-operate position. The upper limit is recommended to be 1.7m. In this way, power can be quickly cut off in the event of an emergency, reducing losses and casualties.
3. Requirements of CNC equipment for compressed air supply system
CNC machine tools generally use a lot of pneumatic components, so the workshop should be connected to a clean and dry compressed air supply system network. Its flow and pressure should meet the requirements. The compressed air machine should be installed away from the CNC machine tool. According to the layout of the factory building and the amount of gas consumption, it should be considered to install refrigerated air in the coal machine, air filter, gas storage tank, safety valve and other equipment for the compressed air supply system network.
4, CNC equipment requirements for the working environment
Precision CNC equipment generally requires constant temperature environment. Only under constant temperature conditions can the machine tool accuracy and processing degree be ensured. Generally, ordinary CNC machine tools have no specific requirements for room temperature, but a lot of practice shows that when the room temperature is too high, the failure rate of the CNC system is greatly increased.
A humid environment will reduce the reliability of CNC machine tools, especially in a humid environment with large acid gas, it will cause corrosion of printed circuit boards and connectors, and electrical failures of machine tools will also increase. Therefore, some users in southern China have measures to dehumidify the CNC machine tool environment in summer and rainy seasons.
- 1. The temperature of the working environment should be between 0 and 35 °C, to avoid direct sunlight on the CNC machine tool, and the room should be equipped with good lighting equipment.
- 2. In order to improve the accuracy of machined parts and reduce the thermal deformation of the machine tool, if conditions permit, the CNC machine tool can be installed in a relatively closed workshop with air conditioning equipment.
- 3. The relative humidity of the working environment should be less than 75%. CNC machine tools should be installed in places away from liquid splashes and to prevent leakage in the workshop.
- 4. Keep away from the environment with excessive dust and corrosive gas.
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