The construction quality detector is mainly used to detect the construction and completion quality of engineering construction, decoration, bridge construction and equipment installation [1-4]. Whether the detection ability of building quality inspectors is accurate or not is related to the quality and safety of many building projects. According to the national calibration standard JJF 1 165438-2003, the calibration items, technical indicators and calibration methods of calibration engineering quality detectors are clearly expounded, which is an effective legal measurement calibration standard at present. However, the description of the calibration device in the specification is too simple, and the structural design of the device is too idealistic, which is not easy to realize. Therefore, according to the technical requirements of the calibration standard JJF1/KLOC-0-2003, combined with my own work practice, it is urgent to develop a calibration device to meet the calibration needs of the indication error of the verticality measuring ruler of the building engineering quality detector. At the same time, it is necessary to ensure the reliability of calibration values and provide effective technical support for the quality of construction projects.
Structure and design principle of 1 device
The device is designed according to the technical requirements of JJF 11-2003 "Calibration Specification for Building Engineering Quality Testing Instruments", as shown in figure1. The device mainly includes a main bracket, a clamping part and a measuring part. Wherein, the main support comprises a marble upright post, a marble base and supporting feet; The clamping part includes: the fixed sleeve of the measured ruler and the fixed frame at the top of the device; The measuring part includes: multiple microscopes, a top ruler assembly, a workbench lifting assembly and a differential head fixture seat. During calibration, firstly, the upper end of the measured ruler is fixed in the special sleeve, and then the measured ruler fixed in the sleeve is put on the fixing frame together, so that the measured ruler can swing freely in the horizontal direction under the action of gravity; Adjust the height of the workbench, so that the lower end of the measured ruler is located on the measuring axis of the differential degree and top ruler assembly; Adjust the knob of the digital microscope, make the indicator pointer of the measured ruler swing to zero, and at the same time adjust the digital microscope to zero, so that the indication change and indication error of the measured ruler can be calibrated according to JJF11/KLOC-0-2003 "Calibration Specification for Building Engineering Quality Testing Instruments".
1. 1 main support
As shown in figure 1, the main support of the device consists of three parts: marble column, marble base and supporting feet. The flatness of both sides of the marble column of the main support is less than 0.005mm, which can complete the straightness calibration of the verticality measuring ruler. Punching holes in the bracket can not only reduce the weight but also reduce the release of internal stress after cutting. The final physical device is shown in Figure 2.
1.2 Clamping parts
One of the technical key parts of the device is the clamping part of the measured ruler, because it not only solves the problem of fixing the verticality measuring ruler, but also ensures that the engineering ruler can swing freely in the left and right direction based on its own vertical line. We adopted the fixed scheme as shown in Figure 3, and the specific object is shown in Figure 4. As shown in Figure 4, the device mainly fixes the verticality measuring ruler of the construction quality detector on the top of the column through the upper clamping assembly. The upper clamping assembly consists of a top fixing frame and a sleeve, and the sleeve is provided with a plastic screws, so that the measured ruler can be fixed in the sleeve; At the same time, the top fixing frame is provided with a V-shaped groove, and both ends of the sleeve are designed with short shafts that rotate in cooperation with the V-shaped groove; Through the cooperation of the V-shaped groove and the shaft, the sleeve and the fixing frame can be installed together, which not only meets the fixing requirements of the measured ruler, but also ensures the free rotation of the measured ruler in the horizontal direction under its own gravity, so that the measured ruler can be calibrated.
1.3 measurement section
The measuring part includes: multiple microscopes, a top ruler assembly, a workbench lifting assembly and a differential head fixture seat. During calibration, the lower end of the measured ruler will be located between the micrometer head and the top ruler assembly, and the top ruler assembly is equipped with a spring, which can freely expand and contract, so as to ensure that one side of the measured ruler is always close to the probe of the micrometer head, and at the same time, the position of the calibration point of the measured ruler can be fixed, so that the swing amplitude of the measured ruler can be changed by adjusting the displacement of the probe of the micrometer head, and then the displacement values of the two can be read out, thus realizing calibration. Considering that the difference between the clamping position of the verticality measuring ruler at the upper end and its own length may lead to the lower measuring end not being accurately located on the measuring axis of the micro-dividing head and the top ruler assembly, the height of the measuring axis of the micro-dividing head and the top ruler assembly can be adjusted up and down by using the lifting workbench. The schematic diagram and the physical diagram are shown in Figure 5 and Figure 6 respectively. As shown in fig. 6, the lifting table is connected with the rotating handle and the lifting screw through the synchronous belt, so that the rotating handle in the front and rear direction can drive the lifting screw to rotate in the same direction and control the workbench to move up and down, thus realizing micro-splitting and adjusting the height of the measuring shaft of the top ruler assembly. The moving stroke of the workbench is 20mm, which is completely compatible with the size of the building quality detector on the market at present.
2 device function realization and innovation
2. 1 clamping part
Through practical application, it is verified that the clamping mode of the device can solve the problem that the measured ruler can swing flexibly from side to side while being fixed. The innovative points of this clamping method are: 1) the measured ruler is fixed by sleeve, which is convenient to take and use, and can be flexibly loaded and unloaded directly on the ground; 2) The sleeve and the fixing frame at the top of the calibration device are matched with the V-shaped frame through the shaft, which is consistent with the actual use state of the measured ruler; 3) The size design of the fixing sleeve can also meet the fixing requirements of various types of measuring rulers.
2.2 measurement part
A digital microscope with a resolution of 0.00 1mm is selected. Through a series of stability and repeatability tests, this measurement method can completely calibrate the indication error of verticality measuring ruler and meet its accuracy requirements. The innovations of the measuring part are as follows: 1) The measuring table adopts a lifting structure, which ensures that the lower measuring end is on the measuring axis of the micro-dividing head and the top ruler assembly during calibration; 2) The digital micro-splitting and top ruler assembly can move relatively along the measuring axis on the workbench, and the optimal measuring position can be adjusted according to the measured ruler; 3) The installation position of the digital microscope is not designed according to the differential display head installation method specified in JJF1/KLOC-0—2003 "Calibration Specification for Quality Detector Group of Building Engineering". In the calibration specification, the digital microscope needs to be installed in the direction perpendicular to the column, and at the same time, it needs to pass through the column and cooperate with the top ruler assembly for measurement. However, in this device, the digital microscope beam splitter and the top ruler assembly are installed in the direction parallel to the marble column. This design scheme is not only simple to process and convenient to install, but also the marble column will not interfere with the free swing of the measured ruler in the horizontal direction during calibration, which is more reasonable from the point of view of use.
2.3 Overall function
Combined with the above analysis, the innovation points of the overall function of the device are: 1) According to the technical requirements of JJF165438-2003 Calibration Specification for Building Quality Detector, it can complete the calibration of the indication error of the verticality measuring ruler of the building quality detector, and the calibration results are repeatable and stable, so it is an instrument that can meet the calibration items in the market at present. 2) The flatness of both sides of the marble column of the device is less than < 0.005mm, and the straightness of the verticality measuring ruler can also be calibrated. Compared with the straightness calibration with large flat plate, it is more convenient, faster and saves space.
3 Conclusion
The calibration device of building quality detector can not only meet the technical indexes involved in JJF110—2003 "Calibration Specification for Building Quality Detector", but also make up for the shortcomings of the calibration device in the calibration specification. The device has the advantages of reasonable design, convenient use and accurate and rapid calibration results. It effectively solves the problems of accuracy, stability and repeatability of calibration work of building quality detector, and improves the calibration technology of vertical measuring ruler of building detector, which is worthy of wide popularization and application. The device has applied for patent, advanced technical performance index, unique realization method and good application prospect.
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