Aluminum alloy building profile wall thickness is an important quality index that affects the quality of construction projects. At the same time, it is an economic indicator related to construction project cost. This article helps to compare the wall thickness inspection standards in national standards, industry standards, and local laws and regulations. The production enterprises have increased their understanding of the regulations on the wall thickness of aluminum alloy profiles in national standards, industry standards and local laws and regulations, discussed the reasonable control of aluminum alloy building profile wall thickness in the production of aluminum profiles, improved the quality of construction projects, and reduced the cost of construction projects. For aluminum alloy building profiles production enterprises have great significance.
Smaller measured wall thickness tolerance member tolerance
1 Overview
Aluminum alloy building profiles, as an important raw material for construction projects, play a fundamental role in the national economic system. Due to the spurring of the automobile and real estate industries, the output of aluminum alloy building profiles in China continues to rise, and the output from 1990 is only 390,000 tons, jumped to 2.74 million tons in 2002, the annual growth rate of 17%, much higher than the domestic GDP growth over the same period. The China Non-Ferrous Metals Processing Association predicts that the peak consumption of aluminum in China will come after 2005 and reach a higher peak in 2022. The annual demand will exceed 10 million tons. However, at present, the domestic alumina industry is affected by the small size of the company and its layout is scattered and high. Grades of bauxite resources are constrained by "soft ribs" such as congenital deficiencies. China's domestic supply shortage of alumina is expected to continue until the end of 2006, and the aluminum wall thickness is reasonably controlled under the premise of ensuring the quality of the project through calculations, which will reduce the consumption of aluminum resources. The cost of construction projects and the improvement of market competitiveness of aluminum profiles are of great significance.
Aluminum alloy building profile wall thickness is an important quality index that affects the quality of construction projects, and it is also an economic index that relates building construction cost. On the one hand, some aluminum extrusion factories are eager for quick success, producing thin-walled profiles, disrupting the market, leaving quality and safety hazards for construction projects, and suppressing the thin wall phenomenon of doors, windows and curtain wall profiles for the decoration industry in order to facilitate market supervision and spot checks. , To protect consumer rights, GB/T 5237-2000 "Aluminum Alloy Building Profiles" specifies the smaller measured wall thickness of the bar profiles for the doors, windows and curtain walls. On the other hand, the engineering design unit calculates the selected wall thickness according to the conditions of use of the profile, and some of the data are different from those of the GB/T5237-2000 Aluminum Alloy Building Profiles. How to fully understand the national standards, industry standards and local laws and regulations on the aluminum alloy wall thickness requirements, the production of reasonable control of aluminum alloy building profile wall thickness, is the aluminum alloy building profile production enterprises must face an important issue.
2GB/T5237-2000 "aluminum alloy building profiles" related regulations
The author once discussed with the technical personnel of a number of aluminum profile manufacturers GB/T5237-2000 "aluminum alloy building profiles" on the provisions of the wall thickness, found that a considerable number of manufacturers ignore or not fully understand the 5.4.1.4 clause on the balance of wall thickness Sexual regulations.
GB/T5237-2000 "aluminum alloy building profiles" 5.4.1.4 provides that "the wall thickness difference between the nominal thickness and the allowable deviation of the nominal wall thickness in the cross-section should not exceed half of the corresponding wall thickness tolerance". This applies. The condition is that “the nominal size and allowable deviation of the wall thickness in the cross section are the sameâ€. Under this condition, the difference between the larger measured wall thickness and the smaller measured wall thickness should be less than or equal to half of the tolerance of the nominal size. The tolerance is The sum of positive and negative deviations, this clause can be understood as:
Larger measured wall thickness - smaller measured wall thickness ≤ (positive deviation + negative deviation) / 2
In the actual production process of aluminum extrusion, due to the impact of die, extrusion equipment, and production process fluctuations, it is prone to unbalanced extrusion extrusion speed, wall thickness deviation, especially in hollow profile prone to partial wall phenomenon, need to be strengthened On-site quality control,
In order to ensure the quality and safety of construction projects, GB/T5237-2000 “Profile for Aluminum Alloy Buildings†stipulates that “When profile bars are used as bearing bars, the profile wall thickness should be selected by calculation according to the conditions of use. However, the doors and windows are subject to The smaller measured wall thickness of the bar profile should be ≥1.2?, and the smaller measured wall thickness of the bar profile for the curtain wall should be ≥3.0?â€. In the engineering design, firstly, the required wall thickness of the profile in different situations should be determined by calculating the required transmission force of the profile in different use situations. Then, in the design of the product, the stress member and the non-forced member should be clearly identified. The standard note 1 states that “the so-called force member refers to the member in the door and window structure calculation, and the pillar and beam of the curtain wall are subjected to force. Lever".
In order to minimize the impact of standard lag, Standard Note 2 clearly states: “When the “smaller measured wall thickness†specified in this standard is inconsistent with the newer national standards for aluminum doors, windows, and curtain walls, the gate should be implemented. Newer regulations for national standards for windows, windows, and curtain walls." GB/T8479-2003 "Aluminum alloy windows", which was implemented on September 1, 2003, clause 5.1 states that "Aluminum alloy window members shall be subjected to tests or calculations. After the surface treatment of the smaller measured wall thickness should be ≥ 1.4? The GB/T8478-2003 "aluminum alloy door" that was implemented on September 1, 2003, section 5.1 stipulates that "the aluminum alloy door bearing member shall be tested or determined by calculation. The smaller measured wall thickness of the profile without surface treatment shall be ≥ 2.0?".
Therefore, the actual measured external wall thickness of the external construction of the project should be ≥1.4?, and the external construction of the project should have a smaller measured wall thickness ≥2.0?. Generally, the outside diameter micrometer used for on-site quality inspection of aluminum extrusion companies is usually accurate to 0.01?, when the actual measured wall thickness is 1.35?, according to the provisions of Article 3.3 of GB/T 8170 "Round Restoration Rules": "The value should be rejected. The left-most digit is 5, and when there is no digit or all 0s on the right, if the last digit left is odd (1,3,5,7,9), then it goes to even number (2,4, 6,8,0) then discarded. "The repair is about 1.4?, in line with the corresponding standards.