Abstract: The wall thickness of aluminum alloy building profiles is an important quality index that affects the quality of construction projects. At the same time, it is an economic index that relates to the cost of construction projects. This article passes the inspection of wall thickness inspection standards in national standards, industry standards, and local laws and regulations. To help manufacturers improve their understanding of the regulations concerning the wall thickness of aluminum alloy profiles in national standards, industry standards and local laws and regulations, and to discuss the reasonable control of the wall thickness of aluminum alloy building profiles in the production of aluminum profiles, and to improve the quality of construction projects and reduce construction. The project cost is of great significance to aluminum alloy building profile production enterprises.
ã€Subject words】Minimum Measured Wall Thickness Allowable Deviation Allowable Deviation 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 pulling of the two major industries of automobiles and real estate. , China aluminum alloy building profile output continues to rise, from 1990 production was only 390,000 tons, to 2.74 million tons in 2002, an 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 its peak in 2022. The annual demand will exceed 10 million tons. However, at present, the domestic alumina industry is affected by the small size and scattered distribution of the 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. At the same time, it is an economic indicator that relates to the cost of construction projects. On the one hand, some aluminum extrusion factories are eager for quick success, producing thin-walled profiles, disrupting the market, leaving quality and safety risks 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 surveillance and spot checks. , To protect consumer rights, GB/T5237-2000 “Aluminum Alloy Profiles†specifies the minimum measured wall thickness of the bar profiles for 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 the provisions of GB/T5237-2000 Aluminum Alloy Profiles. How to fully understand the national standards, industry standards and local laws and regulations on the aluminum alloy wall thickness requirements, production and reasonable control of aluminum alloy building profile wall thickness, is the aluminum alloy building profile production enterprises must face an important issue.
2 GB/T5237-2000 "aluminum alloy building profiles," the relevant provisions of the author has been with a number of aluminum extrusion manufacturer technical staff discussed GB/T5237-2000 "aluminum alloy building profiles," the provisions of the wall thickness, found that a considerable number of manufacturers Ignore or fail to fully understand the provisions of Article 5.4.1.4 regarding the balance of wall thickness.
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 maximum measured wall thickness and the minimum measured wall thickness should be less than or equal to half of the tolerance of the nominal size, and the tolerance is the positive deviation. With the sum of the absolute values ​​of the negative deviations, this clause can be understood as:
The maximum measured wall thickness - the minimum measured wall thickness ≤ (∣ positive deviation ∣ + ∣ negative deviation ∣)/2 In the actual production process of aluminum extrusion, due to mold, extrusion equipment, production process fluctuations, prone to profile extrusion Pressure outflow velocity is uneven and wall thickness is deviated. Especially hollow profile is prone to partial wall phenomenon. On-site quality control must be strengthened. In order to ensure construction quality and safety, GB/T5237-2000 "aluminum alloy profile" stipulates that "profile As a stress member, the wall thickness of the profile shall be selected by calculation according to the conditions of use, but the minimum measured wall thickness of the bar profile of the door and window shall be ≥1.2mm, and the minimum thickness of the bar member for curtain wall The measured wall thickness should be ≥3.0mm." That is to say, in the engineering design, the minimum wall thickness needed for the profile in different situations should be determined firstly by calculating the required transmission force of the profile in different use situations. Then, in the design of the product, it is necessary to clearly identify the stress members and the non-forced members. The standard note 1 states that “the so-called force members refer to the members in the calculation of the door and window structure, and the columns and beams of the curtain wall are stressed. Lever".
In order to minimize the impact of standard hysteresis, standard note 2 clearly states: “When the minimum measured wall thickness specified in this standard is inconsistent with the latest regulations on the national standards for aluminum doors, windows, and curtain walls, the doors and windows shall be implemented. And the latest national standards for curtain walls.†GB/T 8479-2003 “Aluminum alloy windowsâ€, which was implemented on September 1, 2003, clause 5.1, states that “Aluminum alloy window members shall be subjected to tests or calculations. No surface treatment is required. The minimum measured wall thickness of the profile shall be ≥ 1.4mmâ€. 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 minimum measured wall thickness of the profile that has not been surface treated shall be ≥2.0 Mm".
Therefore, the minimum measured wall thickness of the main window of the engineering building shall be ≥1.4mm, and the minimum measured wall thickness of the outer door profile of the engineering building shall be ≥2.0mm. Generally, the outside diameter micrometer used for on-site quality inspection of aluminum extrusion companies is usually accurate to 0.01mm, and the minimum measured wall thickness is 1.35mm when tested on site, according to the provisions of Article 3.3 of GB/T 8170 “Round Revision Rulesâ€: “Values ​​to be rejected The leftmost digit is 5, and when there are no digits or all 0s on the right, if the remaining last digit is an odd number (1, 3, 5, 7, 9), then one is even, which is an even number (2, 4, 6) ,8,0) then give up." Repair is about 1.4mm, in line with the corresponding standards.
3 JGJ102-2003 “Specifications for Technical Specifications of Glass Curtain Wall Engineering†To ensure the safe application, advanced technology and economical rationality of the glass curtain wall project, the Ministry of Construction of the People's Republic of China issued the industry standard “Technical Specifications for Glass Curtain Wall Engineering†on November 14, 2003. 》Specify the materials, design, production, installation, construction and acceptance of glass curtain wall projects.
The wind pressure resistance of the glass curtain wall is determined according to the method specified in the current national standard GB/T15227 "Test method for wind pressure deformation of building curtain wall". The wind-resistance performance of the curtain wall refers to the ability of the curtain wall to maintain its normal function without any damage under the vertical wind load. The rating value of the wind-resistant performance of the curtain wall corresponds to the instantaneous wind pressure when the relative deflection value of the main bearing member or the supporting structure reaches the specified value, that is, the instantaneous wind pressure of 3 seconds. The wind-resistance performance of the curtain wall should be greater than the standard value of the wind load it withstands.
Usually, the crossbeam span is small and the corresponding stress is also small. The Ministry of Construction stipulates that the thickness of the main beam section should meet the “When the crossbeam span is not more than 1.2m, the thickness of the main section of the aluminum alloy section should not be Less than 2.0mm; When the span of the beam is greater than 1.2m, the thickness of the main section of the section should not be less than 2.5mm." In order to maintain the reliability of the direct force screw connection and prevent the self-tapping screws from pulling out, when the force is connected, in the part where the screw is directly connected, “the thickness of its partial section shall not be less than the nominal diameter of the screwâ€.
The thickness of the main section of the column section shall comply with the “thickness of the open section of the aluminum profile shall not be less than 3.0 mm, and the thickness of the closed part shall not be less than 2.5 mm; when the profile wall is directly connected with the screw by a threaded force, The local thickness should not be less than the nominal diameter of the screw." The minimum thickness of the main section of the column section is mainly based on the national standard "aluminum alloy construction profile" GB/T 5237 on the minimum thickness of the profile for the curtain wall is 3.0mm, for the closed box section, due to better For resistance to local instability, smaller wall thicknesses can be used, thus allowing the use of profiles with a minimum wall thickness of 2.5 mm.
In actual production, engineering design units often rely on the relevant provisions of JGJ102-2003 "Technical Specifications for Glass Curtain Wall Engineering" to calculate that the selected aluminum alloy profile wall thickness does not meet the requirements of GB/T5237-2000 "Aluminum Alloy Building Profiles", resulting in production. Manufacturers produce products according to customers' design drawings but do not meet national standards. Because the standard clauses are conflicting or unsuitable, the aluminum profile manufacturers, engineering design institutes and customers are confused. At the same time, because of the rigid regulations on wall thickness, a considerable portion of aluminum resources are wasted.
4 DBJ 15-30-2002 "Specifications for the design, construction and acceptance of aluminum alloy doors and windows project" to meet the needs of the construction project, so that the performance of aluminum alloy doors and windows meet the requirements of the building function, ensure the quality of aluminum alloy doors and windows project, targeting Guangdong The climate characteristics of the province and the actual construction of the project, the Guangdong Provincial Construction Department promulgated the Guangdong Provincial Local Standard DBJ 15-30-2002 "Specifications for Design, Construction, and Acceptance of Aluminum Alloy Doors and Windows Projects" on October 18, 2002 to regulate Guangdong. The design, construction and acceptance of aluminum alloy doors and windows for industrial and residential buildings in the province.
Mandatory Clause 3.2.2 stipulates that “the wall thickness of the main profile of aluminum doors and windows shall be determined by calculation or test, and the minimum measured wall thickness of the main section of the door profile shall not be less than 2.0 mm. The minimum measured wall of the main section of the window profile shall be measured. Thickness should not be less than 1.4mmâ€.
For aluminum alloy profiles production enterprises, aluminum alloy doors and windows are its downstream products, the next process is the customer, engineering design, construction and acceptance specifications are the basic requirements of customers, and are the prerequisites for the application of aluminum alloy profiles in the production of windows and doors.
Therefore, in the design, production and quality inspection of aluminum alloy door and window profiles, it is necessary to clearly identify the main profile and the main force components of the section. The so-called main force components, refers to the door and window facade to withstand and pass the door window and its own gravity and horizontal wind load and other forces of the middle cross-box, the middle mullion, fan and other main profile, as well as a combination of doors and windows to fight framed profiles. The so-called cross-section of the main section of the force, refers to the main cross-section of the door and window, the vertical and horizontal load to withstand the force of the web, flange or other parts of the fixed part of the connection force and other major parts.
Clearly identify the main sections and the main force components of the section, carry out targeted quality control during the design and production, ensure that the product meets the relevant requirements of the "aluminum alloy doors and windows project design, construction and acceptance specifications", but also can reasonably control the production cost And customer engineering manufacturing costs.
5 Criteria for Hardness of Aluminum Profile Wall Thickness Inappropriate (1) Definition of Quality The ISO9000:2000 "Quality Management System Basis and Terminology" states that "quality" is defined as "the degree to which a set of inherent characteristics meets the requirements". "Characteristics" are "distinguishing characteristics" and "requirements" are "express, usually implied, or must fulfill requirements or expectations." Aluminum wall thickness is an important indicator of quality characteristics. "Requirements" are mainly reflected in Customer requirements, engineering design needs. For customers, the wall thickness greater than 1.4mm does not mean that the requirements are met. Under the premise of meeting the engineering design requirements, the wall thickness is as small as possible, which is a good quality. For engineering design, the safety factors are related to the cross-section structure of aluminum profiles, door and window (curtain wall) structure, cross beam span, and glass area. The requirements for the wall thickness of aluminum profile should be changed according to the use position and the use status. The aluminum profile wall thickness is greater than 1.4. Mm does not necessarily meet the safety requirements, less than 1.4mm can also meet the safety needs in a considerable part of the project. It is the most scientific method to calculate the wall thickness of aluminum profiles through the state of use of the project.
(2) Energy perspective At present, China's GDP accounts for 1/30 of the world's total GPD, but the consumption of steel accounts for 1/4 of the world's total, aluminum ingot accounts for 1/4, coal accounts for 1/3, and cement accounts for 1/1. 2. The current high-speed economic development in China is based on a large amount of energy consumption.
Hard to regulate the thickness of aluminum profiles, increase the minimum amount of aluminum consumption in some projects, and in a certain extent play a role in wasting energy.
Therefore, the standard rigidly stipulates the wall thickness of aluminum profiles, which does not meet energy conservation, can not protect the interests of customers, can not meet the needs of engineering design, can not coordinate the contradiction between the quality control of production enterprises and market demand, and from the perspective of market economy, it is unscientific .
6 Concluding remarks (1) When the profile is used as a stress member, the profile wall thickness should be selected by calculation according to the conditions of use. Aluminum alloy doors and windows bearing components should be determined by experiment or calculation.
(2) The production enterprise should clearly identify the main profile and the main force components of the cross section during design, and carry out quality control of the aluminum profile wall thickness in the production.
(3) Fully understand the regulations governing the wall thickness of aluminum profiles by national standards, industry standards, local standards and corresponding laws and regulations, and ensure that product quality meets relevant regulations and that construction costs can be reasonably controlled.
ã€Subject words】Minimum Measured Wall Thickness Allowable Deviation Allowable Deviation 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 pulling of the two major industries of automobiles and real estate. , China aluminum alloy building profile output continues to rise, from 1990 production was only 390,000 tons, to 2.74 million tons in 2002, an 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 its peak in 2022. The annual demand will exceed 10 million tons. However, at present, the domestic alumina industry is affected by the small size and scattered distribution of the 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. At the same time, it is an economic indicator that relates to the cost of construction projects. On the one hand, some aluminum extrusion factories are eager for quick success, producing thin-walled profiles, disrupting the market, leaving quality and safety risks 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 surveillance and spot checks. , To protect consumer rights, GB/T5237-2000 “Aluminum Alloy Profiles†specifies the minimum measured wall thickness of the bar profiles for 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 the provisions of GB/T5237-2000 Aluminum Alloy Profiles. How to fully understand the national standards, industry standards and local laws and regulations on the aluminum alloy wall thickness requirements, production and reasonable control of aluminum alloy building profile wall thickness, is the aluminum alloy building profile production enterprises must face an important issue.
2 GB/T5237-2000 "aluminum alloy building profiles," the relevant provisions of the author has been with a number of aluminum extrusion manufacturer technical staff discussed GB/T5237-2000 "aluminum alloy building profiles," the provisions of the wall thickness, found that a considerable number of manufacturers Ignore or fail to fully understand the provisions of Article 5.4.1.4 regarding the balance of wall thickness.
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 maximum measured wall thickness and the minimum measured wall thickness should be less than or equal to half of the tolerance of the nominal size, and the tolerance is the positive deviation. With the sum of the absolute values ​​of the negative deviations, this clause can be understood as:
The maximum measured wall thickness - the minimum measured wall thickness ≤ (∣ positive deviation ∣ + ∣ negative deviation ∣)/2 In the actual production process of aluminum extrusion, due to mold, extrusion equipment, production process fluctuations, prone to profile extrusion Pressure outflow velocity is uneven and wall thickness is deviated. Especially hollow profile is prone to partial wall phenomenon. On-site quality control must be strengthened. In order to ensure construction quality and safety, GB/T5237-2000 "aluminum alloy profile" stipulates that "profile As a stress member, the wall thickness of the profile shall be selected by calculation according to the conditions of use, but the minimum measured wall thickness of the bar profile of the door and window shall be ≥1.2mm, and the minimum thickness of the bar member for curtain wall The measured wall thickness should be ≥3.0mm." That is to say, in the engineering design, the minimum wall thickness needed for the profile in different situations should be determined firstly by calculating the required transmission force of the profile in different use situations. Then, in the design of the product, it is necessary to clearly identify the stress members and the non-forced members. The standard note 1 states that “the so-called force members refer to the members in the calculation of the door and window structure, and the columns and beams of the curtain wall are stressed. Lever".
In order to minimize the impact of standard hysteresis, standard note 2 clearly states: “When the minimum measured wall thickness specified in this standard is inconsistent with the latest regulations on the national standards for aluminum doors, windows, and curtain walls, the doors and windows shall be implemented. And the latest national standards for curtain walls.†GB/T 8479-2003 “Aluminum alloy windowsâ€, which was implemented on September 1, 2003, clause 5.1, states that “Aluminum alloy window members shall be subjected to tests or calculations. No surface treatment is required. The minimum measured wall thickness of the profile shall be ≥ 1.4mmâ€. 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 minimum measured wall thickness of the profile that has not been surface treated shall be ≥2.0 Mm".
Therefore, the minimum measured wall thickness of the main window of the engineering building shall be ≥1.4mm, and the minimum measured wall thickness of the outer door profile of the engineering building shall be ≥2.0mm. Generally, the outside diameter micrometer used for on-site quality inspection of aluminum extrusion companies is usually accurate to 0.01mm, and the minimum measured wall thickness is 1.35mm when tested on site, according to the provisions of Article 3.3 of GB/T 8170 “Round Revision Rulesâ€: “Values ​​to be rejected The leftmost digit is 5, and when there are no digits or all 0s on the right, if the remaining last digit is an odd number (1, 3, 5, 7, 9), then one is even, which is an even number (2, 4, 6) ,8,0) then give up." Repair is about 1.4mm, in line with the corresponding standards.
3 JGJ102-2003 “Specifications for Technical Specifications of Glass Curtain Wall Engineering†To ensure the safe application, advanced technology and economical rationality of the glass curtain wall project, the Ministry of Construction of the People's Republic of China issued the industry standard “Technical Specifications for Glass Curtain Wall Engineering†on November 14, 2003. 》Specify the materials, design, production, installation, construction and acceptance of glass curtain wall projects.
The wind pressure resistance of the glass curtain wall is determined according to the method specified in the current national standard GB/T15227 "Test method for wind pressure deformation of building curtain wall". The wind-resistance performance of the curtain wall refers to the ability of the curtain wall to maintain its normal function without any damage under the vertical wind load. The rating value of the wind-resistant performance of the curtain wall corresponds to the instantaneous wind pressure when the relative deflection value of the main bearing member or the supporting structure reaches the specified value, that is, the instantaneous wind pressure of 3 seconds. The wind-resistance performance of the curtain wall should be greater than the standard value of the wind load it withstands.
Usually, the crossbeam span is small and the corresponding stress is also small. The Ministry of Construction stipulates that the thickness of the main beam section should meet the “When the crossbeam span is not more than 1.2m, the thickness of the main section of the aluminum alloy section should not be Less than 2.0mm; When the span of the beam is greater than 1.2m, the thickness of the main section of the section should not be less than 2.5mm." In order to maintain the reliability of the direct force screw connection and prevent the self-tapping screws from pulling out, when the force is connected, in the part where the screw is directly connected, “the thickness of its partial section shall not be less than the nominal diameter of the screwâ€.
The thickness of the main section of the column section shall comply with the “thickness of the open section of the aluminum profile shall not be less than 3.0 mm, and the thickness of the closed part shall not be less than 2.5 mm; when the profile wall is directly connected with the screw by a threaded force, The local thickness should not be less than the nominal diameter of the screw." The minimum thickness of the main section of the column section is mainly based on the national standard "aluminum alloy construction profile" GB/T 5237 on the minimum thickness of the profile for the curtain wall is 3.0mm, for the closed box section, due to better For resistance to local instability, smaller wall thicknesses can be used, thus allowing the use of profiles with a minimum wall thickness of 2.5 mm.
In actual production, engineering design units often rely on the relevant provisions of JGJ102-2003 "Technical Specifications for Glass Curtain Wall Engineering" to calculate that the selected aluminum alloy profile wall thickness does not meet the requirements of GB/T5237-2000 "Aluminum Alloy Building Profiles", resulting in production. Manufacturers produce products according to customers' design drawings but do not meet national standards. Because the standard clauses are conflicting or unsuitable, the aluminum profile manufacturers, engineering design institutes and customers are confused. At the same time, because of the rigid regulations on wall thickness, a considerable portion of aluminum resources are wasted.
4 DBJ 15-30-2002 "Specifications for the design, construction and acceptance of aluminum alloy doors and windows project" to meet the needs of the construction project, so that the performance of aluminum alloy doors and windows meet the requirements of the building function, ensure the quality of aluminum alloy doors and windows project, targeting Guangdong The climate characteristics of the province and the actual construction of the project, the Guangdong Provincial Construction Department promulgated the Guangdong Provincial Local Standard DBJ 15-30-2002 "Specifications for Design, Construction, and Acceptance of Aluminum Alloy Doors and Windows Projects" on October 18, 2002 to regulate Guangdong. The design, construction and acceptance of aluminum alloy doors and windows for industrial and residential buildings in the province.
Mandatory Clause 3.2.2 stipulates that “the wall thickness of the main profile of aluminum doors and windows shall be determined by calculation or test, and the minimum measured wall thickness of the main section of the door profile shall not be less than 2.0 mm. The minimum measured wall of the main section of the window profile shall be measured. Thickness should not be less than 1.4mmâ€.
For aluminum alloy profiles production enterprises, aluminum alloy doors and windows are its downstream products, the next process is the customer, engineering design, construction and acceptance specifications are the basic requirements of customers, and are the prerequisites for the application of aluminum alloy profiles in the production of windows and doors.
Therefore, in the design, production and quality inspection of aluminum alloy door and window profiles, it is necessary to clearly identify the main profile and the main force components of the section. The so-called main force components, refers to the door and window facade to withstand and pass the door window and its own gravity and horizontal wind load and other forces of the middle cross-box, the middle mullion, fan and other main profile, as well as a combination of doors and windows to fight framed profiles. The so-called cross-section of the main section of the force, refers to the main cross-section of the door and window, the vertical and horizontal load to withstand the force of the web, flange or other parts of the fixed part of the connection force and other major parts.
Clearly identify the main sections and the main force components of the section, carry out targeted quality control during the design and production, ensure that the product meets the relevant requirements of the "aluminum alloy doors and windows project design, construction and acceptance specifications", but also can reasonably control the production cost And customer engineering manufacturing costs.
5 Criteria for Hardness of Aluminum Profile Wall Thickness Inappropriate (1) Definition of Quality The ISO9000:2000 "Quality Management System Basis and Terminology" states that "quality" is defined as "the degree to which a set of inherent characteristics meets the requirements". "Characteristics" are "distinguishing characteristics" and "requirements" are "express, usually implied, or must fulfill requirements or expectations." Aluminum wall thickness is an important indicator of quality characteristics. "Requirements" are mainly reflected in Customer requirements, engineering design needs. For customers, the wall thickness greater than 1.4mm does not mean that the requirements are met. Under the premise of meeting the engineering design requirements, the wall thickness is as small as possible, which is a good quality. For engineering design, the safety factors are related to the cross-section structure of aluminum profiles, door and window (curtain wall) structure, cross beam span, and glass area. The requirements for the wall thickness of aluminum profile should be changed according to the use position and the use status. The aluminum profile wall thickness is greater than 1.4. Mm does not necessarily meet the safety requirements, less than 1.4mm can also meet the safety needs in a considerable part of the project. It is the most scientific method to calculate the wall thickness of aluminum profiles through the state of use of the project.
(2) Energy perspective At present, China's GDP accounts for 1/30 of the world's total GPD, but the consumption of steel accounts for 1/4 of the world's total, aluminum ingot accounts for 1/4, coal accounts for 1/3, and cement accounts for 1/1. 2. The current high-speed economic development in China is based on a large amount of energy consumption.
Hard to regulate the thickness of aluminum profiles, increase the minimum amount of aluminum consumption in some projects, and in a certain extent play a role in wasting energy.
Therefore, the standard rigidly stipulates the wall thickness of aluminum profiles, which does not meet energy conservation, can not protect the interests of customers, can not meet the needs of engineering design, can not coordinate the contradiction between the quality control of production enterprises and market demand, and from the perspective of market economy, it is unscientific .
6 Concluding remarks (1) When the profile is used as a stress member, the profile wall thickness should be selected by calculation according to the conditions of use. Aluminum alloy doors and windows bearing components should be determined by experiment or calculation.
(2) The production enterprise should clearly identify the main profile and the main force components of the cross section during design, and carry out quality control of the aluminum profile wall thickness in the production.
(3) Fully understand the regulations governing the wall thickness of aluminum profiles by national standards, industry standards, local standards and corresponding laws and regulations, and ensure that product quality meets relevant regulations and that construction costs can be reasonably controlled.
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