An efficient thermal elongation test method for cables

Abstract

This invention discloses an efficient method for testing the thermal elongation of cables, comprising: heating the inner cavity of a housing to a preset constant temperature; installing a cable suspension assembly with the cable inside the inner cavity of the housing and locking the housing door; measuring the length between two markings on the cable, which is taken as the cable's tensile length; cutting the cable using a cutting assembly, maintaining a constant temperature for a preset time after the load is cut, stopping heating after the preset time, releasing the housing door from the housing, opening the housing door by driving it away from the housing using a driving assembly, cooling for a period of time until the temperature drops to the preset temperature, and then measuring the length between the two markings on the cable again to obtain the recovered cable length. This invention features a high degree of automation and high measurement efficiency, and can be completed in a very short time, thus ensuring that excessive temperature changes over time do not affect the measurement results of the cable's thermal elongation.

Description

Technical Field

[0001] This invention relates to the field of cable thermal elongation testing technology, specifically a highly efficient thermal elongation testing method for cables. Background Technology

[0002] The thermal elongation test of cables needs to be conducted according to the national standard (currently GB / T2951.21-2008). The main requirement is that the cable must withstand the stretching caused by the thermal stress of a constant temperature under gravity. In existing methods, the cable is typically placed in a sealed, constant-temperature chamber. After the cable has stretched within a specified time, the elongation is manually measured, the load is cut, and the cable is kept at the high temperature (standard specified temperature) for another 5 minutes. Then, the cable is removed from the chamber and its stretched length is measured at room temperature, again within a specified time (usually 30 seconds). The cable's elongation rate is obtained by comparing the change in length before and after stretching. This process requires frequent manual opening and closing of the sealed chamber door, which is inefficient and causes temperature fluctuations within the chamber, potentially increasing energy consumption or even affecting the accuracy of the thermal elongation measurement. Therefore, a more efficient and efficient method for testing cable thermal elongation is desired. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a highly efficient thermal elongation test method for cables, which can solve the technical problems described in the background art.

[0004] The technical solution to achieve the objective of this invention is as follows: a highly efficient thermal elongation testing method for cables, based on a thermal elongation testing chamber. The chamber includes a door, a housing, a drive assembly, an electromagnet locking assembly, a cutting assembly, and a cable suspension assembly. The drive assembly drives the door to move closer to or away from the housing, causing the door to fit against or open relative to the housing. The electromagnet locking assembly locks the door to the housing when it is fitted against it. The cutting assembly cuts the cable suspended from the cable suspension assembly. Two markings are pre-marked on the cable, and a load is connected to the lower end of the cable, located below the lowermost marking.

[0005] The method includes the following steps:

[0006] Step 1: Heat the inner cavity of the enclosure to a preset constant temperature. After reaching the preset constant temperature, disconnect the power supply to the electromagnet lock assembly to release the door from the enclosure or lock the door to the enclosure. Drive the door away from the enclosure to open the door. Install the cable suspension assembly with the cable in the inner cavity of the enclosure. Then, drive the door again and turn on the electromagnet lock assembly to lock the door to the enclosure.

[0007] Step 2: Measure the length between the two markings on the cable; this length is taken as the cable's tensile length.

[0008] Step 3: Cut the cable using the cutting component, with the cutting position below the lowest mark line, and cut the load off the cable. After cutting the load, maintain a constant temperature for a preset time. After the preset time is reached, stop heating and disconnect the power to the electromagnet lock component to release the door from the box. Drive the door away from the box using the drive component to open the door. After cooling for a period of time until the temperature drops to the preset temperature, measure the length between the two marks on the cable again to obtain the length of the cable after recovery.

[0009] Furthermore, at least two cables are suspended on the cable suspension assembly. In steps 2 and 3, two or more adjacent cables are grouped together in sequence from left to right or from right to left, and the average value of a group of cables is used as the corresponding stretched length of the current cable or the restored cable length.

[0010] Furthermore, the internal cavity of the enclosure is heated by a temperature control device installed on the enclosure and the temperature is maintained at a preset temperature. The on / off points of the electromagnet lock assembly are controlled by a program pre-programmed into the controller, so that the electromagnet lock assembly locks or unlocks the enclosure door attached to the enclosure at the appropriate time or according to preset conditions.

[0011] Furthermore, the drive assembly includes a driver and a connecting rod assembly, with the driver connected to the door via the connecting rod assembly.

[0012] Furthermore, the cable suspension assembly includes a column, a locking assembly, and a crossbeam. One end of the column is connected to the housing and located inside the housing cavity. The other end of the column is connected to the crossbeam via the locking assembly. The locking assembly is used to connect and disconnect the crossbeam and the column, thereby preventing the crossbeam from swaying.

[0013] Furthermore, in step 3, stopping the heating of the inner cavity of the enclosure and releasing the electromagnet lock assembly are performed simultaneously so that the enclosure door can be opened immediately once heating is stopped.

[0014] Furthermore, the cutting assembly includes a cutting drive, a cutting disc, a cutting connecting column, and a cable anti-detachment assembly. The cutting drive is connected to the cutting disc via the cutting connecting column. The cutting disc is used to cut the cable on the cable suspension assembly located on one side of the cutting assembly. The cable anti-detachment assembly is installed on the cutting disc, and one end of the cable anti-detachment assembly extends out of the cutting disc and is close to the cable. The cable anti-detachment assembly is used to prevent the cable from shifting too much and leaving the working area of ​​the cutting disc.

[0015] Furthermore, the cutting drive is connected to one end of the cutting connecting column, and the cutting disc is connected to the other end of the cutting connecting column, with the cutting disc located at the end of the other end of the cutting connecting column.

[0016] Furthermore, the cable anti-detachment component is installed at the junction of the cutting disc and the cutting connection column.

[0017] Furthermore, the cable anti-detachment assembly includes a fixing plate, a connecting plate, and an inclined plate. The fixing plate is vertically mounted on the cutting disc and fits against the cutting connecting column. A fixing plate is provided on each side of the cutting connecting column. The fixing plate is fixedly connected to the connecting plate. The connecting plate extends radially along the cutting disc and is connected to the inclined plate located outside the cutting disc. The two connecting plates connected by the two fixing plates are spaced apart, so that the two inclined plates connecting the two connecting plates are spaced apart. The inclined plates are extended outward and inclined to connect with the connecting plates, so that the two inclined plates form an outwardly extended connection structure in the shape of an "eight", so that the cable is just between the two inclined plates.

[0018] The beneficial effects of this invention are as follows: During the entire process of cable thermal elongation testing, manual measurement is not required or only one manual measurement is required when measuring the cable tensile length. The chamber door can automatically open or close according to preset time or preset conditions (such as reaching the corresponding temperature). The testing process has a high degree of automation and high measurement efficiency, and can be completed in a very short time, thus ensuring that the temperature change caused by the time process does not affect the measurement results of cable thermal elongation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the thermal extension test chamber;

[0020] Figure 2 This is a schematic diagram of the cable suspension assembly.

[0021] Figure 3 This is a schematic diagram of the structure between the cable suspension assembly and the cutting assembly.

[0022] Figure 4 for Figure 3 Enlarged view of point A in the middle;

[0023] Figure 5This is a flowchart illustrating a preferred embodiment;

[0024] In the diagram, 1-driver, 2-connecting rod assembly, 3-box door, 4-electromagnetic lock assembly, 5-box body, 6-cutting drive, 7-column, 8-locking assembly, 9-beam, 10-cable, 11-cutting disc, 12-cutting connecting column, 13-cable anti-detachment assembly, 131-fixing plate, 132-connecting plate, 133-tilting plate. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0026] like Figures 1 to 5 As shown, an efficient thermal elongation test method for cables is based on a thermal elongation test chamber. The thermal elongation test chamber includes a door 3, a chamber 5, a driver 1, a connecting rod assembly 2, an electromagnet lock assembly 4, a cutting assembly, and a cable suspension assembly. The driver 1 is connected to the door 3 through the connecting rod assembly 2. The driver 1 is used to drive the door 3 to move closer to or away from the chamber 5, so that the door 3 is attached to the chamber 5 or open relative to the chamber 5 (i.e., in an open state). The electromagnet lock assembly 4 is used to lock the door 3 to the chamber 5 when the door 3 is attached to the chamber 5. The cutting assembly is used to cut the cable 10 suspended on the cable suspension assembly. The cable suspension assembly is installed in the cavity of the chamber 5.

[0027] It should be noted that the cable here refers to a cable sample, which is dumbbell-shaped along the axial direction (i.e., the direction of extension) of the cable. The cable sample here is only for testing purposes. It is a cable with a small dumbbell-shaped portion and a large remaining portion, which is taken from the cable insulation material.

[0028] The method includes the following steps:

[0029] Step 1: The internal cavity of chamber 5 is heated by a temperature control device (not shown in the figure) installed on chamber 5 until the internal cavity temperature is maintained at a preset constant temperature, for example, 200°C. After the internal cavity reaches the preset constant temperature, the electromagnet lock assembly 4 is powered on and off by the controller or by a program pre-programmed into the controller, thereby releasing the door 3 from the chamber 5 or locking the door 3 onto the chamber 5. Then, the driver 1 drives the door 3 away from the chamber 5 through the connecting rod assembly 2, thereby opening the door 3. The cable 10 to be tested is suspended on the cable suspension assembly, and then the cable suspension assembly with the cable 10 is installed in the internal cavity of chamber 5. Then, the driver assembly drives the door 3 again and powers on the electromagnet lock assembly 4, thereby locking the door 3 onto the chamber 5.

[0030] The cable suspension assembly includes a column 7, a locking component 8, and a crossbeam 9. One end of the column 7 is connected to the housing 5 and located in the inner cavity of the housing 5. The other end of the column 7 is connected to the crossbeam 9 through the locking component 8. The locking component 8 is used to quickly connect and disconnect the crossbeam 9 and the column 7, thereby fixing the crossbeam 9 in the inner cavity of the housing 5 through the column 7 and preventing the crossbeam 9 from shaking.

[0031] In this step, an alarm will be triggered when the temperature inside the chamber 5 exceeds or falls below a certain temperature (e.g., 200±3℃).

[0032] Step 2: Connect weights or other gravity blocks to the lower end of cable 10 to act as a load, so that the lower end of cable 10 is suspended from the crossbeam 9 under the load. After placing cable 10 into the inner cavity of box 5, after a preset time (the time length can be set according to national standards, industry standards or actual conditions), measure the tensile length of cable 10, that is, measure the length of cable 10 after being stretched due to heat and gravity.

[0033] During the measurement of the elongation length of cable 10, the cabinet door 3 is closed. Therefore, the elongation length of cable 10 can be measured using visual recognition. Specifically, at least a portion of the cabinet door 3 has a transparent area made of glass or other transparent material. A camera is installed directly in front of this transparent area, with cable 10 facing it, and the size of the transparent area is sufficient to cover the length of cable 10. Obtaining the elongation length of cable 10 by image processing from the illumination of cable 10 captured by the camera, using a visual recognition method, is existing technology and will not be elaborated upon here. Alternatively, the cabinet door 3 can be opened, the cable suspension assembly removed, and then the cable 10 can be measured, for example, manually using measuring tools. This process is typically completed within 30 seconds.

[0034] In an optional implementation, timing begins after the internal temperature of the enclosure 5 rises to a preset temperature. After a certain time (e.g., 10 minutes), the length between two pre-marked lines on the cable 10 is measured; this length is taken as the tensile length of the cable 10. For example, two spaced horizontal lines are pre-drawn on the cable using a colored pen; these two lines serve as markers. Multiple cables 10 can be mounted on the crossbeam 9 within the enclosure 5, allowing for the testing of the tensile lengths of multiple cables 10. The average of all or several adjacent cables 10 is taken as the current tensile length of the cable 10. For example, two adjacent cables 10 are grouped from left to right, and the average of the two cables in the group is taken as the tensile length of this group of cables. The load on the cable 10 is located below the lowest marker line.

[0035] Step 3: Cut the load on cable 10 using the cutting component. The cutting position is below the lowest mark line. Cut the load off cable 10. After cutting the load, maintain a constant temperature (e.g., 200±3℃) for a preset time (e.g., 5 minutes). After the preset time is reached, stop heating the inner cavity of the box 5 and simultaneously release the power to the electromagnet lock component 4, thereby releasing the door 3 from the box 5. Then, drive the connecting rod component 2 again through the driver 1 to drive the door 3 and open the door 3. After the inner cavity of the box 5 returns to room temperature (i.e., normal temperature), measure the length of cable 10 again, that is, measure the length between the two mark lines on the cable to obtain the recovered length of cable 10. Record the recovered length of cable 10 as the recovery length, that is, the length of cable 10 after being stretched and recovering itself after being subjected to heat. Therefore, the elongation rate of cable 10 can be calculated based on the initial length, tensile length and recovery length of cable 10. The specific formula for calculating the elongation rate is existing technology and is not within the scope of protection of this application. This embodiment only provides a test method for measuring these parameters, so the specific calculation process and formula for calculating the elongation rate will not be described here.

[0036] Similarly, the elongation (i.e., elongation rate) of the cable 10 can be obtained by taking the average value of two adjacent cables 10 as a group or the average value of multiple cables 10 as the final test result.

[0037] The cutting assembly includes a cutting drive 6, a cutting disc 11, a cutting connecting column 12, and a cable anti-detachment assembly 13. The cutting drive 6 is connected to the cutting disc 11 via the cutting connecting column 12. One end of the cutting drive 6 is connected to the cutting connecting column 12, and the other end of the cutting disc 11 is connected to the cutting connecting column 12, with the cutting disc 11 located at the other end of the cutting connecting column 12. The cutting disc 11 is used to cut the cable 10 located on the cable suspension assembly on one side of the cutting assembly. The cable anti-detachment assembly 13 is installed at the junction of the cutting disc 11 and the cutting connecting column 12, with one end of the cable anti-detachment assembly 13 extending out of the cutting disc 11 and close to the cable 10. The cable anti-detachment assembly 13 is used to prevent the cable 10 from shifting too much and leaving the effective area of ​​the cutting disc 11, thereby preventing the cutting disc 11 from failing to cut or failing to cut the cable 10 stably.

[0038] The cable anti-detachment assembly 13 includes a fixing plate 131, a connecting plate 132, and an inclined plate 133. The fixing plate 131 is vertically mounted on the cutting disc 11 and fits against the cutting connecting column 12. A fixing plate 131 is provided on each side of the cutting connecting column 12. The fixing plate 131 is fixedly connected to the connecting plate 132. The connecting plate 132 extends radially along the cutting disc 11, that is, it extends outward in a direction away from the center of the cutting disc 11 and is connected to the inclined plate 133 located outside the cutting disc 11. The two fixed plates 131 are respectively connected to the two connecting plates 132, which are spaced apart. The two inclined plates 133 connecting the two connecting plates 132 are also spaced apart. The inclined plates 133 are extended outward and inclined to connect with the connecting plates 132, so that the two inclined plates 133 form an outward connection structure in the shape of an "eight". This makes the cable 10 just between the two inclined plates 133. When the cable 10 sways left and right, it can be limited by the inclined plates 133, which prevents the cable 10 from moving out of the working area of ​​the cutting disc 11 and thus not being able to be cut by the cutting disc 11 or not being able to cut the cable 10 from the front, resulting in unstable cutting. In other words, the cable 10 can be well limited to be directly opposite the cutting disc 11.

[0039] Among them, the cutting drive 6 can drive the cutting disc 11 to rotate at high speed, for example, up to 20,000 revolutions per minute, and under such high-speed rotation, it can smoothly cut the cable 10 in a suspended state.

[0040] In the entire process of the thermal elongation test of the cable 10, the present invention can eliminate the need for manual measurement or only require manual measurement once when measuring the tensile length of the cable 10. The door 3 can be automatically opened or closed according to preset time or preset conditions (such as reaching the corresponding temperature). The test process is highly automated and efficient, and can be completed in a very short time, thus ensuring that the temperature change caused by the time process does not affect the measurement results of the thermal elongation of the cable 10.

[0041] The embodiments disclosed in this specification are merely illustrative of one aspect of the invention, and the scope of protection of the invention is not limited to these embodiments. Any other functionally equivalent embodiments fall within the scope of protection of the invention. Those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the scope of protection of the claims of this invention.

Claims

1. A highly efficient method for testing the thermal elongation of cables, characterized in that, It is based on a thermal expansion test chamber, which includes a door, a chamber body, a drive assembly, an electromagnet lock assembly, a cutting assembly, and a cable suspension assembly. The drive assembly is used to drive the door to move closer to or away from the chamber body, so that the door is attached to or open relative to the chamber body. The electromagnet lock assembly is used to lock the door to the chamber body when it is attached to the chamber body. The cutting assembly is used to cut the cable suspended on the cable suspension assembly. The cable is pre-marked with two lines, and a load is connected to the lower end of the cable, with the load located below the lowermost line. The cutting assembly includes a cutting drive, a cutting disc, a cutting connecting column, and a cable anti-detachment assembly. The cutting drive is connected to the cutting disc via the cutting connecting column. The cutting disc is used to cut the cable on the cable suspension assembly located on one side of the cutting assembly. The cable anti-detachment assembly is mounted on the cutting disc, with one end extending out of the cutting disc and close to the cable. The cable anti-detachment assembly is used to prevent the cable from shifting too much and leaving the effective area of ​​the cutting disc. The cable anti-detachment assembly includes a fixing plate, a connecting plate, and an inclined plate. The fixing plate is vertically mounted on the cutting disc and fits against the cutting connecting column. A fixing plate is installed on each side of the cutting connecting column, and the fixing plates are fixedly connected to the connecting plates. The connecting plates extend radially along the cutting disc and connect to the inclined plates located outside the cutting disc. The two connecting plates connected to the two fixing plates are spaced apart, and the two inclined plates connecting the two connecting plates are also spaced apart. The inclined plates extend outwards and connect to the connecting plates, forming an outwardly extending "V"-shaped connection structure, ensuring that the cable is positioned precisely between the two inclined plates. The method includes the following steps: Step 1: Heat the inner cavity of the enclosure to a preset constant temperature. After reaching the preset constant temperature, disconnect the power supply to the electromagnet lock assembly to release the lock on the enclosure door. Drive the enclosure door away from the enclosure to open the enclosure door. Install the cable suspension assembly with the cable in the inner cavity of the enclosure. Then, drive the enclosure door again and turn on the electromagnet lock assembly to lock the enclosure door. Step 2: Measure the length between the two markings on the cable; this length is taken as the cable's tensile length. Step 3: Cut the cable using the cutting component, with the cutting position below the lowest mark line, and cut the load off the cable. After cutting the load, maintain a constant temperature for a preset time. After the preset time is reached, stop heating and disconnect the power to the electromagnet lock component to release the door from the box. Drive the door away from the box using the drive component to open the door. After cooling for a period of time until the temperature drops to the preset temperature, measure the length between the two marks on the cable again to obtain the length of the cable after recovery.

2. The high-efficiency thermal elongation test method for cables according to claim 1, characterized in that, At least two cables are suspended on the cable suspension assembly. In steps 2 and 3, two or more adjacent cables are grouped together in sequence from left to right or from right to left, and the average value of a group of cables is used as the current cable's corresponding stretched length or the restored cable length.

3. The high-efficiency thermal elongation test method for cables according to claim 2, characterized in that, In step 1, the inner cavity of the box is heated by a temperature control device installed on the box and the temperature is maintained at a preset temperature. The electromagnet lock assembly is powered on and off by a program pre-programmed into the controller so that the electromagnet lock assembly locks or unlocks the box door attached to the box at the appropriate time or according to preset conditions.

4. The high-efficiency thermal elongation test method for cables according to claim 3, characterized in that, The drive assembly includes a driver and a connecting rod assembly, with the driver connected to the door via the connecting rod assembly.

5. The high-efficiency thermal elongation test method for cables according to claim 4, characterized in that, The cable suspension assembly includes a column, a locking assembly, and a crossbeam. One end of the column is connected to the housing and located inside the housing cavity. The other end of the column is connected to the crossbeam via the locking assembly. The locking assembly is used to connect and disconnect the crossbeam and the column, thereby preventing the crossbeam from swaying.

6. The high-efficiency thermal elongation test method for cables according to claim 5, characterized in that, The cessation of heating the inner cavity of the enclosure and the release of the electromagnet lock assembly are performed simultaneously, so that the enclosure door can be opened immediately once heating is stopped.

7. The high-efficiency thermal elongation test method for cables according to claim 1, characterized in that, The cutting drive is connected to one end of the cutting connecting column, and the cutting disc is connected to the other end of the cutting connecting column, with the cutting disc located at the end of the other end of the cutting connecting column.

8. The high-efficiency thermal elongation test method for cables according to claim 7, characterized in that, The cable anti-detachment component is installed at the junction of the cutting disc and the cutting connection column.

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