Cable thermal elongation testing device and control method thereof

Abstract

The invention discloses a cable thermal elongation testing device and a control method thereof, and relates to the field of cable tests. The test box is provided with a heating cavity and a display screen; the suspension piece in the heating cavity is detachably connected with the upper end of the test piece, and the test piece comprises a cable sample and two clamping pieces arranged at the upper end and the lower end of the cable sample; a load part which is in vertical sliding connection with a guide rod in the heating cavity is arranged right below the suspension part so as to be detachably connected with the lower end of the test piece; a conductive part on the load part is in sliding contact with the peripheral surface of the resistance part extending up and down and is conductive, so that the up-down distance between the conductive part and the upper end of the resistance part, the length value of the cable sample and the electrified length of the resistance part are equal, and the ampere meter, the direct-current power supply, the conductive part and the upper end of the resistance part are electrically connected in a closed-loop manner; the voltmeter, the conductive piece and the upper end of the resistor are electrically connected in a closed loop; the control processor calculates the length value of the cable sample according to the current value, the voltage value and the unit length resistance value of the resistor, and displays the length value through the display screen. The method is good in test accuracy, safe and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of cable testing, and particularly relates to a cable heat elongation rate testing device and a control method thereof. Background Art

[0002] The heat elongation test is an important test for evaluating the deformation resistance of cable insulation or sheath materials (such as cross-linked polyethylene) under the dual action of high temperature and mechanical load. It is mainly used to verify whether the material reaches the specified degree of cross-linking to ensure that the cable will not undergo excessive deformation or failure due to thermal stress problems during long-term operation.

[0003] When using the existing cable heat elongation test device, the upper end of the sample of the prepared cable insulation or sheath material is fixed in the aging box, and a certain load such as a weight is hung at the lower end of the sample to make the sample in a vertically suspended state; the aging box is closed, and then the temperature in the aging box is raised to the set test temperature such as 200 °C and the timing starts. When the accumulated time reaches the set test time such as 15 minutes, the gauge length after elongation of the sample (i.e., the length L1 between the marks after elongation) is read, so that the heat elongation rate E (or elongation rate under load) can be calculated based on the original gauge length (i.e., the original length L0 between the marks) and the gauge length after elongation.

[0004] However, if the aging box does not have an observation window for the test personnel to read data, or the observation window is difficult for the test personnel to directly and clearly read data, it is necessary to open the aging box to read the data, which will bring inconvenience to the test work and easily cause the test personnel to be scalded by the high temperature of the aging box. Moreover, the test personnel use the visual method to read the gauge data measured by the scale, which will cause the accuracy of the test results to be easily affected by the measurement error of the naked eye and decrease. In addition, if a vision system is used to obtain the elongation data of the sample, the cost of the equipment will increase significantly. Therefore, there is an urgent need to develop a new cable heat elongation measurement device that can conveniently, directly, clearly and accurately obtain test data and has a low cost. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides a cable heat elongation rate testing device and a control method thereof, which can enable the test personnel to conveniently and clearly obtain test data, avoid the reduction of the accuracy of the test results due to the measurement error of the naked eye, and at the same time, prevent the test personnel from being scalded by high temperature and have a low cost.

[0006] The first aspect embodiment of the present invention provides a cable heat elongation rate testing device, which includes: A test chamber, provided with a heating cavity and a display screen, and a guide rod extending in the up and down direction is arranged in the heating cavity; The suspension member is fixedly arranged in the heating cavity for detachably connecting with the upper end of the test piece. The test piece includes a cable sample and two clamping members fixed to the upper and lower ends of the cable sample. The load member is slidably connected to the guide rod in the up-and-down direction and is arranged directly below the suspension member for detachably connecting with the lower end of the test piece. The measurement system includes a resistance member, a conductive member, a DC power supply, an ammeter, and a voltmeter. The resistance member extends in the up-and-down direction and is fixedly arranged in the heating cavity. The conductive member is connected to the load member and is in sliding contact and conductive with the outer peripheral surface of the resistance member, so that the up-and-down distance between the conductive member and the upper end of the resistance member is equal to the length value of the cable sample. The ammeter, the DC power supply, the conductive member, and the upper end of the resistance member are connected in a closed loop so that the ammeter can collect the current value. The voltmeter, the conductive member, and the upper end of the resistance member are connected in a closed loop so that the voltmeter can collect the voltage value. The control processor is electrically connected to the ammeter, the voltmeter, and the display screen, and is used to calculate the energized length of the resistance member according to the current value, the voltage value, and the resistance value per unit length of the resistance member, and control the display screen to display the length value of the cable sample. Wherein, the energized length of the resistance member is the up-and-down distance between the conductive member and the upper end of the resistance member.

[0007] The cable thermal elongation rate test device according to the first aspect embodiment of the present invention has at least the following beneficial effects: When the upper end and the lower end of the test piece are respectively connected to the suspension member and the load member, the test piece is in a suspended state in the heating cavity of the test chamber. At this time, the conductive member on the load member contacts the outer surface of the resistance member. When the test chamber is closed and the temperature in the heating cavity reaches the set temperature, the thermal elongation of the cable sample can be tested under the conditions of high temperature and mechanical load. During this process, the load member and the conductive member can move downward following the elongation of the cable sample. Therefore, the contact position between the conductive member and the resistance member in the up-and-down direction can be changed, so that a mathematical relationship can be established between the energized length of the resistance member and the length value of the cable sample. At the same time, the control processor can receive the data collected by the ammeter and the voltmeter. The ammeter can detect the current value passing through the resistance member, and the voltmeter can detect the voltage value between the upper end of the resistance member and the contact point between the resistance member and the conductive member. When the test time reaches the set time, the control processor can quickly calculate the energized length of the resistance member according to the received current value, voltage value, and the known resistance value per unit length of the resistance member.

[0008] Since the vertical distance between the upper end of the conductive member and the resistive member is designed to be equal to the length value of the cable sample, and the energized length of the resistive member is the vertical distance between the upper end of the conductive member and the resistive member, the calculated energized length of the resistive member is the length value of the cable sample; finally, the length value of the cable sample during the heat elongation test is clearly displayed through the display screen, facilitating the tester to accurately calculate the heat elongation rate of the cable based on the original length of the cable sample measured previously and the length value of the cable sample during the heat elongation test.

[0009] By adopting such a unique design, it is convenient for the tester to operate and obtain the data of the heat elongation test conveniently, and can improve the test accuracy rate, prevent the accuracy rate of the test results from decreasing due to the errors brought by the visual measurement method. At the same time, it can avoid the tester being easily scalded by the test chamber with a high heating temperature, improve the use safety, and moreover, can reduce the manufacturing cost, enabling the cable heat elongation rate testing device to be widely applied.

[0010] In some embodiments of the present invention, the resistive member is cylindrical, there are two resistive members, and they are arranged at intervals in the horizontal direction. The conductive member is provided with two contacts. The conductive member is located between the two resistive members, so that the two contacts are in sliding contact and conductive with the outer peripheral surfaces of the two resistive members respectively. The ammeter, the DC power supply, the upper end of one of the resistive members, the conductive member, and the upper end of the other resistive member are connected in a closed loop electrically to form a first loop. The voltmeter, the upper end of one of the resistive members, the conductive member, and the upper end of the other resistive member are connected in a closed loop electrically to form a second loop; and / or, The guide rod is a round rod and there is at least one, and the load member is provided with a guide sleeve slidably connected to the guide rod.

[0011] In some embodiments of the present invention, the test chamber includes a box body and a box door. The box door is located on one side of the box body along the first direction and is movably connected to the box body to open and close the opening of the heating chamber. The lower end of the suspension member is provided with a first card slot for the upper end of the test piece to be inserted along the first direction, and the upper end of the load member is provided with a second card slot for the lower end of the test piece to be inserted along the first direction. The first direction is perpendicular to the vertical direction.

[0012] In some embodiments of the present invention, the cross-sectional shape of the first card slot is T-shaped, and the cross-sectional shape of the second card slot is inverted T-shaped.

[0013] In some embodiments of the present invention, the cable thermal elongation rate testing device further includes a reset adjusting mechanism. The reset adjusting mechanism includes a first driving member and a lifting member. The lifting member is disposed in the heating chamber and is located below the load member. The first driving member is used to drive the lifting member to move in the up and down direction, so that the lifting member jacks the load member to a set position, enabling the lower end of the test piece to be inserted into the second card slot along a first direction.

[0014] In some embodiments of the present invention, the first driving member is a servo electric cylinder and is disposed outside the heating chamber. The output end of the first driving member extends into the heating chamber and is fixedly connected to the lifting member.

[0015] In some embodiments of the present invention, the cable thermal elongation rate testing device further includes a second driving member. The second driving member is used to drive the cabinet door to open and close. The control processor is electrically connected to the reset adjusting mechanism and the second driving member respectively, and is used to control the second driving member to drive the cabinet door to open after the reset adjusting mechanism drives the load member to move up to the set position.

[0016] In some embodiments of the present invention, the cable thermal elongation rate testing device further includes a temperature sensor. The temperature sensor is used to collect the real-time temperature in the heating chamber. The control processor is electrically connected to a timing unit. The control processor is electrically connected to the temperature sensor. The control processor is used to control the timing unit to perform test time timing when the real-time temperature reaches the set temperature, and to collect the current value and the voltage value when the test time reaches the set time.

[0017] In some embodiments of the present invention, the measurement system further includes a control switch. The control switch, the ammeter, the DC power supply, the conductive member, and the upper end of the resistance member are electrically connected in a closed loop. The control switch is electrically connected to the control processor. The control processor is used to control the control switch to conduct after the second driving member drives the cabinet door to close.

[0018] The second aspect embodiments of the present invention provide a control method for a cable thermal elongation rate testing device, which is applied to the cable thermal elongation rate testing device as described in the first aspect embodiments, and includes the following steps: When the test piece is respectively connected to the suspension member and the load member and the temperature of the heating chamber reaches the set temperature, control the timing unit to work to perform test time timing; When the test time reaches the set time, collect the current current value of the ammeter and the current voltage value of the voltmeter; Calculate the energized length of the resistive element according to the current current value, the current voltage value, and the resistance value per unit length of the resistive element. Control the display screen to display the length value of the cable sample.

[0019] The control method of the cable heat elongation rate test device according to the second aspect embodiment of the present invention has at least the following beneficial effects: After the test piece is installed in the test chamber, close the test chamber and heat it up so that the temperature in the heating chamber can reach the set temperature for the heat elongation test; when the temperature in the heating chamber reaches the requirement, the timing unit can be used to time the test time, allowing the test piece to perform the heat elongation test under the action of high temperature and mechanical load; when the test time accumulates to the set time, the control processor can collect the current current value detected by the ammeter and the current voltage value detected by the voltmeter, and according to the current current value, the current voltage value, and the known resistance value per unit length of the resistive element, quickly calculate the energized length of the resistive element.

[0020] Since the vertical distance between the upper end of the conductive element and the resistive element is designed to be equal to the length value of the cable sample, and the energized length of the resistive element is equal to the vertical distance between the upper end of the conductive element and the resistive element, therefore, the energized length of the resistive element calculated by the control processor is the length value of the cable sample; finally, the control processor controls the operation of the display screen and clearly displays the length value of the cable sample after elongation during the heat elongation test through the display screen, facilitating the test personnel to accurately calculate the heat elongation rate of the cable based on the original length of the cable sample measured previously and the length value of the cable sample during the heat elongation test.

[0021] Other features and advantages of the present invention will be described in the subsequent description, and some of them will be obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the description, the claims, and the drawings. Description of the Drawings

[0022] Figure 1 is the front view of the cable heat elongation rate test device provided by the embodiment of the present invention; Figure 2 is the internal structure schematic diagram of the cable heat elongation rate test device provided by the embodiment of the present invention; Figure 3 is the structural schematic diagram of the sliding contact between the conductive element and two resistive elements in the cable heat elongation rate test device provided by another embodiment of the present invention; Figure 4 is the structural schematic diagram of the reset adjustment mechanism in the cable heat elongation rate test device provided by another embodiment of the present invention; Figure 5It is a schematic internal structure diagram of a cable thermal elongation rate test device provided according to another embodiment of the present invention; Figure 6 It is a schematic electrical connection structure diagram of a measurement system in a cable thermal elongation rate test device provided according to an embodiment of the present invention; Figure 7 It is a schematic electrical connection structure diagram of a measurement system in a cable thermal elongation rate test device provided according to another embodiment of the present invention; Figure 8 It is a schematic electrical connection structure diagram of a measurement system in a cable thermal elongation rate test device provided according to yet another embodiment of the present invention; Figure 9 It is a schematic structure diagram of a control processor electrically connected to a voltmeter, an ammeter, and a display screen respectively in a cable thermal elongation rate test device provided according to an embodiment of the present invention; Figure 10 It is a schematic structure diagram of a control processor electrically connected to a temperature sensor, a voltmeter, an ammeter, a display screen, a timing unit, a reset adjustment mechanism, and a second driving member respectively in a cable thermal elongation rate test device provided according to another embodiment of the present invention; Figure 11 It is a schematic structure diagram of a control processor electrically connected to a temperature sensor, a voltmeter, an ammeter, a display screen, a timing unit, a reset adjustment mechanism, a second driving member, and a control switch respectively in a cable thermal elongation rate test device provided according to yet another embodiment of the present invention; Figure 12 It is a schematic flow diagram of a control method for a cable thermal elongation rate test device provided according to an embodiment of the present invention.

[0023] Reference numerals: 100, test chamber; 110, box body; 111, heating chamber; 120, box door; 130, observation window; 140, display screen; 151, air inlet member; 152, air outlet member; 153, air cavity; 154, heating and air supply device; 210, suspension member; 211, first card slot; 220, load member; 221, second card slot; 222, weight; 230, guide rod; 240, guide sleeve; 310, resistance member; 320, conductive member; 400, reset adjustment mechanism; 410, first driving member; 420, lifting member; 510, cable sample; 520, clamping member; 610, first horizontal line; 620, second horizontal line; 630, third horizontal line; 640, fourth horizontal line. Detailed implementation manners

[0024] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0025] In the description of the present invention, it should be understood that features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Next, reference is made to Figures 1 to 12 Describe a cable thermal elongation rate test device and its control method provided according to an embodiment of the present invention.

[0028] As Figures 1 to 11 shown, the cable thermal elongation rate test device according to the first aspect embodiment of the present invention can be applied to the cable thermal elongation rate test work. It can enable the test personnel to conveniently and clearly obtain the test data of the cable, avoid the reduction of the accuracy of the thermal elongation test result due to the visual measurement error, ensure the high accuracy of the test structure, and at the same time, can also prevent the test personnel from being scalded by high temperature to improve the use safety performance, and moreover, the manufacturing cost is low.

[0029] The cable thermal elongation rate test device has a first direction, a second direction and an up-and-down direction that are perpendicular to each other in pairs. In this embodiment, it is assumed that the first direction is the front-back direction and the second direction is the left-right direction.

[0030] As Figures 1 to 11 shown, the cable thermal elongation rate test device includes a test chamber 100, a suspension member 210, a load member 220, a measurement system and a control processor.

[0031] As Figure 1 and Figure 2As shown in the figure, the test chamber 100 is provided with a heating chamber 111 and a display screen 140. Specifically, the test chamber 100 includes a box body 110 and a box door 120. Among them, the box door 120 is located on one side of the box body 110 along the first direction, and the box door 120 is movably connected to the box body 110 to open and close the opening of the heating chamber 111. The heating chamber 111 provides a sealed space for high-temperature testing of the test piece. A guide rod 230 is provided in the heating chamber 111. The length of the guide rod 230 extends in the up and down direction, and both ends of the guide rod 230 are fixedly connected to the test chamber 100, so that the guide rod 230 remains stable and immovable in the heating chamber 111. The number of guide rods 230 is not limited to one. The display screen 140 is located on the outer surface of the test chamber 100, such as on the front side of the box body 110.

[0032] It can be understood that the test piece includes a cable sample 510 and two clamping pieces 520. The two clamping pieces 520 are respectively fixed to the upper and lower ends of the cable sample 510. The cable sample 510 can be designed in a dumbbell shape during preparation. The clamping piece 520 can be formed by connecting two clamping plates by a bolt connection method. The two clamping plates can effectively and stably clamp and fix the end of the cable sample 510. The cross-sectional shape of the guide rod 230 can be square or circular. After the test piece is placed in the heating chamber 111, the box door 120 is closed, so that the test piece is in a high-temperature sealed test environment. The display screen 140 has the function of displaying data. Of course, the display screen 140 can be a touch display screen, which is configured with functions such as instruction input and data viewing.

[0033] The interior of the test chamber 100 is hollow to form a heating chamber 111 and a wind chamber 153. The heating chamber 111 and the wind chamber 153 are arranged at intervals. In this embodiment, as Figure 2 shown, the wind chamber 153 is located at the rear of the heating chamber 111. A partition plate is provided between the wind chamber 153 and the heating chamber 111. An air inlet member 151 is provided at the upper part of the partition plate, and an air outlet member 152 is provided at the lower part of the partition plate. The air inlet member 151 and the air outlet member 152 are both provided with air holes to promote the communication between the wind chamber 153 and the heating chamber 111. A heating and air supply device 154 is provided in the wind chamber 153. The heating and air supply device 154 includes a fan and a heating element. The heating element can be a heating rod or a heating plate. When the fan and the heating element are working, the air in the heating chamber 111 can flow into the wind chamber 153 through the air inlet member 151, and after absorbing the heat generated by the heating element, it can flow back into the heating chamber 111 through the air outlet member 152, so as to increase the air temperature in the heating chamber 111, make the air temperature reach the test temperature and basically remain unchanged, so that the test chamber 100 can provide a constant-temperature test space for the test piece.

[0034] Of course, it is not excluded to set multiple heating tubes in the heating chamber 111 to increase the air temperature in the heating chamber 111. Additionally, an observation window 130 can be provided on the cabinet door 120, facilitating the experimenter to clearly observe the situation inside the heating chamber 111 through the observation window 130.

[0035] The suspension member 210 is fixedly arranged inside the heating chamber 111 so that the suspension member 210 can be detachably connected to the upper end of the test piece. Specifically, as Figure 2 shown, the upper end of the suspension member 210 can be fixed to the inner top surface of the heating chamber 111 by means of bolt connection or the like. A first card slot 211 is provided at the lower end of the suspension member 210, and the first card slot 211 can be used for the upper end of the test piece to be inserted along the first direction. In this embodiment, when viewed along the first direction, the cross-sectional shape of the first card slot 211 is T-shaped, and the upper end of the clamping member 520 located above the cable sample 510 is designed as a T-shaped convex part so that the clamping member 520 can enter and exit the first card slot 211 along the first direction. After the upper end of the test piece extends into the first card slot 211 along the first direction, the suspension member 210 can provide a certain supporting effect on the test piece, making the test piece in a suspended state.

[0036] The load member 220 is slidably connected to the guide rod 230 in the vertical direction, enabling the load member 220 to move stably up and down along the guide rod 230. As Figure 2 shown, in this embodiment, the guide rod 230 is a round rod, and the load member 220 is provided with a guide sleeve 240, and the guide sleeve 240 is sleeved on the guide rod 230, making the guide sleeve 240 slidably connected to the guide rod 230. At least one guide rod 230 is provided. Moreover, the load member 220 is arranged directly below the suspension member 210 so that the load member 220 can be detachably connected to the lower end of the test piece. Specifically, a second card slot 221 is provided at the upper end of the load member 220, and the second card slot 221 can be used for the lower end of the test piece to be inserted along the first direction. In this embodiment, when viewed along the first direction, the cross-sectional shape of the second card slot 221 is an inverted T-shaped, and the lower end of the clamping member 520 located below the cable sample 510 is designed as an inverted T-shaped convex part so that the clamping member 520 can enter and exit the second card slot 221 along the first direction. After the lower end of the test piece extends into the second card slot 221 along the first direction, the load member 220 can provide a certain load on the test piece.

[0037] It can be understood that the suspension member 210 and the load member 220 can be made of materials such as metal or plastic. The specific shapes of the suspension member 210 and the load member 220 can be designed according to the actual situation and are not specifically limited here. The total weight of the load member 220 meets the load test requirements of the cable sample 510. Weights 222 can be hung below the load member 220, and appropriate weights of weights 222 can be hung on the load member 220 according to the test situation. The guide rod 230 can be arranged behind the load member 220 and the suspension member 210, or can be arranged on the left or right side of the load member 220 and the suspension member 210. The outer surface of the guide rod 230 is smooth, and the load member 220 is equipped with a guide sleeve 240. Therefore, the frictional force between the guide rod 230 and the load member 220 is very small and can be ignored.

[0038] The measurement system includes a resistance member 310, a conductive member 320, a DC power supply, an ammeter, and a voltmeter. Among them, as Figure 2 shown, the length of the resistance member 310 extends in the up and down direction, and moreover, the resistance member 310 is fixedly arranged in the heating chamber 111. Specifically, the resistance member 310 can be fixedly connected to the test chamber 100 through a connecting member such as a fixing clip, so that the resistance member 310 maintains a stable vertical state. The conductive member 320 is connected to the load member 220, the conductive member 320 is fixed relative to the load member 220, and the conductive member 320 is in sliding contact with the outer peripheral surface of the resistance member 310 and conducts electricity with each other, so that the vertical distance H between the upper end of the conductive member 320 and the resistance member 310 is equal to the length value of the cable sample 510.

[0039] It can be understood that the resistance member 310 is cylindrical, and the resistance member 310 can be made of materials such as manganin, constantan, platinum resistance, or nickel-chromium alloy. Preferably, the resistance member 310 is selected to be made of constantan. The applicable temperature range of constantan can be as high as 500 °C. Constantan shows an approximately linear increase in resistance at high temperatures. The resistivity of constantan is excellent in stability within the range of 25 °C to 300 °C. Constantan can still maintain good high-temperature stability under the test temperature conditions and can meet the requirements of the cable thermal elongation test work. The cable thermal elongation test work is carried out under constant temperature conditions. In this embodiment, the set temperature can be set to 200 °C ± 0.5 °C. The resistance change of the resistance member 310 made of constantan is extremely small (about ±0.001%) under a temperature difference of ±0.5 °C and can be ignored; at this time, the resistance value per unit length of the resistance member 310 can be determined according to the resistance value of the resistance member 310 at 200 °C. Of course, the temperature difference can be further reduced to reduce the influence of the temperature difference on the resistance member 310.

[0040] In addition, the resistance member 310 can also be selected to be made of nickel-chromium alloy, and its resistance change is approximately linear within the range of 25 °C to 300 °C.

[0041] For the resistor 310 whose resistance value changes linearly or approximately linearly with temperature, the resistance value of the resistor 310 can be calculated according to the existing resistance-temperature relationship formula, and then the resistance value per unit length of the resistor 310 can be calculated based on the known length value of the resistor 310. In addition, before the cable thermal elongation test, the resistance value of the resistor 310 at the test temperature can be obtained through experiments, and then the resistance value per unit length of the resistor 310 can be calculated based on the known length value of the resistor 310. In order to reduce the influence of temperature fluctuations on the resistance value, making the change of the resistance value within the temperature fluctuation range very small and negligible, materials with good stability are preferably selected to make the resistor 310.

[0042] The resistance value per unit length of the resistor 310 is obtained through the above method, and moreover, the resistance value per unit length of the resistor 310 is known and constant, and can be stored in the control processor. For different test temperatures, the resistance values per unit length of the resistor 310 at different test temperatures can be stored in the control processor.

[0043] The resistor 310 can be located behind, or to the left or right of the load 220. The outer surface of the resistor 310 is smooth. The conductive member 320 has a contact head, and the contact head is in contact with the outer surface of the resistor 310 and can conduct electricity with each other. The frictional force between the conductive member 320 and the resistor 310 is very small and can be ignored; in addition, the contact resistance value between the conductive member 320 and the resistor 310 is very small and can be ignored to avoid affecting the test result of the thermal elongation rate. Electrical insulation design can be adopted between the load 220 and the conductive member 320, such as setting an electrical insulation layer at the connection between the two. The weights of the load 220 and the conductive member 320 are constant.

[0044] As Figure 6 shown, the ammeter, the DC power supply, the upper end of the conductive member 320 and the upper end of the resistor 310 are connected in a closed loop so that the ammeter can collect the current value; the voltmeter, the conductive member 320 and the upper end of the resistor 310 are connected in a closed loop so that the voltmeter can collect the voltage value.

[0045] It can be understood that the upper end of the resistor 310, the ammeter, the DC power supply, and the conductive member 320 are sequentially connected by wires. The conductive member 320 contacts and conducts electricity with the outer peripheral surface of the resistor 310. Therefore, these four can jointly form a first circuit, and the ammeter can detect the current value flowing through the resistor 310 in real time. Of course, an electrical load, such as a heating element or a lamp, can be connected in series on the first circuit. The upper end of the resistor 310, the voltmeter, and the conductive member 320 are sequentially connected by wires. The conductive member 320 contacts and conducts electricity with the outer peripheral surface of the resistor 310. Therefore, these three can jointly form a second circuit, and the voltmeter can detect the current value across the resistor 310 in real time. The wires connected to the conductive member 320 can use wires with relatively light weight, such as existing ultra-fine stranded wires or silicone micro-wires, so that the weight of the wires can be ignored, avoiding affecting the test results of the thermal elongation rate.

[0046] The control processor is electrically connected to the ammeter, the voltmeter, and the display screen 140 through wires. As Figure 9 shown, the control processor can receive the real-time data collected from the ammeter and the voltmeter, and can send control instructions to the display screen 140. The control processor can be used to calculate the energized length of the resistor 310 according to the current value collected by the ammeter, the voltage value collected by the voltmeter, and the known resistance value per unit length of the resistor 310 through the voltage, current, and resistance formulas. Among them, the resistance is equal to the product of the resistance value per unit length of the resistor 310 and the energized length of the resistor 310, and the energized length of the resistor 310 is the vertical distance H between the conductive member 320 and the upper end of the resistor 310, and they are all equal to the length value of the cable sample 510. And the control processor can control the display screen 140 to display the length value of the cable sample 510.

[0047] It can be understood that the control processor can be a control element with functions such as programmable, logical control, and data processing, such as an integrated main board, a 51 single-chip microcomputer, or a PLC controller, and the specific model of the control processor is not limited. Set values such as the resistance value per unit length of the resistor 310, the set time, and the set temperature can be stored in the data storage unit integrated in the control processor.

[0048] As Figure 2As shown, the position of the suspension member 210 within the heating chamber 111 is known to be unchanged. When the upper end surface of the test piece and the inner top surface of the first card slot 211 of the suspension member 210 are both on the first horizontal line 610, the upper end of the test piece can be inserted into the first card slot 211 along the first direction, thereby completing the connection work between the test piece and the suspension member 210. At this time, the upper end surfaces of the cable sample 510 and the resistor member 310 are both on the second horizontal line 620, that is, the two are flush on the horizontal plane. Then, the load member 220 is moved upward to the set height position. At this time, a limit block can be set to ensure that the load member 220 is moved in place. In this way, the lower end surface of the test piece and the inner bottom surface of the second card slot 221 of the load member 220 can both be on the fourth horizontal line 640, and the lower end of the test piece can be inserted into the second card slot 221 along the first direction, thereby completing the connection work between the test piece and the load member 220. At this time, the lower end surface of the cable sample 510 and the central position of the conductive member 320 are both on the third horizontal line 630, that is, the two are flush on the horizontal plane. Therefore, the vertical distance H between the contact point of the resistor member 310 and the conductive member 320 and the upper end surface of the resistor member 310 is equal to the length value of the cable sample 510 in the vertical direction.

[0049] During the thermal elongation rate test of the cable sample 510 under high temperature and mechanical load conditions, the load member 220 and the conductive member 320 will move downward as the cable sample 510 elongates downward, thereby adjusting the contact conductive position between the conductive member 320 and the resistor member 310 and promoting an increase in the energized length of the resistor member 310.

[0050] During the process of using the cable thermal elongation rate test device provided in the first aspect embodiment of the present invention, after the upper and lower ends of the test piece are respectively connected to the suspension member 210 and the load member 220 manually, the test piece is in a stable suspended state within the heating chamber 111 of the test chamber 100. At this time, the conductive member 320 on the load member 220 contacts the outer surface of the resistor member 310 and can conduct electricity with each other; when the test chamber 100 is in a closed state and the temperature within the heating chamber 111 reaches the set temperature, the thermal elongation of the cable sample 510 can be tested under high temperature and mechanical load conditions. During this process, the load member 220 and the conductive member 320 can move downward following the elongation of the cable sample 510. Therefore, the contact position between the conductive member 320 and the resistor member 310 in the vertical direction can be changed, so that a certain mathematical relationship can be established between the energized length of the resistor member 310 and the length value of the cable sample 510, that is, the energized length of the resistor member 310 is equal to the length value of the cable sample 510.

[0051] Meanwhile, the control processor can receive the real-time data transmitted from the ammeter and the voltmeter. The ammeter can detect the current value flowing through the resistor 310, and the voltmeter can detect the voltage value between the upper end of the resistor 310 and the contact between the resistor 310 and the conductive member 320. When the test time reaches the set time, the control processor can, according to the current value, voltage value received at this time and the known unit length resistance value of the resistor 310, and based on the existing Ohm's law formula and the variable resistance value of the resistor 310 being the product of the energized length of the resistor 310 and the unit length resistance value of the resistor 310, quickly calculate the energized length of the resistor 310.

[0052] Since the vertical distance H between the conductive member 320 and the upper end of the resistor 310 is designed to be equal to the length value of the cable sample 510, and the energized length of the resistor 310 is the vertical distance H between the conductive member 320 and the upper end of the resistor 310, therefore, the calculated energized length of the resistor 310 is the length value of the cable sample 510. Finally, the control processor controls the display screen 140 to operate, and clearly displays the length value L1 of the cable sample 510 during the heat elongation test through the display screen 140, facilitating the test personnel to accurately calculate the heat elongation rate of the cable according to the original length L0 of the cable sample 510 measured previously and the length value L1 of the cable sample 510 during the heat elongation test. It can be understood that the calculation formula for the heat elongation rate E of the cable is E = (L1 - L0) * 100% / L0.

[0053] By adopting such a unique structural design in the first aspect embodiment of the present invention, it is convenient for the test personnel to operate and obtain the data of the heat elongation test conveniently, and can improve the test accuracy rate, prevent the accuracy rate of the test result from decreasing due to the error caused by the visual measurement method. At the same time, it can avoid the test personnel from being easily scalded by the test chamber 100 with a high heating temperature, improve the use safety, and moreover, can reduce the manufacturing cost, enabling the cable heat elongation rate testing device to be widely applied.

[0054] In some embodiments, as Figure 3 and Figure 7 shown, when looking in the up and down direction, the resistor 310 is cylindrical, there are two resistor 310s, and moreover, the two resistor 310s are arranged at intervals in the horizontal direction. The two resistor 310s can be arranged at intervals in the first direction or in the second direction. The conductive member 320 is provided with two contacts, and the two contacts are respectively arranged corresponding to the two resistor 310s. The conductive member 320 is fixed on the load member 220, and the conductive member 320 is located between the two resistor 310s, so that the two contacts are in sliding contact and conductive with the outer peripheral surfaces of the two resistor 310s respectively. At this time, the conductive member 320 plays a role like a bridge, enabling electrons to flow from one resistor 310 through the conductive member 320 to the other resistor 310.

[0055] Moreover, as Figure 7 shown, the ammeter, the DC power supply, the upper ends of one of the resistor elements 310, the conductive member 320, and the upper end of the other resistor element 310 are electrically connected in a closed loop to form a first loop. At this time, the ammeter can detect the current value flowing through the two resistor elements 310. At the same time, the voltmeter, the upper end of one of the resistor elements 310, the conductive member 320, and the upper end of the other resistor element 310 are electrically connected in a closed loop to form a second loop. At this time, the voltmeter can detect the voltage value between the upper end of one of the resistor elements 310 and the upper end of the other resistor element 310.

[0056] It can be understood that by such a design, the wires connected to the conductive member 320 can be saved, the influence of the wires on the linear movement of the conductive member 320 in the up and down directions can be avoided, and it is helpful to improve the test accuracy of the thermal elongation rate. In this embodiment, the resistance value is equal to the quotient of the voltage value and the current value. The resistance value is equal to the product of the unit length resistance value of the resistor element 310 and the total energized length of the two resistor elements 310. The total energized length of the two resistor elements 310 is equal to twice the up and down distance H between the conductive member 320 and the upper end of the resistor element 310, and is also equal to twice the length value of the cable sample 510. Then, when the lower end of the cable sample 510 extends downward by a little distance, the total energized length of the two resistor elements 310 doubles, making the change in the current value more significant, so as to be able to play the role of "using a small force to move a heavy object", and it is convenient to more accurately calculate the length value L1 of the cable sample 510 during the thermal elongation test.

[0057] In some embodiments, as Figure 4 and Figure 5 shown, the cable thermal elongation rate test device further includes a reset adjustment mechanism 400. The function of the reset adjustment mechanism 400 is to move the load member 220 upward to the in-place position to complete the reset work of the load member 220, which is convenient for connecting the lower end of the load member 220 to the test piece.

[0058] Among them, the reset adjustment mechanism 400 includes a first driving member 410 and a lifting member 420. The lifting member 420 is arranged in the heating cavity 111, and the lifting member 420 is located below the load member 220. The output end of the first driving member 410 is connected to the lifting member 420. The function of the first driving member 410 is to drive the lifting member 420 to move in the up and down directions, so that the lifting member 420 lifts the load member 220 to a set position, so that the lower end of the test piece can be inserted into the second card slot 221 along the first direction.

[0059] It can be understood that the first driving member 410 can be a linear driving device such as a cylinder, an electric cylinder or a linear module. The lifting member 420 has a supporting surface which can contact the load member 220, so that the lifting member 420 can lift the load member 220 to a set position under the driving action of the first driving member 410. In this embodiment, the first driving member 410 is a servo electric cylinder, and the first driving member 410 is arranged outside the heating cavity 111. The output end of the first driving member 410 extends into the heating cavity 111 and is fixedly connected to the lifting member 420. The connection between the output end of the first driving member 410 and the wall surface of the heating cavity 111 can be heat-insulated by using heat-insulating materials to prevent heat from easily escaping through the gap between the output end of the first driving member 410 and the heating cavity 111.

[0060] After the reset work of the load member 220 is completed, it is convenient to use the manipulator to clamp the upper end and the lower end of the test piece respectively, and accurately insert the upper end and the lower end of the test piece into the first card slot 211 of the suspension member 210 and the second card slot 221 of the load member 220 along the first direction respectively. Moreover, after the heat elongation rate test work is completed, the reset adjusting mechanism 400 can be operated to reset the load member 220, and then the manipulator can clamp the upper end and the lower end of the test piece respectively and disengage them from the first card slot 211 and the second card slot 221; in this way, the feeding and discharging efficiency of the test piece can be improved, and the test personnel can be prevented from being scalded by high temperature, which is convenient for quickly testing multiple batches of test pieces.

[0061] In some embodiments, the cable heat elongation rate testing device further includes a second driving member. The function of the second driving member is to drive the box door 120 to open and close. It can be understood that in some examples, the box door 120 is slidably connected to the box body 110, so that the box door 120 moves horizontally or vertically. Then the second driving member can be a cylinder, an electric cylinder or a linear module, etc. The second driving member can drive the box door 120 to move back and forth along the horizontal direction or the vertical direction, so as to automatically control the opening and closing of the opening of the heating cavity 111. In other examples, the box door 120 is rotatably connected to the box body 110, then the second driving member can be a motor or a rotary cylinder, and the second driving member can drive the box door 120 to rotate forward or backward, so as to control the opening of the heating cavity 111 to be automatically opened or closed.

[0062] The control processor is electrically connected to the reset adjusting mechanism 400 and the second driving member through wires, and the control processor can be used to control the second driving member to drive the box door 120 to open after the reset adjusting mechanism 400 drives the load member 220 to move up to the set position.

[0063] It can be understood that after the heat elongation rate test work is completed, the tester sends a control instruction to the reset adjustment mechanism 400 through the control processor, causing the reset adjustment mechanism 400 to work, so as to drive the load member 220 and the conductive member 320 to move upward by a certain distance, returning the load member 220 to its initial position, which facilitates the quick docking of the load member 220 with the lower end of the test piece. After the reset adjustment mechanism 400 completes the reset work, the control processor will send a control instruction to the second driving member, enabling the second driving member to drive the chamber door 120 to open, so that the manipulator can quickly take out the tested test piece from the heating chamber 111 and place the next test piece in the heating chamber 111 and quickly connect it to the suspension member 210 and the load member 220 respectively.

[0064] With such a design, the automation degree of the cable heat elongation rate test device can be improved, enabling the tester to focus on the preparation of the test piece, measure the original length L0 of the cable sample 510, and place the test pieces on the loading rack one by one, which facilitates the manipulator to place the test pieces on the loading rack into the heating chamber 111 one by one for the heat elongation rate test work.

[0065] In addition, the manipulator can be electrically connected to the control processor. After the manipulator completes the loading work, the control processor will control the second driving member to operate, enabling the second driving member to drive the chamber door 120 to close automatically for the heat elongation rate test work.

[0066] Furthermore, as Figure 10 shown, the cable heat elongation rate test device further includes a temperature sensor. Among them, the function of the temperature sensor is to collect the real-time temperature in the heating chamber 111, and the number of temperature sensors is not limited to one. The installation position of the temperature sensor can be selected according to actual needs and will not be specifically limited here. In the case of multiple temperature sensors, the multiple temperature sensors can be respectively arranged at different corners of the heating chamber 111. When the real-time temperature data collected by the multiple temperature sensors all reach the set temperature, it means that the air temperature in the heating chamber 111 is constant, providing a constant temperature test environment for the cable sample 510.

[0067] Moreover, the control processor is electrically connected to a timing unit and is electrically connected to the temperature sensor. The control processor can also be used to control the timing unit to start timing the test time when the real-time temperature reaches the set temperature, and can collect the current value transmitted by the ammeter and the voltage value transmitted by the voltmeter when the test time reaches the set time.

[0068] With such a design, the automation level of the cable heat elongation rate test device can be improved. While automatically monitoring the real-time temperature in the heating chamber 111, the test time is automatically timed. After the test time ends, the control processor immediately collects the current value and the voltage value, and then displays them through the display screen 140, which is convenient for the test personnel to observe and record. Moreover, it is also convenient for the test personnel to view the data after the test work, without the need for the test personnel to use an additional timer to time and constantly pay attention to the test time, enabling the test personnel to be more concentrated on the preparation work of the test piece.

[0069] Furthermore, as Figure 8 and Figure 11 shown, the measurement system further includes a control switch. Among them, the upper ends of the control switch, the ammeter, the DC power supply, the conductive member 320, and the resistance member 310 are connected in a closed loop to form a third circuit. The function of the control switch is to control the on and off of the third circuit. The control switch is electrically connected to the control processor, and the control processor can also be used to control the control switch to conduct after the second driving member drives the box door 120 to close.

[0070] With such a setting, when the control processor controls the second driving member to drive the box door 120 to switch from the open state to the closed state, the test piece is in a sealed test space. At this time, the control switch can be controlled to conduct, so that the third circuit has current flowing through it, enabling the control processor to continuously collect data from the ammeter and the voltmeter, which is convenient for the test personnel to view the data situation during the test process in real time.

[0071] In some embodiments, there is only one test station in the heating chamber 111 of the test chamber 100, and only one test piece can be placed each time. In other embodiments, there are two or more test stations in the heating chamber 111 of the test chamber 100, and multiple test pieces can be placed each time, which is convenient for obtaining the final result of the heat elongation rate of the cable sample 510 by taking the average value. At this time, there are multiple suspension members 210, load members 220, guide rods 230, and measurement systems; when the reset adjustment mechanism 400 is provided, all the load members 220 can be driven to move upward in place by the same reset adjustment mechanism 400 to complete the reset work of the load members 220.

[0072] As Figures 1 to 12 shown, according to the control method of the cable heat elongation rate test device according to the second aspect embodiment of the present invention, which is applied to the cable heat elongation rate test device according to the first aspect embodiment, the control method of the cable heat elongation rate test device includes the following steps: Step S11: When the test piece is respectively connected to the suspension member 210 and the load member 220 and the temperature of the heating chamber 111 reaches the set temperature, control the timing unit to work to time the test time.

[0073] Step S12: When the test time reaches the set time, collect the current current value of the ammeter and the current voltage value of the voltmeter.

[0074] Step S13: Calculate the energized length of the resistor 310 according to the current current value, the current voltage value, and the unit length resistance value of the resistor 310.

[0075] Step S14: Control the display screen 140 to display the length value of the cable sample 510.

[0076] After the test piece is installed in the test chamber 100, close the test chamber 100 and heat it up so that the temperature in the heating chamber 111 can reach the set temperature for the thermal elongation test; when the temperature in the heating chamber 111 reaches the requirement, the timing unit can be used to time the test time, and the test piece can be subjected to the thermal elongation test under the action of high temperature and mechanical load; when the accumulated test time reaches the set time, the control processor can collect the current current value detected by the ammeter and the current voltage value detected by the voltmeter, and calculate the energized length of the resistor 310 quickly according to the current current value, the current voltage value, and the known unit length resistance value of the resistor 310.

[0077] Since the vertical distance H between the upper end of the conductive member 320 and the resistor 310 is designed to be equal to the length value of the cable sample 510, and the energized length of the resistor 310 is equal to the vertical distance between the conductive member 320 and the upper end of the resistor 310, therefore, the energized length of the resistor 310 calculated by the control processor is the length value of the cable sample 510; finally, the control processor controls the operation of the display screen 140, and clearly displays the length value of the cable sample 510 after elongation during the thermal elongation test through the display screen 140, which is convenient for the test personnel to accurately calculate the thermal elongation rate of the cable according to the original length of the cable sample 510 measured previously and the length value of the cable sample 510 during the thermal elongation test.

[0078] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0079] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A cable thermal elongation rate testing device, characterized in that, Comprising: A test chamber, provided with a heating chamber and a display screen, and a guide rod extending in the vertical direction is provided in the heating chamber; A suspension member, fixedly provided in the heating chamber for detachably connecting with the upper end of the test piece, and the test piece includes a cable sample and two clamping members fixed to the upper and lower ends of the cable sample; A load member, slidably connected to the guide rod in the vertical direction and provided directly below the suspension member for detachably connecting with the lower end of the test piece; A measurement system, including a resistance member, a conductive member, a DC power supply, an ammeter, and a voltmeter. The resistance member extends in the vertical direction and is fixedly provided in the heating chamber. The conductive member is connected to the load member and makes sliding contact and conducts electricity with the outer peripheral surface of the resistance member, so that the vertical distance between the upper end of the conductive member and the resistance member is equal to the length value of the cable sample. The ammeter, the DC power supply, the upper end of the conductive member, and the upper end of the resistance member are closed-loop electrically connected, so that the ammeter can collect the current value. The voltmeter, the conductive member, and the upper end of the resistance member are closed-loop electrically connected, so that the voltmeter can collect the voltage value; A control processor, electrically connected to the ammeter, the voltmeter, and the display screen, and used for calculating the energized length of the resistance member according to the current value, the voltage value, and the resistance value per unit length of the resistance member, and controlling the display screen to display the length value of the cable sample. Wherein, the energized length of the resistance member is the vertical distance between the upper end of the conductive member and the resistance member.

2. The cable thermal elongation rate testing device according to claim 1, wherein, The resistance member is cylindrical, there are two resistance members, and they are arranged at intervals in the horizontal direction. The conductive member is provided with two contacts. The conductive member is located between the two resistance members, so that the two contacts respectively make sliding contact and conduct electricity with the outer peripheral surfaces of the two resistance members. The ammeter, the DC power supply, the upper end of one of the resistance members, the conductive member, and the upper end of the other resistance member are closed-loop electrically connected to form a first loop. The voltmeter, the upper end of one of the resistance members, the conductive member, and the upper end of the other resistance member are closed-loop electrically connected to form a second loop; and / or, The guide rod is a round rod, and there is at least one guide rod. The load member is provided with a guide sleeve slidably connected to the guide rod.

3. The cable thermal elongation rate testing device according to claim 1, wherein, The test chamber includes a box body and a box door. The box door is located on one side of the box body along a first direction and is movably connected to the box body to open and close the opening of the heating chamber. The lower end of the suspension member is provided with a first card slot for the upper end of the test piece to be inserted along the first direction. The upper end of the load member is provided with a second card slot for the lower end of the test piece to be inserted along the first direction. The first direction is perpendicular to the vertical direction.

4. The cable thermal elongation rate testing device according to claim 3, characterized in that The cross-sectional shape of the first card slot is T-shaped, and the cross-sectional shape of the second card slot is inverted T-shaped.

5. The cable thermal elongation rate testing device according to claim 3, wherein It further includes a reset adjustment mechanism, which includes a first driving member and a lifting member. The lifting member is disposed in the heating chamber and is located below the load member. The first driving member is used to drive the lifting member to move in the up and down direction, so that the lifting member jacks up the load member to a set position, enabling the lower end of the test piece to be inserted into the second card slot along the first direction.

6. The cable thermal elongation rate testing device according to claim 5, wherein The first driving member is a servo electric cylinder and is disposed outside the heating chamber. The output end of the first driving member extends into the heating chamber and is fixedly connected to the lifting member.

7. The cable thermal elongation rate testing device according to claim 5, characterized in that, It further includes a second driving member, which is used to drive the cabinet door to open and close. The control processor is electrically connected to the reset adjustment mechanism and the second driving member respectively, and is used to control the second driving member to drive the cabinet door to open after the reset adjustment mechanism drives the load member to move up to the set position.

8. The cable thermal elongation rate testing device according to claim 7, characterized in that, It further includes a temperature sensor, which is used to collect the real-time temperature in the heating chamber. The control processor is electrically connected to a timing unit, and the control processor is electrically connected to the temperature sensor. The control processor is used to control the timing unit to conduct test time timing when the real-time temperature reaches the set temperature, and collect the current value and the voltage value when the test time reaches the set time.

9. The cable thermal elongation rate testing device according to claim 8, characterized in that, The measurement system further includes a control switch. The control switch, the ammeter, the DC power supply, the conductive member and the upper end of the resistance member are electrically connected in a closed loop. The control switch is electrically connected to the control processor, and the control processor is used to control the control switch to conduct after the second driving member drives the cabinet door to close.

10. A control method for a cable thermal elongation rate testing device, applied to the cable thermal elongation rate testing device as described in claim 8 or 9, characterized in that, It includes the following steps: When the test piece is respectively connected to the suspension member and the load member and the temperature of the heating chamber reaches the set temperature, control the timing unit to work to conduct test time timing; When the test time reaches the set time, collect the current current value of the ammeter and the current voltage value of the voltmeter; Calculate the energized length of the resistance member according to the current current value, the current voltage value and the unit length resistance value of the resistance member; Control the display screen to display the length value of the cable sample.

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