Calibration device and method for thermostatic soldering furnace

Abstract

The application discloses a constant-temperature soldering furnace calibration device and method, the calibration device comprises a multichannel temperature recorder and a plurality of temperature sensors arranged in a furnace tank; the cold end of each temperature sensor is connected with the multichannel temperature recorder; the number and distribution position of the temperature sensors are determined by the shape, size and / or molten solder amount of the furnace tank. The application simultaneously arranges a plurality of temperature sensors in the furnace tank, realizes multi-point simultaneous measurement of the furnace temperature, and greatly improves the temperature measurement efficiency; the multi-point simultaneous measurement mode is adopted, the temperature sensor does not need to be moved, and the problem that the movement of a temperature measurement probe affects the uniformity of soldering temperature when single-point temperature measurement is performed is avoided; the constant-temperature soldering furnace calibration device can be used for periodic calibration before the soldering furnace is used and can be used for synchronous monitoring when the soldering furnace is used, local temperature mutation can be found in time, and the decline of soldering quality or the damage of a device is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soldering furnace calibration, and particularly relates to a constant-temperature soldering furnace calibration device and method. BACKGROUND

[0002] The soldering furnace is a welding tool used in electronic welding, and can be used for tinning of circuit printed boards and electronic components. The accuracy of temperature control of the soldering furnace seriously affects the safety of electronic components and the welding quality. The soldering furnace can be divided into internal heating type soldering furnace and external heating type soldering furnace according to the heating mode. The constant-temperature soldering furnace generally refers to the internal heating type soldering furnace with temperature control function. The constant-temperature soldering furnace controls the heating pipe at the bottom or side of the soldering furnace to heat the solder in the furnace by the temperature control instrument on the panel. The furnace tank has two types of circular and square. The diameter of the circular furnace tank is about 100 mm, the soldering amount is less than 3 kg, and the soldering time is generally less than 15 min. The size of the square furnace tank is 100 mm*100 mm (length*width) to 500 mm*500 mm (length*width), the soldering amount is 3 kg to 50 kg, and the soldering time is at least more than 30 min.

[0003] At present, the temperature control range of the constant-temperature soldering furnace is designed to be normal temperature to about 600 DEG C, the constant-temperature index thereof is generally 250 DEG C to 350 DEG C, the temperature deviation control index is ± 5 DEG C, but the related specifications do not have specific control provisions for the temperature uniformity. The local temperature mutation caused by the failure or inaccuracy of a heating piece may lead to the decrease of welding quality or the direct damage of the device.

[0004] The temperature calibration of the constant-temperature soldering furnace mainly uses the immersion type temperature measuring probe to measure the temperature of a single point in the furnace. The specific operation is as follows: when it is needed to measure the temperature of a point in the furnace tank, the temperature measuring probe is placed at the point and needs to be kept constant for 1 min to 5 min at the point. After the temperature reaches stability, the temperature of the point is measured. The temperature measuring probe is moved to measure the temperature of the next point. This single-point temperature measurement method has low efficiency and cannot monitor the furnace temperature mutation. Meanwhile, the movement of the temperature measuring probe affects the soldering temperature uniformity in the furnace tank, cannot effectively calibrate the temperature, and has greater influence on the soldering furnace with large volume. SUMMARY

[0005] The application aims to provide a constant-temperature soldering furnace calibration device and method to solve the problems of low temperature measurement efficiency of the traditional single-point temperature measurement method, the inability to monitor the furnace temperature mutation, and the influence of the movement of the temperature measuring probe on the soldering temperature uniformity.

[0006] The application solves the above technical problems by the following technical scheme: a constant-temperature soldering furnace calibration device, comprising a multi-channel temperature recorder and a plurality of temperature sensors arranged in a furnace tank; the cold end of each temperature sensor is connected with the multi-channel temperature recorder.

[0007] The number and distribution of the temperature sensors are determined by the shape, size and / or amount of molten tin of the furnace tank.

[0008] Further, the cold end of each temperature sensor is connected to the multi-channel temperature recorder through a compensation lead.

[0009] Further, the temperature sensors are selected from K-type or N-type armored thermocouples, and the armored material is titanium alloy or stainless steel.

[0010] Further, the device further comprises a temperature measuring frame, and an installation area is arranged on the temperature measuring frame, and the plurality of temperature sensors are arranged in the furnace tank through the installation area, and the shape of the installation area is similar to the shape of the furnace tank.

[0011] Preferably, the installation area is located in the middle of the furnace tank.

[0012] Preferably, a hand-holding part is arranged on the temperature measuring frame.

[0013] Further, an oval-shaped through hole is arranged at a corresponding position of the installation area according to the distribution position of the temperature sensor, the inner wall of the oval-shaped through hole is jagged, and the temperature sensor is inserted into the oval-shaped through hole obliquely.

[0014] Further, the device further comprises a compensation temperature sensor connected to the multi-channel temperature recorder, and the compensation temperature sensor is used to detect the ambient temperature.

[0015] Further, when the furnace tank and the installation area are square, the number and distribution of the temperature sensors are as follows:

[0016] When the size of the furnace tank is < the first set size, and / or the amount of molten tin is < the first set amount, the number of temperature sensors is at least 3, one of which is located at the geometric center of the installation area, and the other two are located at the two ends of the body diagonal of the installation area;

[0017] When the first set size ≤ the size of the furnace tank < the second set size, and / or the first set amount ≤ the amount of molten tin < the second set amount, the number of temperature sensors is at least 5, one of which is located at the geometric center of the installation area, two of which are located at the two ends of the top face diagonal of the installation area, and the other two are located at the two ends of the bottom face diagonal of the installation area, and the temperature sensors located on the top face diagonal and the bottom face diagonal are arranged opposite to each other in pairs;

[0018] When the second set size ≤ the furnace size < the third set size, and / or the second set amount ≤ the amount of molten tin < the third set amount, the number of temperature sensors is at least 9, wherein one temperature sensor is located at the geometric center of the installation area, and four temperature sensors are respectively located at the four ends of the top surface of the installation area, and another four temperature sensors are respectively located at the four ends of the bottom surface of the installation area.

[0019] When the third set size ≤ the furnace size, and / or the third set amount ≤ the amount of molten tin, the number of temperature sensors is at least 10, wherein one temperature sensor is located at the geometric center of the installation area, and four temperature sensors are respectively located at the four ends of the top surface of the installation area, and another four temperature sensors are respectively located at the four ends of the bottom surface of the installation area; a central temperature measurement area is constructed with a size slightly smaller than one third of the furnace size and with the geometric center of the installation area as the geometric center, and another temperature sensor is arranged at any vertex of the central temperature measurement area.

[0020] Further, the distance between the temperature sensors on the top surface and the bottom surface of the installation area and the inner wall of the furnace is ≥ 1 / 10 of the corresponding side length of the inner wall, the distance between the temperature sensors on the top surface of the installation area and the liquid surface in the furnace is ≥ 1 / 10 of the height of the furnace, and the distance between the temperature sensors on the bottom surface of the installation area and the bottom surface of the furnace is ≥ 1 / 10 of the height of the furnace.

[0021] Further, when the furnace and the installation area are circular, the number and distribution position of the temperature sensors are as follows:

[0022] When the diameter of the furnace ≤ the set diameter, and / or the amount of molten tin ≤ the fourth set amount, the number of temperature sensors is at least 2, wherein one temperature sensor is located at the center of the top surface of the installation area, and another temperature sensor is located at the center of the bottom surface of the installation area.

[0023] When the set diameter < the diameter of the furnace, and / or the fourth set amount < the amount of molten tin, the number of temperature sensors is at least 5, wherein one temperature sensor is located at the center of the top surface of the installation area, one temperature sensor is located at the center of the bottom surface of the installation area, one temperature sensor is located at the circumference of the top surface of the installation area, one temperature sensor is located at the circumference of the middle surface of the installation area, another temperature sensor is located at the circumference of the bottom surface of the installation area, the included angle between two temperature sensors on adjacent circumferences is equal and ≥ 90°, and three temperature sensors on the circumference are not on the same straight line.

[0024] Alternatively, when the first set diameter < the diameter of the furnace, and / or the first set amount < the amount of molten tin, the number of temperature sensors is at least 5, wherein one temperature sensor is located at the center of the top surface of the installation area, one temperature sensor is located at the center of the bottom surface of the installation area, one temperature sensor is located at the center of the middle surface of the installation area, one temperature sensor is located at the circumference of the top surface of the installation area, and another temperature sensor is located at the circumference of the bottom surface of the installation area, and the included angle between two temperature sensors on the circumference is ≥ 180°.

[0025] Further, the distance between the center of the middle surface of the installation area and the center of the top surface of the installation area is equal to the distance between the center of the middle surface of the installation area and the center of the bottom surface of the installation area.

[0026] Further, the distance between the temperature sensor of the center of the top surface of the installation area and the liquid surface of the furnace is greater than or equal to 1 / 10 of the height of the furnace, the distance between the temperature sensor of the center of the bottom surface of the installation area and the bottom surface of the furnace is greater than or equal to 1 / 10 of the height of the furnace, and the distance between the temperature sensor on the circumference and the inner wall of the furnace is greater than or equal to 1 / 10 of the diameter of the furnace.

[0027] Based on the same inventive concept, the present application also provides a method for calibrating a constant-temperature soldering furnace, comprising the following steps:

[0028] placing a soldering bar in the furnace for heating and melting until complete melting;

[0029] determining the number and distribution position of the temperature sensors according to the shape, size and / or amount of molten solder of the furnace;

[0030] installing each temperature sensor at the corresponding position of the installation area of the temperature measuring frame according to the number and distribution position of the temperature sensors, and connecting each temperature sensor with the multi-channel temperature recorder;

[0031] placing the temperature measuring frame with the installed temperature sensors in the furnace;

[0032] setting the temperature of the soldering furnace to a set temperature;

[0033] continuously recording the temperature collection value of the multi-channel temperature recorder before the furnace temperature reaches the current set temperature, continuously recording the temperature collection value of the multi-channel temperature recorder when the furnace temperature reaches the current set temperature and stabilizes for a certain period of time, and continuously recording the temperature collection value of the multi-channel temperature recorder again when the furnace temperature stabilizes again for a certain period of time;

[0034] setting the temperature of the soldering furnace to the next set temperature, and repeating the step of continuously recording the temperature collection value until the recording of the temperature collection value at different set temperatures is completed, to obtain the temperature collection value at different set temperatures;

[0035] calibrating the multi-channel temperature recorder and the temperature sensors to obtain the calibration value of the multi-channel temperature recorder and the temperature sensors, calibrating the temperature collection value at different set temperatures according to the calibration value to obtain the calibrated temperature collection value at different set temperatures;

[0036] calculating the temperature deviation, temperature fluctuation degree, temperature uniformity and temperature overshoot of the soldering furnace at different set temperatures according to the calibrated temperature collection value at different set temperatures.

[0037] Further, the temperature deviation includes a temperature up deviation and a temperature down deviation, the calculation formula of the temperature up deviation is:

[0038] ΔT max = T max - T s

[0039] The calculation formula of the temperature down deviation is: ΔT min = T min - T s ;

[0040] The calculation formula of the temperature fluctuation degree is: ΔT j = T jmax - T jmin ;

[0041] The calculation formula of the temperature uniformity is:

[0042] The calculation formula of the temperature overshoot is: ΔT o = |T - T S | - |ΔT|; ΔT max s min s max s min s j jmax jmin u imax imin n is the number of records after the furnace temperature stabilizes, ΔT o s s max max ​​​​​​​​​​​​​​​​​

[0044] Advantages

[0045] Compared with the prior art, the present application has the advantages that:

[0046] The constant-temperature soldering furnace calibration device and method provided by the present application determine the number and distribution position of temperature sensors according to the shape, size and / or soldering amount of the furnace tank, simultaneously arrange multiple temperature sensors in the furnace tank, realize multi-point simultaneous measurement of the furnace temperature, greatly improve the temperature measurement efficiency, adopt the multi-point simultaneous measurement mode, do not need to move the temperature sensors, avoid the problem that the movement of the temperature measurement probe affects the uniformity of the soldering temperature when single-point temperature measurement is performed, and can both periodically calibrate before the soldering furnace is used and synchronously monitor when the soldering furnace is used, can timely find local temperature mutation, and avoid the decline of the soldering quality or the damage of the device. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only one embodiment of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0048] Figure 1 is a structure schematic view of the constant-temperature soldering furnace calibration device in the embodiment 1 of the present application;

[0049] Figure 2 is a distribution position view of a single installation area and a temperature sensor when a square furnace tank in the embodiment 1 of the present application;

[0050] Figure 3 is a distribution position view of a single installation area and a temperature sensor when a large square furnace tank in the embodiment 1 of the present application;

[0051] Figure 4 is a distribution position view of multiple installation areas and a temperature sensor when a large square furnace tank in the embodiment 1 of the present application;

[0052] Figure 5 is a schematic view of the installation mode of the temperature sensor in the installation area in the embodiment 1 of the present application;

[0053] Figure 6 is a distribution position view of a single installation area and a temperature sensor when a circular furnace tank in the embodiment 2 of the present application.

[0054] In the figure, 1 is a multi-channel temperature recorder, 2 is a computer, 3 is a compensation lead wire, 4 is a temperature sensor, 5 is a temperature measurement frame, 51 is a handheld part, 52 is an installation area, 53 is an elliptical through hole, 6 is a measured soldering furnace, and 7 is a compensation temperature sensor. Detailed Implementation

[0055] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0057] Example 1

[0058] like Figure 1 As shown, the constant temperature soldering furnace calibration device provided in this embodiment of the invention includes a multi-channel temperature recorder 1, a temperature measuring frame 5 with a mounting area 52, and a plurality of temperature sensors 4 disposed in the mounting area 52; the mounting area 52 and the plurality of temperature sensors 4 are disposed in the middle of the furnace tank, and the shape of the mounting area 52 is similar to the shape of the furnace tank; the cold end of each temperature sensor 4 is connected to the input end of the multi-channel temperature recorder 1; the number and distribution position of the temperature sensors 4 are determined by the shape, size and / or amount of molten solder of the furnace tank.

[0059] In one specific embodiment of the present invention, when the furnace trough and the installation area 52 are square, the number and distribution of the temperature sensors 4 are as follows:

[0060] When the furnace tank size is less than the first set size and / or the amount of molten solder is less than the first set amount, the number of temperature sensors 4 is 3, one of which is located at the geometric center of the mounting area 52, and the other two are located at the two ends of the diagonal of the mounting area 52.

[0061] In this embodiment, the first set dimension is 200mm × 150mm (length × width), and the first set weight is 10kg. For example... Figure 2 As shown, the square mounting area 52 of the temperature measuring frame 5 is composed of ABCDEFGH, where point O is the geometric center of the square mounting area 52, and points A, B, C, D, E, F, G, and H are the vertices of the square mounting area 52. When the furnace tank size is <200mm×150mm and / or the amount of molten solder is <10kg, one temperature sensor is set at the geometric center of the mounting area 52 (i.e., point O), and the other two temperature sensors are set at the two ends of the diagonal of the mounting area 52, i.e., points A and G, or B and H, or C and E, or D and F.

[0062] When the first set size ≤ furnace tank size < second set size, and / or the first set amount ≤ molten solder amount < second set amount, the number of temperature sensors 4 is 5, one of which is located at the geometric center of the mounting area 52, two of which are located at the two ends of the top diagonal of the mounting area 52, and the other two are located at the two ends of the bottom diagonal of the mounting area 52. The temperature sensors 4 located on the top and bottom diagonals are arranged opposite each other.

[0063] In this embodiment, the second set dimension is 400mm × 350mm (length × width), and the second set weight is 30kg. For example... Figure 2 As shown, when 200mm×150mm ≤ furnace tank size < 400mm×350mm, and / or 10kg ≤ molten solder amount < 30kg, one temperature sensor is located at the geometric center of the mounting area 52 (i.e., point O), two temperature sensors are located at the two ends of the top diagonal of the mounting area 52 (i.e., points A and C, or points B and D), and two other temperature sensors are located at the two ends of the bottom diagonal of the mounting area 52 (i.e., points E and G, or points F and H). The temperature sensors on the top and bottom diagonals are arranged opposite each other in pairs. For example, when the two temperature sensors on the top surface of the mounting area 52 are at points A and C, the two temperature sensors on the bottom surface of the mounting area 52 are at points F and H, respectively, so that the temperature sensors at points A, C, F, and H are all arranged opposite each other in pairs. For example, temperature sensor 4 is arranged opposite each other at points A and H, and temperature sensor 4 is arranged opposite each other at points C and H.

[0064] When the second set dimension ≤ furnace tank dimension < third set dimension, and / or the second set amount ≤ molten solder amount < third set amount, the number of temperature sensors 4 is 9, one of which is located at the geometric center of the mounting area 52, four of which are located at the four ends of the top surface of the mounting area 52, and the other four are located at the four ends of the bottom surface of the mounting area 52.

[0065] In this embodiment, the third set dimension is 500mm × 400mm (length × width), and the third set weight is 50kg. For example... Figure 2 As shown, when 400mm×350mm≤furnace tank size<500mm×400mm, and / or 30kg≤molten solder amount<50kg, one temperature sensor is located at the geometric center of the mounting area 52 (i.e., point O), four temperature sensors are located at the four ends of the top surface of the mounting area 52 (i.e., points A, B, C and D), and the other four temperature sensors are located at the four ends of the bottom surface of the mounting area 52 (i.e., points E, F, G and H).

[0066] When the third set size ≤ tank size, and / or the third set amount ≤ tin amount, the number of temperature sensors 4 is 10, wherein one temperature sensor is located at the geometric center of the installation area 52, wherein four temperature sensors are respectively located at the four ends of the top surface (or the spliced top surface) of the installation area 52, and another four temperature sensors are respectively located at the four ends of the bottom surface (or the spliced bottom surface) of the installation area 52; a central temperature measurement area is constructed with a length slightly less than one third of the length of the tank, a width slightly less than one third of the width of the tank, a height slightly less than the height of the tank, and a geometric center at the geometric center of the installation area 52, and another temperature sensor is arranged at any vertex of the central temperature measurement area.

[0067] As shown in Figure 3 , a central temperature measurement area A0B0C0D0E0F0G0H0 is constructed with a length of one third of the length of the installation area 52, a width of one third of the width of the installation area 52, a height of the height of the installation area 52, and a geometric center O at the geometric center O of the installation area 52, wherein one temperature sensor is located at the geometric center (i.e. point O) of the installation area 52, wherein four temperature sensors are respectively located at the four ends of the top surface (i.e. points A, B, C and D) of the installation area 52, and another four temperature sensors are respectively located at the four ends of the bottom surface (i.e. points E, F, G, H) of the installation area 52, and another temperature sensor is arranged at any vertex A0 or B0 or C0 or D0 or E0 or F0 or G0 or H0 of the central temperature measurement area. According to the actual use environment and calibration requirements, temperature sensors can also be added at the remaining vertices of the central temperature measurement area.

[0068] Before the temperature calibration or measurement of the soldering furnace, the installation area 52 of the temperature measurement frame 5 is customized according to the tank size, and different size models of the tank use a single installation area 52 with a size slightly smaller than the tank, and for large size tanks, multiple installation areas 52 can be used in splicing. For example, when 500mm×400mm≤ tank size, and / or 50kg≤ tin amount, five installation areas 52 can be used in splicing, and the size of the installation area 52 of each temperature measurement frame 5 is slightly smaller than one third of the size of the tank, as shown in Figure 4 . The five small size installation areas 52 are used in a large size tank, wherein one temperature sensor is located at the geometric center of the installation area 52 (i.e. point O), wherein four temperature sensors are respectively located at the four ends of the spliced top surface of the installation area 52 (i.e. points A1, B2, C3 and D4), and another four temperature sensors are respectively located at the four ends of the spliced bottom surface of the installation area 52 (i.e. points E1, F2, G3, H4), and another temperature sensor is arranged at any vertex A0 or B0 or C0 or D0 or E0 or F0 or G0 or H0 of the central installation area 52 (i.e. the central temperature measurement area).

[0069] In one specific embodiment of the present application, the distance between the temperature sensors on the top and bottom surfaces of the installation area 52 (i.e. the temperature sensors at points A, B, C, D, E, F, G, H) and the inner wall of the furnace is 1 / 10 of the corresponding side length of the inner wall, the distance between the temperature sensors on the top surface of the installation area 52 (i.e. the temperature sensors at points A, B, C, D) and the liquid surface in the furnace is 1 / 10 of the height of the furnace, and the distance between the temperature sensors on the bottom surface of the installation area 52 (i.e. the temperature sensors at points E, F, G, H) and the bottom surface of the furnace is 1 / 10 of the height of the furnace. For example, the distance between the temperature sensor at point A and the inner wall in the width direction of the furnace is 1 / 10 of the width of the furnace, the distance between the temperature sensor at point A and the inner wall in the length direction of the furnace is 1 / 10 of the length of the furnace, the distance between the temperature sensor at point A and the liquid surface in the furnace is 1 / 10 of the height of the furnace, and the distance between the temperature sensor at point E and the bottom surface of the furnace is 1 / 10 of the height of the furnace.

[0070] For a square furnace, the heating pipes are generally located at the bottom of the furnace, and the change in the temperature conditions at the bottom of the furnace has the greatest influence on the temperature field in the furnace. During temperature control of the soldering furnace, heat is conducted from the bottom of the furnace to the liquid surface, and the temperature near the top of the liquid surface is lower due to the greatest distance from the heating pipes and the influence of the ambient temperature. Meanwhile, the inner side wall of the furnace conducts a portion of the heat outward through the heat insulation layer, and the temperature slightly changes. Therefore, eight temperature sensors are arranged at the four ends near the top of the liquid surface (i.e. points A, B, C, D) and the four ends at the bottom of the furnace (i.e. points E, F, G, H), so that the temperature field distribution near the edges in the entire constant-temperature soldering furnace can be obtained. At this time, only one temperature sensor needs to be arranged at the geometric center of the soldering furnace, so that the temperature gradient distribution in the entire soldering furnace can be obtained. If the heating pipes in a certain region of the soldering furnace fail, the temperature in the furnace changes suddenly, and the temperature gradient of the temperature field at the position can be measured in real time by the temperature sensor.

[0071] In one specific embodiment of the present application, a handheld portion 51 is arranged on the temperature measuring frame 5, so as to facilitate the overall movement and taking of the temperature measuring frame 5 before and after measurement. The installation area 52 of the temperature measuring frame 5 is made of titanium alloy material which is resistant to high temperature and corrosion

[0072] In one specific embodiment of the present application, as shown in Figure 5 elliptical through holes 53 are arranged at the corresponding installation positions of each temperature sensor 4 in the installation area 52, the inner wall of the elliptical through hole 53 is sawtooth-shaped and has a certain friction, and the temperature sensor is inclined to be inserted into the elliptical through hole 53, so as to facilitate the fixed installation of the temperature sensor in the installation area 52.

[0073] In one specific embodiment of the present application, the cold end of each temperature sensor 4 is connected to the multi-channel temperature recorder 1 through a compensation lead 3. The compensation lead 3 is made of the same material as the temperature sensor 4, and the length of the compensation lead 3 is greater than 1.5 m. The compensation lead 3 can realize remote temperature measurement and extend the cold end of the temperature sensor 4, so that the cold end of the temperature sensor 4 is not affected by the furnace temperature, and the temperature measurement accuracy is improved.

[0074] In one specific embodiment of the present application, each temperature sensor 4 is a K-type or N-type armored thermocouple made of titanium alloy or stainless steel, which has the advantages of high temperature resistance, corrosion resistance and good stability.

[0075] In one specific embodiment of the present application, the device further comprises a compensation temperature sensor 7 connected to the multi-channel temperature recorder 1. The compensation temperature sensor 7 is used to detect the ambient temperature, and the multi-channel temperature recorder 1 compensates the actual acquisition value of the temperature sensor 4 according to the ambient temperature. The specific compensation method can refer to the calibration specification for base metal thermocouples. In this embodiment, the multi-channel temperature recorder 1 selects an external compensation temperature sensor 7 to realize cold end compensation of the temperature sensor 4.

[0076] In one specific embodiment of the present application, the device further comprises a computer 2 connected to the multi-channel temperature recorder 1 through a USB interface. The computer 2 can be used to control the multi-channel temperature recorder 1 to remotely monitor the plurality of temperature sensors 4 in real time.

[0077] Example 2

[0078] As shown in Figure 1 , the calibration device for the constant-temperature soldering furnace 6 provided by the embodiment of the present application comprises a multi-channel temperature recorder 1, a temperature measuring frame 5 having a mounting area 52, and a plurality of temperature sensors 4 arranged in the mounting area 52. The mounting area 52 and the plurality of temperature sensors 4 are arranged in the middle of the furnace tank, and the shape of the mounting area 52 is similar to that of the furnace tank. The cold end of each temperature sensor 4 is connected to the input end of the multi-channel temperature recorder 1. The number and distribution position of the temperature sensors 4 are determined by the shape, size and / or amount of molten solder of the furnace tank.

[0079] In one specific embodiment of the present application, when the furnace tank and the mounting area 52 are circular, the number and distribution position of the temperature sensors 4 are as follows:

[0080] When the diameter of the furnace tank is ≤ a set diameter, and / or the amount of molten solder is ≤ a fourth set amount, the number of the temperature sensors 4 is 2, one of which is arranged at the center of the top surface of the mounting area 52, and the other is arranged at the center of the bottom surface of the mounting area 52.

[0081] In this embodiment, the set diameter is 100 mm, and the fourth set amount is 3 kg. As shown in Figure 6As shown, the circular mounting area 52 of the temperature measuring frame 5 is composed of O1, O2, and O3, with point O1 being the center of the top surface, O3 the center of the bottom surface, and O2 the center of the middle surface. When the furnace tank diameter is ≤100mm and / or the amount of molten solder is ≤3kg, one temperature sensor is located at the center O1 of the top surface of the mounting area 52, and the other temperature sensor is located at the center O3 of the bottom surface of the mounting area 52.

[0082] When the set diameter is less than the furnace bath diameter and / or the fourth set amount is less than the amount of molten solder, the number of temperature sensors 4 is 5. One temperature sensor is located at the center of the top surface of the mounting area 52, one temperature sensor is located at the center of the bottom surface of the mounting area 52, one temperature sensor is located on the circumference of the top surface of the mounting area 52, one temperature sensor is located on the circumference of the middle surface of the mounting area 52, and another temperature sensor is located on the circumference of the bottom surface of the mounting area 52. The included angle between two temperature sensors 4 on adjacent circumferences is equal and ≥90°. The three temperature sensors on the circumference are not on the same straight line.

[0083] like Figure 6 As shown, when 100mm < furnace tank diameter and / or 3kg < molten solder amount, one temperature sensor is located at the center O1 of the top surface of the mounting area 52, one temperature sensor is located at the center O3 of the bottom surface of the mounting area 52, one temperature sensor is located at point I on the circumference of the top surface of the mounting area 52, one temperature sensor is located at point J on the circumference of the middle surface of the mounting area 52, and another temperature sensor is located at point K on the circumference of the bottom surface of the mounting area 52. The included angle θ between the two temperature sensors at points I and J is ≥90°, the included angle θ between the two temperature sensors at points J and K is ≥90°, and the three temperature sensors at points I, J, and K are not on the same straight line.

[0084] Alternatively, when 100mm < furnace bath diameter and / or 3kg < molten solder amount, the number of temperature sensors 4 is 5, of which one temperature sensor is located at the center O1 of the top surface of the mounting area 52, one temperature sensor is located at the center O3 of the bottom surface of the mounting area 52, one temperature sensor is located at the center O2 of the middle surface of the mounting area 52, one temperature sensor is located at point I on the circumference of the top surface of the mounting area 52, and another temperature sensor is located at point K on the circumference of the bottom surface of the mounting area 52, and the included angle between the two temperature sensors at points I and K is ≥180°.

[0085] For the circular furnace tank, the heating pipes are generally located at the bottom and the sidewall of the furnace tank, and the temperature conditions of the bottom and the sidewall of the furnace tank have the same influence on the temperature field in the furnace. During the temperature control of the soldering furnace, heat is conducted from the bottom and the sidewall to the center of the soldering furnace. The temperature near the top of the liquid surface is lower due to the farthest distance from the heating pipe and the influence of the external environment temperature. Since the components are directly placed in the center of the soldering furnace in the actual soldering process, for the circular soldering furnace with small volume, only two temperature sensors are needed to be arranged at the bottom and the top of the central axis of the soldering furnace, so as to obtain the temperature gradient distribution from the bottom to the top of the soldering furnace. If the temperature of a certain position of the sidewall suddenly changes, it can be quickly measured by the temperature sensor in real time. For the circular soldering furnace with large volume, the temperature sensors with an included angle of not less than 90° are arranged on the outside, so as to estimate the temperature gradient from the sidewall to the center.

[0086] In one specific embodiment of the present application, the distance between the center O2 of the middle surface of the mounting area 52 and the center O1 of the top surface of the mounting area 52 is equal to the distance between the center O2 of the middle surface of the mounting area 52 and the center O3 of the bottom surface of the mounting area 52.

[0087] In one specific embodiment of the present application, the distance between the temperature sensor at the center O1 of the top surface of the mounting area 52 and the liquid surface of the furnace tank is 1 / 10 of the height of the furnace tank, the distance between the temperature sensor at the center O3 of the bottom surface of the mounting area 52 and the bottom surface of the furnace tank is 1 / 10 of the height of the furnace tank, and the distance between the temperature sensors at the points I, J and K and the inner wall of the furnace tank is 1 / 10 of the diameter of the furnace tank.

[0088] Example 3

[0089] The calibration of the constant-temperature soldering furnace can be periodic calibration before use to detect whether the soldering furnace heating is normal, or online calibration during use to monitor the heating state online when it is working. The present application provides a method for calibrating a constant-temperature soldering furnace, which comprises the following steps:

[0090] Step 1: In the empty state, place a sufficient amount of soldering tin in the furnace tank of the soldering furnace to heat and melt until completely melted. In this embodiment, the melting tin temperature is set to 250℃.

[0091] Step 2: Determine the number and distribution position of the temperature sensors according to the shape, size and / or amount of the melting tin of the furnace tank. The specific determination method of the number and distribution position of the temperature sensors is described in Example 1 and Example 2.

[0092] Step 3: According to the number and distribution position of the temperature sensors, install each temperature sensor at the corresponding position of the mounting area of the temperature measuring frame, and connect each temperature sensor with the input end of the multi-channel temperature recorder.

[0093] Step 4: After the soldering tin bar is completely melted, the temperature measuring frame with the temperature sensor installed is placed in the middle of the furnace groove, and the distance between the temperature sensor in the installation area and the furnace groove is ensured to meet the distance requirement described in Embodiment 1 and Embodiment 2, that is, at least 1 / 10 of the corresponding side length or height.

[0094] Step 5: Set the temperature of the soldering tin furnace to the set temperature to collect the temperature values of each temperature sensor (or each temperature measuring point) at different set temperatures.

[0095] Generally, the set temperatures are set from low to high, for example, the set temperatures are 280℃, 300℃, 320℃, and so on. In this step, the first set temperature is 280℃.

[0096] Step 6: Before the furnace temperature reaches the current set temperature, continuously record the temperature collection values of the multi-channel temperature recorder, and record the temperature collection values of each temperature measuring point every 2 minutes;

[0097] When the furnace temperature reaches the current set temperature and stabilizes for a certain period of time (for example, 30 minutes), continuously record the temperature collection values of the multi-channel temperature recorder, and record the temperature collection values of each temperature measuring point every 2 minutes, a total of 30 times;

[0098] After the furnace temperature stabilizes for a certain period of time (for example, 60 minutes) again, continuously record the temperature collection values of the multi-channel temperature recorder, and record the temperature collection values of each temperature measuring point every 2 minutes, a total of 30 times.

[0099] When the set temperature is 280℃, the temperature collection values of each temperature measuring point before the furnace temperature reaches the set temperature and the 60 temperature collection values of each temperature measuring point after the furnace temperature stabilizes at the set temperature of 280℃ are obtained.

[0100] Step 7: Set the temperature of the soldering tin furnace to the next set temperature, repeat Step 6 until the temperature collection values at different set temperatures are recorded to obtain the temperature collection values at different set temperatures. During the entire temperature collection value measurement process, the temperature measuring frame remains stationary, that is, the temperature sensor remains stationary.

[0101] Step 8: Calibrate the multi-channel temperature recorder and the temperature sensor to obtain the calibration values of the multi-channel temperature recorder and the temperature sensor, and calibrate the temperature collection values at different set temperatures according to the calibration values to obtain the calibrated temperature collection values at different set temperatures.

[0102] Send the multi-channel temperature recorder and the temperature sensor to a professional calibration institution, and calibrate the multi-channel temperature recorder and the temperature sensor by the professional calibration institution to obtain the calibration values of the multi-channel temperature recorder and the temperature sensor.

[0103] Step 9: Calculate the temperature deviation, temperature fluctuation, temperature uniformity, and temperature overshoot of the soldering furnace under different set temperatures based on the calibrated temperature acquisition values ​​at different set temperatures.

[0104] Temperature deviation includes upper temperature deviation and lower temperature deviation. The formula for calculating upper temperature deviation is: ΔT max =T max -T s ;

[0105] The formula for calculating the temperature deviation is: ΔT min =T min -T s ;

[0106] The formula for calculating temperature fluctuation is: ΔT j =T jmax -T jmin ;

[0107] The formula for calculating temperature uniformity is:

[0108] The formula for calculating temperature overshoot is: ΔT o =|TT S |-|ΔT|;

[0109] Where, ΔT max To set temperature T s Temperature deviation above, ΔT min To set temperature T s Temperature deviation, T max To set temperature T s The highest temperature value (T) among all temperature measurement points in a continuous record (e.g., 60 records) after the furnace temperature has stabilized. min To set temperature T s The lowest temperature value ΔT is recorded from all temperature measurement points in a continuous record (e.g., 60 records) after the furnace temperature has stabilized. j Let T be the temperature fluctuation at the j-th temperature measurement point. jmax T represents the highest temperature value collected at the j-th temperature measurement point in a series of continuous records (e.g., 60 records) after the furnace temperature has stabilized. jmin ΔT represents the lowest temperature recorded at the j-th temperature measurement point in a series of continuous records (e.g., 60 records) after the furnace temperature has stabilized. u For temperature uniformity, T imax T represents the highest temperature recorded at all temperature measurement points in the i-th record after the furnace temperature has stabilized. imin Let ΔT be the lowest temperature value collected from all temperature measurement points in the i-th record after the furnace temperature has stabilized, where n is the number of records after the furnace temperature has stabilized (e.g., 60). o To set temperature T stemperature overshoot, T is the temperature of the furnace rising to the set temperature T s the highest temperature collection value in all temperature measuring points in the process, and ΔT is the allowable deviation value of the soldering furnace temperature.

[0110] The temperature deviation, temperature fluctuation, temperature uniformity and temperature overshoot of the soldering furnace at different set temperatures are actual temperature calibration values of the soldering furnace.

[0111] The number, distribution position and test time selection of the temperature sensor of the present application fully consider the actual use requirement (i.e. long-term work requirement) of the soldering furnace. Usually, the temperature deviation, temperature uniformity should be less than 5℃, the temperature fluctuation should be less than 2℃, and the temperature overshoot should be less than 10℃.

[0112] Compared with single-point temperature measurement, the present application can measure the temperature field in the soldering furnace in real time and estimate the temperature gradient, and can obtain the distribution of the temperature field in the furnace with higher precision with the least temperature sensor. The present application can increase or decrease the number of temperature sensors in the temperature field center according to the size of the furnace tank and the actual precision requirement, so as to obtain the temperature distribution gradient of the entire soldering furnace.

[0113] The above only discloses the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or modifications within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A constant temperature soldering furnace calibration device, characterized in that: It includes a multi-channel temperature recorder, a temperature measuring frame, and multiple temperature sensors installed in the furnace tank; the cold end of each of the temperature sensors is connected to the multi-channel temperature recorder. The temperature measuring frame has an installation area, through which multiple temperature sensors are installed in the furnace bath. The shape of the installation area is similar to the shape of the furnace bath. The number and distribution of the temperature sensors are determined by the shape, size and molten solder amount of the furnace bath. When the furnace trough and installation area are square, the specific number and distribution of temperature sensors are as follows: When the furnace tank size is less than the first set size and the amount of molten solder is less than the first set amount, the number of temperature sensors is at least 3, with one temperature sensor located at the geometric center of the mounting area and the other two temperature sensors located at the two ends of the diagonal of the mounting area. When the first set size ≤ furnace tank size < second set size, and the first set amount ≤ molten solder amount < second set amount, the number of temperature sensors is at least 5, one of which is located at the geometric center of the mounting area, two of which are located at the two ends of the top diagonal of the mounting area, and the other two are located at the two ends of the bottom diagonal of the mounting area, and the temperature sensors located on the top diagonal and the bottom diagonal are arranged opposite each other. When the second set dimension ≤ furnace tank dimension < third set dimension, and the second set amount ≤ molten solder amount < third set amount, the number of temperature sensors is at least 9, of which one temperature sensor is located at the geometric center of the mounting area, four temperature sensors are located at the four ends of the top surface of the mounting area, and the other four temperature sensors are located at the four ends of the bottom surface of the mounting area. When the third set dimension is less than or equal to the furnace tank dimension and the third set amount is less than or equal to the amount of molten solder, the number of temperature sensors is at least 10, one of which is located at the geometric center of the mounting area, four of which are located at the four ends of the top surface of the mounting area, and four of which are located at the four ends of the bottom surface of the mounting area. A central temperature measurement area is constructed with a dimension slightly smaller than one-third of the furnace tank dimension and with the geometric center of the mounting area as the geometric center. Another temperature sensor is located at any vertex of the central temperature measurement area.

2. The constant temperature soldering furnace calibration device according to claim 1, characterized in that: The cold end of each of the temperature sensors is connected to the multichannel temperature recorder via a compensating wire.

3. The constant temperature soldering furnace calibration device according to claim 1, characterized in that: The temperature sensor is a type K or type N armored thermocouple, and the armor material is titanium alloy or stainless steel.

4. The constant temperature soldering furnace calibration device according to claim 1, characterized in that: It also includes a compensated temperature sensor connected to the multi-channel temperature recorder, the compensated temperature sensor being used to detect ambient temperature.

5. The constant temperature soldering furnace calibration device according to claim 1, characterized in that: The temperature measuring frame is equipped with a handheld part.

6. The constant temperature soldering furnace calibration device according to claim 1, characterized in that: According to the distribution of the temperature sensors, elliptical through holes are set at corresponding positions in the installation area. The inner wall of the elliptical through holes is serrated, and the temperature sensors are inserted at an angle into the elliptical through holes.

7. The constant temperature soldering furnace calibration device according to claim 1, characterized in that: The distance between the temperature sensors on the top and bottom surfaces of the installation area and the inner wall of the furnace trough is ≥ 1 / 10 of the corresponding side length of the inner wall; the distance between the temperature sensors on the top surface of the installation area and the liquid surface in the furnace trough is ≥ 1 / 10 of the height of the furnace trough; and the distance between the temperature sensors on the bottom surface of the installation area and the bottom surface of the furnace trough is ≥ 1 / 10 of the height of the furnace trough.

8. A method for calibrating a constant-temperature soldering furnace, characterized in that, Based on the constant temperature soldering furnace calibration device according to any one of claims 1 to 7, the method includes the following steps: Place the solder bar in the furnace bath and heat it until it is completely melted; The number and distribution of temperature sensors are determined based on the shape, size, and amount of molten solder in the furnace. Based on the number and distribution of temperature sensors, each temperature sensor is installed in the corresponding position of the installation area of ​​the temperature measuring frame, and each temperature sensor is connected to a multi-channel temperature recorder. Place the temperature measuring frame with the temperature sensor installed inside the furnace tank; Set the temperature of the soldering furnace to the set temperature; Before the furnace temperature reaches the current set temperature, the temperature data collected by the multi-channel temperature recorder is continuously recorded; after the furnace temperature reaches the current set temperature and stabilizes for a certain period of time, the temperature data collected by the multi-channel temperature recorder is continuously recorded; after the furnace temperature stabilizes again for a certain period of time, the temperature data collected by the multi-channel temperature recorder is continuously recorded again. Set the temperature of the soldering furnace to the next set temperature, and repeat the step of continuously recording the temperature acquisition values ​​until the temperature acquisition values ​​at different set temperatures are recorded, thus obtaining the temperature acquisition values ​​at different set temperatures. The multi-channel temperature recorder and temperature sensor are calibrated to obtain calibration values. Based on the calibration values, the temperature acquisition values ​​at different set temperatures are calibrated to obtain calibrated temperature acquisition values ​​at different set temperatures. The temperature deviation, temperature fluctuation, temperature uniformity, and temperature overshoot of the soldering furnace under different set temperatures are calculated based on the calibrated temperature acquisition values ​​at different set temperatures.

9. The method for calibrating a constant-temperature soldering furnace according to claim 8, characterized in that, When the furnace trough and installation area are square, the specific number and distribution of temperature sensors are as follows: When the furnace tank size is less than the first set size and the amount of molten solder is less than the first set amount, the number of temperature sensors is at least 3, one of which is located at the geometric center of the installation area, and the other two are located at the two ends of the diagonal of the installation area. When the first set size ≤ furnace tank size < second set size and the first set amount ≤ molten solder amount < second set amount, the number of temperature sensors is at least 5, one of which is located at the geometric center of the mounting area, two of which are located at the two ends of the top diagonal of the mounting area, and the other two are located at the two ends of the bottom diagonal of the mounting area, and the temperature sensors located on the top diagonal and the bottom diagonal are arranged opposite each other. When the second set dimension ≤ furnace tank dimension < third set dimension, and the second set amount ≤ molten solder amount < third set amount, the number of temperature sensors is at least 9, of which one temperature sensor is located at the geometric center of the mounting area, four temperature sensors are located at the four ends of the top surface of the mounting area, and the other four temperature sensors are located at the four ends of the bottom surface of the mounting area. When the third set dimension is less than or equal to the furnace tank dimension and the third set amount is less than or equal to the amount of molten solder, the number of temperature sensors is at least 10, one of which is located at the geometric center of the mounting area, four of which are located at the four ends of the top surface of the mounting area, and four of which are located at the four ends of the bottom surface of the mounting area. A central temperature measurement area is constructed with a dimension slightly smaller than one-third of the furnace tank dimension and with the geometric center of the mounting area as the geometric center. Another temperature sensor is located at any vertex of the central temperature measurement area.

10. The method for calibrating a constant-temperature soldering furnace according to claim 8 or 9, characterized in that, The temperature deviation includes upper temperature deviation and lower temperature deviation, and the formula for calculating the upper temperature deviation is: ΔT max =T max -T s The formula for calculating the temperature deviation is: ΔT min =T min -T s ; The formula for calculating the temperature fluctuation is: ΔT j =T jmax -T jmin ; The formula for calculating the temperature uniformity is: The formula for calculating the temperature overshoot is: ΔT o =|TT S |-|ΔT|; Where, ΔT max To set temperature T s Temperature deviation above, ΔT min To set temperature T s Temperature deviation, T max To set temperature T s The highest temperature value (T) among all temperature measurement points recorded continuously after the furnace temperature stabilizes. min To set temperature T s The lowest temperature value, ΔT, is recorded at all temperature measurement points in a continuous record after the furnace temperature has stabilized. j Let T be the temperature fluctuation at the j-th temperature measurement point. jmax T represents the highest temperature value collected at the j-th temperature measurement point in the continuous recording after the furnace temperature has stabilized. jmin Let ΔT be the lowest temperature value collected at the j-th temperature measurement point in the continuous recording after the furnace temperature has stabilized. u For temperature uniformity, T imax T represents the highest temperature recorded at all temperature measurement points in the i-th record after the furnace temperature has stabilized. imin Let ΔT be the lowest temperature value collected from all temperature measurement points in the i-th record after the furnace temperature has stabilized, where n is the number of records after the furnace temperature has stabilized. o To set temperature T s Temperature overshoot, T is the furnace temperature rising to the set temperature T. s The highest temperature value collected at all temperature measurement points during the process, ΔT is the allowable deviation value of the soldering furnace temperature.

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