A heating device and pultrusion process

Abstract

The present application discloses a heating device, comprising: a connecting shaft for installing the heating device inside a mold; a heating element fixed to the connecting shaft; and a heat-conducting elastic element tightly clamped between the heating element and the inner wall of the mold. The present application also discloses a pultrusion molding process, which uses the aforementioned heating device to heat the mold; along the forward direction of pultrusion, the heating area is provided with a preheating zone, a gel zone, and a molding zone, and the temperatures of the preheating zone and the gel zone are lower than the temperature of the molding zone. The heating device of the present application adopts contact heating and contact temperature measurement, which has high heating efficiency and accurate temperature control, and realizes segmented temperature control of the heating area, making the product performance more stable.

Description

Technical Field

[0001] The present application relates to the technical field of composite material forming equipment, and in particular to a heating device and a pultrusion forming process. Background Art

[0002] At present, the mold of the hollow pultrusion molding device of composite materials adopts a structure in which a core mold and an outer mold cooperate with each other. During the molding process, the core mold and the outer mold need to be heated separately. The existing core mold heating method is usually: a heating tube (commonly used heating resistance wire) and a temperature measuring probe are installed inside the core mold, and heat is generated by the electric heating tube, and the air is dry-burned to achieve the purpose of heating the core mold. However, this heating method has the following defects: 1) Since there is air between the heating device and the core mold, the thermal conductivity of the air is low, resulting in large heat loss and low heating efficiency; 2) The existing temperature measuring probe is usually installed inside the core mold and the probe is not in direct contact with the inner wall of the core mold. The measured temperature is the air temperature, which is greatly different from the set temperature and cannot be accurately controlled; 3) When using the dry-burning air heating method, the air flow causes the temperature of the heating zone to be consistent, and the temperature gradient cannot be achieved, thereby affecting product performance. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, one of the purposes of this application is to provide a heating device that adopts contact heating and contact temperature measurement, has high heating efficiency, accurate temperature control, and realizes segmented temperature control of the heating area, making the product performance more stable.

[0004] In order to solve the above technical problems, the technical solution adopted in this application is: to provide a heating device, including: a connecting shaft for installing the heating device inside the mold; a heating element fixed on the connecting shaft; a heat-conducting elastic element tightly clamped between the heating element and the inner wall of the mold, so that contact heating can be achieved between the heating element and the mold, reducing heat loss, high heating efficiency, and increasing energy utilization by 60%.

[0005] It also includes a temperature measuring piece, which is fixed on the heating piece and in close contact with the heat-conducting elastic piece, and is used to monitor the temperature of the mold.

[0006] Among them, the end of the temperature measuring part used for temperature measurement extends out of the outer surface of the thermally conductive elastic part and is in close contact with the inner wall of the mold. At this time, the measured temperature is the actual temperature of the mold, which is highly accurate and helps to achieve precise temperature control of the mold during the production process.

[0007] Among them, the heating element includes several sub-heating elements arranged along the axial direction of the heating element, and the adjacent sub-heating elements are connected and fixed by an insulation plate. The several sub-heating elements and the several insulation plates are arranged at intervals to form several heating zones. The setting of the insulation plates prevents heat from flowing between the heating zones.

[0008] The heat insulation plate is sleeved on the outer periphery of the connecting shaft and seals the end of the sub-heating element, thereby realizing the connection between the sub-heating element and the connecting shaft.

[0009] Among them, the heating element includes a heating wire, several insulating plates and a shell. The several insulating plates are arranged circumferentially, the heating wire is wrapped around the outer circumference of the insulating plates, and the shell covers the heating wire and the insulating plates. This heating method has high heating efficiency and uniform heat distribution.

[0010] Among them, the thermally conductive elastic part is made of thermally conductive silicone, which has good thermal conductivity and resilience, and can maintain a stable state under long-term high temperature conditions.

[0011] Among them, the heat insulation board is a polyimide board or a glass fiber reinforced plastic board, which has the advantages of high temperature resistance, wear resistance, deformation resistance, and stable performance. It can maintain stable performance under high temperature conditions during the production process and can isolate heat transfer.

[0012] The second purpose of this application is to provide a pultrusion molding process, which uses the aforementioned heating device to heat the mold. Along the pultrusion forward direction, the heating area is provided with a preheating zone, a gel zone, and a molding zone. The temperatures of the preheating zone and the gel zone are lower than the temperature of the molding zone, which can gradually heat up the hollow pultruded tube and completely solidify it, thereby reducing internal defects of the product and stabilizing product quality.

[0013] Among them, the temperature of the preheating zone is 80℃~130℃; the temperature of the gel zone is 110℃~150℃; the temperature of the molding zone is 140℃~180℃. The use of a heating device to heat the core mold in sections can increase the pultrusion speed and improve production capacity.

[0014] The beneficial effects of the present application are: different from the prior art, the heating device of the present application includes a connecting shaft, a heating element, and a thermally conductive elastic element, and has the following advantages: 1) The thermally conductive elastic element is tightly clamped between the heating element and the inner wall of the mold, so that contact heating is achieved between the heating element and the mold, heat loss is reduced, heating efficiency is high, and energy utilization rate is increased by 60%; 2) The end of the temperature measuring element used for temperature measurement is in close contact with the inner wall of the mold, and the measured temperature is the actual temperature of the mold, which is highly accurate and helps to achieve precise temperature control of the mold during the production process; 3) Several sub-heating elements, insulation boards, thermally conductive elastic elements, and temperature measuring elements that cooperate with each other can form several heating zones with precise temperature control, realize the segmented temperature control function, and be used in conjunction with the pultrusion molding process. The product quality is stable, and the production capacity can be doubled, the product scrap loss is reduced by 20%, the yield rate is increased by 60%, and the production efficiency is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts. Among them:

[0016] Figure 1 1 is a schematic structural diagram of a heating device 100 according to an embodiment of the present application;

[0017] Figure 2 is a partial cross-sectional view of a heating device 100 in one embodiment of the present application;

[0018] Figure 3 yes Figure 2 Enlarged view of point D in the middle;

[0019] Figure 4 This is a schematic structural diagram of the temperature measuring element 140 in one embodiment of the present application;

[0020] Figure 5 This is a schematic structural diagram of a heat insulation board 150 in one embodiment of the present application;

[0021] Figure 6 1 is a cross-sectional view of the assembly of the heating device 100 and the mold 10 in one embodiment of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] In one embodiment, see Figure 1 、 Figure 2 、 Figure 6 , provides a heating device 100 for heating the mold 10, the heating device 100 includes: a connecting shaft 110, used to install the heating device 100 inside the mold 10; a heating element 120, fixed on the connecting shaft 110; a heat-conductive elastic element 130, tightly clamped between the heating element 120 and the inner wall of the mold 10.

[0024] The connecting shaft 110 is a long rod-shaped structure, and the cross-section of the connecting shaft 110 can be circular, square, elliptical or other shapes. The heating element 120 is a hollow cylindrical body. The connecting shaft 110 passes through the inner cavity of the heating element 120 along the axial direction of the heating element 120, and both ends of the connecting shaft 110 extend out of the heating element 120, so that the connecting shaft 110 is located at the center of the heating device 100. Then, the length direction of the connecting shaft 110, the axial direction of the heating element 120 and the axial direction of the heating device 100 are located on the same straight line. At the same time, two heat insulation plates 150 are sleeved on the outer periphery of the connecting shaft 110 and cover the two ends of the heating element 120 respectively, so as to realize the connection between the heating element 120 and the connecting shaft 110. Furthermore, during the installation process of the heating device 100, the heating device 100 can be conveniently pushed into the inner cavity of the mold 10 by pushing the connecting shaft 110, thereby realizing the installation and fixation of the heating device 100 and the mold 10.

[0025] Among them, the heating element 120 is a heating ring, which is hollow cylindrical and has a circular cross-section. Specifically, the heating element 120 includes a heating wire, several insulating plates and an outer shell (not shown). Several insulating plates are arranged circumferentially to form a hollow cylindrical structure. The heating wire is evenly spaced and wound around the outer periphery of the insulating plate in a spiral shape. The outer shell covers the heating wire and the insulating plate. As a heating material, the heating wire needs to be made of a material with high resistivity and low temperature coefficient of resistance. Therefore, iron-aluminum alloy wire is used as the heating wire. The insulating plate adopts a mica soft plate, and the heating wire is evenly spaced and wound around the outer periphery of the insulating plate so that adjacent heating wires are insulated from each other. The outer shell covers the heating wire and the insulating plate, and is a thin metal plate made of aluminum. The heating element 120 realizes the heating function by electrically heating the heating wire and converting electrical energy into thermal energy by utilizing the Joule effect of electric current. This method has high heating efficiency and uniform heat distribution. In other embodiments, the heating wire in the heating coil may be other heating alloy wires such as nickel-chromium alloy wire or other non-metallic heating wires, the insulating plate may be other insulating materials such as ceramic plate, and the outer shell may be made of materials such as stainless steel, etc., without specific restrictions here.

[0026] Continue reading Figure 2 、 Figure 3 and Figure 6The mold 10 is hollow cylindrical and is used to form a tubular member. The heating device 100 is located in the hollow inner cavity of the mold 10. A heat-conducting elastic member 130 is sleeved on the outer circumference of the heating element 120, and the heat-conducting elastic member 130 tightly wraps the entire circumference of the heating element 120. That is, the heat-conducting elastic member 130 is also hollow cylindrical and has a circular cross-section. The outer diameter of the heating element 120 is set to be smaller than the inner diameter of the mold 10, so that the heating element 120 without the thermally conductive elastic member 130 can be smoothly placed in the inner cavity of the mold 10. When the thermally conductive elastic member 130 of a certain thickness is mounted on the outer wall of the heating element 120, the outer diameter of the heating device 100 is slightly larger than the inner diameter of the mold 10. When the heating device 100 is installed in the inner cavity of the mold 10, the thermally conductive elastic member 130 and the inner wall of the mold 10 achieve an interference fit. That is, the thermally conductive elastic member 130 undergoes elastic deformation, and its outer surface is in close contact with the inner wall of the mold 10, so that the thermally conductive elastic member 130 is tightly sandwiched between the heating element 120 and the inner wall of the mold 10. The thermally conductive elastic member 130 is bonded to the outer periphery of the heating element 120 with an adhesive, ensuring that the thermally conductive elastic member 130 can tightly wrap the entire outer periphery of the heating element 120.

[0027] The thermally conductive elastic member 130 is made of thermally conductive silicone. Thermally conductive silicone has excellent thermal conductivity and resilience, and can maintain a stable state under long-term high-temperature conditions. The good thermal conductivity allows the heat generated by the heating element 120 to be quickly transferred to the mold 10 through the thermally conductive elastic member 130, resulting in high heating efficiency. The good resilience allows the thermally conductive elastic member 130 to achieve an interference fit with the inner wall of the mold 10 after the heating device 100 is installed in the inner cavity of the mold 10. In other embodiments, the thermally conductive elastic member can also be made of other materials, as long as it has good thermal conductivity and resilience and can maintain a stable state under long-term high-temperature working conditions. There is no specific limitation here.

[0028] Since the inner surface of the thermally conductive elastic member 130 tightly covers the outer wall of the heating member 120, the outer surface of the thermally conductive elastic member 130 is in close contact with the inner wall of the mold 10, and the thermally conductive elastic member 130 has good thermal conductivity, contact heating can be achieved between the heating member 120 and the mold 10, avoiding heat loss, and having high heating efficiency, and the energy utilization rate can be increased by 60%.

[0029] See Figure 1 and Figure 4The heating device 100 further includes a temperature measuring element 140, which is fixed on the heating element 120 and extends out of the heating element 120 to be in close contact with the heat-conducting elastic element 130, and is used to monitor the temperature of the mold 10. Specifically, the temperature measuring element 140 is a long rod-shaped structure. The temperature measuring element 140 includes a connecting portion 142 and a fixing nut 143. The outer surface of the connecting portion 142 is provided with an external thread (not shown), and the heating element 120 is provided with a corresponding matching threaded hole (not shown). After the connecting portion 142 is screwed into the threaded hole of the heating element 120, it is tightened by the fixing nut 143 to fix the temperature measuring element 140 on the heating element 120. The fixing nut 143 is used to limit the position of the temperature measuring element 140. According to actual conditions, it can be fixed at an appropriate position along the length direction of the temperature measuring element 140 on the connecting portion 142 to adjust the relative position of the temperature measuring element 140 and the heating element 120. One end of the temperature measuring element 140, extending from the heating element 120, is equipped with a probe 141. This probe 141 is in close contact with the thermally conductive elastic element 130. The other end of the temperature measuring element 140 is connected to an electrical meter via a wire. Probe 141 houses a thermocouple that converts temperature changes it detects into voltage signals, which can then be read using an electrical meter to determine the temperature being measured.

[0030] In this embodiment, the end of the temperature measuring component 140 used for temperature measurement also extends out of the outer surface of the thermally conductive elastic component 130 and is in close contact with the inner wall of the mold 10. Specifically, a through hole (not shown) is provided on the thermally conductive elastic component 130. The end of the temperature measuring component 140 used for temperature measurement, i.e., the probe 141, extends through the through hole out of the outer surface of the thermally conductive elastic component 130 and is in close contact with the inner wall of the mold 10. At this time, the temperature measured by the probe 141 is the actual temperature of the mold 10, which is highly accurate and helps to achieve precise temperature control of the mold 10 during the production process.

[0031] During the stable heating process of the heating device 100, the temperature of the thermally conductive elastic member 130 is substantially the same as that of the mold 10. Therefore, the temperature of the thermally conductive elastic member 130 can be considered to be the temperature of the mold 10. Therefore, in other embodiments, the probe may not extend beyond the outer surface of the thermally conductive elastic member, and the temperature measuring member may be another type of temperature sensor, as long as close contact between the temperature measuring member and the thermally conductive elastic member is ensured. No specific limitations are imposed herein.

[0032] See Figure 1 、 Figure 2 and Figure 5 The heating element 120 includes several sub-heating elements 121 arranged along the axial direction of the heating element 120. The adjacent sub-heating elements 121 are connected and fixed by a heat insulation plate 150, that is, the several sub-heating elements 121 are arranged at intervals by several heat insulation plates 150 to form several heating zones. The setting of the heat insulation plates 150 prevents heat from flowing between the heating zones, which facilitates segmented heating and control of the heating temperature.

[0033] Among them, the heat insulation plate 150 is sleeved on the outer circumference of the connecting shaft 110 and seals the end of the cover heater 121, thereby realizing the connection between the sub-heating element 121 and the connecting shaft 110. Specifically, the heat insulation plate 150 includes a main body 151 and two bosses 152. The main body 151 and the bosses 152 are both discs and are coaxially arranged. The two bosses 152 are respectively located on the disc surfaces on both sides of the main body 151. The diameter of the bosses 152 is equal to the inner diameter of the heater 120 and smaller than the diameter of the main body 151. By clamping the end of the sub-heating element 121 on the bosses 152, the heat insulation plate 150 can conveniently seal the end of the cover heater 121. In other embodiments, the cross-sections of the main body and the bosses can also be other shapes, such as quadrilateral, hexagonal, etc., as long as the bosses can match and connect with the sub-heating element to realize that the heat insulation plate seals the end of the cover heater, and no specific limitation is made here.

[0034] The center of the heat shield 150 is provided with a first through hole 153 for passing the connecting shaft 110. The connecting shaft 110 is passed through the first through hole 153, so that the heat shield 150 is sleeved on the outer periphery of the connecting shaft 110. Since the heat shield 150 seals the end of the sub-heating element 121, the connecting shaft 110 is passed through the inner cavity of the sub-heating element 121 along the axial direction of the sub-heating element 121, thereby achieving a coaxial arrangement of the connecting shaft 110, the plurality of sub-heating elements 121, and the heat shield 150, and facilitating the installation of the heating device 100 into the inner cavity of the mold 10.

[0035] Two second through-holes 154 are provided on either side of the first through-hole 153 for passing the wires of the heating element 120 and the temperature measuring element 140. Passing the wires through the second through-holes 154 not only maintains a certain distance between the wires and the heating element 120, but also prevents safety accidents caused by prolonged heat damage to the wires. Furthermore, passing the wires of the heating element 120 and the temperature measuring element 140 through the second through-holes 154 ensures a clear arrangement of the wires within the heating device 100, facilitating maintenance.

[0036] The heat insulation board 150 is a polyimide board. The polyimide board has the advantages of high temperature resistance, wear resistance, deformation resistance, and stable performance. It can maintain stable performance under high temperature conditions during the production process and can isolate heat transfer. The heat insulation board 150 is sealed on the end of the sub-heating element 121, which can reduce the heat loss of the sub-heating element 121 during heating, improve the heating efficiency, and at the same time prevent heat from being transferred between the heating zones, avoiding inaccurate temperature control caused by heat transfer between adjacent sub-heating elements 121. In other embodiments, the heat insulation board can also be made of other materials, such as glass fiber reinforced plastic board, etc., as long as it can maintain stable performance under high temperature conditions and has a heat insulation effect, there is no specific limitation here.

[0037] Combine Figure 1 and Figure 2In this embodiment, the heating element 120 includes four sub-heating elements 121 arranged axially along the heating element 120. Adjacent sub-heating elements 121 are connected and fixed by thermal insulation plates 150. Specifically, two adjacent sub-heating elements 121 are respectively clamped onto two bosses 152 of the same thermal insulation plate 150. That is, the four sub-heating elements 121 are sequentially connected and fixed via three thermal insulation plates 150. Two additional thermal insulation plates 150 cover the two outermost ends of the heating element 120, namely, the free ends of the first and last sub-heating elements 121 of the heating element 120. Ultimately, the four sub-heating elements 121 and five thermal insulation plates 150 are arranged alternately in sequence to form four heating zones.

[0038] Furthermore, the number of sub-heating elements 121, thermally conductive elastic elements 130, and temperature measuring elements 140 is the same. Specifically, the heating device 100 includes four thermally conductive elastic elements 130, which are respectively sleeved on the outer periphery of the four sub-heating elements 121, and the four thermally conductive elastic elements 130 tightly wrap the entire outer periphery of the four sub-heating elements 121. After the heating device 100 is installed in the inner cavity of the mold 10, the four thermally conductive elastic elements 130 are all interference fit with the inner wall of the mold 10, that is, the four thermally conductive elastic elements 130 are elastically deformed, and their outer surfaces are in close contact with the inner wall of the mold 10, so that the four thermally conductive elastic elements 130 are tightly clamped between the four sub-heating elements 121 and the inner wall of the mold 10. The heating device 100 also includes four temperature measuring elements 140, which are respectively fixed on the four sub-heating elements 121 and extend out of the sub-heating elements 121 to be in close contact with the four thermally conductive elastic elements 130, and are respectively used to monitor the temperature of the mold 10 in the four heating zones.

[0039] Through the mutual cooperation of the four sub-heating elements 121, the five heat insulation plates 150, the four thermally conductive elastic elements 130, and the four temperature measuring elements 140, the heating device 100 forms four heating zones with precise temperature control, which can control the temperature gradient change and achieve segmented temperature control. When used in conjunction with the pultrusion process, it helps to stabilize the performance of the product. In other embodiments, the number of heating zones can also be two, three, five, etc., that is, the number of sub-heating elements, thermally conductive elastic elements, and temperature measuring elements can also be two, three, five, etc., and the number of heat insulation plates can also be three, four, six, etc. As long as the sub-heating elements, heat insulation plates, thermally conductive elastic elements, and temperature measuring elements cooperate with each other to achieve segmented temperature control, the specific design can be based on the heating scheme of the pultrusion process.

[0040] See Figure 1 and Figure 6The heating device 100 also includes a mounting assembly 160, which is connected to one end of the connecting shaft 110. The mounting assembly 160 includes a limiting plate 161 and a mounting plate 162. The limiting plate 161 is clamped on the inner wall of the mold 10 to fix the heating device 100 in the inner cavity of the mold 10 along the axial position of the mold 10. The mounting plate 162 covers the end of the mold 10 to fix the heating device 100 in the inner cavity of the mold 10 along the circumferential position of the mold 10.

[0041] Specifically, the mold 10 includes a mounting section 11 and a core section 12. The inner diameter of the mounting section 11 is larger than that of the core section 12, and a stepped engaging portion 13 is formed at the junction of the mounting section 11 and the core section 12. A limiting plate 161 is a circular disk with a diameter larger than the inner diameter of the core section 12 and smaller than the inner diameter of the mounting section 11. When the heating device 100 is pushed from the mounting section 11 of the mold 10 into the core section 12, the limiting plate 161 is secured to the inner wall of the mold 10. That is, the limiting plate 161 is engaged with the engaging portion 13, thereby fixing the heating device 100 in the axial position of the mold 10 within the inner cavity of the mold 10. The limiting plate 161 is provided with a first limiting hole 1611 and two second limiting holes 1612. The first limiting hole 1611 is located at the center of the limiting plate 161 and is used to fix the limiting plate 161 and the connecting shaft 110; the two second limiting holes 1612 are located on both sides of the first limiting hole 1611 and are used to fix the limiting plate 161 and the mounting plate 162.

[0042] After the heating device 100 is installed in the inner cavity of the mold 10, the limiting plate 161 is located inside the mold 10, making it inconvenient to directly secure the limiting plate 161 to the mold 10. Therefore, a mounting plate 162 is provided. Mounting plate 162 is also a circular disc with a diameter equal to the outer diameter of the mold 10, allowing mounting plate 162 to cover the ends of the mold 10. Mounting plate 162 is defined by a first mounting hole 1621, two second mounting holes 1622, and four third mounting holes 1623. First mounting hole 1621 is located in the center of mounting plate 162 and is used for lifting the mold 10 after the heating device 100 is installed in the inner cavity of the mold 10. The two second mounting holes 1622 are located on both sides of the first mounting hole 1621 and are arranged corresponding to the second limiting hole 1612, and are used to fix the mounting plate 162 and the limiting plate 161, that is, fasteners, such as studs and nuts that cooperate with each other, are passed through the corresponding second mounting holes 1622 and the second limiting holes 1612 to achieve fixed connection between the mounting plate 162 and the limiting plate 161, and the distance between the mounting plate 162 and the limiting plate 161 can be adjusted through the bolt connection to match the length of the mounting section 11 of the mold 10, that is, to ensure that the limiting plate 161 is clamped on the clamping part 13 while the mounting plate 162 covers the end of the mold 10. The four third mounting holes 1623 are distributed along the circumference of the mounting plate 162 at the edge of the mounting plate 162 and are used to fix the mounting plate 162 to the mold 10. Specifically, the end of the mounting section 11 of the mold 10 away from the core section 12 is provided with four mold mounting holes corresponding to the third mounting holes 1623. Bolts are passed through the corresponding third mounting holes 1623 and the mold mounting holes and tightened to achieve a fixed connection between the mounting plate 162 and the mold 10. Finally, the mounting plate 162 covers the end of the mold 10 to fix the heating device 100 in the inner cavity of the mold 10 along the circumferential position of the mold 10.

[0043] In other embodiments, the limiting plate and the mounting plate may also be other shapes, such as a triangle, a square, etc., as long as the limiting plate can fix the heating device in the inner cavity of the mold along the axial position of the mold, and the mounting plate can cover the end of the mold.

[0044] In this embodiment, the limiting plate 161 and the connecting shaft 110, the mounting plate 162 and the limiting plate 161, and the mounting plate 162 and the mold 10 are all fixedly connected by fasteners, providing reliable connections and convenient installation and removal. In other embodiments, the limiting plate and the connecting shaft, the mounting plate and the limiting plate, and the mounting plate and the mold may be connected by means of a snap connection or other methods, as long as the limiting plate and the connecting shaft, the mounting plate and the limiting plate, and the mounting plate and the mold can be reliably connected.

[0045] In other embodiments, the number of the second mounting holes and the second limiting holes may not be two, such as three, four, etc., as long as the fixed connection between the mounting plate and the limiting plate can be achieved; the number of the third mounting holes and the mold mounting holes may not be four, such as three, five, six, etc., as long as the heating device can be fixed in the inner cavity of the mold along the circumferential position of the mold.

[0046] See Figure 2 The heating device 100 also includes two positioning members 170, which are interconnected with the connecting shaft 110. The two positioning members 170 are located at both ends of the heating member 120 and are close to the outside of the heat insulation board 150, and are used to position the heating member 120. Specifically, the positioning members 170 are positioning nuts 170. The two positioning nuts 170 are screwed onto the connecting shaft 110 and are close to the outside of the heat insulation board 150 at both ends of the heating member 120, so that the position of the heating member 120 on the connecting shaft 110 is fixed. By adjusting the position of the two positioning nuts 170 on the connecting shaft 110, the position of the heating member 120 on the connecting shaft 110 can be adjusted, and then the relative position of the heating member 120 and the mold 10 after the heating device 100 is installed in the inner cavity of the mold 10 is adjusted, thereby controlling the heating area of the mold 10. In other embodiments, the positioning members can also be other structures, such as screws, pins, etc., as long as they can fix the heating member on the connecting shaft.

[0047] Continue reading Figures 1-6 After the heating device 100 is installed in the inner cavity of the mold 10, the wires of each sub-heating element 121 and each temperature measuring element 140 are passed through the second through hole 154 of each insulation board 150, and then pass through the second through hole 154 on the insulation board 150 farthest from the installation component 160, and finally pass through the port of the core segment 12 away from the installation segment 11 and connected to the electrical control cabinet, thereby realizing the precise temperature control function of the heating device 100.

[0048] In another embodiment, a pultrusion molding process for a hollow pipe is provided, in which the above-mentioned heating device 100 is used to heat the mold. Along the forward direction of pultrusion, the heating area is provided with a preheating zone, a gel zone, and a molding zone, and the temperatures of the preheating zone and the gel zone are lower than the temperature of the molding zone. This can gradually heat up the hollow pipe and completely solidify it, thereby reducing internal defects of the product and stabilizing product quality.

[0049] See Figure 6, the above-mentioned mold 10 is used as the core mold 10, and after the above-mentioned heating device 100 is installed in the inner cavity of the core mold 10, along the pultrusion forward direction a, the heating element 120 forms a heating area inside the core mold 10, and the four sub-heating elements 121 form the core mold preheating area A, the core mold gel area B, the core mold first molding area C1, and the core mold second molding area C2 in sequence. At the same time, the pultrusion molding die of the hollow pipe fitting also includes an outer mold (not shown in the figure), which is sleeved on the outer periphery of the core mold 10 and forms an annular channel for the molding of the hollow pipe fitting between the core mold 10. During the pultrusion process of the hollow pipe fitting, the core mold 10 and the outer mold need to be heated at the same time so that the inner and outer surfaces of the hollow pipe fitting are solidified at the same time. Therefore, the outer mold is heated on the outside of the outer mold by equipment such as an oven, and in the radial direction of the core mold 10, the outer mold corresponding to the core mold 10 is also provided with an outer mold preheating area, an outer mold gel area, an outer mold first molding area, and an outer mold second molding area.

[0050] Among them, the temperatures of the heating areas corresponding to the core mold 10 and the outer mold are equal, ensuring that the molded hollow pipe is heated evenly, that is, the temperature of the core mold preheating zone A is equal to the temperature of the outer mold preheating zone, hereinafter collectively referred to as the preheating zone; the temperature of the core mold gel zone B is equal to the temperature of the outer mold gel zone, hereinafter collectively referred to as the gel zone; the temperature of the core mold first molding zone C1 is equal to the temperature of the outer mold first molding zone, hereinafter collectively referred to as the first molding zone; the temperature of the core mold second molding zone C2 is also equal to the temperature of the outer mold second molding zone, hereinafter collectively referred to as the second molding zone.

[0051] In this embodiment, the temperature of the preheating zone is 80°C to 130°C; the temperature of the gelling zone is 110°C to 150°C; and the temperature of the forming zone is 140°C to 180°C. That is, the temperature of the preheating zone can be any value within the range of 80°C to 130°C, as long as it is within the range of 80°C to 130°C. The same applies to the gelling zone, the first forming zone, and the second forming zone, and will not be further described here.

[0052] Furthermore, the temperatures of the preheating zone, gelling zone, and first molding zone increase gradually, and the temperature of the second molding zone is lower than that of the first molding zone. This allows the hollow tube to gradually heat up and fully solidify during the pultrusion process from the preheating zone to the first molding zone. After passing through the second molding zone, the temperature of the hollow tube decreases, and the temperature difference between the hollow tube and room temperature decreases, thereby reducing internal defects in the product and stabilizing product quality. For example, in one embodiment, the temperature of the preheating zone is 90°C, the temperature of the gelling zone is 110°C, the temperature of the first molding zone is 180°C, and the temperature of the second molding zone is 150°C. Alternatively, the temperature of the preheating zone can be 85°C, the temperature of the gelling zone is 125°C, the temperature of the first molding zone is 175°C, and the temperature of the second molding zone is 155°C. As long as the above temperature conditions are met, no further details will be given.

[0053] In this embodiment, four heating areas are set inside the core mold 10 and outside the outer mold. In other embodiments, the number of heating areas can also be five, six, etc., to meet the molding process design requirements of different products. As long as the heating areas inside the core mold and outside the outer mold correspond to each other and can ensure the curing efficiency of the product, no specific restrictions are made here.

[0054] In this embodiment, the pultrusion speed is 5 mm / min to 180 mm / min. Because the pultrusion process uses a heating device 100 to heat the core mold 10 in sections, the pultrusion speed can be increased. Compared to the prior art pultrusion process that only heats the core mold in its entirety, the pultrusion process of this embodiment increases the upper limit of the pultrusion speed from 90 mm / min to 180 mm / min, increasing the production capacity on the same product line by 100%.

[0055] In addition, by using the above-mentioned pultrusion process, product scrap losses are reduced by 20%, the yield rate is increased by about 60%, and production efficiency is significantly improved.

[0056] The beneficial effects of the present application are: different from the prior art, the heating device of the present application includes a connecting shaft, a heating element, and a thermally conductive elastic element, and has the following advantages: 1) The thermally conductive elastic element is tightly clamped between the heating element and the inner wall of the mold, so that contact heating is achieved between the heating element and the mold, heat loss is reduced, heating efficiency is high, and energy utilization rate is increased by 60%; 2) The end of the temperature measuring element used for temperature measurement is in close contact with the inner wall of the mold, and the measured temperature is the actual temperature of the mold, which is highly accurate and helps to achieve precise temperature control of the mold during the production process; 3) Several sub-heating elements, insulation boards, thermally conductive elastic elements, and temperature measuring elements that cooperate with each other can form several heating zones with precise temperature control, realize the segmented temperature control function, and be used in conjunction with the pultrusion molding process. The product quality is stable, and the production capacity can be doubled, the product scrap loss is reduced by 20%, the yield rate is increased by 60%, and the production efficiency is significantly improved.

[0057] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A heating device, characterized in that: include: A connecting shaft, used for installing the heating device inside the mold; A heating element is fixed to the connecting shaft; the heating element includes a plurality of sub-heating elements arranged along the axial direction of the heating element, and two adjacent sub-heating elements are connected and fixed by a heat insulation plate; the heat insulation plate is sleeved on the outer periphery of the connecting shaft and covers the ends of the sub-heating elements; the heating element includes a heating wire, a plurality of insulating plates and a shell, the plurality of insulating plates are arranged circumferentially, the heating wire is wound around the outer periphery of the insulating plates, and the shell covers the heating wire and the insulating plates; The heat-conducting elastic member is tightly sandwiched between the heating member and the inner wall of the mold.

2. The heating device according to claim 1, wherein: It also includes a temperature measuring element, which is fixed on the heating element and is in close contact with the heat-conducting elastic element.

3. The heating device according to claim 2, wherein: The end portion of the temperature measuring component for measuring temperature extends out of the outer surface of the heat-conductive elastic component and is in close contact with the inner wall of the mold.

4. The heating device according to claim 1, wherein: The thermally conductive elastic member is made of thermally conductive silicone.

5. The heating device according to claim 1, wherein: The heat insulation board is a polyimide board or a glass fiber reinforced plastic board.

6. A pultrusion process, characterized in that: The mold is heated using the heating device described in any one of claims 1 to 5. Along the pultrusion forward direction, the heating area is provided with a preheating zone, a gel zone, and a molding zone. The temperatures of the preheating zone and the gel zone are lower than the temperature of the molding zone.

7. The pultrusion process according to claim 6, characterized in that The temperature of the preheating zone is 80°C to 130°C; the temperature of the gelling zone is 110°C to 150°C; and the temperature of the molding zone is 140°C to 180°C.

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