Production process of PTC (Positive Temperature Coefficient) electric heater

Abstract

The invention provides a production process of a PTC electric heater, and the PTC electric heater comprises a PTC heating core, a hollow aluminum tube, and two corrugated sheets with tooth-shaped structures. Comprising the following steps that (1) corrugated sheets are shaped, specifically, the two corrugated sheets are shaped through two shaping molds, shaping insertion teeth matched with the corrugated sheets are arranged on the shaping molds, and tooth grooves of the corrugated sheets are arranged on the shaping insertion teeth of the shaping molds in a sleeving mode; (2) laser welding positioning is conducted, specifically, the two corrugated sheets shaped through the shaping molds are placed on the upper side and the lower side of the aluminum pipe, laser welding is conducted on the corrugated sheets and the aluminum pipe through a laser welding machine, and the two shaping molds are detached after fixing; the pre-fixed aluminum pipe and the corrugated sheet are subjected to hot melting welding and fixing through a heating furnace, (4) PTC heating core installation is carried out, the PTC heating core is inserted into a hollow hole of the aluminum pipe, and (5) pressing and fixing are carried out, and two pressing molds are controlled through a hydraulic machine to press the aluminum pipe.

Description

Technical Field

[0001] This invention relates to the field of PTC electric heater technology, and in particular to a manufacturing process for a PTC electric heater. Background Technology

[0002] The PTC heating element consists of a PTC ceramic heating element and an aluminum tube. This type of PTC heating element has the advantages of low thermal resistance and high heat exchange efficiency, making it an automatic temperature-controlled and energy-saving electric heater. Its outstanding feature lies in its safety performance; under any application conditions, it will not produce the surface "reddening" phenomenon seen in electric heating tube heaters, thus avoiding safety hazards such as burns and fires.

[0003] During the manufacturing process of a PTC electric heater, the PTC heating element needs to be inserted into an aluminum tube, and the aluminum tube is then pressed together using a hydraulic press to fix the PTC heating element inside the aluminum tube. Since corrugated fins for heat dissipation need to be installed on the top and bottom sides of the aluminum tube, the following two methods are currently commonly used in the manufacturing process:

[0004] (1) The width of the aluminum tube is set to be wider than that of the corrugated sheet. The corrugated sheet is welded to the aluminum tube. The pressing parts are reserved on the front and back sides of the corrugated sheet. The PTC heating core is inserted into the aluminum tube. Then, the front and back sides of the aluminum tube are pressed together by a hydraulic press to press and fix the PTC heating core. However, this method has the disadvantage of high cost because the aluminum tube needs to be set wider and more materials are used. Moreover, pressing only the front and back sides will also lead to poor adhesion and reduced thermal conductivity.

[0005] (2) First, the PTC heating element is installed into the aluminum tube and pressed and fixed by a hydraulic press. Then, the corrugated sheet and the upper and lower aluminum sheets are assembled into a heat dissipation strip. The heat dissipation strip is then fixed to the upper and lower sides of the aluminum tube by adhesive bonding. Although this method is the most traditional processing method, it has many defects. Since the aluminum tube is pressed first and then the corrugated sheet is fixed, welding cannot be used. Because the temperature is too high during welding, it will directly affect the function of the PTC heating element. Adhesive bonding requires heat conduction through the silicone layer, which inhibits the function of the heating element, makes it difficult to transfer heat, reduces the heat conduction performance, and thus affects its performance. Moreover, the corrugated sheet in this method needs to be assembled with the upper and lower bottom sheets into a heat dissipation structure before being bonded to the aluminum tube. This assembly process requires assembly, positioning, welding and other processes, which is inefficient and costly. Moreover, since adhesive bonding is used, the thickness of the corrugated sheet needs to be controlled above 0.2mm, otherwise it cannot withstand the pressure of the bonding process and will deform, which will also increase the cost. Summary of the Invention

[0006] The purpose of this invention is to provide a manufacturing process for a PTC electric heater to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A manufacturing process for a PTC electric heater, the PTC electric heater comprising a PTC heating core, a hollow aluminum tube, and two corrugated plates with a toothed structure, includes the following steps:

[0009] 1) Corrugated sheet shaping: Two corrugated sheets are shaped using two shaping molds. The shaping molds have shaping teeth that are adapted to the corrugated sheets. The toothed grooves of the corrugated sheets are fitted onto the shaping teeth of the shaping molds.

[0010] 2) Laser welding positioning: After the two corrugated sheets are shaped by the shaping mold, they are placed on the upper and lower sides of the aluminum tube and fixed in position. The corrugated sheets are then laser welded to the aluminum tube by a laser welding machine to pre-fix the corrugated sheets on the aluminum tube. After fixing, the two shaping molds are removed.

[0011] 3) Brazing fixation: The pre-fixed aluminum tube and corrugated sheet are fixed by hot melting welding in a heating furnace. During the heating process in the heating furnace, the aluminum brazing material melts and the corrugated sheet and aluminum tube are welded and fixed.

[0012] 4) PTC heating element installation: Insert the PTC heating element into the hollow hole of the aluminum tube;

[0013] 5) Pressing and fixing: The aluminum tube is pressed by two pressing molds controlled by a hydraulic press. The pressing molds have pressing teeth, which are inserted into the grooves of the corrugated sheet. Pressure is then applied to the aluminum tube to achieve pressing. After pressing, the aluminum tube presses and fixes the PTC heating core, completing the processing.

[0014] As further described in the present invention, the width of the aluminum tube is the same as the width of the corrugated sheet.

[0015] As further described in the present invention, the tooth pitch of the corrugated sheet is 1.0mm-5.0mm.

[0016] As further described in the present invention, the left and right sides of the aluminum tube are V-shaped structures that are recessed inward.

[0017] As further described in the present invention, the thickness of the corrugated sheet is 0.05mm-0.12mm.

[0018] In a further description of the present invention, in step (3), the laser welding machine performs laser welding on one side of the corrugated pipe and the aluminum pipe.

[0019] In a further description of the present invention, in step (6), the pressing mold is first inserted laterally into the toothed groove of the corrugated sheet, and then pressure is applied radially to the aluminum tube.

[0020] In a further description of the present invention, in step (6), the end of the pressing teeth of the pressing mold inserted into the corrugated sheet is a guide cone structure.

[0021] A PTC electric heater is manufactured using the aforementioned PTC electric heater production process.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) In this design, the corrugated sheet is shaped by a mold and then laser welded to the aluminum tube. This method makes the tooth pitch uniform after the corrugated sheet is fixed on the aluminum tube, which lays the foundation for the subsequent pressing and fixing of the aluminum tube. Only by controlling the tooth pitch of the corrugated sheet uniformly can normal pressing and demolding be guaranteed during pressing and fixing.

[0024] (2) This design adopts the method of welding the corrugated sheet first and then installing the PTC heating core. This method can significantly reduce the thickness of the corrugated sheet, thereby reducing the cost.

[0025] (3) In this design, when pressing and fixing, a pressing mold is inserted into the tooth groove of the corrugated sheet, and then the aluminum tube is pressed. This method eliminates the need to reserve pressing positions on the left and right sides of the aluminum tube, which greatly reduces the material cost of the aluminum tube.

[0026] (4) The pressing mold of this design is inserted into the corrugated sheet and then pressed into the aluminum tube. The pressing strength is greater and more stable, which makes the aluminum tube and the PTC heating core more tightly bonded, with higher thermal conductivity and better consistency.

[0027] (5) The corrugated aluminum tube welded in this design is a completely metallic heat conductor with better thermal conductivity. Attached Figure Description

[0028] Figure 1 This is a structural diagram of the PTC electric heater of the present invention;

[0029] Figure 2 yes Figure 1 Sectional view of AA;

[0030] Figure 3 This is a schematic diagram of the state of two corrugated sheets being shaped by two shaping molds in step 2 of the present invention;

[0031] Figure 4 This is a schematic diagram showing the positioning of the corrugated sheet and aluminum tube before laser welding in step 3 of the present invention.

[0032] Figure 5 This is a schematic diagram showing the state after laser welding and disassembly of the shaping mold in step 3 of the present invention;

[0033] Figure 6 This is a schematic diagram showing the state of the PTC heating element being installed in the aluminum tube in step 5 of the present invention;

[0034] Figure 7 This is a structural diagram of the pressing mold of the present invention;

[0035] Figure 8 This is a top view of the pressing teeth of the present invention;

[0036] Figure 9 This is a side view of the state of the pressing mold inserted into the toothed groove of the corrugated sheet in step 6 of the present invention.

[0037] Figure 10 This is a side view of the pressing state of the aluminum tube by the pressing mold in step 6 of the invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings:

[0039] like Figure 1-10 As shown, a manufacturing process for a PTC electric heater is described. The PTC heater includes a PTC heating core 1, a hollow aluminum tube 2, and two corrugated sheets 3 with tooth-like structures.

[0040] In this design, the width W1 of the aluminum tube is the same as the width W2 of the corrugated sheet. There is no need to reserve protruding parts on the left and right sides of the aluminum tube 2 for the pressing process, which reduces production costs.

[0041] The left and right sides of the aluminum tube 2 are V-shaped structures 21 that are recessed inwards; this makes it easy for the sidewalls of the aluminum tube 2 to deform during the subsequent pressing and fixing process. In addition, depending on the requirements, the left and right sides of the aluminum tube 2 can also be set as V-shaped structures that bulge outwards, or as arc-shaped structures that bulge outwards or are recessed inwards.

[0042] The tooth pitch of the corrugated sheet 3 in this design is controlled between 1.0mm and 5.0mm. Since this design requires the subsequent use of a shaping mold 4 to shape the teeth and a pressing mold 5 to insert the corrugated sheet 3 into the tooth groove before pressing the aluminum tube 2, the tooth pitch needs to be controlled within this range. If the tooth pitch is too small, it will be difficult to shape the tooth through the mold and insert it into the tooth groove. If the tooth pitch is too large, it will affect the use of the product. The tooth pitch in this design is 4.0mm.

[0043] The thickness of the corrugated sheet 3 in this design is 0.05mm-0.12mm. Since the corrugated sheet 3 in this design is fixed to the aluminum tube 2 by welding process, the thickness can be set to be thinner, thereby reducing the cost.

[0044] The processing steps are as follows:

[0045] 1) Corrugated sheet 3 shaping: Two corrugated sheets 3 are shaped by two shaping molds 4 respectively. The shaping mold 4 has shaping teeth 41 that are adapted to the corrugated sheets. The tooth groove of the corrugated sheet 3 is fitted onto the shaping teeth 41 of the shaping mold 4. This setting is to fix the position of the corrugated sheet 3 and avoid displacement during the welding process, which would affect the pressing process.

[0046] 2) Laser welding positioning: The two corrugated sheets 3, after being shaped by the shaping mold 4, are placed on the upper and lower sides of the aluminum tube 2 and fixed in position. The corrugated sheets 3 and the aluminum tube 2 are laser welded by the laser welding machine to achieve the pre-fixation of the corrugated sheets 3 on the aluminum tube 2. After the fixation is completed, the two shaping molds 4 are removed. The laser welding machine in this design only needs to perform laser welding on one side of the corrugated tube and the aluminum tube 2, because this process only needs to ensure that the corrugated sheets 3 are pre-fixed on the aluminum tube 2, without the need for double-sided welding, which reduces costs and improves efficiency.

[0047] 3) Brazing fixation: The pre-fixed aluminum tube 2 and corrugated sheet 3 are fixed by hot melting welding in a heating furnace. During the heating process in the heating furnace, the aluminum brazing material melts and the corrugated sheet 3 and aluminum tube 2 are welded and fixed.

[0048] 4) Installation of PTC heating element 1: Insert PTC heating element 1 into the hollow hole of aluminum tube 2; after installation, PTC heating element 1 is in a loose state, ready for the pressing and fixing process.

[0049] 5) Pressing and Fixing: Two pressing molds 5 are controlled by a hydraulic press to press the aluminum tube 2. The pressing molds 5 have pressing teeth 51 that mate with the toothed structure of the corrugated sheet 3. The pressing teeth 51 are inserted into the toothed grooves of the corrugated sheet 3, and pressure is applied to the aluminum tube 2 to achieve pressing. After pressing, the aluminum tube 2 firmly fixes the PTC heating element 1, completing the processing. This design uses a method where the pressing mold 5 is inserted into the toothed grooves of the corrugated sheet 3 before pressing the aluminum tube 2. In the pressing and fixing process, since the teeth of the corrugated sheet 3 were shaped by the shaping mold 4 in step (2), the tooth pitch of the corrugated sheet 3 fixed on the aluminum tube 2 is uniform. Therefore, in this process, the pressing teeth 51 of the pressing mold 5 are the same as the shaping teeth 41 of the shaping mold 4, so they can be smoothly inserted into the corrugated sheet 3 and can also be smoothly removed after pressing. The tooth-type pressing and fixing method is adopted, and there is no need to reserve protruding pressing parts on the left and right sides of the aluminum tube 2, thus reducing production costs.

[0050] The pressing mold 5 is first inserted laterally into the tooth groove of the corrugated sheet 3, and then pressure is applied radially to the aluminum tube 2; the pressing tooth 51 of the pressing mold 5 is inserted into one end of the corrugated sheet 3 with a guide cone structure. The lateral insertion method can adapt to different tooth shapes. The design of the guide cone is to guide and facilitate insertion into the tooth groove of the corrugated sheet 3.

[0051] A PTC electric heater is manufactured using the aforementioned PTC electric heater manufacturing process.

[0052] The above description is not intended to limit the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A manufacturing process for a PTC electric heater, the PTC electric heater comprising a PTC heating core, a hollow aluminum tube, and two corrugated plates with toothed structures, characterized in that: Includes the following steps: 1) Corrugated Sheet Shaping: Two corrugated sheets are shaped using two shaping molds. Each mold has shaping teeth that fit the corrugated sheets. The corrugated sheets are fitted onto the shaping teeth of the molds. 2) Laser Welding Positioning: The two corrugated sheets, shaped using the molds, are placed on the upper and lower sides of the aluminum tube and fixed in position. A laser welding machine is then used to laser weld the corrugated sheets to the aluminum tube, pre-fixing the corrugated sheets to the aluminum tube. After fixing, the two shaping molds are removed. 3) Brazing Fixing: The pre-fixed... The aluminum tube and corrugated sheet are fixed by hot-melt welding in a heating furnace. During the heating process, the aluminum brazing filler melts and the corrugated sheet and aluminum tube are welded and fixed. 4) PTC heating element installation: The PTC heating element is inserted into the hollow hole of the aluminum tube. 5) Pressing and fixing: The aluminum tube is pressed by two pressing molds controlled by a hydraulic press. The pressing molds have pressing teeth. The pressing teeth are inserted into the tooth grooves of the corrugated sheet. Pressure is then applied to the aluminum tube to achieve pressing. After pressing, the aluminum tube presses and fixes the PTC heating element, completing the processing.

2. The manufacturing process of a PTC electric heater according to claim 1, characterized in that: The width of the aluminum tube is the same as the width of the corrugated sheet.

3. The manufacturing process of a PTC electric heater according to claim 1, characterized in that: The tooth pitch of the corrugated sheet is 1.0mm-5.0mm.

4. The manufacturing process of a PTC electric heater according to claim 1, characterized in that: The aluminum tube has V-shaped structures that are concave inward on both the left and right sides.

5. The manufacturing process of a PTC electric heater according to claim 1, characterized in that: The thickness of the corrugated sheet is 0.05mm-0.12mm.

6. The manufacturing process of a PTC electric heater according to claim 1, characterized in that: In step 2), the laser welding machine performs laser welding on one side of the corrugated pipe and the aluminum pipe.

7. The manufacturing process of a PTC electric heater according to claim 1, characterized in that: In step (5), the pressing mold is first inserted laterally into the toothed groove of the corrugated sheet, and then pressure is applied radially to the aluminum tube.

8. The manufacturing process of a PTC electric heater according to claim 7, characterized in that: In step (5), the end of the pressing teeth of the pressing mold inserted into the corrugated sheet is a guide cone structure.

9. A PTC electric heater, characterized in that: It is manufactured using the production process of a PTC electric heater as described in any one of claims 1-8.

Images