Method for reducing difficulty of ultrasonic welding of engineering plastic

Abstract

The application discloses a method for reducing the difficulty of ultrasonic welding of engineering plastics, and is characterized in that the method comprises the following steps: S1, before the engineering plastics are subjected to ultrasonic welding, an auxiliary welding agent is coated on the welding surface of the engineering plastics, and the auxiliary welding agent comprises an activator. According to the method, the welding surface of the engineering plastics is treated by selecting the auxiliary welding agent, the surface of the engineering plastics is subjected to pre-dissolution and activation treatment before ultrasonic welding, and then only low-power ultrasonic welding equipment is needed for welding, so that the welding difficulty is reduced, the strength and functional requirements of the welded assembly are ensured, the power requirement of the welding equipment is reduced, cost is saved, and the unification and standardization of the equipment are promoted.

Description

Technical Field

[0001] This invention relates to a method for reducing the difficulty of ultrasonic welding of engineering plastics. Background Technology

[0002] Currently, more and more engineering plastics are being used in the injection molding industry. For injection molding, the main welding methods for parts are ultrasonic welding and hot plate welding. Relatively speaking, hot plate welding produces a lot of slag, smoke, has a long cycle, high space occupancy, and is not suitable for full automation. Ultrasonic welding, on the other hand, has a short cycle, low space occupancy, is environmentally friendly, and is easier to automate, making it highly favored. However, due to the different materials, the choice of welding method is greatly restricted. For example, polyamide (PA) has a high melting temperature and strong shock absorption. Therefore, compared with hot plate welding, ultrasonic welding has extremely high requirements for welding equipment, and the welding effect is still not ideal. Therefore, it is particularly necessary to effectively reduce the difficulty of ultrasonic welding of engineering plastics. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a method for reducing the difficulty of ultrasonic welding of engineering plastics.

[0004] The present invention is achieved through the following technical solution: a method for reducing the difficulty of ultrasonic welding of engineering plastics, comprising step S1: before ultrasonic welding of the engineering plastics, an auxiliary welding reagent is pre-coated on the welding surface of the engineering plastics, the auxiliary welding reagent including an activator.

[0005] Preferably, the activator is lithium aluminum hydride triethoxy activator.

[0006] Preferably, the auxiliary welding reagent also includes a pre-dissolved solvent.

[0007] Preferably, the auxiliary welding agent is applied to the welding surface of the engineering plastic using a 3D printing liquid extrusion device.

[0008] Preferably, the engineering plastic is PA engineering plastic.

[0009] Preferably, the process also includes step S2: after the engineering plastic has been pre-melted and activated, it is then subjected to ultrasonic welding using an ultrasonic welding device.

[0010] Preferably, the auxiliary welding agent further includes formic acid and a fast-volatile solvent.

[0011] Preferably, the engineering plastic is pre-melted and activated for 1 to 3 minutes before welding, and after a 30-minute interval, the peak destructive force of the weld surface is 63.3 to 75.6 kN.

[0012] Preferably, the auxiliary welding agent further includes formic acid and a slow-volatile solvent.

[0013] Preferably, the engineering plastic is pre-melted and activated for 1-5 minutes before welding, and a 30-minute interval is observed after welding. The peak destructive force of the weld surface is 56.1-73.8 kN.

[0014] Compared to the existing technology of directly ultrasonically welding engineering plastic parts, this invention uses auxiliary welding reagents to treat the welding surface of the engineering plastic, so that the surface of the engineering plastic is pre-dissolved and activated before ultrasonic welding. After that, only low-power ultrasonic welding equipment is needed to generate waves for welding. This method can reduce the welding difficulty, ensure the strength and functional requirements of the welded components, reduce the power requirements of the welding equipment, save costs, and promote the standardization and unification of equipment. Attached Figure Description

[0015] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a process diagram of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0018] A method for reducing the difficulty of ultrasonic welding of engineering plastics includes coating the welding surface A1 of engineering plastic A with an auxiliary welding agent before ultrasonic welding. This auxiliary welding agent activates the surface of engineering plastic A, thereby reducing the resistance during ultrasonic welding. The auxiliary welding agent includes an activator, such as lithium aluminum hydride triethoxylate activator. Furthermore, the auxiliary welding agent also includes a pre-dissolving solvent. When this pre-dissolving solvent is applied to the surface of the engineering plastic, it pre-dissolves the surface and improves the activation efficiency of the activator, further reducing the difficulty of ultrasonic welding. Of course, different pre-dissolving solvents can be selected according to the requirements of different plastic substrates.

[0019] Specifically, please refer to the instruction manual appendix. Figure 1A method to reduce the difficulty of ultrasonic welding of engineering plastics, the steps of which are as follows:

[0020] S1: Select engineering plastic A and engineering plastic B. Preferably, a weld guide line B2 is provided on the welding surface of engineering plastic B.

[0021] S2: Using the 3D printing liquid extrusion equipment C, an auxiliary welding agent is precisely applied to the welding surface A1 of engineering plastic A or the welding surface B1 of engineering plastic B.

[0022] S3: The engineering plastic A or engineering plastic B undergoes a period of pre-dissolution and activation;

[0023] S4: Using low-power ultrasonic welding equipment to generate waves for welding.

[0024] The aforementioned engineering plastic is, for example, PA engineering plastic. Compared with the prior art of directly ultrasonically welding PA engineering plastic parts, the present invention treats the welding surface of the engineering plastic by selecting auxiliary welding reagents, so that the surface of the PA engineering plastic is pre-dissolved and activated before ultrasonic welding. After that, only low-power ultrasonic welding equipment is needed for wave welding. This method can reduce the welding difficulty, ensure the strength and functional requirements of the welded components, reduce the power requirements of the welding equipment, save costs, and promote equipment standardization and uniformity.

[0025] In one specific embodiment, the comparison data of PA engineering plastics pre-dissolving and activating with auxiliary welding reagents versus PA engineering plastics not treated with auxiliary welding reagents are shown in the table below:

[0026]

[0027]

[0028] Sample 1 was prepared by coating the surface of engineering plastic with formic acid, followed by pre-dissolution and activation with a fast-volatile solvent and an activator (auxiliary welding reagent). Sample 2 was prepared by coating the surface of engineering plastic with formic acid, followed by pre-dissolution and activation with a slow-volatile solvent and an activator (auxiliary welding reagent). Sample 3 was an engineering plastic without the coating of auxiliary welding reagent. The fast-volatile solvent could be diethyl ether, the slow-volatile solvent could be tetrahydrofuran, and the activator could be lithium aluminum hydride triethoxy activator.

[0029] The fast-evaporating solvent selected here takes about 5 minutes to evaporate completely, while the slow-evaporating solvent takes about 30 minutes to evaporate completely, during which the peak destructive force on the weld surface can be reached. In addition, compared with the welding of engineering plastics without the treatment of the welding surface with auxiliary welding reagents, the resistance during ultrasonic welding is very large, requiring a high-power (4200W) welding machine of 15KHZ to perform welding. However, when engineering plastics are treated with auxiliary welding reagents, only a low-power (2000W) welding machine of 20KHZ is required to perform welding.

[0030] The data above shows that: First, within the complete evaporation time and with the same solvent, a certain post-activation drying time is beneficial for sufficient activation of the weld surface, resulting in a significantly superior weld strength. However, excessive post-activation drying time leads to excessive solvent loss, reducing the degree of activation of the weld surface and indirectly affecting subsequent weld strength. Second, within the complete evaporation time and with the same solvent and post-activation drying time, a certain drying time after welding is beneficial for the complete evaporation of solvent from the weld surface, thus improving weld strength. Third, with the same activation drying time and post-weld drying time, the faster the solvent evaporates, the higher the weld strength. Fourth, compared to unactivated PA materials, activated materials are easier to weld and more conducive to enhancing their weld strength.

[0031] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for reducing the difficulty of ultrasonic welding of engineering plastics, characterized in that, The process includes step S1: Before ultrasonic welding of the engineering plastic, an auxiliary welding reagent is pre-coated on the welding surface of the engineering plastic, the auxiliary welding reagent including an activator; the auxiliary welding reagent also includes a pre-dissolving solvent; and step S2: After the engineering plastic is pre-dissolved and activated, it is ultrasonically welded using an ultrasonic welding device.

2. The method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 1, characterized in that, The activator is lithium triethoxyaluminum hydride activator.

3. The method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 1, characterized in that, The auxiliary welding reagent is applied to the welding surface of the engineering plastic using a 3D printing liquid extrusion device.

4. The method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 1, characterized in that, The engineering plastic is PA engineering plastic.

5. The method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 4, characterized in that, The pre-dissolved solvent includes formic acid and fast-volatile solvents.

6. The method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 5, characterized in that, The engineering plastic is pre-melted and activated for 1-3 minutes before welding. After a 30-minute interval following welding, the peak destructive force of the weld surface is 63.3-75.6 kN.

7. The method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 4, characterized in that, The pre-dissolved solvent includes formic acid and a slow-volatile solvent.

8. A method for reducing the difficulty of ultrasonic welding of engineering plastics according to claim 7, characterized in that, The engineering plastic is pre-melted and activated for 1-5 minutes before welding. After a 30-minute interval following welding, the peak destructive force of the weld surface is 56.1-73.8 KN.

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