阅读说明：本技术 一种热塑性塑料的激光透射焊接方法 (Laser transmission welding method for thermoplastic plastics ) 是由 林资凯 其他发明人请求不公开姓名 于 2019-10-25 设计创作，主要内容包括：本发明属于激光焊接技术领域,公开了一种热塑性塑料的激光透射焊接方法,包括以下步骤：将上塑料工件、下塑料工件叠压固定到加工位上,所述上塑料工件和所述下塑料工件的接触面形成焊接面；开启激光发射器,调节激光束的参数使得加热区域的温度低于上塑料工件熔融温度,高于下塑料工件的熔融温度；同时,使得激光束依次透过所述加工位上方的V面圆柱、所述上塑料工件,同时所述激光束沿着焊接面来回移动,在所述焊接面上形成加热区域,在压力和激光作用下,所述上塑料工件和所述下塑料工件粘合；该热塑性塑料的激光透射焊接方法可实现精确焊接路径和焊接强度控制,增加焊接件的整体强度和刚度,可防止发生灼烧缺陷。(The invention belongs to the technical field of laser welding, and discloses a laser transmission welding method of thermoplastic plastics, which comprises the following steps: laminating and fixing an upper plastic workpiece and a lower plastic workpiece on a processing station, wherein a welding surface is formed on the contact surface of the upper plastic workpiece and the lower plastic workpiece; starting a laser emitter, and adjusting the parameters of a laser beam to ensure that the temperature of a heating area is lower than the melting temperature of an upper plastic workpiece and higher than the melting temperature of a lower plastic workpiece; meanwhile, enabling a laser beam to sequentially penetrate through the V-surface cylinder above the processing position and the upper plastic workpiece, enabling the laser beam to move back and forth along a welding surface, forming a heating area on the welding surface, and bonding the upper plastic workpiece and the lower plastic workpiece under the action of pressure and laser; the laser transmission welding method of the thermoplastic plastics can realize accurate welding path and welding strength control, increase the overall strength and rigidity of a welding part and prevent burning defects.)

1. A method of laser transmission welding of thermoplastics, comprising the steps of:

laminating and fixing an upper plastic workpiece and a lower plastic workpiece on a processing station, wherein a welding surface is formed on the contact surface of the upper plastic workpiece and the lower plastic workpiece;

starting a laser emitter, and adjusting the parameters of a laser beam to ensure that the temperature of a heating area is lower than the melting temperature of an upper plastic workpiece and higher than the melting temperature of a lower plastic workpiece; at the same time, the user can select the desired position,

and enabling the laser beam to sequentially penetrate through the V-surface cylinder above the processing position and the upper plastic workpiece, and meanwhile, enabling the laser beam to move back and forth along the welding surface to form a heating area on the welding surface, and bonding the upper plastic workpiece and the lower plastic workpiece under the action of pressure and laser.

2. The method of claim 1 wherein the upper plastic workpiece is made of a beam transmissive material.

3. The method of claim 1 wherein the melting point of the V-faced cylinder is greater than the melting point of the upper plastic workpiece.

4. The laser transmission welding method for thermoplastic plastics according to claim 1, wherein said laser beam is caused to sequentially penetrate through said upper plastic workpiece and said V-plane cylinder above said processing position to form a heating region on said welding surface, and said upper plastic workpiece and said lower plastic workpiece are bonded under pressure of 40 ± 3MPa by the action of the laser beam and the pressure.

5. The method of claim 1 wherein said laminating and affixing the upper and lower plastic workpieces to the processing station further comprises applying a laser to the interface between the upper and lower plastic workpieces to form a weld surface

And respectively carrying out hot air cleaning on the corresponding laminated surfaces of the upper plastic workpiece and the lower plastic workpiece.

6. The method of claim 5, wherein the hot air temperature is 120 ℃ ± 5 ℃.

Technical Field

The invention relates to the technical field of laser welding, in particular to a laser transmission welding method for thermoplastic plastics.

Background

The connection method of plastics and composite materials thereof generally has three methods: mechanical attachment, adhesive bonding and welding. Mechanical connections include rivet or compression joint connections using separate fasteners such as metal or plastic screws. (2) Adhesive bonding is the application of an adhesive between the parts to be joined to join the parts. (3) The welding is to melt or soften the polymer at the interface by heating, so that the polymer molecular chains are diffused through the interface to form chain entanglement under the action of certain pressure and time, and finally the strength of the welding point is obtained. The welding methods are divided into two main categories according to the heating mode adopted: external heating and internal heating. External heating methods heat the weld surface by convection or conduction, including hot tool welding, hot gas welding, extrusion welding, implant induction welding, and implant resistance welding. The internal heating method is a method of directly generating a heat source inside a material by a technique, thereby replacing external heating. It is divided into two categories: mechanical heating and electromagnetic heating. Mechanical internal heating is the conversion of mechanical energy into heat by surface friction or intermolecular friction, including ultrasonic, vibration and spin welding. Electromagnetic internal heating methods rely on the absorption of electromagnetic radiation for conversion to heat, including infrared, laser, radio frequency and microwave welding.

The traditional thermoplastic plastic connecting method has many defects, the mechanical connecting strength of adopting screws, snap rings and the like is not easy to meet the requirement and can not have the requirement on the quality of the connecting surface; the adhesive bonding method needs the procedures of surface roughening, gluing, bonding, curing, ironing by an electric iron, finishing and the like, all the procedures are manually operated, the labor intensity is high, the procedures are multiple, the production efficiency is low, the quality is difficult to ensure, and the volatile components of the adhesive pollute the environment and influence the body health of operators; the plastic part is easy to be bonded with a heating source by adopting external heating welding, and air pollution can be caused; the strength of a welding joint is influenced when an implant for implant welding is left on a welding surface; mechanical internal heating can leave the final product with residual vibrational and thermal stresses that accelerate the aging of the product.

Laser transmission welding is a novel plastic welding process developed in recent years, and the principle is that an infrared laser beam (the wavelength is generally 800-. The two parts to be welded must have one transparent to the laser beam, i.e. the laser beam penetrates it without loss of energy, and the other opaque, i.e. absorbs the energy of the laser radiation; in order to increase the ability of the material to absorb radiant energy, the contact surfaces of the two parts to be welded are provided with a laser-absorbing additive coating. The radiation penetrates through a transparent weld part of the two parts to be welded, and the other opaque part absorbs the laser radiation on the contact surface to form a heat-affected zone, and the plastic in the heat-affected zone is melted; during the subsequent solidification process, the melted material forms a joint and the parts to be welded are joined. However, the current laser transmission welding technology only can play a role in connection, and cannot change the properties of the welded thermoplastic plastic material, such as electrical conductivity, thermal conductivity and the like; due to the characteristics of low melting point and easy burning of plastics, the range of laser welding process parameters is difficult to optimize; and neither of the two welded workpieces can be substantially separated.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a laser transmission welding method of thermoplastic plastics; the laser transmission welding method of the thermoplastic plastics can realize accurate welding path and welding strength control, increase the overall strength and rigidity of a welding part and prevent burning defects.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method of laser transmission welding of thermoplastics comprising the steps of:

laminating and fixing an upper plastic workpiece and a lower plastic workpiece on a processing station, wherein a welding surface is formed on the contact surface of the upper plastic workpiece and the lower plastic workpiece;

starting a laser emitter, and adjusting the parameters of a laser beam to ensure that the temperature of a heating area is lower than the melting temperature of an upper plastic workpiece and higher than the melting temperature of a lower plastic workpiece; at the same time, the user can select the desired position,

and enabling the laser beam to sequentially penetrate through the V-surface cylinder above the processing position and the upper plastic workpiece, and meanwhile, enabling the laser beam to move back and forth along the welding surface to form a heating area on the welding surface, and bonding the upper plastic workpiece and the lower plastic workpiece under the action of pressure and laser.

Specifically, the upper plastic workpiece is made of a light beam transmitting material.

Specifically, the melting point of the V-face cylinder is greater than the melting point of the upper plastic workpiece.

Specifically, the laser beam sequentially penetrates through the V-surface cylinder above the processing position and the upper plastic workpiece, a heating area is formed on the welding surface, and the upper plastic workpiece and the lower plastic workpiece are bonded under the action of pressure and laser, wherein the pressure is 40 +/-3 MPa.

Specifically, the method for laminating and fixing the upper plastic workpiece and the lower plastic workpiece on the processing station further comprises the step of laminating and fixing the two plastic workpieces on the processing station before the contact surfaces of the upper plastic workpiece and the lower plastic workpiece form the welding surface

And respectively carrying out hot air cleaning on the corresponding laminated surfaces of the upper plastic workpiece and the lower plastic workpiece.

Specifically, the temperature of the hot air is 120 ℃ +/-5 ℃.

The invention has the beneficial characteristics that:

1. according to the invention, the point-shaped laser beam is changed into the linear laser beam by adopting the V-surface cylinder, so that the surface scanning of the welding surface is realized, the welding speed is improved on one hand, the heat of the welding surface is homogenized on the other hand, the welding quality is further improved, and the overlarge local welding mark or uneven welding is avoided.

2. In the welding method, only the position scanned by the laser is welded, so that the welding path can be selected, the welding position is more accurate, and fine welding is easy to realize; the position, size and shape of the through hole can be set at will, and the strength requirements of different welding joints at different positions are met.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Compared with other welding technologies, the plastic laser welding technology has the advantages of non-contact, air tightness, no water leakage, high welding speed, high precision, high welding line strength, no flash, no residue, minimum thermal stress, easy control, good flexibility, good adaptability and the like; during welding, high-energy laser penetrates through the transparent energy transfer plastic workpiece to be focused on the plastic workpiece absorbing the light energy, a heat forming area is formed at the light energy focusing position, the heat forming area absorbs the heat energy converted by the laser, the contact surfaces of the two plastic workpieces are melted, a welding area is finally formed, and meanwhile, the two workpieces are combined together under the action of external pressure.