CN104626543B - Welding method for thermoplastic composite material - Google Patents

Abstract

The invention discloses a thermoplastic composite material welding method, which includes the following steps: S1: pretreating the surface to be welded of a first workpiece and the surface to be welded of a second workpiece, wherein the first workpiece is a thermoplastic composite material, and the second workpiece is made of a thermoplastic composite material. The second workpiece is a thermoplastic composite material or metal material; S2: splicing and fixing the surface to be welded of the first workpiece and the surface to be welded of the second workpiece to obtain a combination to be welded, wherein there is a metal material in the combination to be welded ; After the laser is focused, it scans the surface of the metal material in the assembly to be welded according to the preset path to complete the welding process. The welding method of the present invention can successfully realize laser welding between thermoplastic composite materials and thermoplastic composite materials, as well as between thermoplastic composite materials and metal materials, with uniform weld seams and high welding quality, and is useful in the fields of new energy vehicles, unmanned aerial vehicles, and aerospace. Wide application prospects.

Description

Welding methods for thermoplastic composites

technical field

The invention relates to the field of welding technology, in particular to a welding method for thermoplastic composite materials.

Background technique

At present, thermoplastic composite materials are mainly welded by resistance implant welding, electromagnetic induction welding and ultrasonic welding. Among them, the resistance implantation welding process is simple, the equipment is flexible, and no surface treatment is required, but during the welding process, the welding head will introduce impurities, thereby reducing the fatigue performance of the welding head and the uniformity of electrical properties; electromagnetic induction welding can be carried out continuously Welding, however, has problems such as high cost of implanted materials, filler materials affecting welding strength, and difficulty in welding structures with complex welding surfaces; ultrasonic welding has the advantages of high welding efficiency and high joint strength, but it has difficulties in making energy directors and The limitation of a small weldable area at one time.

Laser welding has the advantages of simple process, low cost, fast heating speed, strong penetration ability, small heat-affected zone, high joint strength, uniform composition, etc., and can complete one-time large-area welding. During the welding process, due to the high relative temperature of the laser, the melting point of the thermoplastic composite material is relatively low, which often causes the melting area of the thermoplastic composite material to be too large to cause deformation of the plastic material, which leads to the failure of laser welding to proceed smoothly or the welding quality poor.

Contents of the invention

The invention provides a welding method for thermoplastic composite materials, which solves the problem that the welding process cannot be smoothly carried out or the welding quality is poor due to the welding of thermoplastic composite materials by laser.

To achieve the above object, the present invention adopts the following technical solutions:

A welding method for thermoplastic composite materials, comprising the steps of:

S1: Pretreat the surface to be welded of the first workpiece and the surface to be welded of the second workpiece, wherein the first workpiece is a thermoplastic composite material, and the second workpiece is a thermoplastic composite material or a metal material;

S2: splicing and fixing the surface to be welded of the first workpiece and the surface to be welded of the second workpiece to obtain an assembly to be welded, wherein there is a metal material in the assembly to be welded; focus the laser Then, the surface of the metal material in the assembly to be welded is scanned according to a preset path to complete the welding process.

In one of the embodiments, when the second workpiece is a metal material,

S2 includes the following steps: splicing and directly fixing the surface to be welded of the first workpiece and the surface to be welded of the second workpiece to obtain a combination to be welded; focusing the laser on the surface of the second workpiece Scanning according to the preset path, and after the scanning is completed, the laser is turned off to complete the welding process.

In one of the embodiments, when the second workpiece is a thermoplastic composite material,

S2 includes the following steps: splicing the surface to be welded of the first workpiece and the surface to be welded of the second workpiece, and then affixing a metal transition piece on both sides of the splicing area, and attaching the metal transition piece, The first workpiece and the second workpiece are fixed to obtain the assembly to be welded; after the laser is focused, the surface of the metal transition piece in the assembly to be welded is scanned according to a preset path, and after the scanning is completed, the laser is turned off , to complete the welding process.

In one of the embodiments, before attaching the metal transition piece on both sides of the splicing area, the following steps are further included:

The surface of the metal transition piece is sanded roughened and cleaned and dried.

In one embodiment, the metal transition piece has a thickness of 1mm-10cm.

In one of the embodiments, the pretreatment step of the first workpiece is: cleaning and drying the surface to be welded of the first workpiece;

When the second workpiece is a thermoplastic composite material, the pretreatment step of the second workpiece is: cleaning and drying the surface to be welded of the second workpiece;

When the second workpiece is a metal material, the pretreatment step of the second workpiece is: roughening, cleaning and drying the surface to be welded of the second workpiece.

In one embodiment, the thermoplastic composite material is a fiber-reinforced thermoplastic resin-based composite material.

In one of the embodiments, the thermoplastic composite material is carbon fiber, boron fiber, graphite fiber or silicon carbide reinforced PE-polyethylene, PVC-polyvinyl chloride, PS-polystyrene, PA-polyamide, POM-polyethylene Formaldehyde, PC-polycarbonate, polyphenylene ether, polysulfone or rubber.

In one of the embodiments, the fixing of the first workpiece and the second workpiece comprises the following steps:

The first workpiece and the second workpiece are fixed by a clamp, and a certain pressure is applied to the first workpiece and the second workpiece by the clamp.

In one of the embodiments, the joining manner of the first workpiece and the second workpiece is lap joint, butt joint or corner joint.

The beneficial effects of the present invention are as follows:

The welding method of the thermoplastic composite material of the present invention realizes the welding process by means of heat conduction. First, the laser is applied to the surface of the metal material, and the heat is transferred to the thermoplastic composite material through the metal material. The surface of the thermoplastic composite material is heated and melted, and the molten thermoplastic material Acts as a solder that, when cooled, joins the two workpieces together. This method has the advantages of simple process, low cost, fast heating speed, strong penetration ability, small heat-affected zone, high joint strength, uniform composition, etc., and can complete one-time large-area welding, which can avoid direct laser irradiation on thermoplastic composite materials. The melting area caused by the above is too large to cause deformation of the thermoplastic material. When the melting point of the thermoplastic composite material is low, the welding between the thermoplastic composite material and the thermoplastic composite material, and between the thermoplastic composite material and the metal material can also be smoothly realized. , and the welding seam is uniform and the welding quality is good. It has broad application prospects in the processing of thermoplastic composite parts in the fields of new energy vehicles, drones, and aerospace.

Description of drawings

Fig. 1 is the splicing schematic diagram of an embodiment of workpieces to be welded in the welding method of thermoplastic composite materials of the present invention;

Fig. 2 is a splicing schematic diagram of an embodiment of workpieces to be welded in the welding method of thermoplastic composite materials of the present invention;

Fig. 3 is a schematic splicing diagram of an embodiment of workpieces to be welded in the thermoplastic composite material welding method of the present invention.

detailed description

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The invention provides a thermoplastic composite material welding method, which can realize reliable welding between thermoplastic composite materials and thermoplastic composite materials, and between thermoplastic composite materials and metal materials. Below in conjunction with Fig. 1 to Fig. 3, the welding method of the present invention is described in detail, the welding method of the present invention comprises the following steps:

S1: Perform pretreatment on the surface to be welded of the first workpiece 110 and the surface to be welded of the second workpiece 120, wherein the first workpiece 110 is a thermoplastic composite material, and the second workpiece 120 is a thermoplastic composite material or a metal material.

In the present invention, the purpose of pretreatment is to enhance the welding strength of the material. As a possible implementation manner, the pretreatment method of the first workpiece 110 is: cleaning and drying the surface to be welded of the first workpiece 110 . Preferably, the surface to be welded of the first workpiece 110 may be ultrasonically cleaned with acetone or alcohol to effectively remove stains. The pretreatment method of the second workpiece 120 is divided into two cases: ① When the second workpiece 120 is a thermoplastic composite material, the pretreatment method is the same as that of the first workpiece 110; ② When the second workpiece 120 is a metal material, the pretreatment method is the same as that of the first workpiece 110; The treatment method is: roughen the surface to be welded of the second workpiece 120, clean it and dry it, wherein the function of the roughening is to increase the roughness of the surface to be welded of the second workpiece 120 so as to increase the amount of solder in the welding process. The degree of penetration increases the firmness of the weld. In addition, the first workpiece 110 and the second workpiece 120 may also be processed by other existing pretreatment methods.

Preferably, the thermoplastic composite material in the present invention is a fiber-reinforced thermoplastic resin composite material, preferably carbon fiber, boron fiber, graphite fiber or silicon carbide reinforced PE-polyethylene, PVC-polyvinyl chloride, PS-polystyrene , PA-polyamide, POM-polyoxymethylene, PC-polycarbonate, polyphenylene ether, polysulfone or rubber, this kind of thermoplastic composite material has the characteristics of small specific gravity, high strength, corrosion resistance and fatigue resistance.

Further, the metal material in the present invention is selected from one of stainless steel, carbon steel and aluminum alloy. It has high strength and can form a good combination with thermoplastic composite materials, and is widely used in new energy vehicles, drones, aerospace and other fields.

S2: Splice and fix the surface to be welded of the first workpiece 110 and the surface to be welded of the second workpiece 120 to obtain the assembly to be welded 100, wherein there is a metal material in the assembly to be welded 100; after focusing the laser 200 The surface of the metal material in the assembly to be welded 100 is scanned according to a preset path to complete the welding process.

It should be noted that in the present invention, there is no special limitation on the laser scanning path, laser intensity, laser scanning speed and scanning time, which will vary with the specific workpiece to be welded and welding requirements.

In step S2, the assembly to be welded 100 is obtained by splicing and fixing the first workpiece 110 and the second workpiece 120. Since there are metal materials in the assembly to be welded 100, during laser welding, the laser 200 can be directly It is shot on the metal material in the assembly to be welded 100, and the energy of the laser 200 is transmitted to the thermoplastic composite material through the metal material. The thermoplastic composite material is heated and melted, and the molten thermoplastic composite material acts as a solder. A workpiece 110 and a second workpiece 120 are welded together.

It should be noted that during the scanning process of the laser 200, the maximum temperature reached by the laser 200 acting on the assembly to be welded 100 should be higher than the melting temperature of the thermoplastic composite material in the assembly to be welded 100, and lower than the melting temperature of the assembly to be welded. The melting temperature of the metal material in the body 100. Wherein, the maximum temperature reached by the laser 200 acting on the workpiece to be welded is related to the scanning speed of the laser. In the present invention, the scanning speed of the laser 200 is preferably 5 m/s to 10 m/s. Within this range, the uniformity of the weld Good degree, high welding strength.

In the present invention, according to different welding requirements, the first workpiece 110 and the second workpiece 120 can be spliced in different ways, such as lap joint, butt joint, corner joint and so on.

Preferably, as shown in FIG. 1, when the first workpiece 110 is a thermoplastic composite material and the second workpiece 120 is a metal material, S2 includes the following steps: overlapping the first workpiece 110 and the second workpiece 120, and then passing the clamp 300 is directly fixed, and a certain pressure is applied to the first workpiece 110 and the second workpiece 120 through the fixture 300 (the size of the pressure depends on the specific welding process), and then the assembly 100 to be welded is obtained; after focusing the laser 200, the Second, the surface of the workpiece 120 is scanned according to a preset path. After the scanning is completed, the laser is turned off, and the clamp 300 is removed to complete the welding process. In this embodiment, the fixture 300 exerts a certain pressure on the workpieces to be welded, under the action of the pressure, the molten thermoplastic composite material can better connect the first workpiece 110 and the second workpiece 120 together, improving the welding quality .

It should be noted that, in other embodiments, when the first workpiece 110 is a thermoplastic composite material and the second workpiece 120 is a metal material, the joining manner of the first workpiece 110 and the second workpiece 120 may also be butt joint or corner joint.

2 and 3, when the first workpiece 110 is a thermoplastic composite material and the second workpiece 120 is a metal material, S2 includes the following steps: the surface to be welded of the first workpiece 110 and the surface to be welded of the second workpiece 120 Then, attach the metal transition piece 130 on both sides of the butt joint area or the corner joint area, and then fix the metal transition piece 200, the first workpiece 110 and the second workpiece 120 by the clamp 300, and apply a certain pressure (the The size of the pressure depends on the specific welding process), and the assembly 100 to be welded is obtained; after the laser 200 is focused, it is scanned on the surface of the metal transition piece 130 according to the preset path. After scanning, the laser is turned off, and the clamp 300 is removed to complete welding process.

It should be noted that, in other embodiments, when the first workpiece 110 is a thermoplastic composite material and the second workpiece 120 is a metal material, the joining manner of the first workpiece 110 and the second workpiece 120 may also be overlapping.

Preferably, before laminating the metal transition piece 130 , the metal transition piece 130 needs to be pre-treated. As a possible implementation, the pre-treatment process is: roughening the surface of the metal transition piece 130 , and cleaning and drying. This way can increase the roughness of the metal transition piece 130, making the welding more firm.

Among them, the metal transition piece 130 can be made of stainless steel, carbon steel or aluminum alloy; and the thickness of the metal transition piece 130 should not be too large or too small, if the thickness is too large, the heat conduction effect of the laser 200 is not good, and the impact on the workpiece to be welded is relatively large. If the thickness is too small, it will easily lead to the deformation of the thermoplastic composite material. Preferably, the thickness of the metal transition piece 130 is 1 mm to 10 cm, which can effectively transmit the energy of the laser 200 to the workpiece to be welded, and can ensure the melting of the surface of the thermoplastic composite material, thereby completing the welding process, while avoiding heat The occurrence of deformation of thermoplastic composites caused by too fast conduction.

In the present invention, the laser 200 used has a wide range, preferably infrared light, visible light and ultraviolet light; the welding method can be spot welding or continuous welding; the scanning path of the laser 200 can be a straight line or a curve, depending on the specific welding Workpiece and welding requirements depend.

In the welding method of the thermoplastic composite material of the present invention, the laser is first applied to the surface of the metal material, and the heat is transferred to the thermoplastic composite material through the metal material, and the surface of the thermoplastic composite material is heated and melted, and the molten thermoplastic material acts as a solder. The two workpieces can be welded together. The invention realizes the welding process through heat conduction, avoids the deformation of the thermoplastic material due to the excessive melting area caused by direct laser irradiation on the thermoplastic composite material, and can also smoothly realize thermoplastic composite when the melting point of the thermoplastic composite material is low. The welding between materials and thermoplastic composite materials, as well as between thermoplastic composite materials and metal materials, has uniform welding seams and high welding quality.

The thermoplastic composite material welding method of the present invention has the advantages of simple process, low cost, fast heating speed, strong penetration ability, small heat-affected zone, high joint strength, uniform composition, etc., and can complete one-time large-area welding. There are broad application prospects in the processing of thermoplastic composite parts in new energy vehicles, unmanned aerial vehicles, and aerospace fields.

In order to better understand the present invention, the welding method of the thermoplastic composite material of the present invention will be further described through specific examples below.

Example 1

(1) Grinding and roughening the surface to be welded of the aluminum alloy workpiece, cleaning it with acetone and blowing it dry;

(2) Clean and dry the surface to be welded of the PE-polyethylene workpiece reinforced by carbon fiber;

(3) according to the mode shown in Fig. 1, the aluminum alloy workpiece is placed on the PE-polyethylene workpiece of carbon fiber reinforcement and overlaps, and makes the surfaces to be welded of the two contact each other;

(4) Fix the aluminum alloy workpiece to be welded and the PE-polyethylene workpiece reinforced by carbon fiber with a clamp, and apply a pressure of 20N to the aluminum alloy workpiece and the PE-polyethylene workpiece reinforced by carbon fiber by the clamp;

(5) Focus the laser and heat it on the surface of the aluminum alloy, and scan along the preset path at a speed of 5m/s;

(6) After scanning, turn off the laser, remove the fixture, and complete the welding process.

Example 2

(1) The surface to be welded of the PC-polycarbonate workpiece reinforced by boron fiber and the polyphenylene ether workpiece reinforced by graphite fiber is cleaned and dried with acetone;

(2) Grinding and roughening the surfaces of two aluminum alloy transition pieces with a thickness of 3 cm, cleaning them with acetone and blowing them dry;

(3) According to the method shown in Figure 2, the surfaces to be welded of the PC-polycarbonate workpiece reinforced by boron fiber and the polyphenylene ether workpiece reinforced by graphite fiber are butted; , and fix it with a clamp, and at the same time apply a pressure of 10N to the metal transition piece through the clamp;

(5) After focusing the laser, heat the surface of the aluminum alloy transition piece on both sides of the docking area in turn, and scan along the preset path at a speed of 8m/s;

(6) After scanning, turn off the laser, remove the fixture, and complete the welding process.

Example 3

(1) The surface to be welded of the PE-polyethylene workpiece reinforced by boron fiber and the PE-polyethylene workpiece reinforced by graphite fiber is cleaned and dried with acetone;

(2) Polish the surface of two aluminum alloy transition pieces with a thickness of 3 cm, clean them with acetone and dry them. One of the aluminum alloy transition pieces is a straight piece, and the other aluminum alloy transition piece has a certain bending angle;

(3) According to the method shown in Figure 3, the PE-polyethylene workpiece reinforced by boron fiber and the PE-polyethylene workpiece reinforced by graphite fiber are fillet-joined; and aluminum alloy is pasted on both sides of the junction area The transition piece is fixed with a clamp, and at the same time, a pressure of 25N is applied to the metal transition piece through the clamp;

(4) After the laser is focused, it is sequentially heated on the surface of the aluminum alloy transition piece on both sides of the junction area, and scanned along the preset path at a speed of 10m/s;

(5) After scanning, turn off the laser, remove the fixture, and complete the welding process.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. a kind of welding method of thermoplastic composite is it is characterised in that comprise the following steps：

S1：The surface to be welded of the surface to be welded of the first workpiece and second workpiece is pre-processed, wherein, described first workpiece is thermoplastic Property composite, described second workpiece be thermoplastic composite or metal material；

S2：The surface to be welded of the surface to be welded of described first workpiece and described second workpiece is stitched together and fixes, obtains to be welded , wherein, in described assembly to be welded, there is metal material in assembly；The gold in assembly to be welded will directly be beaten after Laser Focusing Belong on material, the metal material surface in described assembly to be welded scans according to preset path, completes welding process.

2. the welding method of thermoplastic composite according to claim 1 is it is characterised in that described second workpiece is gold When belonging to material,

S2 comprises the following steps：The surface to be welded of the surface to be welded of described first workpiece and described second workpiece is stitched together and directly Connect fixation, obtain assembly to be welded；To scan according to preset path on the surface of described second workpiece after Laser Focusing, scan through Bi Hou, closes described laser, completes welding process.

3. the welding method of thermoplastic composite according to claim 1 is it is characterised in that described second workpiece is heat During plastic composites,

S2 comprises the following steps：The surface to be welded of the surface to be welded of described first workpiece and described second workpiece is stitched together, so Fit metal transition piece in the both sides of splicing regions afterwards, and by described metal transfer part, described first workpiece and described second work Part is fixed, and obtains assembly to be welded；By the metal transfer part surface in described assembly to be welded after Laser Focusing according to default Path scan, scanned after, close described laser, complete welding process.

4. the welding method of thermoplastic composite according to claim 3 is it is characterised in that in described splicing regions Before both sides laminating metal transition piece, further comprising the steps of：

By the surface polishing texturing of metal transfer part, and cleaning-drying.

5. the welding method of thermoplastic composite according to claim 3 is it is characterised in that described metal transfer part Thickness is 1mm-10cm.

6. thermoplastic composite according to claim 1 welding method it is characterised in that described first workpiece pre- Process step is：The surface to be welded of described first workpiece is cleaned up and is dried；

When described second workpiece is thermoplastic composite, the pre-treatment step of described second workpiece is：By described second workpiece Surface to be welded clean up and be dried；

When described second workpiece is metal material, the pre-treatment step of described second workpiece is：Described second workpiece is to be welded Face polishing texturing, cleans up and is dried.

7. the welding method of thermoplastic composite according to claim 1 is it is characterised in that described thermoplastic composite material Expect for fibre-reinforced thermoplastic resin based composite material.

8. the welding method of thermoplastic composite according to claim 7 is it is characterised in that described thermoplastic composite material Expect PE- polyethylene for carbon fiber, boron fibre, graphite fibre or SiC reinforcement, PVC- polyvinyl chloride, PS- polystyrene, PA- polyamide, POM- polyformaldehyde, PC- Merlon, polyphenylene oxide, polysulfones or rubber.

9. the welding method of thermoplastic composite according to claim 1 is it is characterised in that described first workpiece and institute The fixation stating second workpiece comprises the following steps：

By fixture, described first workpiece and described second workpiece are fixed, and by described fixture to described first workpiece Apply certain pressure with described second workpiece.

10. thermoplastic composite according to claim 1 welding method it is characterised in that described first workpiece and The connecting method of described second workpiece is overlap joint, docks or corner connection.