CN114407372B - A device and method for improving the laser connection strength between metal parts and plastic parts - Google Patents

Abstract

The invention relates to the field of metal and plastic connection, and discloses a method for improving the laser connection strength of a metal piece and a plastic piece, which comprises the following steps: (1) pretreating the surface of a metal piece; (2) The incident beam of the laser corresponds to the position to be processed of the metal; (3) Starting a laser and a coaxial powder feeder to deposit a raised micro-texture on the surface of the metal piece to obtain the metal piece with the raised micro-texture on the surface; (4) Placing the step (3) above the plastic part to obtain a metal part with raised micro-texture, and attaching one surface of the raised micro-texture of the metal to the plastic; (5) applying pressure to the joint of the metal piece and the plastic piece; and (6) carrying out laser connection on the metal piece and the plastic piece. The invention solves the problem of low quality of the connecting joint between the metal piece and the plastic piece, and has ingenious conception, reasonable design and strong adaptability.

Description

A device and method for improving the laser connection strength between metal parts and plastic parts

Technical Field

The invention relates to the field of connecting dissimilar materials, and more particularly to a device and method for improving the laser connection strength between a metal part and a plastic part.

Background Art

As the demand for lightweight structures in advanced manufacturing industries such as automobiles, rail transit, and aerospace gradually increases, the connection of heterogeneous lightweight materials has become a hot spot for achieving lightweight. By combining plastics and metals, heterogeneous structures can have both lightweight and high-strength and impact-resistant properties. Achieving high-quality connection between the two materials has great advantages and application prospects for achieving lightweight.

The weak part of this composite structure is often at the joint, which means that the quality of the joint directly determines the service life of the composite structure. The connection between metal and plastic is limited by the obvious difference in thermal physical properties between the two, such as melting point, thermal conductivity and linear expansion coefficient, and it is difficult to form a high-quality joint. At present, the connection processes between metal parts and plastic parts mainly include riveting, gluing and thermal connection. Riveting technology is contrary to the concept of lightweight because it uses screws, etc.; gluing technology has serious aging phenomenon and will cause environmental pollution. Laser welding has good application prospects in the thermal connection of metal parts and plastic parts due to its advantages such as high efficiency, small heat-affected zone and good flexibility. For example, the Chinese patent of "a new laser transmission welding connection method" (application number 201210581561.6) changes the surface morphology by preparing pits on the metal surface, and then uses laser transmission connection to achieve the connection of plastic and metal materials. However, the technology uses chemical corrosion to prepare pits, which is not environmentally friendly, and it is difficult to treat the local part of the metal part. This technology can only be used for plastics with good light transmittance, and cannot adapt to composite plastics with reinforced fibers and poor light transmittance. In addition, the metal parts of this technology need to be processed in advance, the chemical treatment time is long, and insulation is required, which greatly reduces the overall connection efficiency and significantly increases the connection cost, which is not conducive to promotion and application.

Summary of the invention

In order to solve the problem of low connection quality of the connection joint between metal parts and plastic parts in the prior art, the present invention provides a device and method for improving the laser connection strength between metal parts and plastic parts.

The specific solution adopted by the present invention is: a method for improving the laser connection strength between a metal part and a plastic part, the method comprising the following steps:

(1) Pre-treat the surface of metal parts;

(2) Align the incident beam of the laser with the position of the metal to be processed;

(3) turning on the laser and the coaxial powder feeder to deposit the raised micro-texture on the surface of the metal part, thereby obtaining a metal part having the raised micro-texture on the surface;

(4) placing the metal part with raised micro-texture obtained in step (3) on the plastic part, with one side of the metal with raised micro-texture being bonded to the plastic part;

(5) Apply pressure to the joint between the metal part and the plastic part;

(6) Laser connection of metal parts and plastic parts.

The width or diameter of the raised micro-texture is 500 μm-800 μm, and the height is 200 μm-600 μm.

The conditions for laser connection in step (6) are as follows: laser power of 600W-1200W, laser scanning rate of 0.3m/min-0.9m/min, laser defocus of 0mm-+60mm, laser deflection angle of 0°-15°, protective gas flow of 15L/min-20L/min, and cylinder pressure of 0.3-0.6MPa.

The metal part is any one of titanium alloy, stainless steel, aluminum alloy and magnesium alloy.

The plastic part is a carbon fiber reinforced thermoplastic composite material, such as any one of carbon fiber reinforced polyetheretherketone, carbon fiber reinforced nylon, carbon fiber reinforced polyethylene terephthalate or carbon fiber reinforced polyphenylene sulfide.

The laser is protected by inert gas when working.

On the other hand, the present invention provides a device for improving the laser connection strength between metal parts and plastic parts, the device comprising a laser, a coaxial powder feeder and a moving platform; the coaxial powder feeder is arranged below the laser head; a cylinder is arranged below the moving platform, the output end of the cylinder is connected to the cylinder clamp, a laser connection clamp is placed above the cylinder clamp, plastic and metal are placed between the cylinder clamp and the laser connection clamp, and when connecting, the output end of the cylinder pushes up to clamp the plastic and metal between the laser connection clamp and the cylinder clamp.

A motor is arranged at one side of the mobile platform, the output end of the motor is connected to a lead screw, the lead screw is connected to the mobile platform, and the motor drives the lead screw to rotate and then drives the mobile platform to move.

A gasket is arranged under the moving platform, and the plastic sheet or metal sheet is placed on the gasket.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention uses a laser and a coaxial powder feeder to melt a raised micro-texture on the surface of a metal part, thereby obtaining a metal part with a raised micro-texture on the surface, and placing the metal part with the raised micro-texture on the plastic part, and the raised micro-texture side of the metal is attached to the plastic to complete the laser connection. The present invention can achieve high-efficiency and high-quality connection between metal parts and plastic parts, and solves the connection problem of low quality of the connection joint between metal parts and plastic parts in the prior art.

On the other hand, the present invention uses laser as a heat source, which reduces the hazards caused by thermal deformation and thermal damage. The present invention prepares surface protrusion micro-texture on the surface of the metal part, and optimizes the effective area, power, scanning speed and deflection angle of the continuous laser, as well as the morphology and size of the micro-texture on the surface of the metal substrate. Under the action of interface pressure, the molten plastic is promoted to wetting and spreading on the surface of the metal substrate, and the micro-texture on the surface of the metal substrate is embedded in the plastic, increasing the interface contact area, promoting the occurrence of mechanical interlocking, and increasing the probability of chemical bonding, thereby improving the bonding strength of the laser connection between the metal part and the plastic part.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a device for preparing a surface protrusion micro-texture on a metal part surface according to the present invention;

FIG2 is a schematic diagram of a device for laser connection of a metal part and a plastic part according to the present invention;

FIG3 is a schematic diagram of a mobile platform and a cylinder in the present invention;

FIG4 is a right side view of FIG3;

FIG. 5 is a top view of FIG. 3 .

Wherein, the reference numerals are respectively:

1-laser head; 2-coaxial powder feeder; 3-metal powder; 4-laser beam; 5-fastening screws; 6-mobile platform fixture; 7-laser cladding fixture; 8-laser connection fixture; 9-mobile platform; 10-cylinder fixture; 11-metal parts; 12-plastic parts; 13-gasket; 14-raised microtexture; 15-laser connection weld; 16-motor; 17-screw; 18-cylinder; 19-threaded processing hole.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Exemplary embodiments of the present invention will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the specific goals of the developer. It should be noted that the embodiments and features of the present invention can be combined with each other without conflict. In order to avoid unnecessary details obscuring the present embodiment, only the structures and method steps closely related to the present invention are shown in the accompanying drawings, and details that are not closely related to the present invention are omitted.

The present invention provides a method for improving the laser connection strength between a metal part and a plastic part, the method comprising the following steps:

(1) Pre-treat the surface of metal parts;

(2) Align the incident beam of the laser with the position of the metal to be processed;

(3) turning on the laser and the coaxial powder feeder to deposit the raised micro-texture on the surface of the metal part, thereby obtaining a metal part having the raised micro-texture on the surface;

(4) placing the metal part with raised micro-texture obtained in step (3) on the plastic part, with one side of the metal with raised micro-texture being bonded to the plastic part;

(5) Apply pressure to the joint between the metal part and the plastic part;

(6) Laser connection of metal parts and plastic parts.

The plastic part melts on the side close to the metal part due to heat conduction. Under the action of pressure, the raised micro-texture on the lower surface of the metal is embedded in the molten plastic. After cooling, the metal part and the plastic part are connected as one.

The surface of the metal parts in step (1) is pretreated by cleaning in a mixed solution of 80% distilled water + 15% nitric acid + 5% hydrofluoric acid for 30 seconds to remove the surface oxide film and then drying with a hair dryer. The plates to be connected are placed in an ultrasonic cleaning container and cleaned with a mixed solution of 50% acetone + 50% alcohol for 180 seconds. The cleaned plates are then placed in a drying oven at 80°C and dried for 24 hours.

The width or diameter of the raised micro-texture is 500 μm-800 μm, and the height is 200 μm-600 μm.

The conditions for laser connection in step (6) are as follows: laser power of 600W-1200W, laser scanning rate of 0.3m/min-0.9m/min, laser defocus of 0mm-+60mm, laser deflection angle of 0°-15°, protective gas flow of 15L/min-20L/min, and cylinder pressure of 0.3-0.6MPa.

The metal part is any one of titanium alloy, stainless steel, aluminum alloy and magnesium alloy.

The plastic part is a carbon fiber reinforced thermoplastic composite material, such as any one of carbon fiber reinforced polyetheretherketone, carbon fiber reinforced nylon, carbon fiber reinforced polyethylene terephthalate or carbon fiber reinforced polyphenylene sulfide.

The laser is protected by inert gas when working.

On the other hand, the present invention provides a device for improving the laser connection strength between metal parts and plastic parts, the device comprising a laser, a coaxial powder feeder 2 and a mobile platform 9; the coaxial powder feeder 2 is arranged below the laser head 1 of the laser; a mobile platform fixture 6 is installed on the mobile platform 9, and a connection hole is arranged on the mobile platform fixture 6; a cylinder 18 is arranged below the mobile platform 9, the output end of the cylinder 18 is connected to the cylinder fixture 10, a laser connection fixture 8 is placed directly above the cylinder fixture 10, and plastic 12 and metal 11 are placed between the cylinder fixture 10 and the laser connection fixture 8. When connecting, the cylinder output end pushes up to clamp the plastic and metal between the laser connection fixture and the cylinder fixture. The laser connection fixture extends into the connection hole to play a fixing role.

The laser cladding fixture 7 is used in step (3), and the laser connection fixture 8 is used in step (4). The mobile platform fixture 6 is used to fix the laser cladding fixture and the laser connection fixture.

The coaxial powder feeder 2 is equipped with a coaxial four-hole powder feeding tube and cooperates with the laser head 1 to realize the delivery of various metal powders. The laser is further preferably a fiber laser.

The laser head 1 of the fiber laser is equipped with a coaxial four-hole powder feeding tube, which can move forward, backward, left and right, and can also achieve left and right pitching movements, so that the position of the incident laser beam corresponds to the processing hole.

A motor 16 is arranged on one side of the mobile platform 9, and the output end of the motor 16 is connected to a lead screw 17, and the lead screw 17 is connected to the mobile platform 9. The motor 16 drives the lead screw 17 to rotate and then drives the mobile platform 9. A gasket 13 is arranged under the mobile platform 9, and the metal sheet 11 is placed on the gasket 13.

Example 1

A method for improving the laser connection strength of a metal part and a plastic part, wherein the metal part is 304 stainless steel and the plastic part is carbon fiber reinforced nylon (CF-PA6).

(1) Pre-treating the surface of metal parts; placing the 304 stainless steel substrate to be connected in a mixed solution of 80% distilled water + 15% nitric acid + 5% hydrofluoric acid for 30 seconds to remove the surface oxide film and then drying it with a hair dryer; placing the CF-PA6 plate to be connected in an ultrasonic cleaning container and cleaning it with a mixed solution of 50% acetone + 50% alcohol for 180 seconds; and then placing the cleaned CF-PA6 plate in a drying oven at 80°C for 24 hours;

(2) The 304 stainless steel substrate 11 treated as above is clamped using the clamping method shown in FIG. 1 . The mobile platform 9 is moved to the center of the cylinder 18 by a motor and aligned with the center line of the mobile platform 9 . The laser cladding fixture is placed on the mobile platform 9 in a centered manner. The laser cladding fixture is fastened to the mobile platform by fastening screws 5 , the mobile platform fixture 6 and the threaded processing holes 19 on the mobile platform 9 . The cylinder fixture 10 and the 304 stainless steel substrate 11 are arranged in order from bottom to top so that the position to be processed of the 304 stainless steel substrate 11 corresponds to the processing hole position of the laser cladding fixture. The cylinder is pressurized to lift the cylinder fixture 10 and the 304 stainless steel substrate 11 upward to clamp and fix the 304 stainless steel substrate 11 . The laser head motion control system is used to adjust the position of the laser head so that it corresponds to the starting position to be processed.

(3) The 304 stainless steel substrate 11 subjected to the above operation is used to prepare a surface linear/grid-shaped raised microtexture 14 by the laser cladding method shown in FIG1 , and the laser head control system of the optical fiber laser is used to set the laser cladding surface raised microtexture morphology to a surface raised microtexture of a square grid morphology with a line spacing of 1 mm, plan the laser scanning path, and write the path program; the laser power is set to 1200 W, the laser scanning rate is set to 0.8 m/min, the laser defocus amount is set to 0 mm, the laser deflection angle is set to 0°, the shielding gas flow rate is set to 15 L/min, the powder feeder flow rate is set to 15 L/min, 304 stainless steel powder is selected as the metal powder 3, the shielding gas advance time is set to 8 s, and the laser parameter program is written; the laser parameters and the path program are input into the laser head computer control system to control the laser head scanning path, the optical fiber laser control system will control the laser output parameters and the shielding gas, and the coaxial powder feeder control system will control the powder feeding and the powder feeding gas; a laser cladding surface raised microtexture with a width of 600 μm and a height of 500 μm is obtained.

(4) Remove the 304 stainless steel substrate 11 after the above operation, use a brush and a wire brush to clean the excess powder and splash on the surface, respectively, clamp the 304 stainless steel substrate and the carbon fiber reinforced nylon using the clamping method of the schematic diagram of laser connection of metal parts and plastic parts shown in FIG2, use the motor to move the mobile platform 9 to the center of the cylinder 18, align the center line of the mobile platform 9, and place the laser connection fixture 8 suitable for laser connection on the mobile platform 9 in a centered manner, and use the fastening screws 5 and the threaded processing holes 19 on the mobile platform 9 to fasten the laser connection fixture 8 to the mobile platform; The 304 stainless steel substrate and the carbon fiber reinforced nylon are overlapped from top to bottom, wherein the side on which the laser cladding surface raised micro-texture is prepared is connected to the plastic part and placed on the cylinder fixture 10, and a gasket 13 with a thickness consistent with that of the plastic part is placed under the 304 stainless steel substrate, so that the position to be processed of the 304 stainless steel substrate corresponds to the position of the processing hole of the laser connection fixture 8, and the cylinder is pressurized to lift the cylinder fixture 10, the 304 stainless steel substrate and the carbon fiber reinforced nylon upward, and the 304 stainless steel substrate and the carbon fiber reinforced nylon are clamped and fixed, and the position of the laser head is adjusted to correspond to the starting position to be processed.

(5) Connect the 304 stainless steel substrate and the carbon fiber reinforced nylon after the above operation by the laser connection process shown in FIG2, plan the connection path, write the path program; set the laser power to 1000W, the laser scanning rate to 0.5m/min, the laser defocus amount to 0mm, the laser deflection angle to 0°, the shielding gas flow rate to 15L/min, and write the laser parameter program; input the laser parameters and the path program into the laser head computer control system, the laser head motion control system controls the laser head scanning path, and the fiber laser control system controls the laser output parameters and shielding gas. The laser connection of the 304 stainless steel substrate 11 and the carbon fiber reinforced nylon 12 is realized, and after cooling, the metal surface raised micro-texture 304 stainless steel/carbon fiber reinforced nylon CF-PA6 laser connection joint can be obtained.

At present, metal and plastic heterostructures are one of the methods to replace all-metal structures to achieve further structural lightweight, and the strength of their joints is the key to determine whether metal and plastic structures can be applied. The method of the present invention provides a method for enhancing the strength of metal and plastic connections, and achieves the strength of the metal and plastic heterostructure connection joint by increasing the contact area of the connection interface and the mechanical interlocking force, and can realize the integration of pre-treatment equipment and connection equipment, which is convenient for application and development.

The present invention uses a laser and a coaxial powder feeder to melt a raised micro-texture on the surface of a metal part, thereby obtaining a metal part with a raised micro-texture on the surface, and placing the metal part with the raised micro-texture on the plastic part, and the raised micro-texture side of the metal is attached to the plastic to complete the laser connection. The present invention can achieve high-efficiency and high-quality connection between metal parts and plastic parts, and solves the connection problem of low quality of the connection joint between metal parts and plastic parts in the prior art.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (1)

1. A method for improving the laser connection strength between a metal part and a plastic part, characterized in that the method comprises the following steps: (1) Pre-treat the surface of metal parts; The metal part is any one of titanium alloy, stainless steel, aluminum alloy and magnesium alloy; (2) Align the incident beam of the laser with the position of the metal to be processed; (3) turning on the laser and the coaxial powder feeder to deposit the raised micro-texture on the surface of the metal part, thereby obtaining a metal part having the raised micro-texture on the surface; The width or diameter of the raised microtexture is 500 μm-800 μm, and the height is 200 μm-600 μm; (4) placing the metal part with raised micro-texture obtained in step (3) on the plastic part, with one side of the metal with raised micro-texture being bonded to the plastic part; The plastic part is a carbon fiber reinforced thermoplastic composite material, any one of carbon fiber reinforced polyetheretherketone, carbon fiber reinforced nylon, carbon fiber reinforced polyethylene terephthalate or carbon fiber reinforced polyphenylene sulfide; (5) Apply pressure to the joint between the metal part and the plastic part; (6) Laser connection of metal parts and plastic parts; The conditions for laser connection in step (6) are as follows: laser power of 600W-1200W, laser scanning rate of 0.3m/min-0.9m/min, laser defocus of 0mm-+60mm, laser deflection angle of 0-15°, protective gas flow of 15L/min-20L/min, and cylinder pressure of 0.3-0.6MPa; The laser is protected by inert gas when working; The device includes a laser, a coaxial powder feeder and a mobile platform; the coaxial powder feeder is arranged below the laser head; a cylinder is arranged below the mobile platform, the output end of the cylinder is connected to a cylinder fixture, a laser connection fixture is placed above the cylinder fixture, plastic and metal are placed between the cylinder fixture and the laser connection fixture, and when connecting, the output end of the cylinder pushes up to clamp the plastic and metal between the laser connection fixture and the cylinder fixture; A motor is arranged on one side of the mobile platform, the output end of the motor is connected to a lead screw, the lead screw is connected to the mobile platform, and the motor drives the lead screw to rotate and then drives the mobile platform to move; A gasket is arranged under the moving platform, and the metal sheet is placed on the gasket.