Synchronous laser welding process method and device

Abstract

The invention belongs to the technical field of laser welding, and particularly relates to a synchronous laser welding process method and device.The synchronous laser welding process method comprises the following steps that in the initial stage, a workpiece to be welded is placed in a profiling cavity of a lower die, the lower die drives the workpiece to be welded to ascend to the position making contact with a waveguide device, and the waveguide device is welded; a certain pre-pressure is formed between the waveguide device and the workpiece to be welded; in the preheating stage, the preheating temperature is set so as to preheat the to-be-welded workpiece; in the welding stage, the welding fusion depth is decomposed into N sections for treatment, the fusion depth of each welding section is set, and all the welding sections are welded in sequence; wherein N is a positive integer greater than or equal to 2; in the pressure maintaining stage, after the to-be-welded workpiece is welded, the temperature is reduced through pressure maintaining cooling, so that a welding seam of the workpiece is fused and formed; by controlling the temperature, the welding penetration and the welding pressure, the stability of product welding is achieved, and the phenomenon of over-welding or coking of a welding surface caused by continuous output of laser can be effectively avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welding, and in particular relates to a synchronous laser welding process method and device. Background Art

[0002] Synchronous laser welding is an advanced plastic welding technology that uses multiple laser beams to weld simultaneously, solving the problems of low welding efficiency and poor weld quality in traditional single-beam laser welding. This method is particularly suitable for application scenarios with high requirements for welding quality.

[0003] The basic principle of synchronous laser welding is to use the laser beams emitted by two or more lasers, which are shaped and guided by optical elements so that the laser beams are synchronously irradiated along the contour of the welded parts, and heat is generated at the weld, so that the entire contour is melted and bonded together at the same time. The main advantages of this method are to reduce the internal stress after welding, improve welding efficiency and improve weld quality. Since this method has high requirements for equipment and technology, its cost is relatively high, but in fields that require high-quality welding, such as medical equipment manufacturing and welding of automobile taillights, synchronous laser welding is widely used.

[0004] When synchronous laser welding technology is currently used, it is limited by the quality of the beam splitting optical fiber in the laser, and the actual light output power has a large deviation. During the continuous output of the laser, the energy density deviation at some positions of the welding surface is large, resulting in bubbles after welding, affecting the aesthetics of the weld of the product after welding. The deviation in energy density further affects the welding stability of the product.

[0005] Based on this, it is necessary to improve the defects of the prior art to overcome the deficiencies in practical applications. Summary of the invention

[0006] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide a synchronous laser welding process method that meets one or more of the above-mentioned needs.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a synchronous laser welding process method, comprising the following steps:

[0009] Initial stage: the workpiece to be welded is placed in the contoured cavity of the lower mold, and the lower mold drives the workpiece to be welded to rise to the contact position with the waveguide, so that there is a certain pre-pressure between the waveguide and the workpiece to be welded;

[0010] Preheating stage: set the preheating temperature to preheat the workpiece to be welded;

[0011] Welding stage: Decompose the welding penetration into N sections, set the penetration of each welding section, and weld each welding section in turn; where N is a positive integer greater than or equal to 2;

[0012] Pressure holding stage: After the workpieces to be welded are welded, they are cooled by pressure holding to melt and form the weld of the workpieces.

[0013] As a preferred solution, in the preheating stage, the power change is adjusted by temperature control so that the set preheating temperature is lower than the melting temperature of the workpiece to be welded, and the workpiece to be welded is preheated at a constant preheating temperature; the preheating is stopped when the pressure on the workpiece to be welded is less than 1500N.

[0014] As a preferred solution, the welding stage includes a first welding section and a second welding section, and the first welding temperature and the first welding penetration of the first welding section are set, the first welding is performed on the workpiece to be welded by pressing the workpiece to be welded and controlling the laser, and the welding is stopped when the welding depth reaches the first welding penetration;

[0015] By setting the second welding temperature and the second welding penetration in the second welding section, applying a clamping force to the workpiece to be welded and controlling the laser to perform a second welding on the workpiece to be welded, the welding is stopped when the welding depth reaches the second welding penetration.

[0016] As a preferred solution, the first welding temperature is set to the melting temperature of the workpieces to be welded, and the second welding temperature is 10-20% higher than the first welding temperature.

[0017] As a preferred solution, the second weld penetration is 20-50% less than the first weld penetration, and the second weld penetration varies linearly with the first weld penetration.

[0018] As a preferred embodiment, a first pressing force is applied to the workpiece to be welded in the first welding section, and a second pressing force is applied to the workpiece to be welded in the second welding section, the first pressing force is smaller than the second pressing force, and the first pressing force and the second pressing force are respectively smaller than the upper limit value of the set pressing force.

[0019] As a preferred solution, during the pressure holding stage, the workpieces to be welded are controlled to maintain a constant pressure so that the temperature of the weld gradually decreases and cools.

[0020] A synchronous laser welding device is applied to the welding process method as described in any of the above schemes, comprising a frame, an upper mold and a lower mold, wherein the lower mold is provided with a contour cavity in which a workpiece to be welded is placed; and the upper mold is provided with an optical waveguide and a laser for laser welding the workpiece to be welded.

[0021] As a preferred solution, the optical waveguide has multiple temperature control sensors built in to detect the temperature of the weld.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a synchronous laser welding process method, which achieves the stability of product welding by controlling temperature, welding penetration and welding pressure, and can effectively avoid the phenomenon of over-welding or coking of the welding surface caused by continuous output of laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a schematic flow chart of a synchronous laser welding process method according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of changes in temperature, penetration and pressure during welding in an embodiment of the present invention;

[0027] Figure 3 is a structural schematic diagram of a synchronous laser welding device according to an embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of the lower mold structure of an embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of the optical waveguide structure of an embodiment of the present invention;

[0030] In the figure: 1 a machine frame, 2 an upper mold, 21 an optical waveguide, 211 a temperature control sensor, 22 an optical fiber fixing plate, 23 an optical fiber bundle support, 3 a lower mold, 31 a contour cavity, 4 a workpiece to be welded. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the embodiments of the present application, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0032] In the description of the embodiments of the present application, the terms "upper", "lower", "front", "rear", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", etc. are only used to distinguish in the description and have no special meaning.

[0033] According to some embodiments of the present application, please refer to Figure 1 As shown, a synchronous laser welding process method is now provided, comprising the following steps:

[0034] S1. Initial stage: Place the workpiece to be welded in the contoured cavity of the lower mold, and use the lower mold to drive the workpiece to be welded to rise to the contact position with the waveguide, so that there is a certain pre-pressure between the waveguide and the workpiece to be welded, so that the workpiece to be welded is kept in a compacted state, so as to be compacted and fixed during laser welding.

[0035] S2, preheating stage: set the preheating temperature to preheat the workpiece to be welded.

[0036] Specifically, in the preheating stage, the power change is adjusted by temperature control so that the set preheating temperature is lower than the melting temperature of the workpiece to be welded, and the workpiece to be welded is preheated at a constant preheating temperature; when the pressure on the workpiece to be welded is less than 1500N, the preheating is stopped.

[0037] S3, welding stage: decompose the welding penetration into N sections, set the penetration of each welding section, and weld each welding section in turn; wherein N is a positive integer greater than or equal to 2.

[0038] In a specific embodiment, the welding stage includes a first welding section and a second welding section. By setting a first welding temperature and a first welding depth in the first welding section, the first welding is performed on the workpiece to be welded by pressing the workpiece to be welded and controlling the laser, and the welding is stopped when the welding depth reaches the first welding depth.

[0039] By setting the second welding temperature and the second welding penetration in the second welding section, applying a clamping force to the workpiece to be welded and controlling the laser to perform a second welding on the workpiece to be welded, the welding is stopped when the welding depth reaches the second welding penetration.

[0040] Furthermore, the first welding temperature is set to the melting temperature of the workpiece to be welded, and the second welding temperature is 10-20% greater than the first welding temperature.

[0041] Furthermore, the second welding penetration is 20-50% less than the first welding penetration, and the second welding penetration changes linearly with the first welding penetration.

[0042] Furthermore, a first pressing force is applied to the workpiece to be welded in the first welding section, and a second pressing force is applied to the workpiece to be welded in the second welding section. The first pressing force is smaller than the second pressing force, and the first pressing force and the second pressing force are respectively smaller than the upper limit values ​​of the set pressing forces.

[0043] S4, pressure holding stage: after the workpieces to be welded are welded, the temperature is lowered by pressure holding and cooling to melt and form the weld of the workpieces.

[0044] Specifically, in the pressure holding stage, the workpieces to be welded are controlled to maintain a constant pressure so that the temperature of the weld gradually decreases and cools.

[0045] like Figure 2 As shown, in some embodiments of the present application, by performing synchronous laser welding on the workpiece to be welded, during the different stages of the preheating stage, the first welding section, the second welding section and the pressure holding stage, the temperature, the penetration depth of the workpiece weld and the pressure on the workpiece change. By controlling the temperature, the welding penetration depth and the welding pressure, the stability of the product welding is achieved, and the phenomenon of over-welding or coking of the welding surface due to continuous laser output can be effectively avoided.

[0046] In a specific embodiment, laser welding is performed on the headlight cover, the materials of which are PMMA and ABS, wherein the melting temperature of the ABS material is 230-285°C: the pressure value set in the initial state is 2000N, and a preheating process is performed after the workpiece is pressed, and the temperature of the preheating stage is set to 200°C; when the pressure value of the pressure sensor decreases to less than 1500N (there is a gap at the welding position due to low pressure), the welding of the first welding section is started, the temperature of the first stage is set to 230°C, the welding depth is set to 0.6mm, and the upper limit of the welding pressure is set to 10000N (excessive pressure causes product damage), and the pressure exceeds the upper limit. An alarm will be sounded and welding will be stopped; when the first welding section reaches the set welding depth of 0.6mm, the second welding section will be welded; the temperature of the second welding section is set to 250℃, the welding depth is set to 0.3mm, and when the second welding section reaches the set welding depth of 0.3mm, the third welding section will be welded; the temperature of the third welding section is set to 280℃, the welding depth is set to 0.1mm, and when the third welding section reaches the set welding depth of 0.1mm, welding will be stopped; enter the pressure holding stage, and the pressure is maintained for the product after welding. The temperature of the welding surface position is reduced, which is conducive to the formation of the weld. During the pressure holding process, the servo position is kept constant.

[0047] According to some embodiments of the present application, Figures 3 to 5As shown, a synchronous laser welding device is also provided, which is applied to the welding process method as described above, including a frame 1, an upper mold 2 and a lower mold 3, the lower mold 3 is configured with a contour cavity, and the workpiece to be welded is placed in the contour cavity; the upper mold 2 is equipped with an optical waveguide and a laser for laser welding the workpiece to be welded.

[0048] Specifically, the frame 1 includes four supporting shafts, and the upper mold 2 and the lower mold 3 are supported by installing the supporting shafts to facilitate installation and disassembly.

[0049] Furthermore, an optical fiber bundle bracket 23 is provided above the upper mold 2, which is mainly used for connecting with the laser channel to facilitate the transmission of the laser. The upper mold and the lower mold are supported by the support shaft, which is convenient for the use of the mold installation equipment.

[0050] Furthermore, an optical fiber fixing plate 22 is installed above the upper mold 2, and the optical waveguide 21 is fixed on the optical fiber fixing plate. The optical waveguide 21 has multiple temperature control sensors 211 built in, which are used to detect the temperature of the weld and feed the temperature back to the temperature control system to make rapid adjustments to the laser power in time.

[0051] When the lower mold 3 is in the process of rising, the workpiece 4 to be welded is pre-contacted with the optical waveguide, and then rises slowly, and stops moving when the pressure sensor reaches a predetermined pressure value.

[0052] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0053] The above description is only a detailed description of the preferred embodiments and principles of the present application. For ordinary technicians in this field, there will be changes in the specific implementation methods based on the ideas provided by the present invention, and these changes should also be regarded as the scope of protection of the present application.

Claims

1. A synchronous laser welding process, characterized in that: The following steps are involved: Initial stage: the workpiece to be welded is placed in the contoured cavity of the lower mold, and the lower mold drives the workpiece to be welded to rise to the contact position with the waveguide, so that there is a certain pre-pressure between the waveguide and the workpiece to be welded; Preheating stage: set the preheating temperature to preheat the workpiece to be welded; Welding stage: Decompose the welding penetration into N sections, set the penetration of each welding section, and weld each welding section in turn; where N is a positive integer greater than or equal to 2; Pressure holding stage: After the workpieces to be welded are welded, they are cooled by pressure holding to melt and form the weld of the workpieces.

2. A synchronous laser welding process according to claim 1, characterized in that: In the preheating stage, the power change is adjusted by temperature control so that the set preheating temperature is lower than the melting temperature of the workpiece to be welded, and the workpiece to be welded is preheated at a constant preheating temperature; when the pressure on the workpiece to be welded is less than 1500N, the preheating is stopped.

3. The synchronous laser welding process according to claim 1, characterized in that: The welding stage includes a first welding section and a second welding section, and the first welding temperature and the first welding penetration of the first welding section are set, the first welding is performed on the workpiece to be welded by pressing the workpiece to be welded and controlling the laser, and the welding is stopped when the welding depth reaches the first welding penetration; By setting the second welding temperature and the second welding penetration in the second welding section, applying a clamping force to the workpiece to be welded and controlling the laser to perform a second welding on the workpiece to be welded, the welding is stopped when the welding depth reaches the second welding penetration.

4. A synchronous laser welding process according to claim 3, characterized in that: The first welding temperature is set to the melting temperature of the workpiece to be welded, and the second welding temperature is 10-20% higher than the first welding temperature.

5. The synchronous laser welding process according to claim 3, characterized in that: The second welding penetration is 20-50% less than the first welding penetration, and the second welding penetration changes linearly with the first welding penetration.

6. The synchronous laser welding process according to claim 3, characterized in that: A first pressing force is applied to the workpiece to be welded in the first welding section, and a second pressing force is applied to the workpiece to be welded in the second welding section. The first pressing force is smaller than the second pressing force, and the first pressing force and the second pressing force are respectively smaller than the upper limit value of the set pressing force.

7. The synchronous laser welding process according to claim 1, characterized in that: During the pressure holding stage, the workpieces to be welded are controlled to maintain a constant pressure so that the temperature of the weld gradually decreases and cools.

8. A synchronous laser welding device, characterized in that: The welding process method applied to any one of claims 1 to 7 comprises a frame, an upper mold and a lower mold, wherein the lower mold is provided with a contoured cavity in which a workpiece to be welded is placed; and the upper mold is provided with an optical waveguide and a laser for laser welding the workpiece to be welded.

9. A synchronous laser welding device according to claim 8, characterized in that: The optical waveguide is built with a plurality of temperature control sensors for detecting the temperature of the welding seam.

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