Ultrasonic welding method and system based on hierarchical pressure control

Abstract

The invention belongs to the technical field of ultrasonic welding, and particularly relates to an ultrasonic welding method and system based on hierarchical pressure control, and the method comprises the following steps: S10, driving a welding head to move from an initial position to a welding position through a Z-axis driving mechanism so as to enable the welding head to abut against a workpiece to be welded; s20, a welding head is driven by a first driver to downwards press the workpiece to be welded, and welding pressure is provided; s30, an ultrasonic generator is controlled by the control device to generate ultrasonic waves; s40, a welding head is driven to work through a second driver, compensation welding pressure is provided, and meanwhile the control time of the compensation welding pressure is adjusted so that welding of the workpiece to be welded can be achieved; s50, after welding is completed, the welding head is driven by a Z-axis driving mechanism to return to the initial position; the response time for adjusting the welding pressure can be effectively shortened, the welding efficiency is improved, and the requirement for efficient welding is met.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic welding technology, specifically relating to an ultrasonic welding method and system based on stepped pressure control. Background Technology

[0002] Ultrasonic welding is based on high-frequency ultrasonic vibration. It uses high-frequency ultrasonic vibration under pressure to solidify and weld the workpieces. It is commonly used for plastics and metals, especially for joining dissimilar materials. The advantages of ultrasonic welding include: low welding resistance, relatively large current throughput, no need for additional welding materials, minimal heat conduction to the workpieces, and the ultrasonic vibration removing contaminants or oxide layers from the metal surface, ensuring a strong weld.

[0003] In the current process of welding IGBT terminals, pins, and other products using ultrasonic welding machines, the inventors have discovered at least the following technical problems in the existing technology:

[0004] On the one hand, ultrasonic welding machines require a fixed welding pressure to weld products, making it impossible to adjust the welding pressure during the welding process. Welding at the same pressure can easily damage the ceramic substrate and cause weld cracks, or even lead to misalignment of the weld marks on the post-weld product. On the other hand, adjusting the welding pressure usually involves controlling the output using a proportional valve in the gas path. The welding pressure is adjusted by changing the proportional valve during the welding process, but the welding response time is long, which cannot meet the time requirements for efficient welding.

[0005] Therefore, it is necessary to improve the existing technology to overcome its shortcomings in practical applications. Summary of the Invention

[0006] Based on the aforementioned shortcomings and deficiencies in the prior art, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the prior art. In other words, one of the objectives of this invention is to provide an ultrasonic welding method and system based on stepped pressure control that meets one or more of the aforementioned requirements.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] This invention provides an ultrasonic welding method based on stepped pressure control, applicable to ultrasonic welding systems. The method includes the following steps:

[0009] S10. Drive the welding head from the initial position to the welding position through the Z-axis drive mechanism so that the welding head comes into contact with the workpiece to be welded;

[0010] S20. The welding head is driven by the first driver to press down on the workpiece to be welded and to provide welding pressure.

[0011] S30. Control the ultrasonic generator to emit ultrasonic waves through the control device;

[0012] S40. Drive the welding head to work through the second driver and provide compensated welding pressure, while adjusting the control time of the compensated welding pressure to achieve welding of the workpiece to be welded.

[0013] S50. After welding is completed, the welding head is driven back to the initial position by the Z-axis drive mechanism.

[0014] As a preferred embodiment, the method further includes the following steps before step S10:

[0015] By adjusting the set welding pressure of the welding machine, the set welding pressure of the welding machine can be made to reach the calibration pressure, thereby achieving pressure calibration of the welding machine.

[0016] As a preferred embodiment, the range of the compensating welding pressure is set to -50N to +50N, ​​and the compensating welding pressure is linearly adjustable.

[0017] As a preferred embodiment, the first driver is configured as a cylinder, and the second driver is configured as a voice coil motor.

[0018] As a preferred embodiment, the total working time of the ultrasonic generator is T, the time to start triggering the second driver is t1, and the time to complete the adjustment is t2, wherein 0 < t1 < t2 < T, and Δt = t2 - t1 and is less than 50 ms.

[0019] The present invention also provides an ultrasonic welding system based on stepped pressure control, comprising:

[0020] An ultrasonic generator, used to produce ultrasonic waves;

[0021] An ultrasonic welding machine is used to press against the workpiece to be welded and perform ultrasonic welding on the workpiece.

[0022] The control device is electrically connected to the ultrasonic welding machine and the ultrasonic generator, respectively, and is used to control the position information, welding pressure and compensation welding pressure during ultrasonic welding, so as to realize the ultrasonic welding method as described in any of the above schemes.

[0023] As a preferred embodiment, the ultrasonic welding machine includes a Z-axis drive mechanism, a first guide mechanism, a first frame, a first driver, a second driver, and a welding head. The Z-axis drive mechanism is drivenly connected to the first guide mechanism, the first guide mechanism is drivenly connected to the first frame, and the first driver, the second driver, and the welding head are disposed on the first frame.

[0024] As a preferred embodiment, a second guide mechanism, a second frame, a third frame, and a pressure sensor are mounted on the first frame. The pressure sensor is mounted on the second frame, and the welding head is mounted on the third frame. The third frame and the first frame are connected by a transmission mechanism.

[0025] As a preferred embodiment, the second actuator is disposed on the second frame and is located above the pressure sensor.

[0026] Compared with the prior art, the beneficial effects of this invention are:

[0027] This invention provides an ultrasonic welding method based on stepped pressure control. By controlling the stepped welding pressure during the welding process, the pressure is lower at the beginning of welding and then increased after a certain welding time. This effectively reduces the response time for adjusting the welding pressure, improves welding efficiency, and meets the requirements of high-efficiency welding. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a flowchart of an ultrasonic welding method based on stepped pressure control according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structural connection of the ultrasonic welding machine according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of a test using a proportional valve to adjust the pressure upwards and the response time in existing technology;

[0032] Figure 4 This is a schematic diagram of a test using a proportional valve to adjust the pressure downwards and the response time in the existing technology;

[0033] Figure 5 This is a test diagram illustrating the upward pressure-response time using a voice coil motor according to an embodiment of the present invention;

[0034] Figure 6 This is a test diagram illustrating the downward pressure-response time of a voice coil motor according to an embodiment of the present invention.

[0035] In the figure: 1. Z-axis drive mechanism; 2. First guide mechanism; 3. First frame; 31. Second guide mechanism; 32. Second frame; 33. Third frame; 4. First driver; 5. Second driver; 6. Welding head; 7. Pressure sensor. Detailed Implementation

[0036] To more clearly illustrate the embodiments of this application, the specific implementation methods of this application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0037] In the description of the embodiments of this application, the terms "upper," "lower," "front," "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first," "second," etc., are only used for distinction in description and have no special meaning.

[0038] Traditional welding pressure is controlled by a proportional valve in the gas path. During the welding process, the pressure is adjusted by regulating the proportional valve. However, the proportional valve is slow to adjust. Normal welding time is within 100-150ms, but the adjustment time of the proportional valve is generally more than 800ms. The adjustment time is longer than the normal welding time, which cannot meet the time accuracy requirements of welding.

[0039] According to some embodiments of this application, please refer to Figure 1 As shown, an ultrasonic welding method based on stepped pressure control is provided and applied to an ultrasonic welding system. The control method includes the following steps:

[0040] S10. Drive the welding head from the initial position to the welding position through the Z-axis drive mechanism so that the welding head abuts against the workpiece to be welded. The welding position is configured as the contact position between the welding head and the workpiece to be welded.

[0041] S20. The welding head is driven by the first driver to press down on the workpiece to be welded and to provide welding pressure.

[0042] S30. Control the ultrasonic generator to emit ultrasonic waves through the control device.

[0043] S40. The welding head is driven by the second driver and provides compensated welding pressure. At the same time, the control time of the compensated welding pressure is adjusted to achieve welding of the workpiece to be welded.

[0044] S50. After welding is completed, the welding head is driven back to the initial position by the Z-axis drive mechanism.

[0045] Furthermore, the procedure before step S10 includes:

[0046] By adjusting the set welding pressure of the welding machine to reach the calibration pressure, the pressure of the welding machine can be calibrated, reducing pressure fluctuations during the welding process and making the welding effect more stable.

[0047] In the embodiments of this application, the range of the compensated welding pressure is set to -50N to +50N, ​​and the compensated welding pressure changes linearly.

[0048] In the embodiments of this application, the first driver is configured as a cylinder, and the second driver is configured as a voice coil motor. The voice coil motor and the cylinder are connected in parallel to provide welding pressure to the welding head. By adding a voice coil motor to provide compensating welding pressure to the welding head, the adjustment time can be controlled within 30ms, reducing the response adjustment time and increasing the efficiency by more than 25 times. It can ensure that the welding force change requirement is completed within 100 to 150ms during normal welding time.

[0049] In the embodiments of this application, the total working time of the ultrasonic generator is T, the time to start triggering the second driver is t1, and the time to complete the adjustment is t2, wherein 0 < t1 < t2 < T, and Δt = t2 - t1 and is less than 50 ms.

[0050] like Figure 3 The diagram shown illustrates a test using a proportional valve to adjust the pressure upwards and the response time in the prior art. Figure 5 The diagram shown is a test schematic of the response time of using a voice coil motor to increase the pressure according to an embodiment of this application. The response time is significantly reduced.

[0051] like Figure 4 The diagram shown illustrates a test using a proportional valve to adjust the pressure downwards and the response time in the prior art. Figure 6 The diagram shown is a test schematic of the response time when the pressure of the voice coil motor is adjusted downward according to an embodiment of this application. The response time is significantly reduced.

[0052] By setting stepped welding pressure during the welding process of the workpiece, the response time for adjusting the welding pressure can be effectively reduced, welding efficiency can be improved, and the demand for high-efficiency welding can be met.

[0053] According to some embodiments of this application, an ultrasonic welding system based on stepped pressure control is also provided, comprising:

[0054] An ultrasonic generator, used to produce ultrasonic waves;

[0055] An ultrasonic welding machine is used to press against the workpiece to be welded and perform ultrasonic welding on the workpiece.

[0056] The control device is electrically connected to the ultrasonic welding machine and the ultrasonic generator, respectively, and is used to control the position information, welding pressure and compensation welding pressure during ultrasonic welding, so as to realize the ultrasonic welding method described above.

[0057] Furthermore, such as Figure 2 As shown, the ultrasonic welding machine includes a Z-axis drive mechanism 1, a first guide mechanism 2, a first frame 3, a first driver 4, a second driver 5, and a welding head 6. The Z-axis drive mechanism 1 is connected to the first guide mechanism 2, the first guide mechanism 2 is connected to the first frame 3, and the first driver 4, the second driver 5, and the welding head 6 are disposed on the first frame 3.

[0058] Furthermore, a second guide mechanism 31, a second frame 32, a third frame 33, and a pressure sensor 7 are installed on the first frame 3. The pressure sensor 7 is installed on the second frame 32, and the welding head 6 is installed on the third frame 33. The third frame 33 and the first frame 3 are connected by transmission through the second guide mechanism 31.

[0059] Furthermore, the second actuator 5 is disposed on the second frame 32 and is located above the pressure sensor 7.

[0060] The first frame is driven from the initial position to the welding position by the Z-axis drive mechanism, so that the welding head abuts against the surface of the workpiece to be welded; the ultrasonic generator is started and the welding pressure is provided by the first driver, while the second driver adjusts the pressure to perform ultrasonic welding on the workpiece to be welded.

[0061] In embodiments of this application, the workpiece to be soldered may be configured as a power module. It is understood that the term "power module" as used in embodiments of this application refers to a module for housing one or more power components (e.g., power semiconductor devices). Exemplary power components include MOSFETs, IGBTs, BJTs, thyristors, GTPs, and JFETs. Such modules typically also include a power electronics substrate for carrying the power components. Compared to discrete power semiconductors, power modules tend to provide higher power density.

[0062] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0063] The above description is only a detailed explanation of the preferred embodiments and principles of this application. For those skilled in the art, there may be changes in the specific implementation based on the ideas provided by this invention, and these changes should also be considered within the scope of protection of this application.

Claims

1. An ultrasonic welding method based on stepped pressure control, characterized in that, Applied to ultrasonic welding systems, the method includes the following steps: S10. Drive the welding head from the initial position to the welding position through the Z-axis drive mechanism so that the welding head comes into contact with the workpiece to be welded; S20. The welding head is driven by the first driver to press down on the workpiece to be welded and to provide welding pressure. S30. Control the ultrasonic generator to emit ultrasonic waves through the control device; S40. Drive the welding head to work through the second driver and provide compensated welding pressure, while adjusting the control time of the compensated welding pressure to achieve welding of the workpiece to be welded. S50. After welding is completed, the welding head is driven back to the initial position by the Z-axis drive mechanism.

2. The ultrasonic welding method based on stepped pressure control according to claim 1, characterized in that, The procedure preceding step S10 also includes: By adjusting the set welding pressure of the welding machine, the set welding pressure of the welding machine can be made to reach the calibration pressure, thereby achieving pressure calibration of the welding machine.

3. The ultrasonic welding method based on stepped pressure control according to claim 1, characterized in that, The range of the compensating welding pressure is set to -50N to +50N, ​​and the compensating welding pressure is linearly adjustable.

4. The ultrasonic welding method based on stepped pressure control according to claim 1, characterized in that, The first driver is configured as a cylinder, and the second driver is configured as a voice coil motor.

5. The ultrasonic welding method based on stepped pressure control according to claim 1, characterized in that, The total working time of the ultrasonic generator is T, the time to start triggering the second driver is t1, and the time to complete the adjustment is t2, where 0 < t1 < t2 < T, and Δt = t2 - t1 and is less than 50 ms.

6. An ultrasonic welding system based on stepped pressure control, characterized in that, include: An ultrasonic generator, used to produce ultrasonic waves; An ultrasonic welding machine is used to press against the workpiece to be welded and perform ultrasonic welding on the workpiece. A control device is electrically connected to the ultrasonic welding machine and the ultrasonic generator, respectively, and is used to control the position information, welding pressure and compensation welding pressure during ultrasonic welding, so as to realize the ultrasonic welding method as described in any one of claims 1 to 5.

7. The ultrasonic welding system based on stepped pressure control according to claim 6, characterized in that, The ultrasonic welding machine includes a Z-axis drive mechanism, a first guide mechanism, a first frame, a first driver, a second driver, and a welding head. The Z-axis drive mechanism is driven by the first guide mechanism, the first guide mechanism is driven by the first frame, and the first driver, the second driver, and the welding head are disposed on the first frame.

8. The ultrasonic welding system based on stepped pressure control according to claim 6, characterized in that, A second guide mechanism, a second frame, a third frame, and a pressure sensor are mounted on the first frame. The pressure sensor is mounted on the second frame, and the welding head is mounted on the third frame. The third frame and the first frame are connected by the second guide mechanism.

9. The ultrasonic welding system based on stepped pressure control according to claim 8, characterized in that, The second actuator is disposed on the second frame and is located above the pressure sensor.

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