Stress monitoring device and mask machine

Abstract

The application provides a stress monitoring device and a mask machine. The stress monitoring device comprises a stress monitoring plate, which is arranged between an ultrasonic welding head and a piston rod of a welding head action cylinder used for driving the ultrasonic welding head to move, and is provided with a mounting groove; and a strain gauge, which is mounted in the mounting groove and connected with a controller of the mask machine through a connecting line, so as to solve the problem that the existing technology has no recognition ability for the ear band feeding abnormality, the welding head loosening, the ultrasonic generator loosening and the like of the mask machine.

Description

Technical Field

[0001] This invention relates to the field of mask machine technology, and more specifically, to a stress monitoring device and a mask machine. Background Technology

[0002] Patent CN104872866B discloses a fully automatic folding mask machine, which has devices for roller welding, ear loop welding, and fold seam welding, but it lacks online monitoring of welding quality abnormalities caused by feeding, positioning, welding parameters, etc.

[0003] Patent CN210184572U discloses a flexible AI vision fully automatic mask machine, which uses AI vision monitoring to automatically monitor the quality of mask pieces to ensure product quality. However, its monitoring efficiency and accuracy cannot meet the monitoring needs of high-speed mask machines.

[0004] Patent CN111497250B discloses a mask folding ear loop production line based on a one-to-two mask machine. By folding the ear loops, the welding steps are reduced, thereby reducing the probability of equipment failure and improving productivity and quality.

[0005] Patent CN111557518B discloses a mask-making machine for producing protective masks. It improves the stability of the ear loops on the mask by nailing and welding the ear loop components, reducing the occurrence of loose ear loops falling off, and improving product quality.

[0006] However, the above solution cannot promptly identify anomalies such as those in the earpiece material feeding, ultrasonic welding parameters, and power supply fluctuations, thus affecting production quality.

[0007] With the innovation of servo control and manufacturing technology, and the rapid development of high-speed manufacturing equipment for flat and folding masks, such as patent CN210256869U (an intelligent mask machine and its high-speed mask forming mold), patent CN215283447U (a high-speed ear loop welding machine for masks), patent CN112641160B (a high-speed edge sealing device for KN95 masks), patent CN213154245U (a high-speed production equipment for three-dimensional masks), patent KR102267892B1 (a melting and cutting device for a high-speed mask manufacturing machine), and patent CN213428588U (a high-speed sheet forming device for masks), the importance of production quality monitoring for key processes such as roller welding, ear loop welding, and fold seam welding in flat and folding masks is receiving increasing attention.

[0008] With the upgrading of ultrasonic welding equipment, the current ultrasonic welding process monitors welding power, current, etc., and can set corresponding thresholds to automatically alarm in case of abnormality. However, in actual work, these devices can only detect situations such as severe overheating of the welding head and power fluctuations. They have no ability to identify abnormal ear loop feeding, loose welding head, or loose ultrasonic generator (including transducer). Summary of the Invention

[0009] The main objective of this invention is to provide a stress monitoring device and a mask-making machine to solve the problem that the prior art lacks the ability to identify abnormalities in ear loop feeding, loose welding heads, and loose ultrasonic generators (including transducers) in mask-making machines.

[0010] To achieve the above objectives, according to one aspect of the present invention, a stress monitoring device is provided, comprising: a stress monitoring plate disposed between an ultrasonic welding head and a piston rod of a welding head actuation cylinder for driving the movement of the ultrasonic welding head, the stress monitoring plate being provided with a mounting groove; and a strain gauge installed in the mounting groove, the strain gauge being connected to a controller of a mask machine via a connecting wire.

[0011] Furthermore, the piston rod includes a connecting shaft section and an insert shaft section connected sequentially along the direction close to the ultrasonic welding head, the outer diameter of the connecting shaft section being larger than the outer diameter of the insert shaft section; a first through hole is provided on the stress monitoring plate for the insert shaft section to pass through; a second through hole is provided on the ultrasonic welding head for the insert shaft section to be inserted; the ultrasonic welding head is also provided with a threaded hole communicating with the second through hole, the threaded hole being used for threaded connection with a fastener, one end of the fastener passing through the threaded hole and abutting against the insert shaft section.

[0012] Furthermore, the stress monitoring plate is a circular plate with a first through hole located in the center of the circular plate. There are multiple mounting slots, which are spaced around the first through hole. There are also multiple strain gauges, which are installed one-to-one in the multiple mounting slots.

[0013] Furthermore, the stress monitoring plate is bonded to the ultrasonic welding head.

[0014] Furthermore, the stress monitoring plate is bonded to the ultrasonic welding head.

[0015] Furthermore, the stress monitoring plate is made of copper.

[0016] Furthermore, the thickness of the stress monitoring plate is H, where 2.5mm≤H≤3.5mm.

[0017] Furthermore, the outer diameter of the stress monitoring plate is D, where 15mm≤D≤17mm.

[0018] Furthermore, the depth of the mounting groove is h, where 1mm≤h≤1.5mm.

[0019] According to another aspect of the present invention, a mask-making machine is provided, comprising: a workbench with a welding station for placing masks; an ultrasonic welding head disposed above the welding station; a mounting frame disposed on the workbench; a welding head actuation cylinder disposed on the mounting frame and driven and connected to the ultrasonic welding head; an ultrasonic amplifier disposed at the welding station and below the mask; a transducer disposed below the ultrasonic amplifier; and the aforementioned stress monitoring device disposed on the ultrasonic welding head.

[0020] According to the technical solution of the present invention, the stress monitoring device of the present invention includes: a stress monitoring plate, which is disposed between an ultrasonic welding head and a piston rod of a welding head actuation cylinder for driving the ultrasonic welding head to move, and a mounting groove is provided on the stress monitoring plate; and a strain gauge, which is installed in the mounting groove and is connected to the controller of a mask machine through a connecting wire. Thus, the stress monitoring device of the present invention is equipped with a four-channel stress monitoring plate and strain gauges on each ultrasonic welding head. By monitoring the stress state of the ultrasonic welding head during the operation of the ultrasonic equipment of the mask machine online, and by calculating and analyzing the four-channel data of the same ultrasonic welding head, it can promptly detect abnormalities such as ultrasonic welding head loosening, ultrasonic welding head breakage, transducer fixing loosening, and severe ear loop feeding misalignment. This avoids the occurrence of batch quality abnormalities, so as to promptly alarm and stop the machine when abnormalities occur, prevent the equipment from producing with defects, and eliminate the quality problems of ear loop leakage, false welding, welding misalignment, welding burrs, and over-welding in the mass production of masks caused by related abnormalities. It solves the problem that the prior art has no ability to identify abnormalities in ear loop feeding, loose welding head, and loose ultrasonic generator (including transducer) of mask machine. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 A schematic diagram of an embodiment of the stress monitoring device according to the present invention is shown;

[0023] Figure 2 It shows Figure 1 A top view of the stress monitoring device shown;

[0024] Figure 3 It shows Figure 2 The stress monitoring device shown is a cross-sectional view along the AA direction;

[0025] Figure 4 It shows Figure 1 The diagram shows the installation of the stress monitoring device on the ultrasonic welding head.

[0026] Figure 5 It shows having Figure 1 A schematic diagram of an embodiment of a mask-making machine with a stress monitoring device shown;

[0027] Figure 6 It shows Figure 5 A magnified view of part B of the mask-making machine shown;

[0028] Figure 7 It shows Figure 5 The diagram shown is a schematic of the main servo control timing principle of the entire mask-making machine.

[0029] Figure 8 It shows Figure 1 The diagram shows the real-time stress acquisition data (four-channel differential, maximum value) and normal range data of the stress monitoring device.

[0030] The above figures include the following reference numerals:

[0031] 100. Mask machine; 110. Ultrasonic welding head; 111. Second through hole; 112. Threaded hole; 113. Guide boss; 120. Worktable; 130. Welding station; 140. Mounting bracket; 150. Welding head actuation cylinder; 151. Cylinder housing; 152. Piston rod; 160. Ultrasonic amplifier; 170. Guide component; 180. Fastener;

[0032] 200. Face masks;

[0033] 300. Stress monitoring device; 1. Stress monitoring plate; 11. Mounting groove; 12. First through hole; 2. Strain gauge; 3. Connecting wire. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] like Figures 1 to 6 As shown, the present invention provides a stress monitoring device 300, comprising: a stress monitoring plate 1, which is disposed between an ultrasonic welding head 110 and a piston rod 152 of a welding head actuation cylinder 150 for driving the ultrasonic welding head 110 to move, and a mounting groove 11 is provided on the stress monitoring plate 1; and a strain gauge 2, which is installed in the mounting groove 11 and is connected to the controller of a mask machine 100 via a connecting wire 3.

[0036] Thus, the stress monitoring device of the present invention is equipped with a four-channel stress monitoring plate and strain gauge 2 on each ultrasonic welding head 110. By monitoring the stress state of the ultrasonic welding head 110 during the operation of the ultrasonic equipment of the mask machine online, and by calculating and analyzing the four-channel data of the same ultrasonic welding head 110, it can promptly detect abnormalities such as loose ultrasonic welding head 110, ultrasonic welding head 110 breakage, transducer fixation loosening, and severe ear loop feeding misalignment. This avoids the occurrence of batch quality abnormalities, so as to promptly alarm and stop the machine when abnormalities occur, prevent the equipment from producing with defects, and eliminate the quality problems such as ear loop leakage, false welding, misaligned welding, welding burrs, and over-welding in the batch production of masks caused by related abnormalities. It solves the problem that the prior art has no ability to identify abnormalities in ear loop feeding, loose welding head, and loose ultrasonic generator (including transducer) of mask machine.

[0037] In addition, the mounting groove 11 on the stress monitoring plate 1 can amplify the strain and improve the sensitivity of the stress monitoring device.

[0038] Specifically, the piston rod 152 includes a connecting shaft section and an insert shaft section connected sequentially along the direction close to the ultrasonic welding head 110. The outer diameter of the connecting shaft section is larger than the outer diameter of the insert shaft section. The stress monitoring plate 1 is provided with a first through hole 12 for the insert shaft section to pass through. The ultrasonic welding head 110 is provided with a second through hole 111 for the insert shaft section to be inserted. The ultrasonic welding head 110 is also provided with a threaded hole 112 communicating with the second through hole 111. The threaded hole 112 is used for threaded connection with the fastener 180. One end of the fastener 180 passes through the threaded hole 112 and abuts against the insert shaft section.

[0039] The number of threaded holes 112 is multiple, and the multiple threaded holes 112 are arranged at intervals around the periphery of the ultrasonic welding head 110. Each threaded hole 112 is equipped with a fastener 180.

[0040] Preferably, the stress monitoring plate 1 is a circular plate, the first through hole 12 is located in the middle of the circular plate, and there are multiple mounting grooves 11, which are spaced around the first through hole 12; there are also multiple strain gauges 2, which are arranged one-to-one in the multiple mounting grooves 11.

[0041] Specifically, there are four mounting slots 11, which are arranged at intervals around the first through hole 12; there are also four strain gauges 2, which are arranged one-to-one in the four mounting slots 11.

[0042] More preferably, the stress monitoring plate 1 is bonded to the ultrasonic welding head 110.

[0043] like Figure 4 and Figure 6As shown, the mounting groove 11 is located on the side of the stress monitoring plate 1 away from the ultrasonic welding head 110.

[0044] Specifically, stress monitoring plate 1 is a copper plate.

[0045] The thickness of the stress monitoring plate 1 of the present invention is H, wherein 2.5mm≤H≤3.5mm.

[0046] The outer diameter of the stress monitoring plate 1 of the present invention is D, wherein 15mm≤D≤17mm.

[0047] The diameter of the first through hole 12 of the stress monitoring plate 1 of the present invention is d, wherein 10mm≤d≤11mm.

[0048] The depth of the mounting groove 11 of the stress monitoring plate 1 of the present invention is h, wherein 1mm≤h≤1.5mm.

[0049] like Figure 5 and Figure 6 As shown, the present invention also provides a mask machine, comprising: a workbench 120, on which a welding station 130 for placing masks is provided; an ultrasonic welding head 110, disposed above the welding station 130; a mounting frame 140, disposed on the workbench; a welding head actuation cylinder 150, the cylinder housing 151 of the welding head actuation cylinder 150 being disposed on the mounting frame 140, and the piston rod 152 of the welding head actuation cylinder 150 being drivenly connected to the ultrasonic welding head 110; an ultrasonic amplifier 160, disposed at the welding station 130 and located below the mask 200; a transducer, disposed below the ultrasonic amplifier 160; and the aforementioned stress monitoring device 300, disposed on the ultrasonic welding head 110.

[0050] The ultrasonic welding head 110 is provided with a guide boss 113 extending along its own movement direction. The mask machine also includes a guide member 170 provided on one side of the ultrasonic welding head 110. The guide member 170 is mounted on the mounting frame 140 and is provided with a guide groove for slidingly engaging with the guide boss 113 to guide the movement of the ultrasonic welding head 110.

[0051] Mask-making machines frequently experience abnormalities during the welding process, such as loose welding heads, cracked welding heads, loose ultrasonic generators (including transducers), and severely misaligned ear loops. With the rapid development of high-speed manufacturing equipment for flat and folding masks through innovation in servo control and manufacturing technology, these machines are unable to promptly identify and detect quality abnormalities, significantly impacting product quality and cost.

[0052] Specifically, the quality of mask sheet roller welding (commonly known as sheet welding) of mask machines is generally stable, and the ear loop welding adopts ultrasonic welding. Its working voltage generally does not exceed 500V, the working frequency is a distorted sine wave of 15kHz to 20kHz, and the welding power is 1.5kw to 3kw.

[0053] The ear loop welding process is a critical step in mask welding. Due to the repeated impact of the welding head cylinder 150 during welding and the vibration impact of the transducer during welding, the ultrasonic welding head 110 and the transducer are prone to loosening and displacement. At the same time, since the ear loops are made of 3mm diameter cotton thread, feeding misalignment can easily occur, leading to severe weld misalignment and welding burrs.

[0054] The installation steps of the stress monitoring device of the present invention are as follows:

[0055] Stop the mask machine 100 to retract the welding head cylinder 150. Place the stress monitoring device on the ultrasonic welding head 110. Use a tool to insert the piston rod 152 through the first through hole 12 and into the second through hole 111. Then tighten the fastener 180 into the threaded hole 112 to achieve a tight and reliable connection between the ultrasonic welding head 110 and the piston rod 152. Finally, zero the strain after installation.

[0056] The stress monitoring device of the present invention is used as follows:

[0057] During the main servo drive cycle, the strain of the four channels of the stress monitoring plate is collected when the welding cylinder is in motion and when it is not. Through differential, summation, and maximum value calculations, and comparison with the threshold, the abnormalities caused by welding cylinder impact, welding vibration, etc. in the welding tool head, ear loop feed, and ultrasonic welding transducer are detected online in a timely manner through calculation parameters. The abnormalities are identified and the machine is stopped in time to prevent the equipment from being produced with defects, which could lead to quality problems such as ear loop leakage, false welding, crooked welding, welding burrs, and over-welding in the high-speed mass production of masks.

[0058] (1) Installation stress monitoring and functional role of ultrasonic welding head 110

[0059] Online monitoring of loose installation of ultrasonic welding head 110: During the main servo drive cycle, such as... Figure 7 When the welding head cylinder 150 is not activated, four-channel strain is collected, and calculations are performed using differential, summation, and maximum value methods. The collected values ​​are then compared with a threshold value. Figure 8The first acquisition interval. If the acquired value is within the normal range shown in the figure, it is determined that the ultrasonic welding head 110 is firmly installed and not loose. Otherwise, it is determined that the ultrasonic welding head 110 is loose, and the entire mask machine is stopped by controlling the controller of the mask machine, and the alarm message "The first ultrasonic welding head 110 or the second ultrasonic welding head 110 is loose" is displayed on the display connected to the controller.

[0060] (2) Monitoring and Functions of Ultrasonic Welding Head 110 Welding Working Stress

[0061] ① Online monitoring of severe ear loop feeding misalignment: During the main servo drive cycle, if... Figure 7 After the welding head cylinder 150 actuates, parameters are collected after a certain time. Four-channel strain is acquired, and calculations are performed using differential, summation, and maximum value methods. The results are then compared with a threshold value. Figure 8 The second sampling interval. If the sampled value is within the normal range shown in the figure, the ear loop feeding is considered normal. Otherwise, the ear loop feeding is considered skewed, and the mask machine is stopped by the controller. An alarm message "Ear loop feeding skewed at the first ultrasonic welding head 110 or the second ultrasonic welding head 110" is displayed on the monitor connected to the controller.

[0062] ② Abnormalities in the ear loop welding process, such as loosening or displacement of the transducer and welding head cylinder 150 of the ultrasonic welding equipment, will also cause the above-mentioned alarm abnormalities. In handling abnormalities, it is necessary to simultaneously check whether the mounting screws of the transducer and welding head cylinder 150 are loose or displaced, and whether the tightening marks are misaligned.

[0063] ③ Online monitoring of transducer installation loosening and displacement in ultrasonic welding equipment: During the main servo drive cycle, if... Figure 7 After the welding head cylinder 150 actuates, parameters are collected after a certain time. Four-channel strain is acquired, and calculations are performed using differential, summation, and maximum value methods. The results are then compared with a threshold value. Figure 8 The third acquisition interval. If the acquired value is within the normal range shown in the figure, the welding is considered normal. Otherwise, the transducer is considered loose or misaligned, and the entire mask machine is stopped by the controller of the mask machine. The alarm message "The transducer below the first ultrasonic welding head 110 or the second ultrasonic welding head 110 is loose or misaligned" is displayed on the monitor connected to the controller.

[0064] ④ Abnormalities in the ear loop welding process, such as loosening or displacement of the mounting bracket of the welding head actuation cylinder, will also cause the above-mentioned alarm abnormalities. In handling abnormalities, it is necessary to simultaneously check whether the mounting screws of the welding head actuation cylinder 150 are loose or displaced, and whether the tightening marking lines are misaligned.

[0065] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0066] The stress monitoring device of the present invention includes: a stress monitoring plate 1, which is disposed between an ultrasonic welding head 110 and a piston rod 152 of a welding head action cylinder 150 for driving the ultrasonic welding head 110 to move, and a mounting groove 11 is provided on the stress monitoring plate 1; and a strain gauge 2, which is installed in the mounting groove 11 and is connected to the controller of a mask machine 100 through a connecting wire 3. Thus, the stress monitoring device of the present invention is equipped with a four-channel stress monitoring plate and strain gauge 2 on each ultrasonic welding head 110. By monitoring the stress state of the ultrasonic welding head 110 during the operation of the ultrasonic equipment of the mask machine online, and by calculating and analyzing the four-channel data of the same ultrasonic welding head 110, it can promptly detect abnormalities such as loose ultrasonic welding head 110, ultrasonic welding head 110 breakage, transducer fixation loosening, and severe ear loop feeding misalignment. This avoids the occurrence of batch quality abnormalities, so as to promptly alarm and stop the machine when abnormalities occur, prevent the equipment from producing with defects, and eliminate the quality problems such as ear loop leakage, false welding, misaligned welding, welding burrs, and over-welding in the batch production of masks caused by related abnormalities. It solves the problem that the prior art has no ability to identify abnormalities in ear loop feeding, loose welding head, and loose ultrasonic generator (including transducer) of mask machine.

[0067] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0068] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0069] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0070] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0071] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A stress monitoring device, characterized in that, include: A stress monitoring plate (1) is provided between an ultrasonic welding head (110) and the piston rod (152) of a welding head action cylinder (150) for driving the ultrasonic welding head (110) to move. The stress monitoring plate (1) is provided with a mounting groove (11). Strain gauge (2), the strain gauge (2) is installed in the mounting groove (11), and the strain gauge (2) is connected to the controller of the mask machine (100) through the connecting line (3); The piston rod (152) includes a connecting shaft section and a plug-in shaft section connected sequentially in a direction close to the ultrasonic welding head (110), wherein the outer diameter of the connecting shaft section is larger than the outer diameter of the plug-in shaft section; The stress monitoring plate (1) is provided with a first through hole (12) for the insertion shaft section to pass through. The ultrasonic welding head (110) is provided with a second through hole (111) for inserting the plug shaft section. The ultrasonic welding head (110) is also provided with a threaded hole (112) communicating with the second through hole (111). The threaded hole (112) is used to be threadedly connected to the fastener (180). One end of the fastener (180) passes through the threaded hole (112) and abuts against the plug-in shaft section. The stress monitoring plate (1) is a circular plate. The first through hole (12) is located in the middle of the circular plate. There are multiple mounting grooves (11), which are spaced around the first through hole (12). There are also multiple strain gauges (2), which are arranged one-to-one in the multiple mounting grooves (11). The mounting groove (11) is located on the side of the stress monitoring plate (1) away from the ultrasonic welding head (110); The stress monitoring device monitors the stress state of the ultrasonic welding head (110) online, so as to realize the timely detection of loosening or fracture of the ultrasonic welding head (110).

2. The stress monitoring device according to claim 1, characterized in that, The stress monitoring plate (1) is bonded to the ultrasonic welding head (110).

3. The stress monitoring device according to claim 1, characterized in that, The stress monitoring plate (1) is a copper plate.

4. The stress monitoring device according to claim 1, characterized in that, The thickness of the stress monitoring plate (1) is H, where 2.5mm≤H≤3.5mm.

5. The stress monitoring device according to claim 2, characterized in that, The outer diameter of the stress monitoring plate (1) is D, where 15mm≤D≤17mm.

6. The stress monitoring device according to claim 1, characterized in that, The depth of the mounting groove (11) is h, where 1mm≤h≤1.5mm.

7. A mask-making machine, characterized in that, include: A workbench (120) is provided with a welding station (130) for placing masks (200). An ultrasonic welding head (110) is positioned above the welding station (130). Mounting bracket (140) is provided on the workbench (120); A welding head actuation cylinder (150) is mounted on a mounting bracket (140) and driven by the ultrasonic welding head (110); An ultrasonic amplifier (160) is disposed at the welding station (130) and located below the mask (200); A transducer is disposed below the ultrasonic amplifier (160); The stress monitoring device according to any one of claims 1 to 6 is disposed on the ultrasonic welding head (110).

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