JP6947402B2 - High frequency welding device and high frequency welding method - Google Patents

Description

The present invention relates to a high-frequency welding apparatus and a method thereof for pressure welding a laminated welding object sandwiched between opposing electrodes by high-frequency power.

Conventionally, many medical bags, automobile mats, card cases and various packaging bags in the stationery and other industries have been made of thermoplastic resins such as PVC (polyvinyl chloride) and PU (polyurethane), which are insulators. Made of film. This type of product is manufactured by applying physical energy such as high frequency and ultrasonic waves instead of the conventional external heating method using hot air or a hot plate. That is, in this type of product, high frequency or ultrasonic waves are applied by pressing both sides of two laminated films or the like with, for example, a high frequency mold or an ultrasonic mold suitable for a location or shape to be welded in a bag shape. As a result, it is manufactured by heating and melting and welding without interposing foreign matter on the joint surface. Then, high-precision pressure welding control is desired so that the thickness of the welded portion becomes an accurate set dimension.

In Patent Document 1, the optimum values of the oscillation time, the amount of sinking of the horn, and the input energy of the vibrator and their permissible values are described from the optimum welding conditions regarding the ultrasonic horn amplitude, the press pressure, and the oscillation time that have been set and input. An ultrasonic welder welding control device that calculates and automatically determines the quality of welding at the end of welding work is described. That is, Patent Document 1 obtains two other welding conditions that have not been applied to the control method selected by the operator prior to the welding work at the end of the welding work, and the respective permissible values corresponding to these. By comparing, the quality of welding is automatically determined. Further, Patent Document 2 includes a load cell that measures the force with which an ultrasonic horn whose displacement is controlled by a servomotor pressurizes two adherends, and maintains a constant pressing force based on a detection signal of the load cell. An ultrasonic welding device for feedback control of a servomotor is described.

Japanese Unexamined Patent Publication No. 10-11392 Japanese Unexamined Patent Publication No. 2006-231698

By the way, since the heat welding of the laminated resin material is performed under pressure, the dimensions in the thickness direction may be deformed due to restoration or the like after the heat treatment is completed and the pressure is reduced. Therefore, in the manufacturing stage, it is desirable to work in consideration of deformation after decompression.

The ultrasonic welding control device described in Patent Document 1 determines the quality of welding at the end of work by comparing three types of optimum welding conditions of horn sinking amount, oscillation time, and oscillator input energy with their permissible values. It does not take into account deformation due to restoration after welding. The ultrasonic welding device described in Patent Document 2 is for feeding back the detection signal of the load cell to the servomotor in order to keep the pressing force constant, and takes into consideration the control of the welding time and the welding energy. is not it.

The present invention has been made in view of the above, and provides a high-frequency welding apparatus and a method thereof for feeding back load information detected during pressure welding to a welding process to reduce thickness errors as much as possible. ..

The high-frequency welding device according to the present invention includes a high-frequency circuit unit that supplies high-frequency power between opposing electrodes, a control means that drives the high-frequency circuit unit by sandwiching a welded object in a laminated state between the opposing electrodes, and the high-frequency circuit unit. A displacement drive unit that adjusts the distance between the electrodes and a load detection unit that detects the load between the electrodes are provided, and the control means maintains the supply of the high-frequency power at a set thickness of the distance between the electrodes. In this state, the control is performed based on the load signal from the load detection unit.

Further, the high-frequency welding method according to the present invention includes a step of supplying high-frequency power between the opposing electrodes, pressurizing the welding object laminated between the electrodes, and melting and welding until the set thickness is reached. The present invention includes a step of detecting a load between the electrodes and controlling the supply of the high frequency power based on the detected load.

According to such an invention, a welded object in a laminated state is sandwiched between facing electrodes, high-frequency power is supplied, and melting is performed. The welded object laminated between the electrodes is melted and welded in a pressurized state until it reaches the set thickness, and then the load between the electrodes is detected, and based on the detected load, for example, the detected load is determined. When the set load is reached, the supply of high frequency power is controlled, for example stopped, and the welding process ends. Alternatively, an embodiment may be included in which the supply of high-frequency power is controlled when the load change amount calculated using the detected load matches the set load change value.

Therefore, in the present invention, it is sufficient to apply the existing load detection unit. Further, since the supply of high-frequency power is controlled based on the load during welding, it is possible to adjust the product thickness after welding to a specified dimension. For example, even if the set thickness is the same, if the repulsive force is large due to insufficient melting, the restoring force will be large and the finished dimensions will be different, but it can be solved by controlling based on the load. In particular, in the case of a soft resin material, when it is heated and melted by applying pressure, a restoring force may act after melting to change the set thickness. Since the control is performed based on the above, the restoration error can be reduced as much as possible as compared with the mode of controlling by the detected thickness. Therefore, it is possible to provide a welding technique with high molding dimensional accuracy without being affected by the difference in the restored dimensions at the curing stage of the soft resin based on the magnitude of the load during pressure melting. As a problem peculiar to welding to a soft resin material, ultrasonic vibration is attenuated and cannot be melted, high frequency power is suitable, and there is a problem of dimensional accuracy due to a restoration phenomenon after welding of the soft resin material. By applying the present invention, such a problem is solved.

Further, the high-frequency welding device includes a displacement detection unit that detects the distance between the electrodes, and the displacement drive unit maintains the set thickness after detecting that the displacement detection unit matches the set thickness. To do. According to this configuration, by maintaining the set thickness, the load with respect to the set thickness is detected, and the thickness can be controlled.

Further, the load detecting unit starts detecting the set load after the distance between the electrodes reaches the set thickness. According to this configuration, after the set thickness is reached, the load changes in the direction of decreasing, so that it is possible to prevent erroneous detection during a period such as when the load shows an increase.

Further, the control means stops the supply of the high frequency power when the detected load detected by the load detecting unit matches the set load. According to this configuration, by stopping the welding operation at the set load, it is associated with the design thickness, so that a product having a specified thickness after molding can be obtained. It should be noted that a mode may be included in which the load change amount is calculated using the detected load, the time point at which the detected load matches the set load is predicted from the load change amount, and the supply of high frequency power is stopped at the predicted time point.

Further, the control means obtains a load change amount from the detected load detected by the load detection unit, and stops the supply of the high frequency power when the load change amount matches the set load change value. According to this configuration, by stopping the welding operation at the set load change value, it is associated with the design thickness, so that a product having a specified thickness after molding can be obtained. It should be noted that a mode may be included in which the load change amount is calculated using the detected load, the time point at which the applied load change amount matches the set load change value is predicted, and the supply of high frequency power is stopped at the predicted time point.

Further, the displacement drive unit waits for a predetermined cooling time to open the space between the electrodes after the welding operation is completed. According to this configuration, the restoration amount is stabilized by using the cooling time.

According to the present invention, it is possible to apply the existing detection unit to accurately form the dimensions of the welded object after depressurization.

It is a schematic block diagram which shows 1st Embodiment of the high frequency welding apparatus which concerns on this invention. It is a functional block diagram which shows 1st Embodiment of the high frequency welding apparatus shown in FIG. It is a chart which shows an example of the experimental result for demonstrating the relationship between the judgment thickness at the time of welding and the measured thickness after restoration corresponding to the magnitude of a judgment load. It is a figure which shows an example of the experimental result for demonstrating the relationship between the set load and the measured thickness at the end of a welding process and the end of a cooling process. This is an example of a time chart for explaining the operation of each part corresponding to each process. It is an example of the time chart which shows the experimental example of the molding process shown in FIG. It is a flowchart explaining the procedure of the welding process I shown in FIG. It is a schematic block diagram which shows the 2nd Embodiment of the high frequency welding apparatus which concerns on this invention. It is a time chart of another example explaining the operation of each part corresponding to each process. It is a time chart which shows the experimental example of the molding process shown in FIG. It is a flowchart explaining the procedure of welding process II shown in FIG. It is a figure explaining another application method of a set load.

FIG. 1 is a schematic configuration diagram of a side view showing a first embodiment of the high-frequency welding device 1 according to the present invention. The high-frequency welding device 1 includes a box-shaped, for example, rectangular parallelepiped-shaped housing 10, and includes a high-frequency circuit unit 20, a pressure driving unit 30, and a detecting unit 40 inside the housing 10. A board circuit unit (not shown) constituting a high frequency circuit unit 20, a pressure drive unit 30, and a control unit 100 electrically connected to the detection unit 40 is provided on a side portion or an external suitable position of the housing 10. ..

The high frequency circuit unit 20 constitutes a high frequency circuit having a predetermined frequency in the band of several to several hundred MHz, for example, 40.68 MHz. The high-frequency circuit unit 20 includes an oscillator 21 that outputs a predetermined high-frequency power, a matching device 22 that automatically matches the load impedance and efficiently supplies high-frequency energy to the load, and a metal positive electrode. 23 and a negative electrode 24 are provided. The positive electrode 23 and the negative electrode 24 are arranged so as to face the open work space 10a on the front side (left side in FIG. 1) of the housing 10. That is, the negative electrode 24 is arranged on the horizontal table of the housing 10 which is the lower part of the work space 10a. As will be described later, the positive electrode 23 is attached to the lower end of the pressurizing drive unit 30 via a joint plate 231 and is raised and lowered by the pressurizing drive unit 30 so that the distance from the negative electrode 24 can be adjusted. ..

The positive electrode 23 and the negative electrode 24 have electrode surfaces facing each other, and for example, two resin films (hereinafter referred to as works w1 and w2) as welding objects are manually laminated between the electrodes. You can move in and out by a transfer robot (not shown). Although not visible in the figure, the positive electrode 23 is formed in a convex shape according to the location and shape of welding. Further, as is known, a traveling wave / reflected wave power sensor, a matching sensor, and a circuit unit for adjusting output and matching conditions based on these sensors are provided between the oscillator 21 and the matching device 22. ing. The thermoplastic resin material used for welding is mainly polyethylene, polypropylene, polyamide, polyvinyl chloride, polyurethane and the like.

Various mechanisms can be adopted for the pressurizing drive unit 30, but in this example, the cylinder 31 is composed of a hydraulic actuator and is erected at an appropriate position in the housing 10, and a rod that penetrates the inside of the cylinder 31 in the vertical direction. It has 32 and. In FIG. 1, the compressor for raising and lowering the rod 32 and the solenoid valve for raising and lowering adjustment are not visible.

By driving the solenoid valve, the rod 32 moves in the vertical direction. A positive electrode 23 is attached to the lower end of the rod 32 via an insulator (not shown). By moving the rod 32 up and down, the distance between the opposite positive electrode 23 and the negative electrode 24 (electrode distance) is adjusted. A load detection unit 43, which will be described later, is interposed in the middle of the rod 32 in the longitudinal direction. As is known, the pressurizing drive unit 30 adjusts and controls the opening and closing of the solenoid valve to appropriately move the rod 32 in the reciprocating direction (here, the vertical direction) at a required pressure.

The detection unit 40 includes a predetermined thickness detection switch unit 41, a displacement detection unit 42 for detecting the electrode spacing, and a load detection unit 43 for detecting the load generated between the electrodes. The predetermined thickness detection switch portion 41 includes a mechanical micro switch 411 attached to the housing 10 and a stopper 412 attached to the rod 32. The detection signal is output when the rod 32 descends from above and the stopper 412 comes into contact with the detection piece of the micro switch 411. The stopper 412 is attached at a position where a detection signal is output when the electrode spacing reaches a set thickness. By adjusting one of the mounting positions of the micro switch 411 and the stopper 412 in the vertical direction, the set thickness can be changed and adjusted. The pressurizing drive unit 30 receives this detection signal and stops the lowering operation of the rod 32. By stopping the rod 32, the electrode spacing is maintained at the set thickness.

The displacement detection unit 42 constitutes a rotary encoder attached to the rod 32 and including a rack that moves up and down integrally with the rod 32 and a pinion that meshes with the rack. The elevating position of the rod 32 can be detected by measuring the amount of rotation of the pinion corresponding to the direction of rotation. A linear scale may be adopted as the displacement detection unit 42. In this embodiment, it is sufficient to provide either an inexpensive predetermined thickness detection switch unit 41 or a displacement detection unit 42 for detecting the electrode spacing.

A load cell using a pressure-sensitive element such as a piezoelectric element or a magnetostrictive element can be applied to the load detecting unit 43. By interposing the load detection unit 43 in the middle of the rod 32, it is possible to detect the load generated between the electrodes in the state where the works w1 and w2 are in contact with each other.

FIG. 2 is a functional configuration diagram showing a first embodiment of the high-frequency welding apparatus shown in FIG. The high-frequency welding device 1 includes, for example, a control unit 100 having a processor, and is connected to a storage unit 1001 that stores table data necessary for control such as a welding control program and welding conditions described later.

By executing the welding control program, the control unit 100 functions as a high frequency drive control unit 101, a press drive control unit 102, a contact determination unit 103, a quality determination unit 104, and a built-in timer 105. Further, the input unit 11 accepts an input operation from the outside, and inputs welding conditions such as a high frequency output value, a set thickness, and a set load, if necessary. It should be noted that the hydraulic actuator can be initialized with welding conditions by itself, and in that case, input from the input unit 11 is not always necessary. The control unit 100 detects, for example, a signal that the hydraulic actuator has reached the welding condition.

The high frequency drive control unit 101 supplies a high frequency output according to the input welding conditions between the positive electrode 23 and the negative electrode 24, and melts and welds the works w1 and w2 by dielectric heating. For example, a bag body is manufactured as a whole by welding each other with a specified thickness along the peripheral edges of the works w1 and w2.

The press drive control unit 102 lowers the positive electrode 23 while pressing the works w1 and w2 with a required pressure until the set thickness is reached. That is, when the press drive control unit 102 detects that the repulsive force (that is, the load) from the works w1 and w2 decreases as the melting of the works w1 and w2 progresses in the welding process, the load detecting unit 43 detects the rod 32. On the other hand, when the load detection unit 43 detects that the load has returned to the original predetermined pressure due to this lowering, the electrode spacing is gradually narrowed toward the set thickness by repeating the operation of pausing the lowering. I am trying to do it. Further, the press drive control unit 102 stops the rod 32 from descending when the predetermined thickness detection switch unit 41 outputs a detection signal or the displacement detection unit 42 outputs a detection signal for detecting that the set thickness has been reached. And maintain its position. Further, when the welding process is completed, the press drive control unit 102 holds the position for a predetermined cooling time in the subsequent cooling process, and then raises the positive electrode 23 to open the works w1 and w2.

The contact determination unit 103 detects, for example, that the positive electrode 23 has reached or contacted the laminated workpieces w1 and w2 placed on the negative electrode 24 after the rod 32 has started descending, for example, by the load detection unit 43. The change in the rise of the load is determined as having contact. In this example, the contact determination is for the high frequency output start timing. The contact determination may be made by measuring the descending length of the rod 32 or by measuring the descending time with a timer, detecting the stopper 412 at a height corresponding to the contact position, or itself. A mode in which a signal is output from is included.

The quality determination unit 104 determines the quality of welding of the works w1 and w2 based on the detected load at the end of the welding process or the end of the cooling process.

FIG. 3 is a chart showing an example of experimental results for explaining the relationship between the determined thickness at the time of welding and the measured thickness after restoration, which corresponds to the magnitude of the determined load. The example of FIG. 3 shows the restoration state after two pieces of PVC (polyvinyl chloride) having a thickness of 0.3 mm are laminated and welded as the works w1 and w2. Here, 0.40 mm is set as the thickness after welding, and when the load (that is, residual pressure) after the welding time is completed (or the cooling time is completed) is 0.6 kN (kilonewton), the restoration dimension is set. Is almost 0 mm, and it can be seen that the larger the load, the larger the restoration dimension proportionally. For example, when the load is 1.4 kN, the restoration dimension is 0.45 mm, that is, it can be seen that the restoration expansion is as much as 0.05 mm with respect to 0.40 mm. In this case, it means that the thickness is increased by an extra 0.05 mm from the time when the welding or cooling process is completed.

From the above, it can be seen from this example that when the set thickness is set to 0.40 mm as the welding condition, the set load should be set to 0.6 kN. Alternatively, the set load may be set slightly larger than 0.6 kN, while the set thickness may be set thinner than 0.40 mm so that the restored thickness matches 0.40 mm. If the set load is small, the measured thickness after restoration may be thinner (shrink) than the set thickness. Therefore, the set thickness should be set thicker by utilizing this restoration phenomenon. May be good.

FIG. 4 is a chart showing an example of experimental results for explaining the relationship between the set load and the actually measured thickness at the end of the welding process and the end of the cooling process. In the example of FIG. 4, the restoration dimensions after welding two pieces of PVC (polyvinyl chloride) having a thickness of 0.3 mm as the works w1 and w2 are shown corresponding to the load determination value. be. The finishing thickness indicates the one immediately after the completion of the welding process (indicated by black circles) and the one immediately after the completion of the cooling process (indicated by white triangles). In either case, the load determination value and the finish thickness have a high correlation (proportional), and as shown in each regression line, it can be seen that the larger the load determination value, the thicker the finish thickness. From the dispersion status, it can be seen that the correlation is higher immediately after the completion of the cooling process than immediately after the completion of the welding process. Further, if the load determination values are the same, it can be seen that the finishing thickness is thicker immediately after the completion of the cooling process.

FIG. 5 is an example of a time chart for explaining the operation of each unit corresponding to each process (welding, cooling) executed by the control unit 100. In FIG. 5, the time axis is taken on the horizontal axis, the state of high frequency operation, that is, the process is shown on the upper side in the vertical direction, and the state of press operation is shown on the lower side.

First, with the stacked works w1 and w2 placed on the negative electrode 24, the solenoid valve of the pressurizing drive unit 30 is activated at t0, and the rod 32, that is, the positive electrode 23 begins to descend. When the electrode spacing (gap) becomes narrow and the positive electrode 23 comes into contact with the upper surface of the work w1 at t1, the load change due to the contact is detected by the load detection unit 43. Upon receiving this contact detection, the high frequency circuit unit 20 is activated, and a welding operation is started on the works w1 and w2. The pressurizing drive unit 30 gradually lowers the positive electrode 23.

On the other hand, when the work w1 and w2 are melted by the start of welding and the positive electrode 23 is lowered to a predetermined thickness at t2, the lowering of the rod 32 is stopped by the control of the solenoid valve of the pressurizing drive unit 30 and is currently present. The position is maintained. At this t2 point, the detected load changes (switches) in the decreasing direction beyond the peak point, so that the load determination is enabled and the determination operation for the detected load is started. Next, as the melting of the works w1 and w2 progresses, the repulsive force from the works w1 and w2 to the positive electrode 23 decreases, and at t3, when it is determined that the detected load has decreased to the set load, a high frequency is generated. The operation of the circuit unit 20 is stopped and the welding process is completed. When the welding process is completed, the cooling process is subsequently started. The cooling step is performed for a predetermined time while maintaining the electrode spacing at the set thickness. When the predetermined time ends at t4, the pressurizing drive unit 30 moves the rod 32 upward to open the space between the electrodes. After a series of such operations, one step is completed.

FIG. 6 is an example of a time chart showing an experimental example of the molding process shown in FIG. As the works w1 and w2, two PVCs (polyvinyl chloride) having a thickness of 0.3 mm are laminated and welded to obtain a thickness of 0.40 mm. High-frequency power output, set thickness, and set load are adopted as welding conditions. In FIG. 6, high frequency power (800w) is supplied after the contact is detected at t1. When the electrode spacing reaches the set thickness at t2, the load determination is enabled. When high-frequency heating is continued, the load value indicating the repulsive force with the positive electrode 23 decreases as the works w1 and w2 melt, and this phenomenon is shown to change remarkably in the latter half. Then, when it is determined that the detected load reaches the set load at the time of t3, the supply of high frequency power is stopped and the welding process is completed. Then, after the cooling step is performed in the t3 to t4 period, the space between the electrodes is opened. Even if the heating is stopped and the cooling process is started, the load value continues to decrease. Since the heating time and cooling time can be automatically controlled according to the state of the workpieces w1 and w2 by using the detected load, it is sufficient to set the high frequency output, the set load, and the set thickness, and the setting work can be performed. It will be simplified.

FIG. 7 is a flowchart illustrating the procedure of the welding process I shown in FIG. First, a process of reading the welding conditions input from the input unit 11 or preset and registered in the storage unit 1001 is performed (step S1). Next, the pressurizing drive unit 30 is activated, the press lowering is started (step S3), and the contact determination is performed in the middle of the press lowering (step S5). If it is not determined to be in contact for a predetermined time, it is processed as no work, for example, a warning is given (step S7), while if it is determined to be in contact, pressing is started and high frequency heating is started (step S9). ). Next, one of the conditions such that the electrode spacing reaches the set thickness or, for example, a predetermined time has elapsed from the contact determination time is cleared, and the load determination is enabled (step S11). When the electrode spacing reaches the set thickness, the press lowering is stopped at that point, and control is performed to maintain the position.

After that, the determination process of whether or not the detected load has reached the set load is continued, and when it is determined that the detected load has reached the set load (step S13), high frequency heating is terminated at that point and cooling is performed. It is started (step S15). Next, when the load determination is executed during the cooling period and it is determined that the detected load has sufficiently decreased (step S17), the cooling is completed and the press is raised (opening between the electrodes) (step S19). This completes one step. At the end of each process, the traveling wave and reflected wave, which are the outputs of high-frequency power, and the phase, electric energy, and supply time are displayed on the display unit 25 for monitoring, and further, at the end of the welding process and the cooling process. The electrode spacing and the load may also be displayed on the display unit 25 and stored in the storage unit 1001.

FIG. 8 is a schematic configuration diagram showing a second embodiment of the high-frequency welding apparatus according to the present invention. The parts different from FIG. 1 are the pressure drive unit 30B and the detection unit 40B. The pressurizing drive unit 30B is an application of the servomotor 310B, and is an insulating rod whose position is controlled in the vertical direction with respect to the main body 31B by the rotation position control by the main body 31B containing the servomotor 310B and the servomotor 310B. It is equipped with 32B. The detection unit 40B is arranged adjacent to the main body 31B, for example. The detection unit 40B includes a displacement detection unit 42B and a load detection unit 43B, but does not include a detection unit corresponding to the predetermined thickness detection switch unit 41 in FIG. The displacement detection unit 42B calculates the elevating position of the rod 32B, that is, the electrode spacing from the control position signal of the servomotor 310B, and the load detection unit 43B has a load cell built-in. The load detection unit 43B may employ a mode in which the load is calculated from the torque current value flowing through the servomotor 310B.

FIG. 9 is a time chart of another example for explaining the operation of each part corresponding to each step in the apparatus of FIG. The difference from FIG. 5 of the first embodiment is that the electrode spacing is adjusted by the servomotor 310B. The electrode spacing is adjusted as follows. First, press drive, that is, a position signal for lowering the positive electrode 23 at a predetermined speed is sequentially output to the servomotor 310B, and the positive electrode 23 comes into contact with the upper surface of the work w1 while lowering the positive electrode 23 at a constant speed. It is detected (at t11). Subsequently, in parallel with the high-frequency heating operation, pressurization is continued (ON) by press drive, and when the detected load reaches a predetermined load for press drive, pressurization is temporarily stopped (OFF), and then. When the repulsive force decreases as the works w1 and w2 melt, the lowering due to pressurization starts. After that, the descending operation and the stopping operation are repeated. By such continuous operation, the electrode spacing gradually decreases, and when the set thickness is reached (at t12), the pressurization is stopped, and the position is maintained until t14 when the cooling process is completed and the space between the electrodes is opened. do. When the detected load reaches the set load (at t13), the welding process is completed.

FIG. 10 is a time chart showing an experimental example of the molding process shown in FIG. As the works w1 and w2, two PVCs (polyvinyl chloride) having a thickness of 0.3 mm are laminated and welded to obtain a thickness of 0.40 mm. High-frequency power output, set thickness, and set load are adopted as welding conditions. In FIG. 10, high frequency power (800w) is supplied after the contact is detected at t11. When the set thickness is reached at t12, the load determination is enabled. When it is determined that the detected load has reached the set load at t13, the supply of high-frequency power is stopped and the welding process is completed. Then, after the cooling step is performed in the period from t13 to t14, the space between the electrodes is opened.

FIG. 11 is a flowchart illustrating the procedure of the welding process II shown in FIG. FIG. 11 is different from the flowchart of FIG. 7 in that the processing evaluation process after the completion of the cooling step is mainly added. Since steps S31 to S39 are substantially the same, description thereof will be omitted. When the electrode spacing reaches the set thickness (Yes in step S45, step S49) and the high frequency heating and cooling time is completed in step S51 (step S51, at t14 in FIG. 10), the press raising operation is performed (step S51, at t14 in FIG. 10). Along with step S53), the load is detected and the quality of the load value immediately before opening is determined (step S55). Then, when the load value immediately before opening is lowered to a good level (below the judgment threshold value), the OK judgment is output to the display unit 25 or the like (step S57), while the load value immediately before opening is lowered to an appropriate level. If not, the NG determination is output to the display unit 25 or the like on the assumption that the restored dimension is large (step S59). For the set load at the end of welding and the threshold value at the completion of the cooling process, the relationship between the set load at the end of the welding process and the end of the cooling process and the actually measured thickness in FIG. 4 may be obtained in advance and applied. As a result, it is possible to determine the quality of the welding process with high accuracy.

FIG. 12 is a chart illustrating another method of applying the set load. The chart of FIG. 12 automatically controls the welding process time. That is, it is known that a decrease in load during melting exhibits transient characteristics with respect to the works w1 and w2. Therefore, at two different time points (interval T) after the start of melting, the changes in the detected load in the same time width ΔT are detected as P1 and P2. Then, the elapsed time until the set load is reached can be predicted and calculated from the interval T, the detected loads P1 and P2, and the transient characteristic curve. Therefore, by measuring the predicted time using the timer 105, the end of the welding process is managed, and it is possible to always process a good product without requiring the work of constantly detecting the load. It is also possible to change the output of high frequency power in the middle instead of the prediction setting of the welding time.

Further, the setting at the end of the welding process may be performed by applying the change amount (load change amount) of the load value calculated in the same manner as in FIG. 12 instead of the load value. In this case, the end point of the welding process can be determined by comparing the preset load change value with the load change amount calculated from the sequentially detected detected load calculation. From the interval T in FIG. 12, the detected loads P1 and P2, and the transient characteristic curve, the elapsed time until reaching the set load change amount is predicted and calculated, and the predicted time is measured using the timer 105 to perform the welding process. You can manage the termination. Further, the change amount can be applied to the setting method at the end of the cooling process as in FIG.

In the present embodiment, the output of high-frequency power, the set thickness, and the set load are registered in advance for each type of the welding object, and the welding object can be appropriately selected via the input unit 11 during the work. It may be a mode that can correspond to the object to be welded.

Further, the number of laminated objects to be welded is not limited to two, but may be three or more. Furthermore, it is applicable not only to film materials and sheet materials, but also to heel pad welding technology for car mats.

In the first embodiment, the hydraulic actuator is adopted as the pressurizing drive unit 30, but a pneumatic actuator may be adopted instead.

1,1B high frequency welding device 20 high frequency circuit part 23 positive electrode (electrode)
24 Negative electrode (electrode)
30,30B Pressurized drive unit (displacement drive unit)
32, 32B Rod 40, 40B Detection unit 41 Switch unit for predetermined thickness detection (stopper)
42, 42B Displacement detection unit 43, 43B Load detection unit 100 Control unit 101 High frequency drive control unit 102 Press drive control unit w1, w2 Work (welding object)

Claims (7)

A high-frequency circuit unit that supplies high-frequency power between the opposing electrodes,
A control means for driving the high-frequency circuit unit by sandwiching a welded object in a laminated state between the opposing electrodes.
A displacement drive unit that adjusts the distance between the electrodes,
It is provided with a load detection unit that detects the load between the electrodes.
The control means, wherein after the start of supply of high frequency power, and detects a load signal from the previous SL load detection unit intervals while maintaining the set thickness to between the electrodes, when the load signal detected is reduced to a set load A high-frequency welding device that controls the supply of high-frequency power. A displacement detection unit for detecting the distance between the electrodes is provided.
The high-frequency welding device according to claim 1, wherein the displacement driving unit maintains the set thickness after detecting that the displacement detecting unit matches the set thickness. The high-frequency welding device according to claim 1 or 2, wherein the load detecting unit starts detecting the set load after the distance between the electrodes reaches the set thickness. The high-frequency welding device according to any one of claims 1 to 3, wherein the control means stops the supply of the high-frequency power when the detected load detected by the load detection unit matches the set load. The control means obtains a load change amount from the detected load detected by the load detection unit, and when the load change amount matches the set load change value, any one of claims 1 to 3 for stopping the supply of the high frequency power. The high frequency welding device described in. The high-frequency welding device according to any one of claims 1 to 5, wherein the displacement driving unit waits for a predetermined cooling time to open the space between the electrodes after the welding operation is completed. A step of supplying high-frequency power between the opposing electrodes, pressurizing the welded object laminated between the electrodes, and melting and welding the distance between the electrodes until the set thickness is reached.
After the distance between the electrodes reaches the set thickness, the load between the electrodes is detected while the distance between the electrodes is maintained at the set thickness, and when the detected load drops to the set load, the high frequency power is supplied. High frequency welding method with a process to control.

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