JP4874057B2 - Heat staking equipment - Google Patents

Description

  The present invention has a molded article using a thermoplastic resin having a boss integrally formed by supplying current to a heater chip connected to the secondary side of the transformer, and a fitting hole for fitting with the boss. The present invention relates to a heat caulking device for caulking the object to be bonded, and particularly to a temperature control technique at the start of heat caulking.

2. Description of the Related Art Conventionally, a heat caulking device for fixing a part made of a heat deformable material such as a thermoplastic resin to another part by heat caulking is known.
As a fixing method using a heat caulking device, after positioning a welding boss projecting from one side of a thermoplastic resin component in a mounting hole of another component such as a metal, the welding boss is inserted into the mounting hole and then inserted. The tip is protruded to the other side, and a caulking pin (having a function equivalent to a heater chip) is pressed against the tip, and heated to a predetermined temperature (temperature at which the welding boss is thermally deformed) simultaneously with the start of heat caulking. The welding boss is fixed by being thermally deformed to a diameter larger than the diameter of the mounting hole at the tip of the welding boss. Thereafter, the caulking pin is cooled and cooled down to a predetermined temperature or less, and then the caulking pin is separated from the tip of the welding boss, thereby completing the heat caulking process.

The heater chip adopts various shapes and dimensions in accordance with the thermoplastic resin to be caulked by heat, and it is necessary to set various temperatures for the caulking. The suitability of this temperature setting causes an excessive melting of the thermoplastic resin, and is an important factor affecting the quality of heat caulking.
Accordingly, the inventors of the present application considered that it is important to make the actual heater chip temperature appropriately follow a preset target temperature, and investigated related technologies. We have discovered a technology that can be used in the field of joining (Patent Document 1). Next, an outline of this technique will be described.

  2. Description of the Related Art A pulse heat type apparatus is known as a bonding apparatus used for thermocompression bonding of lead wires such as thick film printed wiring boards and thin film printed wiring boards, and reflow soldering of IC leads and the like to printed wiring boards.

  In this method, a heater chip made of a high resistance material such as molybdenum (MO) is pressed against the bonded portion, and in this state, a pulsed large current is passed through the heater chip to generate Joule heat. A part to be joined is locally heated and melted by heat to be joined. For example, in the case of reflow soldering, the solder sandwiched between a pair of parts to be joined is melted, and then the pulse current is stopped and the part to be joined is cooled and waits for the temperature to fall below the solidification temperature of the solder before joining the heater chip. Separate from the part.

  Therefore, in this type of joining apparatus, a head portion having a raising / lowering drive means for pressing or separating the heater chip from the joined portion, and a pulse for supplying a pulse current that changes in accordance with the heating time of the heater chip. A heat power source. In this case, the pulse heat power source feeds back the temperature of the heater chip, that is, the heater temperature, and controls the heater current so that the heater temperature has a preset time / temperature control characteristic (referred to as a temperature profile).

That is, the heater current (alternating current) is phase-controlled so as to reduce the difference between the target temperature obtained from the temperature profile and the fed back heater temperature, and the heater temperature is made to follow the change in the target temperature.
Japanese Patent Laid-Open No. 11-54906

Consider the case where this technology is diverted to a heat caulking device.
In this technique, the current flowing through the heater chip is controlled to be zero before and after heating according to the temperature profile. That is, after a heat caulking start command comes, current starts to flow through the heater chip, and heating of the heater is started. That is, immediately after the start of the heat caulking operation, the temperature of the heater chip is close to room temperature, and even if the heat caulking operation is continuously performed, the temperature of the heater chip is considerably lowered until the next heat caulking operation is started. It will be.
In other words, after the start of heat caulking, a large current flows through the heater chip in an attempt to follow the set temperature profile, and the large current flowing to the heater chip at the start of heat caulking is subject to heat caulking. The problem of causing excessive melting of the thermoplastic resin is not solved.
The present invention has been made to solve the above-described problems, and as a whole, the current supply to the heater chip is subject to heat staking at the start of heat staking while ensuring the current supply to the heater chip suitable for the overall heat staking operation. An object of the present invention is to provide a heat staking device having a high quality of heat staking by preventing the thermoplastic resin from being excessively melted.

  The heat caulking device according to the present invention is fitted with a molded product using a thermoplastic resin having a boss integrally formed by supplying current to a heater chip connected to the secondary side of the transformer, and the boss. In a heat staking device that heats a member having a fitting hole, the difference between the temperature of the heater chip and the temperature of the heater chip obtained by the measurement means is determined in advance. It is characterized by comprising means for reducing, and adjusting means for increasing / decreasing the energization amount to the heater chip in accordance with the temperature difference reduced by this means.

  The heat staking device according to the present invention includes a molded product using a thermoplastic resin having a boss integrally formed by supplying current to a heater chip connected to the secondary side of the transformer, and the boss and the fitting. A heat caulking device for caulking a to-be-coupled body having a mating fitting hole, wherein the boss is pressed by the heater chip, and after heating and forming, a heat caulking device having a cooling means for the boss. A synchronization signal generator that detects a zero-cross point from the current and generates a synchronization signal based on the zero-cross point, and a current supplied to the primary side of the transformer by increasing or decreasing the input AC current based on the gate signal Separately from a phase control unit to be controlled and an amplification unit that detects a voltage corresponding to the temperature of the heater chip with a thermocouple attached to the heater chip and amplifies the voltage at a predetermined amplification degree A target temperature profile generating unit that receives a temperature and time from the provided input means and generates a target temperature profile defined as a target voltage by the same correspondence relationship between the temperature and voltage in the amplifying unit; and from the amplifying unit The operation amount calculation unit that calculates the operation amount as a voltage according to the difference, and the operation amount from the operation amount calculation unit are adjusted. An overshoot prevention unit that reduces the fluctuation of the operation amount immediately after the start of the heat caulking operation by pulling up to a possible voltage, and the gate signal based on the operation amount reduced from the fluctuation from the overshoot prevention unit. And a phase control signal generation unit for generating.

  The overshoot prevention unit used in the heat staking device according to the present invention comprises a variable resistor and a diode. A predetermined voltage is applied to the variable resistor, and the anode of the diode is connected to a terminal capable of changing the voltage. And the voltage of the difference amount is pulled up via the cathode of the diode.

  According to the present invention, not only the feedback control is used for the temperature control of the heater chip of the heat caulking device, but also the adjustment function for limiting the current supplied to the heater chip according to the feedback amount at the start of the heat caulking operation is provided. The operator can appropriately set the supply current to the heater chip at the start of heat caulking in accordance with the thermoplastic resin to be heat caulked. Therefore, since the supply current to the heater chip after the start of the heat caulking operation does not become excessive, this thermoplastic resin will not be excessively melted, and a heat caulking device with good workability and high heat caulking quality will be provided. Can be provided.

Next, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a heat staking device showing the best mode for carrying out the present invention, FIG. 2 is a schematic block diagram of this heat staking device, and FIG. 3 is a waveform diagram of the main part of the schematic block diagram of FIG. is there.

  In FIG. 1, reference numeral 21 denotes a welding power source that supplies a current for heat caulking, 22 denotes a welding transformer that receives a current from the welding power source 21 and steps down to convert it into a large current, and 23 denotes a welding transformer. This is a welding head that causes an electric current to flow through a heater chip 23a (corresponding to a heat-caulking pin of a conventional example) disposed at the tip of the object to heat-cause an object. Note that the welding transformer 22 has a built-in blower for cooling the object after heat caulking. The heater chip 23a is provided with a thermocouple 23aa and a cooling port (not shown) for a post-molding heat caulking object by heat caulking as a temperature detector for the heat caulking object. The welding head 23 is provided with a welding start operation unit 23b and a cooling stop operation unit 23c.

  Reference numeral 24 denotes a power line for supplying current from the welding power source 21 to the welding transformer 22, a ventilation hose for cooling air from the blower, a signal line from the thermocouple 23aa, a welding start operation unit 23b, and a cooling stop operation unit 23c. 25 is a power line for supplying current from the welding transformer 22 to the welding head 23, a signal line from the ventilation hose for the cooling air from the blower and the thermocouple 23aa, the welding start operation section 23b, and cooling stop. This is a signal line from the operation unit 23c.

  In FIG. 2, 1 is a phase control unit that controls the current supplied to the primary side of the transformer by increasing or decreasing the input AC current based on the gate signal, and 2 (22 in FIG. 1) is a low voltage input AC current. A welding transformer for converting to a large current, 3 (23a in FIG. 1) is heated, and a heater chip that heats and caulks the object by pressing, 4 (23aa in FIG. 1) depends on the temperature of the heater chip 3. The thermocouple 5 for detecting the detected voltage 5 is an amplifying section mainly comprising a differential amplifier for amplifying the output voltage of the thermocouple 4 with a predetermined amplification degree.

  Also, 6 is a parameter setting unit for setting a temperature and time as parameters for setting a temperature profile as an input means provided separately, and a solidification temperature unique to the thermoplastic resin to be heat caulked, and 7 is a parameter. In response to the temperature and time from the setting unit 6, a target temperature profile generation unit that generates a target temperature profile defined as a target voltage by the same correspondence as the correspondence between the temperature and voltage in the amplification unit 5, and 8 from the amplification unit 5 Receiving the detected voltage amplified according to the temperature of the heater chip 3 and the amplified target voltage from the target temperature profile generator 7 and calculating the difference and using the manipulated variable for generating the phase control signal PID control unit 11 that calculates and outputs the value, and 11 pulls up the operation amount from PID control unit 8 with an adjustable pull-up voltage. Finally a overshoot preventing portion for pressing the overshoot of the temperature of the heater chip 3 by gentle manipulation amount of change of from the start to the end of Rinetsukashime operation. Note that this pull-up voltage can be adjusted, and heat caulking is performed using an actual heat caulking object, and an experiment is performed according to the heat caulking object.

  Reference numeral 9 denotes a synchronization signal generator that detects a zero-cross point from the input alternating current and generates a synchronization signal based on the zero-cross point. Reference numeral 10 denotes a carrier signal that is generated based on the synchronization signal from the synchronization signal generator 9. And a phase control signal generation unit that receives the adjusted operation amount matched to the heat caulking object in the overshoot prevention unit 11 and generates a gate signal as a phase control signal by comparing the carrier signal and the adjusted operation amount. It is.

Reference numeral 12 denotes a detected voltage amplified according to the temperature of the heater chip 3 from the amplifying unit 5, a temperature rise time t 1 from the target temperature profile generation unit, a holding time t 2, and a resin from the resin solidification temperature setting unit 11. In response to the solidification temperature, the target voltage is obtained by the same correspondence as the correspondence between the temperature and the voltage in the amplifying unit 5, and after the temperature rise time t1 and the holding time t2 have elapsed, the detected voltage is compared with the target voltage to perform heat caulking A comparison unit for detecting that the set temperature has reached the set solidification temperature; 13 is a notification unit for receiving solidification temperature arrival detection from the comparison unit 12 and reporting the solidification of the thermoplastic resin by a buzzer sound, etc. After the elapse of the rising temperature t1 and the holding time, the cooling air starts to be sent to the heat caulking object, and after confirming the notification, the cooling air comprising a blower that stops sending the cooling air by the cooling stop signal. It is a part.
The start signal is a signal for starting the heat caulking operation and is generated when the welding start operation unit 23b is operated. The cooling stop signal is a signal for stopping the blower and stopping the cooling, and the cooling stop operation unit. It is generated when 23c is operated.

  Next, the operation of such a heat caulking device will be described. At this time, the waveform diagram of the main part shown in FIG. 3 and the temperature profile diagram during operation of the heat caulking device shown in FIG.

[Operation before heat staking operation]
Since the start signal is generated by the operation of the welding start operation unit 23b and the heat caulking is started, the gate signal output from the phase control signal generation unit 10 is turned off in all periods. Since the phase control unit 1 is not turned on, an alternating current does not flow on the primary side of the transformer 2 even if the input alternating current power source is connected to the heat caulking device. Therefore, since no alternating current is generated on the secondary side of the transformer 2, no current flows to the heater chip 3, so that the heater chip 3 does not generate heat.

[Parameter settings]
Before starting the heat staking operation, the parameter setting unit 6 sets the following parameters in accordance with the heat staking object.
There are two temperature parameters: a heat caulking temperature T2 where the temperature of the heater chip 3 is determined according to the heat caulking object and a solidification temperature T3 which is determined according to the heat caulking object, and a time parameter is the heat caulking temperature T2. Holding time t2 and the temperature rise time t1 from the heat caulking operation start temperature T1 to the heat caulking temperature T2, and the cooling parameter is the pressure of the cooling air.

  Here, the heat caulking operation start temperature T1 is the temperature in the room where the heat caulking device is installed before the start of using the heat caulking device, and when the heat caulking operation is continuously performed, cooling is performed after the previous heat caulking operation. This is the temperature after Accordingly, in either case, the temperature T1 is detected by the thermocouple 4 and is not set by the parameter setting unit 6.

  Based on these parameters, the target temperature profile generation unit 7 generates a target temperature profile. That is, from the start of the heat caulking operation until the heat caulking temperature T2 is reached, the temperature is increased linearly with the result obtained by dividing the temperature difference between the heat caulking operation start temperature T1 and the heat caulking temperature T2 by the temperature rise time t1. After reaching the heat caulking temperature T2, this temperature is held for the holding time t2 ((a) in FIG. 4). The temperature profile data is composed of voltages for comparison with the voltage detected by the PID controller 8 according to the temperature of the heater chip 3 by the thermocouple 4 as described above.

  Here, the heat caulking operation start temperature T1 is the temperature in the room where the heat caulking device is installed before the start of using the heat caulking device, and when the heat caulking operation is continuously performed, cooling is performed after the previous heat caulking operation. This is the temperature after Accordingly, in either case, the temperature T1 is detected by the thermocouple 4 and is not set by the parameter setting unit 6.

  Based on these parameters, the target temperature profile generation unit 7 generates a target temperature profile. That is, from the start of the heat caulking operation until the heat caulking temperature T2 is reached, the temperature is increased linearly with the result obtained by dividing the temperature difference between the heat caulking operation start temperature T1 and the heat caulking temperature T2 by the temperature rise time t1. After reaching the heat caulking temperature T2, this temperature is held for the holding time t2 ((a) in FIG. 4). The temperature profile data is composed of voltages for comparison with the voltage detected by the PID controller 8 according to the temperature of the heater chip 3 by the thermocouple 4 as described above.

[Heat staking action]
Next, the operation of the heat caulking device when the heat caulking operation is actually performed will be described.
The operator first turns on the power of the entire heat caulking device and sets various parameters according to the object. At this time, the pull-up voltage is set appropriately by operating the variable resistor in the overshoot prevention unit 11 at the same time. For the setting of the pull-up voltage, it is preferable to use a value empirically obtained in accordance with the thermoplastic resin to be heat caulked.
Then, the welding head 23 is moved while being held by hand, and the welding head 23 is aligned so that the heater chip 23a is aligned with a boss (not shown) which is a heat-caulking portion of the object to be heat-caulked. Then, the operator senses that the welding head 23 has reached the boss.

  After detecting the arrival at the boss, the operator operates a welding start operating portion 23b provided on the welding head 23 to generate a start signal. The start signal is input to the target temperature profile generation unit 7 and the phase control signal generation unit 10 to start the heat caulking operation.

  Upon receiving this start signal, the target temperature profile generation unit 7 sends voltage data as the target temperature profile generated previously to the PID control unit 8 every time. On the other hand, the phase control signal generation unit 10 receives the start signal, generates and outputs a gate signal that is a phase control amount of the phase control unit 1. This gate signal is sent to the phase controller 1 until the holding time t2 elapses from the start of the heat caulking operation through the temperature rise time t1.

  Both the target voltage as the target temperature from the target temperature profile generation unit 7 and the detection voltage corresponding to the temperature of the heater chip 3 from the amplification unit 5 are sent to the PID control unit 8. These voltage values are compared by the PID control unit 8 to obtain a difference amount, and an operation amount for generating a phase control signal corresponding to the difference amount is calculated (operation amount a shown by a dotted line in FIG. 3). The manipulated variable is sent to the overshoot prevention unit 11, where the manipulated variable voltage is raised by the pull-up voltage (difference c in FIG. 3). Then, the operation amount (the operation amount a shown by the solid line in FIG. 3) with this voltage raised is sent to the phase control signal generator 10. In addition to the manipulated variable, the phase control signal generation unit 10 receives a synchronization signal from the synchronization signal generation unit 9. A sawtooth carrier signal is generated based on this synchronization signal (FIG. 3C).

  The phase control signal generation unit 10 compares the carrier signal with the operation amount (operation amount a), and generates a gate signal that turns on the phase control unit 1 when the operation amount i is smaller than the carrier signal. (FIG. 3 (d)). This gate signal has a shorter ON period than that generated from the operation amount (operation amount a) before adjustment (d in FIG. 3D). The phase control unit 1 is controlled by this gate signal. When the pulse width of this gate signal is large according to the operation amount (when the difference amount is large), the ON period of the phase control unit 1 becomes long. Therefore, since the input AC current flowing on the primary side of the welding transformer 2 is limited by the control of the phase control unit 1 by this gate signal, the current induced on the secondary side of the welding transformer 2 is also limited after all.

  When the phase control unit 1 receives this gate signal, the difference between the heat caulking operation start temperature T1 and the heat caulking temperature T2 is large at first. 2 also flows for a relatively long time on the primary side. Then, an alternating current is induced on the secondary side of the welding transformer 2 by the alternating current on the primary side of the welding transformer 2, so that an alternating current flows through the heater chip 3 for a relatively long period. The heater chip 3 generates heat by this alternating current, and the heat staking operation is started by heating the boss.

  The temperature of the boss, which is a heat caulking object, is always detected as a voltage corresponding to the temperature by a thermocouple 4 attached to the heater chip 3, and this detected voltage is predetermined by an amplifying unit 5 composed mainly of a differential amplifier. And sent to the PID control unit 8. Then, the operation amount is obtained by the PID control unit 8 as described above, and this operation amount is sent to the phase control signal generation unit 10 via the overshoot prevention unit 11, where the gate signal is generated based on this operation amount. Generated.

Such control is repeatedly executed after the temperature rise time t1 until the holding time t2 of the heat caulking temperature T2 elapses. The temperature of the heater chip 23a is set by the parameter setting unit 6 and generated by the target temperature profile generation unit 7. The target temperature profile set will be realized. While the heater chip 3 is energized, the worker continues to press the boss with an appropriate force by the welding head 23 while heating the boss. During this time, the actual temperature change of the heater chip 3 is slightly overshooting the set temperature profile (a in FIG. 4) (a in FIG. 4).
As a result, the boss is formed.

[Cooling operation]
Finally, the cooling operation will be described.
As described above, the boss is formed. Then, in order to cool the boss after molding, energization to the heater chip 3 is stopped, and at the same time, the cooling unit 14 is driven to start cooling the boss after molding.

  At this time, the comparison unit 12 receives the detected voltage amplified in accordance with the temperature of the heater chip 23a from the amplification unit 5 and the resin solidification temperature T3 from the parameter setting unit 6, and then the temperature and voltage of the amplification unit 5 are detected. The target voltage is obtained by the same correspondence relationship as the correspondence, and comparison between the detected voltage and the target voltage is started. After the start of the comparison, after a certain time has elapsed in the material and outer shape of the target object, the temperature of the boss after molding reaches the set resin solidification temperature T3, so this state can be detected.

At this time, a solidification temperature arrival signal is generated by the comparison unit 12 and sent to the notification unit 13, and the notification unit 13 sounds a buzzer to notify the operator that the boss after molding has reached the solidification temperature. Upon receiving this notification, the operator operates the cooling stop operation unit 23 c attached to the welding head 23 to generate a cooling stop signal and sends it to the welding power source 21. This cooling stop signal is sent to the cooling unit 14, the blower of the cooling unit 14 is stopped, the cooling air is stopped, and the cooling of the boss after molding is finished. Then, after the operator senses that the cooling air has stopped, the operator raises the welding head 23 from the molded boss and separates it.
As described above, a series of heat caulking operations is completed.

  In the present embodiment, the operator performs the heat caulking by holding the welding head in his / her hand, but automating the vertical movement of the welding head and the start / stop of cooling without changing the gist of the present invention. It is possible to respond. In this case, the welding head may be provided with a vertical movement mechanism such as an air cylinder or a motor, an electromagnetic valve for controlling the cooling operation, and the like, and these controls are preferably formed as one control block.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the heat crimping apparatus which shows the best form for implementing this invention. The schematic block diagram of the heat crimping apparatus of FIG. The wave form diagram of the principal part of the general | schematic block of the heat crimping apparatus of FIG. The figure which shows the temperature profile at the time of operation | movement of the heat crimping apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Phase control part 2 Transformer 3 Heater chip 4 Thermocouple 5 Amplification part 6 Parameter setting part 7 Target temperature profile generation part 8 PID control part 9 Synchronization signal generation part 10 Phase control signal generation part 11 Resin coagulation temperature setting part 12 Comparison part 13 Notification unit 14 Cooling unit 21 Welding power source 22 Welding transformer 23 Welding head 23a Heater chip 23b Welding start operation unit 23c Cooling stop operation unit

Claims (2)

A molded product using a thermoplastic resin having a boss integrally formed by supplying a current to a heater chip connected to the secondary side of the transformer, and a joined body having a fitting hole fitted to the boss; In the heat staking apparatus that heats and squeezes the boss, presses the boss by the heater chip, and has a cooling means for the boss after heating and molding,
A synchronization signal generator that detects a zero-cross point from the input AC current and generates a synchronization signal based on the zero-cross point;
By increasing / decreasing the input AC current based on the gate signal, the transformer 1
A phase control unit for controlling the current supplied to the next side;
An amplifying unit that detects a voltage corresponding to the temperature of the heater chip with a thermocouple attached to the heater chip, and amplifies the voltage at a predetermined amplification degree;
A target temperature profile generation unit that receives a temperature and time from an input unit provided separately, and generates a target temperature profile that is defined as a target voltage by the same correspondence relationship between the temperature and the voltage in the amplification unit;
An operation amount calculation unit that calculates a difference between a detection voltage from the amplification unit and a target voltage from the target temperature profile generation unit, and calculates an operation amount as a voltage according to the difference;
An overshoot prevention unit that reduces the fluctuation of the operation amount immediately after the start of the heat caulking operation by pulling up the operation amount from the operation amount calculation unit to an adjustable voltage;
A phase control signal generation unit that generates the gate signal based on an operation amount in which variation from the overshoot prevention unit is reduced;
Heat staking apparatus you comprising: a. The overshoot prevention unit includes a variable resistor and a diode, applies a predetermined voltage to the variable resistor, connects the anode of the diode to a terminal capable of changing the voltage, and passes through the cathode of the diode. heat staking apparatus of claim 1 Symbol mounting, characterized in that pulling up the voltage of the difference amount.

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