JP6137543B2 - Thermal processing method and apparatus - Google Patents

Description

  The present invention relates to a thermal processing method suitable for thermal caulking of resin parts and the like, and a thermal processing apparatus used for this method.

  In a reflow soldering apparatus that has been widely used conventionally, a heater chip is heated while being pressed against a work (target to be soldered) through a spring to melt the solder. Then, when the predetermined heating end time is reached, the heating is stopped (or the temperature is lowered) and the heater chip is raised after the solder is solidified (Patent Document 1).

  It has also been proposed to provide a stopper that restricts the lowering of the heater chip on the lifting head in order to hold the heater chip up and down on the lifting head and prevent the spring force of the spring pressing the heater chip from crushing the workpiece. (Patent Document 2).

JP 2011-110574 A JP 2007-173522 A

  The conventional apparatus having the spring type lifting head that presses down the heater chip with the spring as described above is premised on use for reflow soldering. In reflow soldering, the heater chip is pressed against the workpiece, and the amount of descending as the solder melts is small. Therefore, the change in the pressing force (spring restoring force) of the heater chip is extremely small. For this reason, it was thought that there was no problem in soldering.

  However, in the case of heat caulking of resin parts, the deformation (lowering amount) of the heater chip is large because the deformation due to softening or melting of the resin is large, and the change in the spring force when the heater chip is pressed down becomes large. For this reason, there has been a problem that the finish of heat processing such as heat caulking becomes uneven and the finish is not stable. In soldering, depending on the workpiece, the displacement of the heater chip may be large, and it has been found that there are similar problems in this case.

  The present invention has been made in view of such circumstances, and when the amount of displacement of the heater chip is large due to thermal processing such as thermal caulking or soldering of resin parts, the amount of change in the pressing force of the heater chip against the workpiece is reduced. It is a first object to provide a thermal processing method that can reduce the amount, make the finish uniform, and stabilize the finish. It is a second object of the present invention to provide a thermal processing apparatus that is directly used for carrying out this method.

According to the present invention, the first object is
An elevator head that can be moved up and down with respect to the base and holds the heater chip, which is biased downward by a spring, is held in a vertically movable manner, and the elevator head is lowered to press the heater chip against the work piece instantaneously by heating a thermal processing method of heating processing the workpiece,
a) Lowering the elevating head to stop the lowering of the heater chip when the pressing force of the heater chip against the work reaches a predetermined pressure, and thermally processing the work,
b) When the pressing force on the workpiece becomes a predetermined pressure or less due to the lowering of the heater chip during the thermal processing of the workpiece, the lifting head is lowered to perform the thermal processing with the pressing force within a predetermined pressure range.
c) Repeat the above a) to b),
A thermal processing method characterized by
Is achieved.

The second purpose is
An elevator head that can be moved up and down with respect to the base and holds the heater chip, which is biased downward by a spring, is held in a vertically movable manner, and the elevator head is moved downward to press the heater chip against the workpiece instantaneously. In a heat processing apparatus that heats the workpiece by heat generation;
A spring-pressurized lifting head that presses the heater chip against the workpiece via a spring;
A spring force detection sensor for detecting a spring pressure applied to the work of the heater chip;
A motor that drives the lifting head to move up and down;
A motor drive controller for controlling the motor;
A temperature sensor for detecting the heater chip temperature;
Temperature control means for controlling the heating current supplied to the heater chip;
While controlling the raising and lowering of the elevating head and the temperature of the heater chip, when the spring force detected by the spring force detection sensor reaches a predetermined pressure due to the lowering of the elevating head, the heater chip is instantaneously heated, and the heater chip accompanying the thermal processing of the workpiece When the spring force falls below a predetermined pressure due to the lowering, the lifting head is lowered and the lifting head is lowered intermittently so as to keep the spring force within a predetermined pressure range. Main control means for terminating the thermal processing when the pressure does not fall below the predetermined pressure;
A thermal processing apparatus comprising:
Is achieved.

According to the first invention, during the thermal processing of the workpiece, the workpiece is softened or melted by heating the heater chip, since the thermal processing is performed while lowering the lifting head so that the pressing force of the heater chip on the workpiece does not become a predetermined pressure or less. Then, even if the heater chip is lowered and the spring force is reduced by this lowering, the lifting head is lowered so that the pressing force does not become a predetermined pressure or less. For this reason, the pressing force of the heater chip against the workpiece does not become excessive, the finish of the thermal processing can be made uniform, and the finish can be stabilized.
Further, it is possible to perform thermal processing while lowering the elevating head while monitoring the pressing force of the heater chip against the workpiece and maintaining the pressing force at a predetermined pressure or higher. In this case, the lowering of the lifting head is stopped when the pressing force reaches a predetermined pressure, and the lifting head is lowered when the pressing force becomes lower than the predetermined pressure due to the lowering of the heater chip accompanying the thermal processing of the workpiece. Thus, the lowering is controlled discontinuously, so that the pressing head is detected and the lifting head is lowered intermittently, so that the pressing force can be controlled with high accuracy.

  For this reason, it becomes suitable for thermal processing such as processing of a heat caulking portion of a resin having a large thermal deformation or soldering of a portion where the sinking of the heater chip is large. According to the second invention, a thermal processing apparatus used directly for carrying out the first invention is obtained.

The perspective view of the heat processing apparatus which is one Example of this invention Partial cross-sectional side view showing the pressurization lifting head of this device Similarly, functional block diagram of this device Flow chart of the operation of this device Diagram showing an application example of this thermal processing method The figure which shows the other example of application of this heat processing method The figure which shows the other example of application of this heat processing method

In the present invention, the thermal processing can be terminated when the pressing force does not fall below a predetermined pressure due to the lowering of the heater chip accompanying the thermal processing of the heated work of the heater chip ( Claim 2 ). The pressing force of the heater chip against the work can be obtained by detecting the spring force of the spring housed in the lifting head and pressing the heater chip ( Claim 3 ). The pressing force, a change in the compression of the spring is detected by the photo sensor, the amount of this compression can be made to turn on or off when a predetermined amount corresponding to the predetermined pressing force (claim 4). For example, the displacement of the heater chip relative to the elevating head is fixed to a light sensor and a light receiving body fixed to the elevating head and a rod that holds the heater chip so that the heater chip can be raised and lowered. The photosensor is configured to turn on when the pressing force of the heater chip falls within a predetermined pressure range and to turn off when the pressure becomes equal to or lower than the predetermined pressure. I can do it.

The workpiece may be, for example, a resin part having a heat crimping portion, and the heater chip may heat the heat crimping portion ( claim 5 ). For example, the present invention can be applied to one in which the tip of a resin boss that fixes a resin component to a wiring board is heat-caulked (Staking), and one in which a lens is assembled into a resin component and heat-caulked (Swaging). It can also be applied to a camera module (image sensor) that is reflow soldered to a circuit board such as an FPC.

  1 and 3, reference numeral 10 denotes a main control means (main controller), 12 denotes a power source, and 14 denotes a welding machine. Reference numeral 16 denotes a power switch provided in the main control means 10 (FIG. 1). The main controller 10 includes a control unit 10A, a motor driver 10B, and a display panel 20 shown in FIG. The control unit 10A is formed by a CPU. The display panel 20 has a function as a display unit 20A for displaying a menu screen, various data and setting values (including an allowable range of setting values) associated with thermal processing, and a transparent touch sensor provided on the surface thereof. It has the function of the setting part 20B which is an input means which consists of (not shown) (FIG. 3). Various setting values to be described later are set from the setting unit 20B.

  As shown in detail in FIG. 2, the welding machine 14 is supported by a base 22, a support column 24 that stands vertically from the support base 22, and can be lifted and lowered by the motor 24 (FIG. 2). It has an elevating head 28, a rod 30 that is held by the elevating head 28 so as to be movable up and down and protrudes downward, and a heater chip (tool) 32 fixed to the lower end of the rod 30. The rod 30 is urged downward by a coil spring 36 loaded in a cylinder 34 fixed to the elevating head 28.

  The motor 26 is a stepping motor or a servo motor, and the position of the elevating head 28 can be feedback controlled by the amount of rotation. That is, the rack 26A is fixed to the column 24, and the worm gear 26B meshing with the rack 26A is rotationally driven by the motor 26 (FIG. 2). By the forward / reverse rotation of the worm gear 26B, the elevating head 28 moves up and down with respect to the rack 26A and the column 24 integrated therewith.

  The upper end of the coil spring 36 is supported by a cap 38 that is a spring force adjusting means screwed onto the upper end of the tube 34. The lower end of the coil spring 36 is supported by a pressure sensor 40 that is a spring force detection sensor attached to the upper end of the rod 30. For this pressure sensor 40, an appropriate sensor from various detection principles such as a strain gauge (load cell), a piezoelectric element, and a pressure sensitive diode is used. A plate 42 as a stopper serving as a lower limit position setting member is fixed to the rod 30, and this plate 42 is positioned in contact with the inner bottom wall of the elevating head 28 when the rod 30 is lowered (position in FIG. 2).

  The heater chip 32 is made of an electric resistance material that is formed in a substantially U shape by forming a slit that opens upward, and generates heat instantaneously by passing a current between both ends. The heater chip 32 is connected to the secondary side of the welding transformer 12A (FIG. 3) accommodated in the power supply unit 12 by a weld cable 44 (FIG. 1).

Further, the power supply unit 12 includes a current control unit 12 </ b> B serving as a temperature control unit for the heater chip 32. The current control unit 12B controls the temperature of the heater chip 32 based on the temperature command P ₁ by the control section 10A of the main controller 10 outputs. That is, the current control unit 12B is fed back with the heater chip temperature θ detected by the thermocouple 46 (FIG. 3) fixed near the tip of the heater chip 32 so that the heater chip temperature θ matches the temperature command P _1. The pulse current P ₂ whose pulse width is controlled is sent to the welding transformer 12A. Welding transformer 12A causes the feed heating the heater chip 32 by boosting the pulse current P _2.

Motor driver 10B controls the motor 26 based on the rotation command Q ₁ by the control unit 10A outputs. That motor driver 10B rotates the predetermined rotation amount by the motor 26 in the forward or reverse rotational direction by the rotation command Q _1. Here, the motor 26 is a stepping motor or a servo motor, and the height of the elevating head 28 is accurately controlled by the amount of rotation thereof.

  Reference numeral 48 denotes a workpiece to be heated. As shown in FIG. 5, the work 48 includes a resin boss 52 (Plastic Boss) 52 integrally formed on a resin equipment chassis (Chassis) 50 and a printed wiring board (PWB, Printed Wiring Board). 54 is passed through the mounting hole. The heater chip 32 is pressed against the projecting end (upper end) of the boss 52 and heated to melt and thermally deform the tip of the boss to be crushed and coupled in a rivet shape. In this case, the pressing surface of the heater chip 32 is formed with a concave portion 56 that matches the shape of the boss 52. FIG. 5A shows the state before thermal processing, and FIG. 5B shows the state after thermal processing.

The controller 10A of the main controller 10 receives a pressing force (compression pressure) R of the spring 36 detected by the pressure sensor 40, and this pressing force R is set to a predetermined set pressure (predetermined pressure) R ₀ (or its allowable _value ). The motor 26 is controlled so that the upper limit pressure of the range is reached. That is, the direction and amount of rotation of the motor 26 are instructed to the motor driver 10B, and the motor driver 10B controls the motor 26 according to this instruction.

Next, the operation will be described with reference to FIG. When the power switch 16 of the main controller 10 is turned on, the CPU is activated and a menu screen is displayed on the display panel 20. The operator selects “data setting” on the menu screen and sets various data (setting values). The data set here is mainly data corresponding to the pressing force, heating temperature, thermal processing end condition, etc. of the workpiece 48. In this embodiment, the end condition is that the pressing force R of the spring 36 is reduced to the set value R ₀ when the heater chip 32 is lowered while melting the resin boss 52 (FIG. 5) with the lifting head 28 fixed. Do not do. By detecting the thermal processing end condition, the heating of the heater chip 32 is stopped, and after cooling, the elevating head 28 is raised.

  Prior to the start of thermal processing, the rod 30 of the heater chip 32 is always pressed downward by the spring 36, and the plate 42 serving as a stopper is held at the lower limit position by contacting the inner bottom wall of the elevating head 28. Here, the spring force (pressing force, compression pressure) of the spring 36 is initially set by a cap 38 serving as a spring force adjusting means. That is, the spring force of the spring 36 is adjusted by rotating the cap 38, and an initial setting is made so that the detection value of the pressure sensor 40 for detecting the spring force becomes a predetermined value.

  When the data setting and the spring force setting of the spring 36 are completed, the control unit 10A including the CPU of the main controller 10 lowers the elevating head 28 by the motor 26, and accordingly lowers the heater chip 32 (step S100). When the heater chip 32 comes into contact with the workpiece 48, the plate 42 serving as a stopper of the rod 30 is separated from the inner bottom wall of the lifting head 28, and the lifting head 28 continues to descend while the positions of the workpiece 48 and the rod 30 are fixed. As the elevating head 28 is lowered, the cylinder 34 integrated with the elevating head 28 and the cap 38 screwed into the upper end of the cylinder 34 are also lowered, so that the spring 36 is compressed.

For this reason, the compression force of the spring 36 becomes the pressing force of the heater chip 32, that is, the pressing force R against the work 48. The elevating head 28 is lowered until the detected pressing force R reaches the set pressure R ₀ (or its upper limit value) (S102). When the set pressure R ₀ (or its upper limit value) is reached, the motor 28 is stopped, and accordingly the lowering of the elevating head 28 is stopped (S104). The control unit 10A sends the temperature command P ₁ to the power supply unit 12 to generate heat cheetahs chip 32, to hold the temperature to the set temperature (S106).

When the resin boss 52 of the workpiece 48 is melted by the heat generated by the heater chip 32, the heater chip 32 is lowered by the spring 36 in the elevating head 28, so that the spring 36 extends and the detection pressure (pressing force) R of the pressure sensor 40 decreases. (S108). When the control unit 10A detects that the pressure R is equal to or lower than the set pressure R ₀ (or the lower limit value of the allowable range of the set pressure R ₀ ), the control unit 10A starts the motor 26 and lowers the lifting head 28 ( S100). In this way, the operations in steps S100 to S108 are repeated. In step S108, when the pressing force R does not become equal to or lower than the set pressure R ₀ (or its lower limit value), the control unit 10A stops heating the heater chip 32 (S110), and the temperature θ of the cheetah chip 32 is changed to the resin boss. After cooling to a curing temperature θ _{0 of} 52 or lower (S112), the elevating head 28 is raised (S114). Then, the next work 48 is replaced, and the above operation is repeated.

  In the first embodiment, the pressure sensor 40 detects the applied pressure of the spring 36. However, instead of this, the compression amount of the spring 36 may be detected. For example, a photosensor 40A shown in FIG. 2 can be used. The photosensor 40A is composed of a light emitter (light emitting diode) and a light receiver (light sensor) fixed to the inner wall of the elevating head 28, and a light shielding plate 40a fixed to the rod 30 is interposed between the light emitter and the light receiver. Enter / exit.

By appropriately setting the relative mounting position between the photosensor 40A and the light shielding plate 40a, it is possible to detect that the compression amount of the spring 36 has reached the compression amount corresponding to the predetermined set pressure _R0. is there.

  FIG. 6 shows a case where the present invention is applied to a work 48A for assembling a lens on a resin part. (A) of the figure shows before heat processing, and (B) shows after heat processing. In this figure, 60 is a cylindrical resin case, and 62 is a lens fixed to the opening of the resin case 60. The opening edge of the resin case 60 protrudes upward from the outer periphery of the lens 60, and the heater chip 32A is pressed against the protruding portion 64 for heat caulking. In this case, an annular recess 66 that covers the protrusion 62 is formed in the heater chip 32A. In the second embodiment, a heater chip 32A is used instead of the heater chip 32 in the first embodiment described with reference to FIGS.

  FIG. 7 shows a case where the present invention is applied to the assembly of a camera module. In this figure, reference numeral 70 denotes an image sensor, which is held by a holder 72. The output terminals of the image sensor 70 are arranged on the upper surface of the holder 72. These output ends are aligned with the corresponding electrode rows of the flexible printed circuit board (FPC) 74, and solder (cream solder or solder plating) sandwiched between both electrodes. Etc.) 76 is subjected to reflow soldering.

  In this case, the heater chip 32B is applied to the upper surface of the FPC 74 from above and the solder 76 is heated and melted. However, the sinking amount of the heater chip 32B becomes relatively large due to thermal deformation of the FPC 74 and melting of the solder 76. Therefore, the heater chip 32B is used instead of the heater chip 32B of the first embodiment. In this case, the control may be performed in the same manner as in the first embodiment.

10 Main control means (main controller)
10B Motor driver (motor drive controller)
12 Power supply unit 12B Current control unit (temperature control means)
DESCRIPTION OF SYMBOLS 14 Welding machine 22 Base 24 Support | pillar 26 Motor 28 Lifting head 30 Rod 32, 32A, 32B Heater chip 36 Spring 40 Pressure sensor (spring force detection sensor)
40A Photosensor 46 Thermocouple (Temperature Sensor)
48, 48A, 48B Workpiece R Pressing force R ₀ Set pressure (predetermined pressure)

Claims (7)

A heater chip that is spring-biased downward is held on a lift head that can be lifted and fixed with respect to the base so as to move up and down, and the lift head is lowered to press the heater chip against the workpiece and instantaneous by heating a thermal processing method of heating processing the workpiece,
a) Lowering the elevating head to stop the lowering of the heater chip when the pressing force of the heater chip against the work reaches a predetermined pressure, and thermally processing the work,
b) When the pressing force on the workpiece becomes a predetermined pressure or less due to the lowering of the heater chip during the thermal processing of the workpiece, the lifting head is lowered to perform the thermal processing with the pressing force within a predetermined pressure range.
c) Repeat the above a) to b),
The thermal processing method characterized by the above-mentioned. The thermal processing method according to claim 1 , wherein in step b), the thermal processing is terminated when the pressing force does not become a predetermined pressure or lower due to the lowering of the heater chip accompanying the thermal processing of the workpiece. The thermal processing method according to claim 1, wherein the pressing force of the heater chip against the workpiece is obtained by detecting a spring force of a spring that is housed in a lifting head and depresses the heater chip . The displacement of the heater chip relative to the elevating head is determined between a light sensor and a photosensor fixed to the elevating head, and a rod that holds the heater chip so that the heater chip can be raised and lowered. The thermal processing according to claim 1, wherein the photosensor is turned on when the pressure of the heater chip is within a predetermined pressure range and turned off when the pressure is below a predetermined pressure. Method. The thermal processing method according to claim 1, wherein the workpiece is a resin part having a thermal crimping portion, and the heater chip thermally processes the thermal crimping portion.   An elevator head that can be moved up and down with respect to the base and holds the heater chip, which is biased downward by a spring, is held in a vertically movable manner, and the elevator head is moved downward to press the heater chip against the workpiece instantaneously. A heat processing apparatus for heat-processing the work by generating heat;
  A spring-pressurized lifting head that presses the heater chip against the workpiece via a spring;
  A spring force detection sensor for detecting a spring pressure applied to the work of the heater chip;
  A motor that drives the lifting head to move up and down;
  A motor drive controller for controlling the motor;
  A temperature sensor for detecting the heater chip temperature;
  Temperature control means for controlling the heating current supplied to the heater chip;
  While controlling the raising and lowering of the elevating head and the temperature of the heater chip, when the spring force detected by the spring force detection sensor reaches a predetermined pressure due to the lowering of the elevating head, the heater chip is instantaneously heated, and the heater chip accompanying the thermal processing of the workpiece When the spring force falls below a predetermined pressure due to the lowering, the lifting head is lowered and the lifting head is lowered intermittently so as to keep the spring force within a predetermined pressure range. Main control means for terminating the thermal processing when the pressure does not fall below the predetermined pressure;
A thermal processing apparatus comprising:   7. The thermal processing apparatus according to claim 6, wherein the main control means terminates the thermal processing when the spring force does not fall below a predetermined pressure due to the lowering of the heater chip accompanying the thermal processing of the workpiece.

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