JP4831685B2 - Repair method for heat caulking - 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 operation for caulking the object to be bonded, and particularly to a method for repairing a defective heat caulking portion caused by problems such as alignment when performing 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 according to the thermoplastic resin to be heat squeezed, and it is necessary to properly position the heater chip on the heat staking part, and the temperature required for the heat staking is also various. Must be set to The suitability of this alignment and temperature setting has the disadvantage that the quality of the heat-caulking is deteriorated due to the bias of the heat-caulking part and the excessive melting of the thermoplastic resin. In addition, there is a drawback that a defect that affects the quality of heat caulking occurs due to a work mistake. Needless to say, it is necessary to develop technology to prevent such defects from occurring, but on the other hand, making it possible to use it as a non-defective product by repairing it reduces production costs and reduces environmental damage. Technology development that repairs defective products and makes them usable is also an important issue in terms of reducing the amount of waste.

  Therefore, the inventors of the present application have developed technology from the viewpoint of how to repair a defective heat caulking part and regenerate it as a non-defective product on the premise that the above-mentioned defects occur to some extent in the heat caulking work. Decided to proceed. And when related technology was investigated first, it did not come to discover the literature described about the repair method of the defective heat caulking part using a direct heat caulking apparatus.

For this reason, although it was a simple method, the idea came to the idea that the thermoplastic resin could be repaired by utilizing the feature of melting when it reaches a predetermined temperature by heating.
In order to solve the above-mentioned problems, the present invention is made from such a viewpoint, and removes a boss after welding which becomes a defective caulking portion, and from the same thermoplastic resin in the same volume as the removed boss after welding. It is an object of the present invention to provide a method for easily repairing a heat caulked portion by reheating caulking of the pellet and the remaining boss using the resulting pellet.

The method for repairing a heat caulking portion 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, and a cover having a fitting hole for fitting with the boss. A method for repairing a defective caulking portion that occurs when a bonded body is caulked with heat, and is characterized by comprising the following steps.
a) Step of removing the defective caulking portion from the surface of the bonded body b) Step of preparing a pellet made of the same thermoplastic resin as the material of the molded article having substantially the same volume as the removed defective caulking portion c) The pellet D) is placed on the center of the fitting hole and placed on the remaining portion of the boss of the molded product after the defective heat caulked portion is removed. D) The pellet is heated with the heater chip, Heat caulking the remaining portion of the boss of the molded product in the fitting hole.

According to the present invention, since the steps as described above are taken, it is possible to provide a method for repairing a heat caulking portion that can easily repair a heat caulking defect. In addition, since the generation of defective products is reduced, the number of discarded products is reduced, which has the effect of improving manufacturing costs and preventing environmental destruction.
And the repair method of this heat caulking part melts and solidifies the pellet and the molded product which were made separately by applying the heating and the load using the pellet made of the same thermosetting resin as the material of the molded product. Therefore, when the thickness of the joined body is thin, this repair method can be used for heat caulking even when a boss is not formed on the molded product. Furthermore, even if it is not possible to form a boss with a sufficient caulking volume from the viewpoint of the structure of the molded product, the addition of pellets can compensate for the lack of strength of the heat caulking part and improve the appearance. There is also an effect that can be achieved.

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 flowchart showing a defective heat staking portion repair method using this heat staking device. FIGS. 3 and 4 Is a schematic cross-sectional view of a portion corresponding to the heat-caulking portion for each step of the repair method of the defective heat-caulking portion, and FIGS. FIG.

  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 order to perform heat caulking using a heat caulking apparatus having such a configuration, after setting parameters such as the heat caulking time and the heating temperature, the welding head is manually positioned by the operator to be heat caulked. This is achieved by applying heat while applying an appropriate load. And control of heating temperature is implement | achieved by measuring the temperature of a heat crimping part using the thermocouple 23aa attached to the heater chip 23a, and performing feedback control of the value.

  Next, a method for repairing a defective heat caulking portion using such a heat caulking device will be described with reference to an operation flowchart of FIG. At this time, reference is made to FIGS. 3 to 6, 1 is a molded article using a thermoplastic resin having an integrally formed boss 1 a (hereinafter simply referred to as a molded article), and 2 is a joined body having a fitting hole 2 a for fitting with the boss 1 a ( Hereinafter, it is simply a coupled body).

[Heat caulking work]
Before explaining the repair method of the defective heat caulking part, the heat caulking work will be explained.
First, the molded product 1 and the coupled body 2 are prepared (FIG. 5A), and the boss 1a of the molded product 1 is inserted into the fitting hole 2a of the coupled body 2 (FIG. 5B).
Next, the operator turns on the power of the entire heat staking device and sets various parameters according to the heat staking object. Then, the welding head 23 is moved by holding it so that the heater chip 23a at the tip of the welding head 23 is aligned with the boss 1a to be heat caulked (FIG. 5C). )). Then, the operator senses that the welding head 23 has reached the boss 1a.

  After detecting the arrival at the boss 1 a, the operator generates a start signal by operating the welding start operation unit 23 b provided on the welding head 23. Then, the heat caulking operation is started when the entire heat caulking device starts operating in response to the start signal.

  When the heat caulking operation is started, the heater chip 23a reaches a predetermined temperature for a predetermined time according to the previously set parameters, and the heat caulking is completed. During this time, the thermocouple 23aa detects the temperature of the heat caulking portion, and this temperature is fed back to control the temperature so as to be set. After the boss 1aa serving as the heat staking part is formed by heat staking in this way, cooling is started in order to quickly solidify the thermoplastic resin that is the material of the heat squeezed boss 1aa, and a predetermined temperature is reached. When it reaches, the operator is notified by voice or the like, so the operator operates the cooling stop operating unit 23c to stop the cooling operation. In this way, a series of heat caulking operations is completed ((d) in FIG. 5, S101 in FIG. 2).

[Repair work for defective heat caulking part]
In the heat caulking operation as described above, the operator pays careful attention to align the welding head 23a with the heat caulking portion. When the alignment is successful, the welding boss 1aa by heat caulking is formed around the center of the fitting hole 2a as shown in FIG. 5D, so that high quality heat caulking can be performed. .

However, since this alignment is performed by the operator's sense, it is not always the case when it is successful. For example, this is a case where the center of the heater chip 23a at the tip of the welding head 23 is shifted to the right side from the center of the boss 1a (FIG. 6B). In such a case, the welding boss 1aa by heat caulking is formed to be shifted to the right ((c) in FIG. 6, (a) in FIG. 3).

Next, the repair work of the defective heat caulking portion according to the present invention will be described.
After completion of the heat caulking operation, the heat caulking part is sent to a process for checking whether the position is appropriate (S102 in FIG. 2). Then, a position inspection is performed, and it is inspected whether or not the heat caulking position is defective (S103 in FIG. 2). If it is determined that the position is not defective in this inspection, repair is unnecessary (S104 in FIG. 2). On the other hand, when it is determined that the position is poor, the welding boss 1aa is removed by cutting with the cutting machine 4 such as a sharp cutter knife at the surface of the coupled body 2 (S105 in FIG. 2, (b in FIG. 3). )).

Next, a pellet 5 made of the same thermoplastic resin as the material of the molded product 1 having substantially the same volume as the welded boss 1aa which is the defective heat-caulked portion cut and removed is prepared (S106 in FIG. 2). Here, the reason why the pellets having substantially the same volume are prepared is that the pellets 5 replace the welding bosses 1aa which are the heat caulked portions after the repair. Then, the center of the pellet 5 is aligned with the center of the fitting hole 2a and placed on the remaining portion of the welding boss 1aa (S107 in FIG. 2, (c) in FIG. 3).

  Finally, the center of the pellet 5 and the center of the heater chip 23a at the tip of the welding head 23 are aligned (FIG. 4D), and the above-described heat caulking operation is performed again (S108 in FIG. 2, FIG. 4). (E)). In this way, repair of the defective heat caulking portion is completed.

[Other embodiments]
The present invention is intended to repair defective heat caulked portions as described above, but can also be used when a thin object to be bonded is heat caulked with a molded product in which a boss portion is not formed.
That is, heat caulking is performed in the following procedure.

  First, pellets having an appropriate volume made of the same thermoplastic resin as the material of the molded product that becomes the heat caulking portion are prepared. Next, the to-be-coupled body in which the fitting hole is formed is placed on the molded product on which the boss portion is not formed, with the caulking portion aligned. Then, the center of the fitting hole and the center of the prepared pellet are aligned and placed so as to cover the fitting hole. Finally, the center of the heater chip of the welding head is aligned with the center of the pellet, and an appropriate load and heat are applied from above the pellet.

By carrying out like this, since the said molded article in the position which opposes this pellet with this pellet is fuse | melted, this pellet and this molded article will be fusion-integrated. Thereafter, the molded product and the bonded body are caulked by cooling. The reason why such heat caulking is possible is that when the plate is thin, the heat applied to the pellets is sufficiently conducted to the molded product even if they are formed separately.

  As another example, even when the boss portion can be formed, there may be a case where the boss portion having a sufficient volume in terms of structure cannot be formed. In other words, once heat-caulking and the molded product and the bonded body are fixed by heat caulking, if sufficient adhering cannot be secured, prepare a pellet of the required volume and add this pellet to this heat-caulking part By re-caulking in the form, it becomes possible to firmly fix the heat-caulking portion as a whole.

  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. Similarly, the quality determination of the heat-caulking part can be automated using visual inspection instead of visual inspection.

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 flowchart figure which shows the defective heat caulking part repair method. The first half of a schematic cross-sectional view of a portion corresponding to a heat caulking portion for each step of a repair method for a defective heat caulking portion. The latter half part of the schematic sectional drawing of the site | part corresponded to the heat caulking part for every process of the repair method of a defective heat caulking part. The first half of a schematic cross-sectional view of a portion corresponding to the heat staking portion of a part of the process during the heat staking operation. The latter half part of the schematic sectional drawing of the site | part corresponded to the heat caulking part of the one part process at the time of heat caulking operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molded article 2 To-be-joined body 4 Cutting machine 5 Pellet 21 Welding power source 22 Welding transformer 23 Welding head 23a Heater chip 23b Welding start operation part 23c Cooling stop operation part

Claims (1)

Defects that occur when a molded product using a thermoplastic resin having a boss integrally formed by supplying current to the heater chip and a bonded body having a fitting hole to be fitted to the boss are caulked. A method for repairing a caulking portion, comprising the following steps.
a) Step of removing the defective caulking portion from the surface of the bonded body b) Step of preparing a pellet made of the same thermoplastic resin as the material of the molded article having substantially the same volume as the removed defective caulking portion c) The pellet D) is placed on the center of the fitting hole and placed on the remaining portion of the boss of the molded product after the defective heat caulked portion is removed. D) The pellet is heated with the heater chip, Heat caulking the remaining portion of the boss of the molded product in the fitting hole.

Images